The Net Effect? - Whale and Dolphin Conservation Society

The Net Effect?A review of cetacean bycatch in pelagic trawlsand other fisheries in the north-east Atlantic

Ali Ross and Stephen Isaac

A WDCS report for Greenpeace

The north-east Atlantic

1. Gulf of Bothania2. Baltic Sea3. Kattegat Sea4. Skagerak Sea5. Norwegian Sea6. North Sea7. English Channel8. Celtic Sea9. Irish Sea10. Bay of Biscay

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Executive Summary

The incidental capture, or bycatch, of non-target species such as mammals, birds,turtles, fish and other marine species in fish-eries is recognised to be a major problem inmany parts of the world. It has been estimat-ed that 23% of the global fisheries catch isthrown back into the sea dead and wasted.Globally, the toll on all cetaceans (whales,dolphins and porpoises) is estimated toexceed 300,000 animals each year andbycatch is acknowledged to be a seriousthreat to the conservation of cetaceans in thenorth-east Atlantic region. However, despiteevidence of thousands of dolphins and por-poises being killed each year in a variety offisheries in this region, some at clearly unsus-tainable levels, there has been remarkablylittle policy or practical response to the issueat either national or EU level.

The cetacean species caught in the greatestnumbers in the north-east Atlantic are thecommon dolphin and the harbour porpoise.High levels of common dolphin bycatch havebeen recorded in pelagic trawl fisheries suchas the UK sea bass pair trawl fishery and theIrish albacore pair trawl fishery, but thelimited monitoring of pelagic fisheries to dateprecludes an assessment of total mortalitylevels. However, the number and scale ofpelagic trawl fisheries operating in the CelticSea, Biscay and Channel area, which alsoinclude large French, Dutch and Danishfleets, coupled with the number of bycaughtdolphins that strand on surrounding coasts,indicate that the total annual mortality figureis in the thousands, possibly many thou-sands, and is probably unsustainable.

Other species caught include Atlantic white-sided dolphins, striped dolphins, long-finnedpilot whales, and bottlenose dolphins. Theconservation implications for these speciesare difficult to assess, but they may also be acause for major concern.

The harbour porpoise is killed in highnumbers in bottom-set gillnet fisheries.

Observer monitoring in some areas hasrecorded large and unsustainable bycatchlevels: some 2,200 porpoises per year in theCeltic Sea and around 8,000 per year in theNorth Sea. In the Baltic Sea, where theharbour porpoise population is extremelylow, and affected by both bottom-set netsand driftnets, even a very low level ofbycatch is critical in conservation terms.

Given all the major areas of uncertainty, itis vital that extreme precaution is applied inassessing the significance of cetacean bycatchand, in particular, in defining conservationand management objectives. It is recom-mended that the intermediate precautionaryobjective identified by ASCOBANS (theAgreement on the Conservation of SmallCetaceans of the Baltic and North Seas), toreduce bycatches to less than 1% of the best

available population estimate, is the absolutemaximum threshold that should be applied,and that targets and timeframes to reducebycatch to below this level, and ultimatelytowards zero, should be adopted.

The main options currently being pursuedfor mitigating bycatch involve technicalmeasures: the dolphin exclusion device thatis being developed in the UK sea bass pelagictrawl fishery; and acoustic deterrent devices(pingers), developed primarily for gillnet fish-eries but now also being tried in pelagictrawls. Management options includetime/area restrictions, effort reduction, alter-native gear types and fishery closures. Overallreduction in fishing pressure should lead to areduction of bycatch, but to be most effectiveit must be targeted at those gears or fisherieswith the highest bycatch rates.

EU Member States are obliged under theHabitats Directive to monitor the incidentalcapture of cetaceans and to take furtherresearch or conservation measures asrequired to ensure that it does not have a sig-nificant negative impact on the species con-cerned. Parties to ASCOBANS have also

identified conservation objectives and a defi-nition of an “unacceptable” bycatch levelbelow which they have undertaken to reducebycatch. However, these commitments arenot being fulfilled. This fact was acknowl-edged by the European Commission inlaunching a proposal in July 2003 for a newEC Regulation to address cetacean bycatch.

The Commission’s proposal consists of threemain measures:

• a limit on the length of driftnets used inthe Baltic Sea to 2.5 km, followed by atotal prohibition by 2007;

• compulsory use of acoustic deterrentdevices (pingers) in specified gillnet fish-eries associated with high levels ofharbour porpoise bycatch; and

• compulsory onboard observer monitoringof cetacean bycatch in specified fisheriesand areas, including fisheries required touse pingers, other bottom-set net fisheriesand pelagic trawl fisheries in the CelticSea, Biscay, Channel area.

The proposal has generally been welcomedby conservationists. However, it has alsogiven rise to a number of concerns about theemphasis on pingers, the adequacy ofproposed observer coverage levels, the lackof management objectives, targets or a man-agement framework for bycatch reductionand, more specifically, the absence of anymeasures, or even stated intent, to reducebycatch in pelagic trawl fisheries.

In conclusion, in order to address effectivelythe problem of cetacean bycatch in thenorth-east Atlantic it is proposed that:

• Precautionary management objectivesmust be identified, with the ultimate aimof reducing bycatch to zero.

• A management framework for bycatchreduction must be introduced at EU levelat the earliest opportunity to ensure thatbycatch reduction targets are identifiedand met.

• The proposed EC Regulation on cetaceanbycatch must be tightened up and adoptedas soon as possible. In particular: • compulsory observer monitoring, with

adequate coverage, must be introducedwithout delay in order to assessbycatch levels in all fisheries that posea threat to cetaceans, and the efficacyof mitigation measures;

• any compulsory use of pingers must betime-limited and accompanied by com-prehensive observer monitoring toassess efficacy of deployment andbycatch rates, investigation of anyhabitat exclusion effects and researchinto alternative mitigation and fishingmethods; and

• the proposed length restriction andsubsequent prohibition of driftnets inthe Baltic Sea must be introduced, withno slippage in the proposed timing.

• The European Community must actwithout delay to introduce measures toreduce bycatch in those pelagic trawl fish-eries where levels are problematic.

• Environmental impact assessment mustbe conducted for new fisheries or changesin fisheries policy in order to prevent newproblems from arising.

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Contents

1. Introduction 6

1.1 Bycatch worldwide 6

1.2 Cetacean bycatch in the

north-east Atlantic 7

1.3 Current state of play 8

2. Cetaceans Under Threat 10

2.1 Cetacean species of the

north-east Atlantic 10

2.2 Harbour porpoise Phocoena phocoena 10

2.2.1 Ecology, population and distribution 10

2.2.2 Bycatch of harbour porpoises 11

2.3 Common dolphin Delphinus delphis 13


2.3.2 Bycatch of common dolphins 14

2.4 Striped dolphin Stenella coeruleoalba 17


2.4.2 Bycatch of striped dolphins 18

2.5 Atlantic white-sided dolphin

Lagenorhyncus acutus 18


2.5.2 Bycatch of Atlantic white-sided dolphins 19

2.6 Bottlenose dolphin Tursiops truncatus 20


2.6.2 Bycatch of bottlenose dolphins 21

2.7 Long-finned pilot whale Globicephala melas 21


2.7.2 Bycatch of long-finned pilot whales 22

3. Fisheries associated with Bycatch 23

3.1 Overview 23

3.2 Pelagic trawls 24

3.2.1 French pelagic trawl fisheries 26

3.2.2 Dutch pelagic trawl fisheries 27

3.2.3 UK pelagic trawl fisheries 29

3.2.4 Irish pelagic trawl fisheries 30

3.2.5 Danish pelagic trawl fisheries 32

3.2.6 Spanish pelagic trawl fisheries 32

3.3 Bottom-set gillnets 33

3.3.1 Danish bottom-set gillnets 32

3.3.2 UK bottom-set gillnets 34

3.3.3 French, Portuguese and Spanish

bottom-set gillnets 35

3.3.4 Baltic bottom-set gillnets 35

3.4 Driftnets 36

3.4.1 North-east Atlantic and Mediterranean 36

3.4.2 Baltic 37

4. Measures to reduce Bycatch 39

4.1 Why cetaceans get caught 39

4.2 Technical mitigation measures 40

4.2.1 Exclusion devices 40

4.2.2 Acoustic deterrent devices

(pingers) in set nets 42


(pingers) in pelagic trawls 44

4.2.4 Net modifications 45

4.3 Management mitigation measures 45

4.3.1 Effort reduction 45

4.3.2 Time and area restrictions 46

4.3.3 Alternative gear types 47

4.3.4 Emergency measures 47

4.4 Bycatch management framework 47

5. Bycatch regulation 49

5.1 Regulation of bycatch around the world 49

5.1.1 International treaties, conventions

and agreements 49

5.1.2 National legislation elsewhere 49

5.2 Existing obligations within

the north-east Atlantic 51

5.2.1 Regional conventions and agreements 51

5.2.2 ASCOBANS 51

5.3 Existing EU legislation 53

5.3.1 Common Fisheries Policy 53

5.3.2 Habitats Directive 54

5.4 Proposed EU regulation on

incidental catches of cetaceans 54

6. Conclusions and recommendations 56

6.1 Significance of cetacean bycatch 56

6.2 Assessment and monitoring of fisheries 57

6.3 Proposed new EU regulation 58

6.4 Pelagic trawl fisheries 59

Figure 1: Schematic representation 25

of a pair trawl operation

Figure 2: Schematic model of the exclusion grid 40

Table 1: Pelagic trawl fisheries known or

suspected to catch cetaceans in the

NE Atlantic 25

Table 2: Details of French pelagic trawl fisheries

sampled during the 1994-95 study 26

Table 3: Comparison of catches between

pairs with standard tows and one

fitted with a selection grid and

associated experimental equipment 41

Appendix 1: Map of ICES fisheries areas

in the north-east Atlantic 62

Appendix 2: Details of the French

pelagic fleet for 1992 63

Appendix 3: Table of scientific names

of species referred to 64

1.1 Bycatch worldwide

The term bycatch refers to the unintendedmortality of non-target species in fisheries.The phenomenon is common and wide-spread, affecting an extremely wide range ofspecies from marine mammals, sea birds andturtles to sharks and numerous other non-target fish species. The scale of this mortalityis such that bycatch may affect the structureand function of marine systems at the popu-lation, community and ecosystem levels(Crowder & Murawski 1998). Indeed,bycatch is widely recognised as one of themost serious environmental impacts ofmodern commercial fisheries (Alverson et al.

1994; Dayton et al. 1995).

It has been estimated that 23% of the globalfisheries catch is thrown back into the sea –dead and wasted. This figure includes non-target species as well as target species thatcannot be landed because they are, forinstance, over quota or undersized. Thisfigure translates to some 20 million tonnesof marine life being discarded every year(Horsten & Kirkegaard 2002).

Long-lived and slow-reproducing speciessuch as sharks, turtles and marine mammalsare likely to be most vulnerable to the deple-tion of populations through fisheries bycatch(Read 2000). In the case of harbour porpois-es, it has been agreed internationally that anannual loss of even 1% of a populationshould be a cause for concern that meritsinvestigation as a matter of priority (Bjørge& Donovan 1995). Indeed there are cases,such as that of the vaquita, a small porpoisefound only in the Gulf of California, Mexico,where bycatch is driving a species to extinc-tion (D’Agrosa et al. 2000).

A recent study of estimated marine mammalbycatches in fisheries in the United States inthe 1990s, extrapolated to figures for fishingeffort worldwide, concluded that globalbycatch of cetaceans (all whales, dolphinsand porpoises) is likely to exceed 300,000

animals each year (Read et al. 2003). Inaddition to the large bycatches that areknown and documented in some areas, theauthors note that, with mortality levels onthis scale, it is likely that important conserva-tion problems exist that have not yet beenidentified and that bycatch is likely to be animportant factor influencing the dynamics ofmany marine mammal populations.

Cetaceans get caught in a very wide varietyof fishing gear including active towed gearssuch as trawls and seines, hooks and lines,passive gillnets and driftnets and even thelines of pots and creels. The significance ofthese different gears for cetacean bycatchvaries in different areas according to the fish-eries present, the distribution of cetaceanspecies and the vulnerability of populations.However, on a global scale, the vast majorityof cetacean bycatches are thought to occur ingillnet fisheries (Read et al. 2003).

There is a great deal that is still unknownabout cetacean bycatch in fisheries, withregard to both the scale and impact of theinteractions involved, and the magnitude andcomposition of the fishing fleets in manyparts of the world (Read et al. 2003). Evenin fisheries where the bycatch of cetaceanshas been quantified, there is still a dearth ofinformation on the nature and causes of theinteractions, such as is required in order toidentify effective mitigation measures oralternative fishing methods (e.g. ICES 2002).

There is now a range of technical and man-agement measures that have been, or arebeing, developed to reduce cetacean bycatchlevels, some of which are being applied withsome success. However, it is recognised thatit is seldom possible to generalise from onebycatch problem to another, and that mostinteractions will require a solution thatreflects the particular species and fisheryinvolved (Read 2000). Moreover, it iswidely considered that effective bycatchreduction requires the establishment of an

Introduction

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appropriate management framework toensure that conservation objectives are iden-tified and that appropriate action is taken tomeet these (Read 2000, CEC 2002b).

1.2 Cetacean bycatch in

the north-east Atlantic

Bycatch in fisheries has been acknowledgedto be a major threat to the conservation ofcetaceans in the north-east Atlantic region bybodies ranging from national governments tothe European Commission (e.g. DEFRA2003; ASCOBANS 2000a; CEC 2003a). It isa problem that has been known about anddocumented in the region for at least 20years (e.g. Andersen & Clausen 1983;Northridge 1984), but it is only relativelyrecently that governments and internationalbodies have started to take action to investi-gate the problem and initiate research into itsmitigation. There are still only a fewexamples of measures that have been activelyintroduced to reduce the bycatch of cetaceansin the north-east Atlantic region.

Cetacean bycatch in the north-east Atlantic,as elsewhere, affects mainly small cetaceans –i.e. dolphins, porpoises and the smallertoothed whales. Species caught in the regionare primarily the harbour porpoise, commondolphin, striped dolphin, Atlantic white-sideddolphin, white-beaked dolphin, bottlenosedolphin and long-finned pilot whale (e.g.CEC 2002a). However, other largercetaceans, such as the minke whale, are alsoamong the victims of fisheries bycatch in theregion (e.g. ASCOBANS 2003a). Chapter 2below examines the main species affected bybycatch in more detail.

The various species have different distribu-tions, behaviour patterns and prey prefer-ences, which result in different levels of inter-action with the various types of fishery. Ingeneral, and as would be expected, theharbour porpoise, which tends to be distrib-uted in the shallower waters on the continen-tal shelf and which often feeds at or near the

seabed, suffers the greatest mortality inbottom-set gillnet and tangle net fisheries.The more oceanic species such as common,striped and Atlantic white-sided dolphins arecaught most frequently in pelagic (i.e. mid-water) trawls and pelagic driftnets. However,some species, including the common dolphin,are known to be bycaught in a number ofdifferent types of fishing gear, even withinthe same sea area, which is likely tocompound the impact on the affected popu-lations (e.g. Tregenza & Collet 1998).

Attention and concern during the 1980s andearly 1990s focused mainly on the issues ofdolphin bycatch in pelagic driftnets andharbour porpoise bycatch in bottom-setgillnets. A series of studies revealed bycatchlevels exceeding what is considered sustain-able in a number of fisheries using thesegears. During and since the 1990s, however,increasing concern has arisen about the levelof bycatch in the pelagic trawl fisheries thatoperate in the north-east Atlantic. The mainfisheries implicated in cetacean bycatch areexamined in Chapter 3.

Although we know which fisheries areresponsible for some of the bycatch in thenorth-east Atlantic and have, in some cases,an indication of the scale of the problem,there remain major deficiencies in the avail-able information. These include lack of infor-mation on: bycatch rates in many fisheries,fisheries data (including effort data, locationand methods used) and cetacean populations(including abundance, distribution and popu-lation structures). As a result, it remainsimpossible in many cases of bycatch to ascer-tain properly the scale of the problem and itssignificance in conservation terms, or tosuggest appropriate mitigation measures.

A number of international bodies haveattempted to establish what level of cetaceanbycatch could be considered ‘sustainable’in conservation terms. For example, theScientific Committee of the International

Whaling Commission (IWC) considered anannual bycatch level of 1% of estimatedabundance to be a threshold for concern forharbour porpoise populations (Bjørge &Donovan 1995). This figure is based onagreement that bycatch should not exceed50% of the maximum annual growth rate ofa population, estimated at between 4% and5% for harbour porpoises (Woodley & Read1991, Caswell et al. 1998), while factoring inthe considerable uncertainty inherent in esti-mates of both bycatch and abundance. Suchlimits have been calculated for very few smallcetacean species (CEC 2002b). The Parties tothe Agreement on the Conservation of SmallCetaceans of the Baltic and North Seas(ASCOBANS) have adopted 1.7% of abun-dance as a general definition of the thresholdof “unacceptable interactions” in the contextof cetacean bycatch (ASCOBANS 2000b;see 5.2.2 below).

As cetaceans are predators at the top of themarine food chain, any decline in their popu-lations could have further knock-on impactson the health of marine ecosystems (Jacksonet al. 2001) which, with our current state ofknowledge, are almost impossible to predict.However it is reasonable to suppose that theimpact of extensive bycatch of cetaceans inthe north-east Atlantic will not be confinedto the population levels of the cetaceansthemselves but will lead to further unantici-pated, and potentially profound, changesto marine ecosystems.

It should be obvious moreover that cetaceanbycatch is not only a conservation issue, butalso a significant animal welfare problem. Theinjuries sustained by bycaught dolphins andporpoises typically include bruising, musculartearing, broken beaks, torn and severed finsand flukes and cuts and abrasions on the skin(Kuiken et al. 1994). Given that thousands ofcetaceans are killed in this manner each yearin the north-east Atlantic region, bycatchclearly also presents an ethical issue.

1.3 Current state of play

There is an obligation on EU Member Statesunder EU law to monitor the incidentalcapture and killing of all cetaceans (see 5.3.2).It is now well established that the only reliableway to gather data on cetacean bycatch isthrough independent onboard observerschemes (Northridge 1996). Despite this, rela-tively few EU fisheries have been subject tothorough or routine observer monitoring.Member States are also required to ensurethat incidental capture and killing does nothave a significant negative impact on thespecies concerned. Again, this requirement isnot being fulfilled. In addition, various goalsand areas for priority action on bycatch havebeen agreed by the Parties to ASCOBANS (see 5.2.2). Once again, these have not beenachieved (ASCOBANS 2003b).

Action has been taken in the case of thecetacean bycatch in EU driftnet fisheries (seesection 3.4.1). This resulted in the adoptionof EU regulations during the 1990s, firstlimiting the length of EU driftnets (exceptnotably in the Baltic Sea) and then prohibit-ing their use entirely in fisheries for tuna,including albacore and bluefin, swordfishand other specified species. However, theextent of enforcement of this prohibitionis a matter of serious concern, particularlyin the Mediterranean Sea.

Similar action to address other known bycatchproblems has been much slower in coming.The problem of harbour porpoise bycatch inbottom-set gillnets has been well studied anddocumented in certain, but by no means all,fisheries in the north-east Atlantic (see 2.2.2and 3.3). It has also been the subject of con-siderable research efforts around the world toestablish effective mitigation measures, withsome notable success (see 4.2.2). However, atpresent the only targeted mitigation measuresbeing taken in this region are the requirementof acoustic deterrent devices (pingers) in onesmall section of Danish set net fisheries in theNorth Sea, and similar measures being consid-

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ered by other countries such as the UK andSweden. Latest strandings figures suggest thatbycatch of harbour porpoises is still a growingproblem in some areas (Sabin et al. 2003).

The problem of cetacean bycatch in pelagictrawls in the north-east Atlantic has beenknown about and documented for over adecade (e.g. Kuiken et al. 1994; Simmonds& Hutchinson 1994). While limited observerstudies have identified some of the fisheriescausing this bycatch (e.g. Morizur et al.

1999; Northridge 2003a; see 3.2) much ofthe evidence of the likely scale of theproblem continues to come from strandingsrecords (Ross 2003). In 2003 the EuropeanCommission commissioned an observer studyof pelagic trawl fisheries in the north-eastAtlantic with a view to identifying the fish-eries responsible for cetacean bycatch (CEC2003b). Research into mitigation of thisproblem is still at an early stage, althoughwork in the UK to develop an exclusiondevice has shown promising first results(Northridge 2003a). In the meantime, norestrictions or other management measures

have been introduced to curb what is anapparently growing bycatch problem inpelagic trawl fisheries.

Various national governments in the regionhave produced (Denmark) or are now produc-ing (UK and Sweden) action plans to addressthe problem of cetacean bycatch (e.g. Ministryof Environment and Energy 1998; DEFRA2003). In July 2003, the EuropeanCommission published a proposal for aCouncil Regulation to address cetaceanbycatch (CEC 2003a; see 5.4). This proposalmakes provisions to limit the length of, andsubsequently prohibit, driftnets in the BalticSea; to require the use of pingers in specifiedbottom-set net fisheries; and to require com-pulsory onboard observer schemes in specifiedfisheries (including many gillnet and pelagictrawl fisheries). Negotiations on this proposaland its final adoption are likely to extend wellinto 2004. However, even after the enactmentof this regulation, there will not be anyrequirement, under EU fisheries law, for man-agement measures to be taken to prevent orreduce cetacean bycatch in pelagic trawls.

2.1 Cetacean species of thenorth-east Atlantic

The distribution of cetaceans in the regionhas been reviewed in a recent publication bythe Joint Nature Conservation Committee,the Atlas of cetacean distribution in north-

west European waters (Reid et al. 2003).

A number of whale species either permanent-ly inhabit or migrate through the north-eastAtlantic region. The baleen whales recordedhere include humpback, minke, sei, blue andfin whales. Most of these have a fairly widerange within the region. Several toothedwhales are also found in this area, includingorca, sperm whale and long and short-finnedpilot whales, although this latter species israrely seen as far north as northern Europe.

A large variety of dolphin species also livein or migrate through this region. The bot-tlenose dolphin has a very wide distributionand can potentially be sighted around manycoasts of the north-east Atlantic as far northas the Faeroe Islands. The striped dolphinoccurs mainly in offshore waters, extendingas far north as the southern British Isles andincluding all of the Mediterranean. Thecommon dolphin is also widespread in mostof the north-east Atlantic, as is the harbourporpoise. Other species include Risso’s white-beaked and Atlantic white-sided dolphins.

The following sections examine in moredetail the species that are thought to be most affected by fisheries bycatch.

2.2 Harbour porpoise(Phocoena phocoena)

2.2.1 Ecology, population

and distribution

The harbour porpoise is a small cetaceanthat generally inhabits coastal areas andis usually found in depths of under 200m(Carwardine 2000), although it has beenrecorded in deep water, for examplebetween the Faeroe Islands and Iceland(Reid et al. 2003).

Harbour porpoises eat a wide variety ofsmall fish species (Read 1999). In the north-east Atlantic these are mainly small gadoidssuch as whiting, poor cod and Norway pout,while herring, sandeels and gobies may beimportant at certain times or locations (Rae1973; Santos Vázquez 1998).

The harbour porpoise is widely distributedacross the north and central North Sea withimportant concentrations off the west coast of Scotland, in the southern Irish Sea, and offsouth-western Ireland (Northridge et al.

1995). There is also evidence of a porpoisecalving ground off the islands of Sylt, Amrumand southern Rømø, off Schleswig-Holstein,Germany (Sonntag et al. 1999). Variationsin porpoise sightings in some areas may beindicative of seasonal movements (Reid et al.

2003), such as those recently reportedbetween Danish inner waters and the NorthSea (Teilmann et al. 2003).

The harbour porpoise is the most numerousmarine mammal in north-western Europeanshelf waters (Reid et al. 2003). Severalsurveys have been conducted in differentparts of the north-east Atlantic region butthe most wide-ranging to date has been theSCANS (Small Cetacean Abundance in theNorth Sea) survey of 1994, which focusedon the distribution and abundance of theharbour porpoise and other small cetaceansin the North Sea and adjacent waters(Hammond et al. 1995). This produced anestimated North Sea population of around280,000 harbour porpoises, with a further36,000 in the Skagerrak and Belt Seas and36,000 over the Celtic shelf between Irelandand Brittany.

During the SCANS survey no harbour por-poises were seen in the English Channel orthe southern tip of the North Sea, producingan abundance estimate of zero for this area(Hammond et al. 1995). However, anincrease in strandings of porpoises along thecoasts of France and Belgium was reported

2. Cetaceans under threat

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in the late 1990s (Jauniaux et al. 2002).Whereas only five porpoise carcasses werecollected between 1990 and 1996, sevenwere collected in 1997 alone, eight in 1998,twenty-seven in 1999 and eight in 2000. Thecause of this increase is uncertain, but it mayhave reflected a temporary increase in theporpoise population in the southern NorthSea, possibly related to the abundance ofprey (Jauniaux et al. 2002).

Other surveys have produced estimates fornorthern Norwegian waters and the BarentsSea of 11,000 porpoises, and for thenorthern North Sea and southern Norwegianwaters of 82,000 (Bjørge & Øien 1995).

An aerial survey of the Baltic Sea in 1995produced an estimated porpoise populationof 599 animals in the southern and westernportions (International Council for theExploration of the Sea, subdivisions 24 and25 excluding the Polish coastal corridor) and817 animals for the Keil and MecklenburgBights in the extreme south-western Baltic(Hiby & Lovell 1996). It is widely acknowl-edged that this Baltic population has suffereda major decline from historic abundancelevels, assumed to have been at least severalthousands, and is now in serious danger(ASCOBANS 2002).

Genetic and other studies have indicated thatthere are several distinct populations ofharbour porpoises within the region (sum-marised in Kaschner 2003). For instance, the harbour porpoises of the Baltic Sea aredistinct from the animals in the Skagerrakand Kattegat Seas, and porpoises in the Keil-Mecklenburg Bights are distinct from thoseelsewhere in the Baltic and in the North Sea.While some of the results are considered con-troversial, the existence of such distinct pop-ulations would indicate a greater risk of localdepletion (IWC 2000).

There is little information available on popu-lation abundance and distribution for

harbour porpoises in the waters of south-western Europe. The harbour porpoise wasnot recorded at all during 14 surveys carriedout over the continental shelf of Portugalbetween 1987 and 1994. However, there arestrandings data for Portugal which show thatthe vast majority of harbour porpoise strand-ings have occurred along the northern andcentral zones of the country’s coast (Sequeira1996). Strandings records for Galicia, north-west Spain, show that harbour porpoises rep-resent 7% of total cetacean strandings(López et al. 2002).

2.2.2 Bycatch of harbour porpoises

Harbour porpoises are highly prone to inci-dental capture in bottom-set gillnets, which is thought to be explained largely by theirfeeding behaviour on or near the seabed.High incidences of capture have beenrecorded in a number of fisheries throughouttheir range.

Concerns over harbour porpoise bycatch inthe north-east Atlantic first arose in theDanish North Sea bottom-set gillnet fisheries.Various studies have been conducted sincethe early 1980s (e.g. Clausen & Andersen1988; Kinze 1994), which demonstrated thatlarge numbers of porpoises are caught mostlyin large-mesh gillnets set for cod, turbot,lumpfish and plaice. Observations duringthe 1990s confirmed substantial catches inthe Danish gillnets, with the highest totalporpoise mortality occurring in the turbotfishery (which has long nets and soak-times)but the highest rate of porpoise catch was inthe cod wreck nets (i.e. gillnets set over ship-wrecks or similar objects), particularly in thethird quarter of the year (Vinther 1999).

A recent revision of the estimated totalporpoise bycatch in Danish bottom-set netshas been produced, based on fishing effort,in terms of days at sea, in the various fisheries(Vinther & Larsen 2002). This produced anestimated mean total catch of 5,591 porpoisesper year from 1987 to 2001; a peak catch of

7,366 in 1994, reducing to a low of 3,887porpoises in 2001. The figures provided for2000 and 2001 are assumed to be overesti-mates (by 570 and 405 animals respectively)as they do not take into account effects of themandatory use of pingers in the cod wreck-net fishery that was introduced in 2000(Vinther & Larsen 2002). The highest annualcatch figure of 7,366 represents 4.3% of theporpoise population in the relevant part ofthe North Sea (170,000 animals) as estimatedby SCANS (Hammond et al. 1995).

Harbour porpoises are also caught in theNorth Sea by UK bottom-set gillnet andtangle-net fisheries targeting cod, sole, skateand turbot. Observer studies of these fisherieshave allowed bycatch levels to be assessed forthe period 1995-99, with annual catches esti-mated to total from 818 porpoises in 1995 to436 animals in 1999 (CEC 2002a). Whileporpoise bycatch rates were found to behighest in the skate fishery, the estimated totalporpoise mortality was greatest in the inshorecod fishery due to the very large fishing effort(Northridge & Hammond 1999). Thedecrease in bycatch levels over the studyperiod is attributed to the decline in fishingeffort (measured in days at sea).

The Celtic Sea bottom-set gillnet fishery forhake presents one of the most acute bycatchproblems for harbour porpoises recorded inthe north-east Atlantic. The UK and Irish set-net fisheries in the Celtic Sea were investigat-ed using onboard observers from 1992 to1994. This study recorded a catch of 43 porpoises, all but one of them caught in hake gillnets and one caught in a tangle net.Extrapolation to the total UK and Irish fleetsproduced an estimated total mortality of2,200 harbour porpoises per year, which represents 6.2% of the estimated populationin the Celtic Sea (Tregenza et al. 1997a).

Latest strandings figures from the UKdemonstrate that harbour porpoise strand-ings have been steadily increasing in the UK

since the beginning of the 1990s, with moremarked increases in 2001 and 2002 (Sabin et

al. 2003). In particular, there has been ageneral increase over this period in thenumber of bycaught harbour porpoisesthat stranded annually in south-westEngland. There has also been an increasein the number of porpoises reported strandedaround the south-west in the winter monthsand into early spring. Bycaught harbour por-poises that strand in the UK typically showexternal signs consistent with wide-meshedmonofilament-type gear (gillnets), in contrastto common dolphins which tend to haveinjuries consistent with smaller-meshed gearsuch as trawl netting. However, it is notablethat many of the bycaught harbour porpoisesexamined in the first quarter of 2002 lackedthe usual monofilament-type net marks. It issuggested that these porpoises may have beencaught in smaller-mesh mobile gear (trawlnets) since they often stranded in the sameareas and in a similar state of decompositionto large numbers of common dolphins thatwere diagnosed as having died due tobycatch (Sabin et al. 2003).

The Baltic Sea, where the population isalready severely depleted, is an area of con-siderable concern for the harbour porpoise.Bycatch is considered to have played animportant role not only in reducing the abun-dance of porpoises, but also in preventingtheir recovery (e.g. Berggren et al. 2002).Bycatches of harbour porpoises are known tohave occurred in many parts of the Baltic insalmon driftnets and bottom-set gillnets (forcod and other demersal species) (ASCOBANS2002). As the density of porpoises in theBaltic is now extremely low, the animals areonly rarely seen or caught, which makesassessing bycatch rates extremely difficult.However, porpoise bycatches have beenreported in recent years in Swedish driftnets,various Polish gillnet fisheries and Finnishfisheries (CEC 2002a). It has been estimatedthat the current minimum bycatch is sevenporpoises per annum (Berggren et al. 2002).

12The Net Effect?


13

The Net Effect?


It has also been calculated that in order toachieve a recovery of the population (towardsthe interim goal of 80% of carrying capacity)then bycatch in the surveyed portion of theBaltic must be reduced to two or feweranimals per year (ASCOBANS 2002).

In the Skagerrak and Kattegat Seas harbourporpoise bycatch is reported in Swedish andDanish gillnet fisheries. Studies of Swedish set-net fisheries targeting cod and pollack wereconducted between 1995 and 1997, revealinga very high bycatch rate per fishing effort andtotal mortalities of more than 100 animals peryear (Berggren & Carlström 1999). Harbourporpoise bycatches are reported to havedeclined in recent years as a result of a declinein effort in all Swedish set-net fisheries (CEC2002a). However, effort information indicatesa substantial increase in effort in Swedishgillnet fisheries operating in the Baltic andcurrent fishing effort in the Skagerrak/Kattegatarea that is only slightly lower than thatreported for 1996 (CEC 2002a).

The harbour porpoise is also frequentlycaught in gillnets off the northern Portuguesecoast, resulting in a significant number ofstrandings (Sequeira 1996). Systematic moni-toring of marine mammal strandings betweenJanuary 2000 and October 2002 recorded atotal of 77 cetaceans, of which 19% wereharbour porpoises. Up to 53% of harbourporpoise strandings are thought to have beenthe result of bycatch in beach purse seinenets, with further mortalities occurring ininshore gillnet fisheries (Ferreira et al. 2003).Beach purse seines are used mainly forsardines and are usually set from a smallboat some distance offshore and thenoperated from the shore (Sequeira 1996).

In Spain, the scale of small cetacean bycatchin fisheries based in Galicia (the main fishingregion in Spain has been examined fromobserver trips on fishing vessels, an interviewsurvey with fishermen and a carcass recoveryscheme (López et al. 2003). Although two

harbour porpoises were handed in out of atotal of 17 bycaught cetaceans recovered, nogillnetters agreed to carry observers on boardtheir vessels. In addition, it was noted thatGalician fishermen do not routinely distin-guish between common dolphins and harbourporpoises, making it difficult to assess theirrespective catches from interview data.

Other gillnet fisheries exist in the region thathave not yet been subject to observer monitor-ing. For instance, there is no programme estab-lished to monitor cetacean bycatch inNorwegian fisheries. However, it has beennoted that harbour porpoises are caught incoastal gillnet fisheries and that this bycatchmay be substantial (CEC 2002a). Therefore the figures presented represent only a minimumestimate of porpoise bycatch in the region.

2.3 Common dolphin (Delphinus delphis)


and distribution

The short-beaked common dolphin is themost numerous offshore cetacean species inthe temperate north-east Atlantic (Reid et al.

2003). They are gregarious animals, fre-quently found in groups of dozens or evenhundreds. They also frequently breach andoften bow-ride.

Two population estimates have been made ofseparate but overlapping areas to the south-west of Britain, both looking at summer pop-ulations. The MICA survey was conducted in1993 to assess the impact of cetaceanbycatch in the French albacore tuna driftnetfishery and estimated the abundance ofcommon dolphins in the tuna fishery area tobe 62,000 (Goujon et al. 1993). The SCANSsurvey in 1994 included the Celtic Shelf andproduced an estimate for this area of 75,500common dolphins (Hammond et al. 1995).The two survey areas overlap along the shelfedge and Goujon (1996) suggested a totalpopulation of around 120,000 commondolphins in the two areas combined.

Off the western coasts of Britain and Irelandthe species is found in continental shelfwaters, such as the Celtic Sea and thewestern approaches to the English Channel,and off southern and western Ireland (Reidet al. 2003). It is frequently seen in the Sea ofthe Hebrides in the summer months and hasbeen observed occasionally in the North Sea.The usual northern limit of this species’range appears to be around 60ºN.

Seasonal movements onto the continentalshelf of the British Isles are reported to occurbetween July and October, whilst in the Bayof Biscay the species occurs throughout theyear but with numbers lowest betweenMarch and May (Evans 1998). In the seasaround Spain and Portugal, commondolphins occur closer to the coast than else-where in the region on account of the conti-nental shelf sloping steeply near the coasts ofthe Iberian Peninsula (Forcada et al. 1990).

The diet of common dolphins comprises awide range of small fish and squid, and themost common prey species in the north-eastAtlantic appear to be pelagic schooling fish(Reid et al. 2003). Mackerel, sprat, pilchard,anchovy, horse mackerel (also known as‘scad’), hake, blue whiting and squid are allknown to be exploited. The distribution ofcommon dolphins is largely controlled by thedistribution of their major prey species,resulting in seasonal movements followingthose of species such as mackerel and bluewhiting (Evans 1980; Collet 1981).

2.3.2 Bycatch of common dolphins

Common dolphins are frequently recorded asthe victims of fisheries bycatch in the north-east Atlantic region, both in strandingsrecords and from observations of fisheries.They have been shown to be caught in anumber of fisheries in the region, althoughpelagic trawls appear to present the greatestcurrent threat to this species (see 3.2).

During the 1990s, substantial common

dolphin bycatches were recorded in severalstudies of the albacore tuna driftnet fishery,which has now been terminated (see 3.4.1).A study was conducted in 1992 and 1993 ofthe French fleet, which operated in north-eastAtlantic waters within and beyond the Bay ofBiscay using driftnets nominally 5 km long(Goujon et al. 1993). This produced an esti-mated bycatch level by the whole Frenchfleet of 1,700 dolphins in each of the yearsstudied. Approximately 400 of these werecommon dolphins, but the majority werestriped dolphins.

The UK in 1995 placed observers on itsmuch smaller albacore driftnet fishery, oper-ating at that time with 2.5 km long nets, pro-ducing an estimated total bycatch for the UKfleet of 165 dolphins, of which 61 werecommon dolphins and 104 striped dolphins(SMRU 1995). Although the total UKdolphin catch was smaller than that recordedin the French study, the rate of dolphinbycatch per 100 tuna caught was found to bealmost three times greater than the Frenchrate. This difference may be at least partiallyexplained by the more northerly distributionof UK fishing effort (SMRU 1995).

In 1996 the Irish driftnet fishery for albacorewas observed and a mean catch rate of twocetaceans per haul was recorded (Harwood et

al. 1999). With just seven boats operating inthe fishery during that year, the estimated totalcetacean bycatch was 535 animals, including134 striped dolphins and 345 commondolphins. However, in 1998 the Irish fleet hadincreased to 18 boats and the extrapolatedannual bycatch for the whole fleet was 964striped dolphins, 2,522 common dolphins andsmaller numbers of less frequently caughtspecies (Harwood et al. 1999).

The first notable peak in common dolphinstrandings in the UK was recorded in 1992when 118 dolphin carcasses came ashore inCornwall and Devon in the first threemonths (Kuiken et al. 1994). Nearly half of

14

The Net Effect?


15The Net Effect?


the animals were positively identified ascommon dolphins and post-mortem exami-nations revealed that most of them had diedas a result of incidental capture in fisheries.The injuries visible on the animals, reportedas being characteristic of capture in a small-meshed net, and the fish present in thedolphins’ stomachs led to the conclusion thatthey had died in trawl or purse seine netsused to catch mackerel or pilchard.

Recent strandings records in the UK haveshown a consistent spatial and seasonalpattern for common dolphins (Sabin et al.

2003). In 2002, 119 common dolphinsstranded, the vast majority in south-westEngland, and 65% of the animals examinedwere diagnosed as bycaught. In 2003, a totalof 116 dead cetaceans (58% of them con-firmed as common dolphins) were recordedstranded in the south-west of England(Cornwall, Devon and Dorset) in Januaryalone, increasing to 131 animals by the endof March (NHM 2003). Overall strandingsfigures for the period from 1990 to 2002show that over 95% of the strandedbycaught common dolphins found were inthe south-west, and the majority stranded inthe first three months of the year. Most ofthese bycaught animals are recorded ashaving injuries consistent with entanglementin small-meshed mobile gear (trawl netting)(Sabin et al. 2003).

Even more pronounced winter peaks ofdolphin strandings have been recorded inFrance in many recent years (Tregenza &Collet 1998). At the end of February 1989more than 600 dead dolphins stranded injust two days on the coasts of the Landesand Vendée, some freshly dead while othershad been decomposing for many weeks. In1997 a prolonged westerly storm brought629 dead cetaceans (mostly commondolphins) ashore on the southern Bretonand Biscay coasts over a three-week periodin February and March. Of the animalsexamined, 74% showed obvious signs of

incidental capture in fisheries. In 2002,more than 300 cetaceans stranded alongthe Atlantic coast of France, south ofBrittany, in a period of 10 days (from about20th to 30th January). By far the dominantspecies was the common dolphin with a fewstriped dolphins and very few harbourporpoises. The majority of these animalsshowed clear marks of bycatch (brokenbeaks, missing fins or flukes, body cut open,etc) (V. Ridoux, Centre de Recherche sur lesMammiféres Marins, pers.comm.).

Taking the common dolphin strandings figuresfor the winter period of 2002 in south-westEngland and in France, and making the con-servative assumption that the strandedanimals represent only 10% of the total mor-tality that occurs in fisheries, provides a veryrough estimate of the likely total mortality inthat year of around 4,000 dolphins (Ross2003). This level would represent a mortalityrate of somewhere between 3% and 5% ofthe estimated common dolphin populationin the Celtic Sea/Biscay area.

During 1993-1995 observer studies wereconducted in pelagic trawl fisheries operatingseasonally in the area from the Bay of Biscaynorth to south-west Ireland and in thewestern approaches to the English Channel.Dolphin catches were recorded in four of the11 fisheries studied: the Dutch horsemackerel fishery, the French hake fishery, theFrench albacore tuna fishery and the Frenchsea bass fishery, although it is emphasisedthat zero observed bycatch in the remainingfisheries does not imply there is no bycatchin them (Morizur et al. 1999). The speciescaught were common dolphin, Atlanticwhite-sided dolphin and a probable bot-tlenose dolphin. This study made no attemptto extrapolate from the observations to atotal cetacean bycatch. However, the reportnotes that the size of the European fleet andthe amount of fishing effort mean that thetotal number of animals caught may be sig-nificant. It also observes that the bycatch

estimate must be treated as a minimumbecause some fishing fleets such as the Irishwest coast mackerel fishery refused to takeobservers on board. Also, in fisheries such asthe UK mackerel and pilchard fisheries thatuse fish pumps to transfer the catch from thenet to the boat, cetaceans would be too largeto be pumped aboard and they would beflushed from the net before it was hauled and thus may go unobserved.

A Dutch observer study of the cetaceanbycatch in the pelagic trawl fishery formackerel and horse mackerel was conductedin 1992-1994 (see also 2.5.2 below).Incidental catches of cetaceans were foundto be largely restricted to late winter/earlyspring in the area along the continentalslope south-west of Ireland, with a peak inlate February/early March (Couperus1997a). The main species caught in thisfishery was the Atlantic white-sided dolphin(83%) but other species caught includedlong-finned pilot whale, common dolphin,bottlenose dolphin and white-beakeddolphin. In 1994, a total catch of 172dolphins was recorded by twelve Dutch and two English vessels in this fishery, but the limited data available prevented the researchers from estimating the overall extent of the bycatch problem.

This Dutch study also included observationsof Dutch pelagic trawling operations in thewestern and northern North Sea (primarilytargeting herring) and in the Channel southof Cornwall (targeting horse mackerel)(Couperus 1997a). In these areas smaller, butstill significant bycatches of cetaceans wererecorded, including five common dolphins,three white-beaked dolphins, five long-finnedpilot whales and twenty-two unidentifieddolphins (assumed to be common or white-beaked dolphins).

Further evidence of common dolphin bycatchin pelagic trawls is provided by the Irishstudy of the trial-use of pelagic pair trawls in

the albacore tuna fishery which occurs in the summer months (BIM 2000). In 1999observers monitored a total of 313 haulsover 160 days and recorded 145 cetaceanscaught by just four pairs of trawlers. Theseincluded 127 common dolphins, the rest con-sisting of striped dolphins, pilot whales andAtlantic white-sided dolphins. A catch of 30dolphins was recorded in a single haul.

In 2001 observers placed on UK pair trawlersengaged in the winter sea bass fishery in ICESarea VII (mainly in the Channel) recorded acatch of 53 common dolphins in 12 tows (outof a total of 116 hauls monitored). A furthereight common dolphins were taken in twotows of the 66 observed in 2002 (CEC2002b). Monitoring was also undertaken inthe UK mackerel, pilchard, blue whiting andanchovy fisheries in this area but no cetaceanmortalities were recorded.

Common dolphins are also caught inbottom-set gillnets. In the study of the UKand Irish gillnet fishery for hake in the CelticSea (see 2.2.2 above), in addition to thebycatch of harbour porpoises, four commondolphins were recorded. This produced anestimated annual catch in this fishery of 200common dolphins (Tregenza & Collet 1998).The dolphins were observed to arrive at thefishing boats significantly more frequentlyduring the setting of the nets, leading to thesuggestion that they may be attracted to the‘float clatter’ of the gillnets as they are set(Tregenza et al. 1997b).

A study of cetacean bycatches in Spain,based on observer trips on fishing boats and interviews with fishermen in Galiciaand Asturias, found that around 80% ofbycatches are probably dolphins, consistingmainly of common dolphins and lesscommonly bottlenose dolphins (Aguilar1997). Offshore trawling was identified asa major contributor to common dolphinbycatch mortality and pair trawls were con-sidered the main cause. According to fisher-

16

The Net Effect?


17

The Net Effect?


men interviewed in this study, during noc-turnal fishing it was rare not to catchdolphins, usually up to 10 animals butsometimes 30 or more. During 1996 and1997 observers were present on four tripsusing pair trawls at night and in all casescommon dolphins were caught, totallingeight individuals (Aguilar 1997).

A subsequent study of Galician fisheries in1998-2000 used observers, carcass recoveryand interviews with fishermen, and recordedsix common dolphins among the 17bycaught animals that were retrieved byskippers of fishing boats (López et al.

2003). Although the observers on board 67fishing trips observed no cetacean bycatch-es, data collected from interviews with fish-ermen allowed total annual catches to beestimated. Highest bycatch rates were foundto occur in offshore gillnets (estimated tototal around 1,500 animals per year) andtrawling in Grand Sole, off south-westIreland (about 350 animals per year). Mostof these bycatches are assumed to becommon dolphins. A further 200 dolphinsper annum were estimated to be bycaught ininshore gillnet fisheries and these areassumed again to be mostly commondolphins, with in addition long-finned pilotwhales, bottlenose dolphins and harbourporpoises (López et al. 2003). The interviewdata collected in this study also producedreferences to cetaceans being used forhuman consumption (69 out of 500 inter-viewees) and use of cetaceans for bait,animal food and as a source of fat was alsomentioned (López et al. 2003).

Records of common dolphin strandings inPortugal between 1975 and 1998 have beenanalysed, revealing that up to 44% of theanimals may have died as a result of fish-eries interactions. Gillnet fisheries wereresponsible for 67% of these mortalities,while beach seine nets and trawling opera-tions killed 11% and 9% respectively (Silva& Sequeira 2003).

2.4 Striped dolphin (Stenella coeruleoalba)


and distribution

In some parts of the world, striped dolphinsoccur in groups of hundreds or even thousandsof individuals. In continental European waters,group sizes of 6-60 are most common, whereasin British and Irish waters sightings are gener-ally of groups of less than 10 individuals andoften in mixed schools with common dolphins(Reid et al. 2003). Groups of striped dolphinscan show segregation by age, and there is alsoevidence of segregation of the sexes outwiththe breeding season.

The striped dolphin is a largely oceanicspecies, tending to occur well beyond thecontinental shelf in depths of 1000 m ormore, although it has been recorded inwaters of 60 m depth or less (Forcada et al.

1990). In the north-east Atlantic, the speciesmainly occurs offshore west of the IberianPeninsula and France, and in the Bay ofBiscay (Forcada et al. 1990). The stripeddolphin occurs rarely in UK waters, but canbe seen in the south-west Channel approach-es and off southern Ireland. Occasional sight-ings and strandings come from as far northas Shetland, and even the Faeroe Islands,Iceland and Norway (Reid et al. 2003). Thespecies was noted for the first time inNorwegian waters in the period from 1986to 1999. The appearance of striped dolphinsin these waters has been attributed to anincrease in sea temperature (Isaksen &Syvertsen 2002) and it has been suggestedthat this species may occur in this areathroughout the year in small numbers, but ismore likely to strand or die between Januaryand March, the coldest time of the year (seealso Bloch et al. 1996).

The only population estimate for stripeddolphins in the north-east Atlantic isderived from the MICA survey (see also2.3.1 above). This produced an estimatedabundance of about 74,000 animals for an

area extending south-west of Ireland toFrance and north-west Spain (excluding theBay of Biscay) and westwards to 20º W(Goujon et al. 1993).

Striped dolphins in the north-east Atlanticfeed on a variety of small pelagic and benthicfish, including sprat, blue whiting, silverypout, hake, horse mackerel, bogue, anchovyand gobies. Squid and crustaceans are alsofrequently taken (e.g. Desportes 1985; SantosVázquez 1998). Surveys in the westernMediterranean indicate the striped dolphinsmay feed along the shelf edge at night andmove offshore during the day (Gannier &David 1997).

2.4.2 Bycatch of striped dolphins

Striped dolphins do not appear to be attract-ed to vessels to the same extent as commondolphins (Reid et al. 2003). However, there isevidence of their entanglement in a numberof fishing operations.

In the 1990s several studies were made ofbycatch in the driftnet fishery for albacoretuna in the north-east Atlantic which occursin the summer months (see also 2.3.2above). Substantial catches of stripeddolphins were recorded in the Frenchdriftnet fleet in 1992 and 1993. This fleetoperated in north-east Atlantic waterswithin and beyond the Bay of Biscay usingdriftnets nominally 5 km long, producing anestimated bycatch by the whole fleet ofalmost 1200 striped dolphins a year (of atotal of 1,700 cetaceans taken) (Goujon et

al. 1993). This bycatch rate was deemed tobe unsustainable (Woodley 1993; CEC1993). Use of a demographic model forstriped dolphins indicated that the popula-tion can only sustain incidental mortalitiesof up to about 1% per year (Woodley1993). This compares with estimated mor-tality rates of 1.62% and 1.56% of the pop-ulation for the years 1992 and 1993 respec-tively in the French driftnet fishery alone(Goujon et al. 1993)

Observation of the UK’s much smalleralbacore driftnet fishery (using 2.5 km longnets) in 1995 resulted in an estimate of totalbycatch for the UK fleet of 165 dolphins, ofwhich 104 were striped dolphins and the restcommon dolphins (SMRU 1995). Subsequentresults from observations of the Irishalbacore driftnet fishery demonstrated aneven higher cetacean bycatch rate, andproduced an estimated total bycatch of 535cetaceans (including 134 striped dolphins) inthe fishery in 1996 (Harwood et al. 1999).The extrapolated bycatch figure for 1998,when the number of vessels in the Irishfishery had increased, was 3,754 (including964 striped dolphins). Largely as a result ofthe cetacean bycatch, the decision was madein 1998 to prohibit of the use of driftnets inthe albacore and similar fisheries, a prohibi-tion which came into force in January 2002(see also 3.4.1).

Bycatch of striped dolphins has also beenrecorded in the Irish pelagic pair trawlfishery for albacore tuna, which ironicallywas introduced to replace the prohibiteddriftnet fishery (see also 2.3.2 above). Thisfishery also occurs in the summer months. A study of the trial fishery in 1999 moni-tored a total of 313 hauls over 160 days byfour pairs of trawlers and recorded a bycatchof 145 cetaceans, eight of which were stripeddolphins (the majority being commondolphins) (BIM 2000).

2.5 Atlantic white-sided dolphin(Lagenorhynchus acutus)


and distribution

Atlantic white-sided dolphins are very gregari-ous animals and frequently mix with othercetacean species, particularly white-beakeddolphins, and sometimes bottlenose andcommon dolphins and larger whale species.The species sometimes gathers in very largegroups of up to 1,000 individuals, withinwhich smaller subgroups of some 2-15 animalscan often be distinguished (Reid et al. 2003).

18

The Net Effect?


19

The Net Effect?


Distribution of the Atlantic white-sideddolphin is limited to the temperate and sub-Arctic seas of the north Atlantic. In the north-east Atlantic it occurs from Iceland, southernSvalbard and the Barents Sea, south to the Bayof Biscay and occasionally to Portugal, thewestern Mediterranean and the Azores. Thespecies is rare in the Irish Sea, the Channel, the southern and German bights of the NorthSea and the Kattegat, Skaggerak and Belt Seas,although groups have been recorded in thesewaters. There is only one record from theBaltic Sea (Reid et al. 2003).

The preferred habitat of white-sideddolphins is cool waters (7-12ºC), particular-ly seaward or along the edges of continentalshelves, and they may also be numerous inmuch deeper oceanic waters (Leopold &Couperus 1995). Large numbers of thespecies have been reported in the Celtic Sea and off south-west Ireland.

Population estimates for the white-sideddolphin in this region are difficult to obtain,largely because of confusion with the white-beaked dolphin during sightings surveys(Hammond et al. 1995). However, anestimate of 21,000 animals has been madefor the Faeroese-Shetland channel in 1998(Macleod 2001).

Little is known of the seasonal movements of this species (Reid et al. 2003). They arefound in deep waters around the north ofScotland throughout the year and arethought to enter the North Sea mainly insummer. The dolphins appear to move intothe waters south-west of Ireland to feed onthe mackerel that migrate southwards tospawn there in February and March(Couperus 1997a). Indeed it is speculatedthat the animals observed south-west ofIreland at this time must come from deeper,westward offshore Atlantic waters as white-sided dolphins are not caught by the trawlersthat exploit the mackerel further northearlier in the year.

The diet of white-sided dolphins includes awide variety of fish including blue whiting,whiting, cod, hake, herring, silvery pout, lanternfishes, pearlsides, mackerel, horse mackerel,salmonids and squid (Reid et al. 2003).

2.5.2 Bycatch of Atlantic

white-sided dolphins

Catches of Atlantic white-sided dolphinshave been recorded in a number of fisheriesin the north-east Atlantic. These include theIrish driftnet fishery and the Irish pelagic pairtrawl fishery for albacore tuna (CEC 2002a;BIM 2000; see 2.3.2 and 2.4.2). In boththese cases, white-sided dolphins constitute a very small proportion of the total cetaceancatch (1 animal out of 253 cetaceansobserved caught in the driftnet fishery; and 2 out of 145 cetaceans observed caught inthe pelagic pair trawls).

However, a large bycatch of this species hasbeen reported in the Dutch pelagic trawlfishery for mackerel and horse mackerel that occurs south-west of Ireland (Couperus1997a) (see also 2.3.2). A study of bycatchwas conducted in 1992-1994, with observersplaced on board five Dutch freezer trawlers(covering about 5% of the annual effort inthe fishery) and subsequent voluntary report-ing of bycatch by skippers. Although themackerel fishery follows the movements ofmackerel southwards broadly from northernNorth Sea/Norwegian waters to the south-west of Ireland during the winter season, the vast majority of cetacean catches (89%)occurred along the continental shelf south-west of Ireland. The main species caught inthis fishing area was the Atlantic white-sideddolphin (83%) but other species caughtincluded long-finned pilot whale, commondolphin, bottlenose dolphin and white-beaked dolphin. Cetacean bycatches werelargely restricted to late winter/early spring,with a peak in late February/early March(Couperus 1997a). The bycatch rate was alsofound to vary considerably from year to year.In 1994, a much higher bycatch level was

recorded than in 1993, with a total catch of172 dolphins reported by twelve Dutch andtwo English vessels in this fishery. However,the limited data available prevented theresearchers from estimating the overall extentof the bycatch problem.

Studies of the stomach contents of dolphinsbycaught in this fishery showed that nearlyall the white-sided dolphins had been feedingvery recently on mackerel (Couperus 1997a).However, none of the white-sided dolphinswere found to contain any remains of horsemackerel, although some of the common andbottlenose dolphins did. Older remains indi-cated that the white-sided dolphins had pre-viously been feeding on other species, mainlysilvery pout, lanternfishes and pearlsides,which suggests that the animals had beenfeeding in deeper waters before they startedto prey on mackerel in the vicinity of thetrawlers (Couperus 1997a).

2.6 Bottlenose dolphin (Tursiops truncatus)


and distribution

The bottlenose dolphin is a social animal,commonly found in groups of 2-25 and occa-sionally low hundreds of animals. Thesedolphins often display breaching, somersaultsand tail slapping and frequently bow-ridevessels. They are commonly observed withpilot whales in offshore habitats and alsoassociate with white-beaked, Atlantic white-sided, common and Risso’s dolphins andoccasionally larger whales.

The bottlenose dolphin has a worldwide distribution in tropical and temperate seas,occurring in all oceans and in habitatsranging from shallow estuaries and bays tothe continental shelf edge and beyond intodeep oceanic waters (Reid et al. 2003). Incoastal waters, the species often favours riverestuaries, headlands and sandbanks, wherethere is uneven bottom relief and/or strongtidal currents (e.g. Lewis & Evans 1993).

In the eastern north Atlantic the species has been recorded as far north as northernNorway and Iceland (Wells & Scott 1999).Bottlenose dolphins are locally common inthe inshore waters of Spain, Portugal, north-west France, western Ireland, the Irish Sea(particularly Cardigan Bay), and north-eastScotland (particularly the Moray Firth).Smaller numbers occur in the Channel, par-ticularly the western portion. The speciesalso occurs around the Faeroe Islands (Reidet al. 2003).

Overall population estimates do not exist for the bottlenose dolphin in the north-eastAtlantic. The resident population in the MorayFirth, Scotland, has been estimated to bearound 130 individuals (Wilson et al. 1997),although it has been calculated that this maybe declining by more than 5% per year(Sanders-Reed et al. 1999). The population inCardigan Bay, Wales, has been variously esti-mated at between 130 and 350 individuals(Lewis 1992; Arnold et al. 1997). An estimated115 dolphins inhabit the Shannon Estuary,Ireland (Ingram et al. 1999). A photo-identifi-cation project in the Channel has catalogued85 individuals from UK and north-westernFrench waters (Liret et al. 1998).

The largest numbers have been seen offwestern Ireland and in the vicinity of theshelf break south-west of Ireland, towardsthe French coast (Reid et al. 2003). However,the species also occurs further offshore indeep waters of the North Atlantic.

In the English Channel, groups around theFrench coast appear to be very stable,whereas those along the southern Englishcoast are wider-ranging and may makeseasonal movements, moving eastwards fromCornwall towards Sussex during the springand summer (Evans 1992; Williams et al.

1996). Seasonal distribution of bottlenosedolphins in this area has been linked to thedistribution of both fish and chlorophyll(Sykes et al. 2003).

20

The Net Effect?


21

The Net Effect?


Bottlenose dolphins are also common alongcoastlines further south. For example, theSado estuary area of Portugal has a year-round population (Sequeira & Texeira 1990).Further offshore, bottlenose dolphins haveoften been sighted near deep underwatercanyons, which are nutrient-rich and arereported to be particularly important feedinggrounds (Sequeira & Texeira 1990).

Bottlenose dolphins take a wide variety ofbenthic and pelagic fish species as well ascephalopods and shellfish (Reid et al. 2003).Records from European animals includehaddock, cod, hake, saithe, eels, bluewhiting, mullet, silvery pout, sea bass,salmon, trout, sprat and sandeels among itsmany dietary preferences. These feedinghabits are adaptable and the dolphins mayfeed alone or cooperatively in groups,herding fish and trapping them against thewater surface, shoreline or tidal interface.

2.6.2 Bycatch of bottlenose dolphins

Bottlenose dolphin bycatches have beenrecorded, albeit at low levels, in a number of the fisheries already described.

For instance, bottlenose dolphins werecaught in the Dutch pelagic trawl fishery formackerel and horse mackerel south-west ofIreland, constituting 1.5% of the recordedcetacean catch incidents (the majority beingAtlantic white-sided dolphins) (Couperus1997a; see 2.5.2). Bottlenose dolphins werealso included in the list of cetacean speciescaught in the French driftnet fishery foralbacore tuna, the majority being striped andcommon dolphins (Goujon et al. 1993; see2.3.2). In addition, a large dolphin, thoughtto be a bottlenose dolphin, was reported asbycaught in the study of the French pelagicpair trawl fishery for tuna in 1994 (Morizuret al. 1999; see 2.3.2).

The carcass recovery scheme operated inGalicia, Spain in 1998 and 1999 resulted inthe retrieval of two bottlenose dolphins out

of seventeen bycaught cetaceans that werehanded in (López et al. 2003). Data from inter-views with the fishermen suggested an estimat-ed bycatch by the Galician fleet of 65 bot-tlenose dolphins (out of a total of 2,000cetaceans). The majority of bottlenose dolphincatches were reported in gillnet fisheries ininshore (24 animals) and offshore (20 animals)waters off Galicia, with fewer animals (12)reported caught in the trawl fisheries operatedin Grand Sole, off southern Ireland.

Cetacean bycatch has been documented inthe pole and line tuna fishery in the Azoresthat targets five tuna species, primarilybigeye and skipjack but also albacore, yel-lowfin and bluefin (Silva et al. 2002). From1998 to 2000, 49 dolphins were recordedhooked in 44 fishing events (out of 6,554events observed). Common dolphins wereinvolved in 36 of these incidents, stripeddolphins in eight and bottlenose in one. Forthe tuna fishery as a whole it was estimatedthat 38 dolphins of all species were caught in1998, 55 in 1999, and 16 in 2000. Althoughall the animals caught were released alive (bycutting the fishing line), it was impossible toknow if they survived the event or if injuriescaused their deaths after release.

2.7 Long-finned pilot whale(Globicephala melas)


and distribution

The long-finned pilot whale is one of thelargest dolphins (despite its name) and can bedifficult to distinguish from the short-finnedpilot whale. However, as the latter is general-ly a tropical and warm-temperate species, thepilot whales seen in more northerly north-east Atlantic waters are more likely to be thelong-finned species (Reid et al. 2003).

Pilot whales usually occur in large pods, with a mean pod size of about 20 animalsrecorded in surveys in the north-eastAtlantic. Large aggregations of up to 1,000animals have been observed offshore west of

the British Isles during April (Evans 1992),which coincides with the start of the peakmating season (Desportes et al. 1993).

Long-finned pilot whales occur in temperateand sub-Arctic regions, mainly in deep-waterhabitat. Surveys in the northern and north-eastern North Atlantic in 1987 and 1989indicate that their core range is deep watersouth-west of the Faeroes and south andwest of Iceland. The species also occurs inthe Bay of Biscay south to the IberianPeninsula (Reid et al. 2003). Long-finnedpilot whales are recorded in high numbers to the north of Scotland and south-east ofthe Faeroes as well as along the continentalshelf edge from southern Ireland south to theBay of Biscay, with most records from watersdeeper than 200 m.

Although little seasonality has been observedin their distribution, a peak of long-finnedpilot whale sightings has been reported in thesouth-west English Channel and North Seabetween November and January, when podswere frequently seen near vessels fishing formackerel (Evans 1980). The species’ distribu-tion has also been linked to its preferred preyof squid. Other species recorded in its dietinclude mid-water shoaling fish species suchas blue whiting and greater argentine, andcrustaceans (Reid et al. 2003).

2.7.2 Bycatch of long-finned

pilot whales

The incidental capture of long-finned pilotwhales has been recorded in a number of thefisheries already described.

Records from the Dutch pelagic trawl fisheryfor mackerel and horse mackerel during1989-94 include the capture of nineteenlong-finned pilot whales off south-westIreland and a further five in other areas(North Sea and Channel). Bycatches of long-finned pilot whales constituted 12% of allthe recorded bycatch events in these fisheries,the majority involving white-sided dolphins(Couperus 1997a; see also 2.5.2).

The study of the Irish pair trawl fishery foralbacore tuna in 1999 recorded 8 pilotwhales caught (out of 145 cetaceans, mainlycommon dolphins) during 313 hauls (BIM2000; see also 2.3.2).

Two bycaught long-finned pilot whales werehanded in during the Spanish carcassrecovery scheme operated in 1998-99, out of 17 retrieved animals (López et al. 2003).Based on interview data from fishermen,about 100 long-finned pilot whales were esti-mated to be caught per year in Galician fish-eries, some 80% of these in gillnets. A fewwere also reported as being bycaught inSpanish trawl fisheries operating in GrandSole off south-west Ireland (see 2.3.2).

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The Net Effect?


23

The Net Effect?


3. Fisheries associatedwith Bycatch

3.1 Overview

The use of almost any kind of fishing gear canbe associated with bycatch (Alverson et al.

1994) and this generality is equally true forcetacean bycatch, which has been recorded ina surprising diversity of fishing operations.While many fisheries in the north-east Atlanticregion have yet to be subjected to observermonitoring, bycatch of cetaceans has beenidentified or is suspected in fisheries that canbe broadly characterised as: towed gears,including pelagic (mid-water) trawls and to a lesser extent purse-seines and demersal(bottom) trawls; and passive gears, primarilybottom-set gillnets but also driftnets andtangle nets. Entanglement of cetaceans hasalso been recorded in trap fisheries such asherring weirs, and in the lines of pots andcreels. Cetaceans are even known to be caughtin some hook and line fisheries. Lost or dis-carded fishing gear (ghost netting) is alsoassumed to be responsible for cetacean deaths.

Fisheries known or suspected to be associat-ed with cetacean bycatch are very diverseand as many vessels in the north-eastAtlantic region use mixed gear types and cantarget a range of fish species, it can be prob-lematic to assess the scale and cause ofbycatch problems.

Although all EU Member States are obligedunder the Habitats Directive to establish asystem to monitor the incidental capture andkilling of cetaceans (see 5.3.2) this require-ment has not been widely fulfilled. It is gener-ally accepted that the only reliable method toestimate cetacean bycatch rates involves theuse of independent observations of fishingactivity (Northridge 1996). However, thereare acknowledged difficulties with observerschemes. For instance, certain fisheries aremore difficult to observe than others, andsmall boats may not have sufficient space to carry an observer. Nevertheless, there areways to get round these difficulties, such asobservation from a nearby platform or patrolvessel, or by sampling only the larger vessels

in the fleet where they fish in the samemanner and area as the smaller ones (CEC2002a). It is also important to note thatobserver schemes can only ever provide aminimum estimate of bycatch, as even themost vigilant observer will miss somebycatches, bycaught animals can fall out of the net while it is being hauled in, andhauling of nets frequently occurs at night.

Observational bycatch data are only usefulfor estimating total bycatch levels wherethere is an adequate measure of the activitylevels of the total fleet, using comparabledata (CEC 2002a). For instance, if bycatchrates are recorded as bycatches per length ofnet per hour of fishing time, extrapolation tothe whole fleet requires full data on length of nets used and duration of sets (soak-time).

For many fisheries there is insufficient collec-tion of data on fishing effort and gear usedto be able either to devise appropriate obser-vation schemes or to extrapolate the datacollected to obtain a total figure. In somecases, total bycatch estimates have had to bederived using the weight of landed catch asan index of fishing effort. While catchlandings are very widely recorded, theyprovide a poor measure of fishing effort,because underreporting can occur and alsobecause fish catches per unit of fishing effortvary, especially with the size of the target fishstock (CEC 2002a). Equally, days at sea is astandard measure of fishing activity, but canrepresent a very different amount of fishingactivity for vessels of different sizes or usingdifferent sized nets.

It is clearly critical that, where bycatch moni-toring occurs, fleet effort records be madeavailable for the estimation of total bycatch.This is frequently not the case. For instance,in EU fisheries, logbook data, which typicallyrecord measures of fishing effort as well ascatches, are maintained solely for enforce-ment purposes and are often not made avail-able for assessment of fisheries (CEC 2002a).

In addition, in most European waters,logbook recording requirements only applyto boats over 10 m, and at present data col-lection requirements do not include those forassessing environmental impacts.

Based on experience from existing andprevious observer monitoring schemes,advisers to the European Commission haverecommended that an initial sampling levelof 5-10% of the total, annual fleet effort isnecessary in most fisheries to determine theapproximate level of bycatch (CEC 2002b).Higher levels than this are recommended inareas where there are known problems ofcetacean bycatch. In particular, observercoverage in the pelagic trawl fisheries in theBiscay, Celtic Sea and Channel area is recom-mended to be “as high as feasible” duringDecember to March when mass strandings of bycaught dolphins occur (CEC 2002b).Clearly, the more observation is conducted,the more precise the estimate of total bycatchwill be (as long as there are adequate data onthe fishing effort).

Where observation schemes are not in place,records of stranded animals, where they havebeen subject to post-mortem examination,can be used to identify the existence of abycatch problem in an area. However,strandings data cannot provide any morethan an absolute minimum level of bycatch,as the rate at which bycaught and discardedanimals are washed ashore is highly variableand unpredictable (CEC 2002a).

Details of injuries of stranded bycaughtanimals can, though, provide an indication of the type of fishery responsible, forinstance whether large-mesh monofilamentnet or small-mesh trawl-type netting wasinvolved (Sabin et al. 2003). In addition,analyses of stomach contents of bycaughtanimals may show which fish the cetaceanswere feeding on when or immediately beforethey were caught, which may again give an

indication of the fishery responsible (e.g.Kuiken et al. 1994). Details of carcassesthat are retrieved by onboard observers, suchas body temperature, can also provide usefulinformation as to how and when the animalswere killed (e.g. Morizur et al. 1999).

The following section describes in somedetail the main pelagic trawl fisheries, andoutlines other key fishing types, where dataare available, that are known or suspected to be associated with cetacean bycatch in thenorth-east Atlantic.

Much of the information presented is theresult of extremely limited observer pro-grammes. Until comprehensive observer datais available and analysed, the true extent ofthe cetacean bycatch problem will not beapparent. However, from the limited dataavailable in the following sections, there isclear cause for concern.

3.2 Pelagic trawls

Pelagic or mid-water trawling involves thetowing of a trawl net, which is essentially abag net with a very wide mouth that gradual-ly tapers to a narrow tube known as theextension piece, leading in turn to the closedend of the net, the cod-end, where the fishare collected. Pelagic trawl nets typicallyhave large floats on the head line at themouth of the net to keep the mouth open,and weights on the footrope at the sides, orwingends, of the net opening. The netconsists of very large mesh size at the mouth,gradually decreasing along the net to a smallmesh at the cod-end, depending on the sizeof fish being targeted. A pelagic trawl net canbe towed either by a single boat (singletrawl) or by a pair of boats (pair trawl), withthe configuration of the gear varying betweenthese two fishing methods, as well asbetween different fleets.

Mid-water trawls are considered to have amuch greater potential to capture cetaceans

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The Net Effect?


25

The Net Effect?


Figure 1. Schematic representation of a pair trawl operation.

from Northridge 2003a.

Table 1. Pelagic trawl fisheries known or suspected to catch cetaceans in the north-east Atlantic

Gear type Nation Season Location Target Bycatch Known or Monitoredspecies species Suspected /estimated

Pelagic trawling Denmark,Sweden, June-September Kattegat, Herring Long-finned pilot Known OpportunisticNorway, UK, Skaggerak, whale, other small record.Germany North Sea cetaceans Suspected

Pelagic trawling Denmark, UK, October-December Kattegat, Mackerel Small cetaceans SuspectedSweden, Norway Skaggerak,

North Sea

Pelagic trawling UK, France, October-December West of Ireland, Blue Whiting, Common dolphin, Known from Morizur etal.1996.Netherlands, January-March Celtic Sea, Mackerel Atlantic white- some métiers,Denmark, Ireland Channel Horse mackerel sided dolphin but not recorded

in all studies.

Pelagic pair France Non-seasonal Bay of Biscay Hake Common dolphin Known Morizur et al.1996.trawling

Pelagic pair France, UK, Summer Bay of Biscay Albacore tuna Common, striped, Known Morizur et al. 1996. trawling Ireland Celtic Sea Atlantic white-sided BIM 2000

and white-beakeddolphins, long-finned pilot whale

Pelagic pair France, UK December-May Western Channel Sea bass Common dolphin Known Morizur et al. 1996.trawling Northridge 2003a

Pelagic pair France November-March Biscay Sea bass Common dolphin Known Morizur et al. 1996.trawling

Pelagic pair France January-March Biscay Anchovy, Pilchard, Small cetaceans Suspectedtrawling June-November Horse mackerel

High aperture Spain Non-seasonal Biscay Hake, Small cetaceans Known CEC 2002ademersal pair Horse mackereltrawling

Adapted from CEC 2002b.

than demersal trawls (Read 1996). This ispartly because the nets can be towed at muchfaster speeds as they are not in contact withthe sea bed, and also because the targetspecies of such fisheries are often importantprey animals for the cetaceans.

Pelagic trawls in the north-east Atlantic areused in fisheries targeting a wide range ofpelagic and shoaling fish species, includingalbacore tuna, hake, herring, mackerel, horsemackerel (scad), blue whiting, sea bass,pilchard (sardine) and anchovy. The mainnations operating pelagic trawl fisheries in theregion are France, Ireland, the Netherlands,the UK, Denmark and Spain. Norway andGermany also have pelagic trawl fisheries, thelatter targeting mainly herring in the NorthSea (CEC 2002b). Monitoring for cetaceanbycatch has been conducted in only a few ofthe fisheries operating in the region, and mostof this has involved a sample size too small tobe able to deduce total bycatch levels.However, the data that are available at leastallow some of the fisheries responsible forbycatch to be identified, and others to be sus-pected by analogy.

Table 1 summarises some of the data avail-able on pelagic trawl fisheries and theirknown or suspected cetacean bycatch in thenorth-east Atlantic region.

3.2.1 French pelagic trawl fisheries

Data on French fleets for 1992 show that up to 268 vessels were active in pelagic trawlfisheries (Biseau et al. 1996; see Appendix 2).Data provided for the study of bycatch in1994-95 (Morizur et al. 1999) give thebreakdown of effort (by number of vessels in1992) between the various fisheries, theirestimated landings (for 1994), area fishedand seasonality as shown in Table 2.

The same vessels participate in a number offisheries, therefore the total fleet is not thesum of the number of vessels listed. Also, dif-ferent fish species may be targeted during the

same fishing trip, therefore for calculation ofeffort each individual tow has to be allocatedto a specific fishery according to the catchcomposition (Morizur et al. 1999). Mostpelagic trawling effort takes place in the Bayof Biscay and some of the boats enter thewestern Channel for the winter sea bassseason (CEC 2002a).

The French fleet first introduced pelagic pairtrawling into the albacore tuna fishery in 1987(CEC 1993), although the techniques employedwere very similar to those already in use byFrench fishermen for other species (BIM 2000).

Characteristics of the nets used in the Frenchpelagic trawl fisheries studied during 1994and 1995 were recorded by Morizur et al.

(1999). While there is variation in mostparameters between the fisheries, the widthof the headline at the mouth of the netranges from 100 m to 200 m, the verticalopening of the net ranges from 20 m to 60m, the depth of the tow ranges from 10 m to80m, and the speed of the tow is between 3and 4.5 knots. The fisheries for sea bass,horse mackerel and anchovy were reportedto consist mainly of pair trawlers, althoughthe characteristics given for these fisheries do not show markedly larger nets or fastertowing speeds than those of the other, pre-sumably single-trawl fisheries.

Data from 2000 indicate that the Frenchpelagic trawl fleet (mainly pair trawlers) com-

26

The Net Effect?


Table 2. Details of French pelagic trawlfisheries sampled during the 1994-95 study

Fishery hake tuna sea horse anchovy black pilchardbass mackerel bream

No. of 120 50 70 130 130 15 90vessels

Est. 3,310 1,907 217 3,235 14,500 691 3,700landings(tonnes)

Area VIIIa-b VIIIa-d VIIe, VIIIa VIIIa-b VIIe VIIIafished VIIIb(ICES div.)

Fishing All Aug- Jan- Jan- June- Apr-Jun April-Octseason year Dec March Aug March Oct-Dec

Adapted from Morizur et al. 1999.

27

The Net Effect?


prises 70 full-time pelagic pair boats and 140mixed (demersal/pelagic) vessels (CEC 2002b).There are three large industrial boats (78-88mlong) that fished mainly in ICES area VII (theChannel, Celtic Sea and west of Ireland) forpilchard, mackerel, horse mackerel andherring, the latter being sold in theNetherlands (Anon. 2003). However, most ofthe French pelagic fleet fall in the range of 16-24m. The full-time pelagic pair trawlers fishedfor anchovy in ICES area VIII (Biscay andwest of Biscay), other seasonal fisheriesincluding sea bass and albacore in areas VIIand VIII, and pilchard, horse mackerel andhake in area VIII. The remaining part-timepelagic fleet fished mainly on small pelagicspecies in area VIII (Anon. 2003). In thealbacore trawl fishery 65 boats were linked to149 months of fishing effort. In other pelagictrawl fisheries the effort amounted to 1,480fishing months among 200 boats (CEC2002b). Direct employment (crew) in theFrench pelagic fleet in 2000 was around 480full-time and 658 part-time men and totalannual landings for 1999-2000 were between58,000 and 80,000 tons (Anon. 2003).

Observation of French pelagic trawlers, con-ducted during 1994-95, recorded cetaceanbycatch in three of the fisheries, targetinghake, tuna and sea bass (Morizur et al.

1999). A total of nine cetaceans wererecorded as bycaught, comprising commondolphins and one probable bottlenosedolphin (see 2.3.2). However, generally lowproportions of these fisheries were observed.

In the hake fishery, seven trips wereobserved, totalling 52 sampled tows over 314hours (representing 0.3% of annual effort).Four common dolphins were caught, whichequates to 0.077 catches per tow (or 0.012catches per hour of towing) (Morizur et al.

1999). The dolphins were caught in twotows, the first at a depth of 100 m with atrawl aperture height of 50m and the secondat a depth of 60m with an aperture height of30 m. In both, the footrope of the trawl was

located just above the seabed. All thebycatches occurred over 64 km from theshore and the seven sampled vessels alwaysworked in pairs (Pouvreau & Morizur 1996).

In the summer albacore tuna fishery, four tripswere observed, totalling 43 sampled tows and265 hours of towing (representing 1.6% ofannual effort). Three common dolphins andone probable bottlenose dolphin were caught,which equates to 0.06 catches per tow (or0.015 catches per hour of towing) (Morizur et

al. 1999). The catches occurred at the end ofSeptember, in the extreme south of the Bay ofBiscay. All the dolphins were caught at night,when the pair trawl was being towed near thesurface, with a trawl aperture height of 38 m(Pouvreau & Morizur 1996).

In the sea bass fishery only two trips wereobserved, with a total of 10 sampled towsand 73 hours of towing (representing 1.6%of annual effort). One common dolphin wasbycaught which equates to 0.1 catches pertow (or 0.014 catches per hour of towing)(Morizur et al. 1999). Like the other Frenchtrawlers examined, the boats were using pairtrawls (Pouvreau & Morizur 1996).

Although no cetacean bycatches were recordedin the horse mackerel, anchovy, black breamand pilchard fisheries, the level of sampling inthese was very low (between less than 0.1%and 0.4% of annual effort). It was noted thatzero recorded bycatch does not imply there isno bycatch in the fishery (Morizur et al. 1999).

3.2.2 Dutch pelagic trawl fisheries

Between 1989 and 1994 the size of the Dutchpelagic trawl fleet in the north-east Atlanticvaried from 11 to 13 freezer trawlers, althoughan additional nine vessels were operating forthe same Dutch company under foreign flags(three German, three British and three French)(Couperus 1996). The smallest of thesetrawlers was 70 m long. The four largesttrawlers were 115-120 m, with a 3,000-5,000tonne storage capacity and engines of 8,000 to

10,000 horsepower. Vessels tend to stay at seauntil their freezer stores are full, which cantake three to five weeks for the larger vessels.Total annual catch in the early 1990s wasabout 300,000 tonnes.

The Dutch pelagic freezer fleet increased to18 vessels by 2000, dropping to 16 vessels in 2001 (Anon. 2003). However, landings in 2001 were recorded as 420,000 tonnes, a 12% increase on the previous year. Thetotal number of crew members in this fleetwas 573 in 2001 (Anon. 2003).

The pelagic trawls are very large with avertical opening of between 30 m and 60 mand the horizontal spread of the wingsranging from 80 m to 120 m. The mesh sizeat the front of the net is up to 30 m, diminish-ing to 4 cm at the cod-end. The trawl is gener-ally towed just a few metres above the seabed,at varying depths depending on the targetspecies, and the duration of each tow mayvary from five minutes to more than tenhours, depending on signals received fromsensors in the cod-end. During the early 1990sabout half the Dutch fleet used fish pumps toempty the cod-end (Couperus 1996).

The target species of the freezer trawlersduring this period were, in order of impor-tance, horse mackerel, herring, mackerel,blue whiting and greater argentine. Themost important fishing areas were on thecontinental slope west of the British Isles, inthe Channel, along the British east coast andin the northern North Sea. The fleet’s annualfishing pattern is described by Couperus(1996). Generally, at the start of the yearpart of the fleet fishes south-west of Irelandand in the northern Bay of Biscay for horsemackerel, and other vessels fish north ofScotland and Shetland for mackerel. Aswinter progresses, the mackerel fleet followsthe mackerel southwards along the continen-tal shelf edge, meeting the horse mackerelfleet south-west of Ireland towards the endof February. In March the whole fleet fishes

along the shelf edge south-west of Ireland,mainly targeting horse mackerel but alsocatching mackerel. By the end of March andinto April some trawlers fish for blue whitingon the Porcupine Bank and west of Scotland.By May and June some of the fleet is stillfishing for horse mackerel south-west ofIreland, some target greater argentine andherring along with blue whiting west ofScotland, and an increasing proportionmoves into the central and northern NorthSea to catch herring. Over the summer, mosttrawlers target herring in the North Sea,along the shelf edge north of Shetland andnorth and west of Scotland. By Septembermost of the fleet moves to the westernapproaches of the English Channel andsouth-west of Ireland to fish for horsemackerel and herring. In October the fisheryfor wintering mackerel north-west ofShetland starts but the horse mackerel fisheryin the western Channel and northern Biscayis still important. By the end of November,the fishery for spawning herring starts in theChannel (Couperus 1996).

An independent observer programmecovering about 5% of annual effort in theDutch pelagic trawl fisheries was conductedbetween 1992 and 1994 (Couperus 1997a).In parallel with this scheme, a self-reportingscheme was set up to cover the same fisheryfor the last two years of the study. With theaddition of data collected from 1989 to1991, bycatch records are available for a six-year period, constituting 71 bycatch incidentsinvolving in total 312 dolphins. Of thesebycatches, 89% occurred south-west ofIreland, and these account for all thereported bycatches in the period February-April. At this time of year both mackereland horse mackerel are found in this area.The vast majority of bycatches were Atlanticwhite-sided dolphins (78% of all identifiedanimals and 83% of animals caught south-west of Ireland; see also 2.5.2). Other speciescaught were long-finned pilot whale (12%),common dolphin (7%), bottlenose dolphin

28

The Net Effect?


29

The Net Effect?


(1.5%) and white-beaked dolphin (1.5%)(Couperus 1997a).

Further monitoring of the Dutch mackereland horse mackerel fishery in the Celtic Seaand south-west of Ireland was conducted inJanuary to March of 1994 and 1995. Thissampled 119 tows over 841 hours of towing,representing 3% of annual effort (Morizur et

al. 1999). The observers recorded catches ofnine dolphins, consisting of five Atlanticwhite-sided and four common dolphins. Thisrepresents a bycatch rate of 0.076 animalsper tow, or 0.01 animals per hour of towing.The animals were all caught at or near thecontinental shelf edge and the bycatchesoccurred either at night or in the earlymorning even though more hauling opera-tions were actually conducted duringdaylight (Couperus 1996).

The body temperature of the bycaughtanimals was measured and ranged from26.6ºC to 38ºC, and exceeded 34ºC for sevenof the individuals, which is close to that for aliving animal (37ºC). This finding, along withthe state of rigor mortis, was taken to indicatethat the animals had only recently died andhad been captured during or close to hauling,perhaps being trapped by net closure duringthe haul-back process. It was also noted thatwhen a vessel turns sharply during a tow, thefishing line is hauled in until the trawl doorsbreak the surface and the net itself is closedjust under the water surface (known as‘turning on the doors’). After turning, the lineis paid out again, the whole process lasting for10-20 minutes in water depths of 200 m. Thisprocedure was also considered likely toincrease dolphin bycatches compared to a haul maintained in the same direction(Couperus 1996).

In five out of the six bycatch incidents thebulk of the fish catch was mackerel(Couperus 1996). Analysis of bycaughtdolphins’ stomach contents has shown thatwhite-sided dolphins were feeding heavily on

mackerel shortly before capture, but not onhorse-mackerel, even when the latter waspresent in the catches (Morizur et al. 1999).Trawling depth for mackerel in this fisherywas reported to be between 100 m and 400m and the duration of hauls in whichdolphins were caught ranged from 4.5 hoursto over 12 hours (Couperus 1996).

Bycatch monitoring continued in the Dutchfishery in 1995-96, when 84 hauls weresampled over 45 days at sea, and eightcetaceans were recorded as bycaught. During the course of the study, an additional37 animals were recorded as bycaught inskippers’ reports. However, there were insuf-ficient data to estimate annual bycatch rates(Couperus 1997b).

No further bycatch monitoring has been con-ducted in the Dutch pelagic trawl fisheries.However, Dutch fishing intensity south-westof Ireland is assumed to have reduced as part of the fleet has moved to Moroccan and Mauritanian waters. The African fishinggrounds are of growing importance andaccounted for more than 35% of the totalearnings of the fleet in 2001 (Anon. 2003).Dolphin bycatch is also reported to be highin the Mauritanian fishery (CEC 2002b).

3.2.3 UK pelagic trawl fisheries

The UK pelagic trawl fleet targets a range offisheries including mackerel, herring, sprat,pilchard, blue whiting, anchovy and sea bass,and operates in waters all around the BritishIsles including the northern waters of ICESarea II and south into the Bay of Biscay. Thenumber of vessels in the UK’s pelagic fleetwas 67 in 1995, decreasing to 47 in 2001.However, the installed engine power of thefleet increased by 30%, from 82,900 hp to108,150 hp, over that period (Anon 2003).The total landings of the UK pelagic fleetwere 324,000 tonnes in 2001. Mackerel isthe most important species, accounting foraround 50% of landings, followed byherring, at around 35%. The other species

each make up 5% or less of the totallandings (Anon 2003).

In 1993-94 observer studies were made ofthe UK’s pilchard and mackerel fisherieswhich operate in the western EnglishChannel from October to December andNovember to March respectively, some usingsingle and some pair trawls (Lewis et al.

1996). No cetacean bycatch was observed ineither of these fisheries but it was noted thatthe use of fish pumps to empty the catchfrom the net would have compromised theability of the observer to record marinemammal catches (Morizur et al. 1999).Cetaceans would be too large to passthrough the pump and, in the case of the UK fisheries, the final emptying of the cod-end occurred outboard and thus anybycaught animals may have gone unob-served, particularly during the night.

Since 2000, the UK has conducted furtherobserver monitoring to estimate the level ofbycatch in UK pelagic fisheries. Initially,observers were placed on board 13 UKvessels for a total of 190 days at sea, coving206 trawling operations around the UK. Thefisheries covered include herring, mackerel,sprat, pilchard, blue whiting, anchovy andsea bass. The only fishery in which cetaceanbycatch has been observed to date is the seabass fishery (DEFRA 2003b).

The UK sea bass trawl fishery consistsmainly of Scottish vessels of 30-40m inlength, with up to four pairs operating in the years since 2000. The trawl nets are of aFrench design and are towed near the surfacewith a wing spread of about 140 m and alength of about 280 m, including a long 40m tunnel to the cod end. The averageduration of the observed tows was 7.4 hours(Northridge 2003a). Fishing effort in the UKsea bass pair trawl fishery (in terms of haulsper year) showed a marked increase from1996 and then a further substantial rise since1999 (Northridge 2003a).

In 2001, the sea bass fishery, operatingmainly in the western English Channel, wasobserved over 71 days at sea, covering 116hauls. A total of 53 common dolphins wereobserved caught in 12 of these hauls. Thefishery occurs between November and Aprilalthough most fishing activity occurs in lateFebruary and March when the sea bass havemoved offshore to spawn in the mid-Channelregion. Indeed all but one of the bycaughtdolphins were observed during March(Northridge 2003a). Further monitoringduring 2002 recorded eight commondolphins caught during observation of 66hauls. By the end of the 2002-03 season over310 tows had been observed in the sea bassfishery during 193 days at sea, and 91cetacean catches (all common dolphins) wererecorded (Northridge 2003a).

Over the course of this observer monitoring,work has also been conducted to investigatepotential bycatch mitigation measures, includ-ing acoustic deterrent devices (pingers), whichhave not been successful (see 4.2.3) and anexclusion device (selection grid), which appearsto be showing more promise (see 4.2.1).

3.2.4 Irish pelagic trawl fisheries

Data from 1992 indicate that pelagic fisheries accounted for 83% of the total fish landed into Irish ports (Berrow et al.

1996). Three species - herring, horsemackerel and mackerel - accounted for 97% of these landings.

In the early 1990s the Celtic Sea herringfishery was perhaps the most importantsingle fishery within the Irish fishing industry(Berrow et al. 1996). In 1994-95 Ireland hada fleet of 49 pelagic vessels active in theherring fishery, operating in pairs, and withannual landings estimated to be 20,000tonnes (Morizur et al. 1999). These vesselsare mainly 21-25 m in length and use rela-tively small trawl nets with a headline widthof 20-30 m and a vertical opening of 15-20m (Berrow et al. 1996). This fishery operates

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from October to February, with a peak ineffort recorded in January during the 1994-95 season.

Observers were placed in the Celtic Seaherring fishery between October 1994 andJanuary 1995, and monitored 78 tows during85 days at sea, mostly close inshore to thesouth and south-east of Ireland (Berrow et al.

1996). The only reported marine mammalbycatch was that of four grey seals, caughtindividually which were found to have beenfeeding on herring at the time of capture. Nocetaceans were caught, although it was alsonoted that no live cetaceans were observedfrom the vessels during this study.

Ireland’s fleet of pelagic pair trawlers thattarget horse mackerel and mackerel consistedof 23 vessels in 2001 and this number hasbeen constant since 1995 (Anon 2003).However, the total installed engine capacityof the fleet increased over this period by 13%,from 48,700 hp to 55,000 hp. These vesselsare listed as being over 24 m and employ atotal crew of 300. Landings of horse mackerelin 2001 were recorded as 63,000 tonnes (justover a third of that recorded for 1995).Landings of mackerel were 70,000 tonnes in2001 and have fluctuated less over theprevious 6 years. These fisheries are bothwidespread, with catches of both speciesoccurring in the northern North Sea andnorthwards, west of the Faeroes and Scotland,and in ICES areas VII and VIII (Anon. 2003).

The researchers who studied bycatch in theIrish pelagic trawls during 1994-95 initiallyapproached the representative organisationof the mackerel fishery but this fleet was notprepared to cooperate with the study and sono observers could be placed (Berrow et al.

1996). However, the report of this study con-cludes that the mackerel/horse mackerelfishery, as one of the largest in Ireland andhaving the largest vessels, should be studiedto quantify incidental capture. It also notesanecdotal reports of up to 50 dolphins taken

in a single tow by Irish pelagic trawlers(Berrow et al. 1996).

In 1998 Ireland initiated an experimentalpelagic pair trawl fishery for albacore tuna inresponse to the EU’s decision to ban the useof driftnets to catch tuna and similar species(see 3.4.1). This is a summer fishery and themain areas targeted are from the Bay ofBiscay north-westwards, broadly followingthe continental shelf edge to the waterssouth-west and west of Ireland. In 1999,there were 16 vessels participating in thetrials, ranging from 21 m to 33 m (BIM2000). Although the number of vesselsdropped in the intervening years, there were16 Irish vessels pelagic pair trawling foralbacore in 2002. These had a total enginepower of 12,000 hp and a crew of 100.Albacore landings by the pelagic trawl fleetrose from 65 tonnes in 1998 to 1,200 tonnesin 2002 (Anon. 2003).

The experimental fishery was studied during1998 and 1999 to evaluate the efficacy ofthis (and other) fishing methods for catchingalbacore. The trials used a variety of net con-structions based on French and Irish trawldesigns, differing mainly in constructionmaterial and the fact that the French boatstow only one warp per vessel, whereas theIrish boats tow two, from the top andbottom of the bridles at the side of the net(BIM 2000). During 1998, the trial fisherywas predominantly south-west of Ireland andalso in the northern Bay of Biscay, fishingfrom August to mid-October. In total, 105hauls by four pairs were monitored and 35cetaceans were caught, including 23 dolphinscaught in a single haul. During 1999, fourpairs were again monitored, from August tolate September, concentrating on waters westand south-west of Ireland and further southto the southern Bay of Biscay. A total of 313hauls were monitored, recording a catch of145 cetaceans (127 common dolphins, 8striped dolphins, 8 long-finned pilot whalesand 2 Atlantic white-sided dolphins). Ninety-

eight of these (68%) were taken in just 10hauls and one haul accounted for 30 animals(BIM 2000). The tows were generally madeat night and lasted from four to six hours.

The researchers analysed the cetaceanbycatch dataset by correlating it with a rangeof factors in the fishery such as geographicposition, water depth, time of haul, towingspeed and albacore catch. The strongest cor-relation was found to be with the depth ofwater during the tow, with cetacean bycatchonly recorded once when the depth of waterexceeded 500 m (BIM 2000).

Research into the use of acoustic deterrentdevices to prevent bycatch in the Irishalbacore pair trawl fishery has been conduct-ed in 2002 and 2003 (see 4.2.3).

3.2.5 Danish pelagic trawl fisheries

Denmark has a fleet of pelagic trawlers thattargets horse mackerel, mackerel and bluewhiting, mostly in ICES areas VII and VIII,with the major fishing grounds located in thewestern Channel and the Western Approaches.The fleet consisted of 21 vessels in 2001,having declined from 35 vessels in 1998-99(Anon 2003). Direct employment in this fleetfor 2001 is given as 119 crew, and annuallandings as 23,000 tonnes (down from 64,000tonnes in 1997). Denmark also has pelagictrawlers that fish in the Kattegat andSkaggerak Seas targeting mackerel and herring.

Danish pelagic fisheries do not appear to havebeen monitored for cetacean bycatch,although given the size and distribution of thefishing effort it would be reasonable toassume a significant level of bycatch byanalogy with other fleets targeting the samefisheries. Occasional catches of long-finnedpilot whales have been recorded in the herringfishery in the Skagerrak Sea and bycatch ofother species is also suspected (CEC 2002b).

3.2.6 Spanish trawl fisheries

Spanish fleets are prohibited from using

pelagic trawls by national legislation.However, a new Spanish gear was introducedin the early 1990s which is in effect ademersal trawl with a very high verticalopening (VHVO or Naberan trawl: CEC2002b). The gear is used by pair trawlers andin 1992 there were 22 Spanish Basque boatsusing it to target hake in the Bay of Biscay. In2000, there were 27 pairs working with thesenets, operating in ICES areas VIIIa and VIIIb(inner Bay of Biscay), while 37 pairs werefishing in area VIIIc (southern Biscay) and 18pairs in area IXa (eastern Portuguese waters)(CEC 2002b). Although the fishing type is dif-ficult to determine, data from 1998 also list243 Spanish boats using “trawls” in watersoffshore of Galicia and 250 boats using“trawls” in inshore Galician waters (CEC2002b). Around 150 Galician vessels, mainlytrawlers and long-liners, are reported to fish atGrand Sole, off south-west Ireland (López et

al. 2003), presumably targeting mainly hake,blue whiting and horse mackerel.

An observer programme covering VHVOtrawls has been conducted by the Institute of Fisheries Research of the Basque Countrysince 1996. During the period 1996-2000,661 hauls were observed over 266 fishingdays and a total of 24 dolphins were caughtin ICES areas VIIIa, b and d (Bay of Biscay)(CEC 2002b). Further observation pro-grammes have been undertaken by theSpanish Institute of Oceanography. In the1997 survey, covering ICES areas VIIIc andIXa, 439 bottom trawl hauls and 45 bottompair trawl hauls were observed and onebycatch incident was recorded, involvingthree animals in area IXa (eastern Portuguesewaters). In 1999-2000, 1,759 bottom trawlhauls and 67 pair trawl hauls were moni-tored and one common dolphin was taken inICES area VII (CEC 2002b).

These apparently low bycatch rates should beconsidered in the context of the extremelyhigh level of fishing effort in the Spanish fleet.For instance, the total number of fishing trips

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by the (full-time) Galician fleet is estimated tobe around 1.1 million per year (López et al.

2003). These findings also appear to be atodds with other recent surveys. For instance, a survey of cetacean bycatch in Galician fish-eries conducted in 1998-1999 recorded nobycatch during 67 observed fishing trips(López et al. 2003). However, data from inter-views with fishermen produced an estimatedannual cetacean bycatch of 415 cetaceans peryear in Galician offshore trawl fisheries and afurther 332 in the trawl fishery on GrandSole. The interviews also yielded numerousreferences to cetaceans being used for humanconsumption (69 out of 500 interviewees) anduse of cetaceans for bait, animal food and as asource of fat was also mentioned (López et al.

2003). An earlier Spanish study, also usingobservers and interviews with fishermen, iden-tified offshore pair trawling as the major causeof common dolphin mortality (Aguilar 1997).In this study, fishermen reported that duringnight-time fishing it was rare not to catchdolphins, usually between one and ten andsometimes thirty or more. During 1996 and1997, observers were present on four tripsusing pair trawls at night and in all casescommon dolphins were caught, totalling eightindividuals (Aguilar 1997).

3.3 Bottom-set gillnets

Gillnetting is a simple, passive form offishing that involves the setting of sheets ofnetting suspended vertically in the water byway of a floatline at the top and a leadline atthe bottom. Fish are caught by swimminginto the net and becoming wedged within amesh opening, or literally ‘gilled’ by the meshcatching behind the gill covers. Bottom-setgillnets are used to catch a wide variety ofdemersal species including cod, turbot, hake,saithe and dogfish. There are several varia-tions on this theme. Tangle nets have little orno flotation so that they are extremely slack,and are used to catch species such as flatfishand crustaceans, which are entangled ratherthan gilled. Trammel nets consist of threeparallel sheets of netting, the middle sheet of

which has a smaller mesh and is hungloosely, so that fish swim through the outersheet and are caught in a pocket of the smallmesh netting. All these nets are usuallyanchored so that they are located on or nearthe seabed. Driftnets are gillnets that are leftto drift at or near the sea surface, sometimesattached to the boat at one end (driftnets areaddressed in 3.4 below).

Although gillnets have a long history, theiruse has increased massively since the intro-duction in the 1950s of nylon yarns and par-ticularly monofilament netting, whichincreased their efficiency (Northridge et al.

1991). The FAO and other organisationsactively promoted the use of gillnets incoastal areas because of their low cost, easeof use and productivity, and they havebecame the most common type of fishinggear in coastal waters worldwide (Crespo &Hall 2001). Gillnets are regarded by fisheriesmanagers as attractive because they can bevery size-selective for the target fish.However, they can be very unselective at aspecies level, both for non-target fish and forother groups such as marine mammals, birdsand turtles. The durability of nylon gillnetsalso means that when they are lost at sea(which frequently happens) they maycontinue to trap fish (ghost fishing) for anindeterminable period, posing an additionalbycatch threat.

The harbour porpoise, in particular, has beenfound to be acutely prone to incidentalcapture in bottom-set gillnets in the north-east Atlantic and many other regionsthroughout its range (see also 2.2.2).

3.3.1 Danish bottom-set gillnets

Denmark has a large bottom-set gillnettingfleet, operating largely in the North Sea andalso in the Kattegat and Skaggerak Seas andinto the Baltic Sea. The main fisheriestargeted in the North Sea are for cod, caughtin bottom-set nets and wreck nets (wheregillnets are set over wrecks and rough

ground), hake, turbot, plaice and sole.

Several programmes of bycatch monitoringhave been conducted in the Danish set-netfisheries, and have indicated high and unsus-tainable levels of harbour porpoise bycatch(outlined in 2.2.2). Total porpoise bycatch bythe Danish fleet is estimated to have peakedat 7,366 animals in 1994 (Vinther & Larsen2002). The greatest porpoise mortalityoccurs in the turbot fishery, which uses longnets with large mesh sizes (mainly 270 mm)and a very long soak-time. However, thehighest rate of porpoise bycatch per km ofnet per hour occurs in the wreck-net fisheryfor cod, particularly in the third quarter ofthe year (Vinther 1999).

As a result of these findings, the DanishGovernment introduced in 2000 a require-ment for the use of pingers in the North Seacod wreck-net fishery in the third quarter ofthe year. This measure is reported to havecompletely eliminated observed bycatch in thewreck-net fishery during this quarter (Larsenet al. 2002a; see also 4.2.2). Danish trials ofhigh-density gillnets have also been conductedand have shown that they reduce porpoisebycatch, but also reduce catches of cod(Larsen et al. 2002b; see also 4.2.4 below).

Since its peak in 1994, bycatch of harbourporpoises in Danish set nets has declinedsteadily, largely as a result of reduced fishingeffort due to poor fish stocks (Vinther &Larsen 2002). However, total annual catchesare still substantial, estimated at 3,482 por-poises in 2001 (CEC 2002b), and no mitiga-tion measures have yet been introduced inmost Danish bottom-set gillnet fisheries.

3.3.2 UK bottom-set gillnets

The UK also has substantial gillnet fisheriesoperating in all waters around the BritishIsles, many of which land mixed species,making categorisation difficult (CEC 2002a).Most gillnetting effort in the central andsouthern North Sea up to 2000 targeted cod

(in both bottom-set and wreck nets),followed by sole, although effort in almostall the North Sea fisheries has decreased sub-stantially since the mid- to late 1990s. InAtlantic and Channel waters a wide varietyof species is targeted. The greatest gillnettingeffort occurs in the coastal waters of theeastern Channel (ICES area VIId), targetingcod, flatfish, cuttlefish and other species, andthere is significant fishing effort in the CelticSea, targeting hake, monkfish (Angler fish)and crustaceans (CEC 2002a). There is alsoan offshore set-net fishery operated by largefreezer-netters which typically operate alongthe continental shelf edge and on offshorebanks. Gillnetting (set and driftnet) effort inmany areas, for example the North Sea, hasdecreased, but there were notable increases ineffort recorded in the few years up to 2000in the waters well offshore west of Scotland(ICES area VIb), the Irish Sea (VIIa), and inthe Celtic Sea (VIIg) (CEC 2002a).

Many UK gillnet fisheries have been moni-tored for cetacean bycatch since the early1990s, and predictably the main speciesrecorded is the harbour porpoise (see 2.2.2).

In 1992-94 the Celtic Sea hake gillnet fisheryfrom the UK and Ireland was investigated,revealing an estimated annual catch of 740porpoises by the UK fleet and an additional1,500 by the Irish fleet, giving a total of2,240 animals (Tregenza et al. 1997a).Bycatches of common dolphins were alsorecorded in this fishery, with an estimatedannual catch of 200 animals (Tregenza &Collet 1998). Fishing effort has declined inthe hake fishery as a result of fish stockrecovery measures. However, there have alsobeen shifts in effort between fisheries, andbycatch in Celtic Sea set-net fisheries is stillconsidered to be at unacceptable levels.

Cetacean bycatch in UK gillnet and tanglenet fisheries was observed in the North Seaand off the west coast of Scotland between1995 and 1997. In the North Sea, porpoise

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The Net Effect?


catches in the cod, sole, skate and turbotfisheries were estimated to total between 600and 800 animals per year (Northridge &Hammond 1999). West of Scotland, fisheriesfor dogfish, crayfish and skate were estimat-ed to catch between 150 and 200 porpoisesper year (Northridge & Hammond 1999).These figures are estimated to have fallen by1999, to around 450 animals in the NorthSea and 22 west of Scotland, as a result offishing effort reductions and the collapse ofthe Scottish crayfish fishery (CEC 2002a).

Since these studies, there has been significantresearch effort in the UK into pingers as apotential mitigation measure, particularly inthe Celtic Sea hake set-net fishery (see 4.2.2).Despite several years of field trials and afinding of 92% reduction in bycatch levels inpingered nets (SMRU 2001), no mitigationmeasures have yet been introduced in theUK. However, the UK Government launcheda consultation paper in March 2003 detailingproposals for a bycatch response strategythat would include compulsory use of pingersin specified bottom-set gillnet and wreck-netfisheries (DEFRA 2003). These proposals arestill under consideration.

3.3.3 French, Spanish and

Portuguese bottom-set gillnets

In 1994, there were around 800 French boatsfishing with bottom-set gillnets (Pouvreau &Morizur 1995). In the Bay of Biscay the maintarget is sole, but hake, monkfish, turbot,whiting and rays are also taken. In thewestern Channel (ICES area VIIe), sole,monkfish, turbot, rays, spider crabs, pollackand hake are targeted, and in the easternChannel set nets are used for cod. There islittle reported bycatch in these French fish-eries, but interviews with fishermen indicatethat some porpoise bycatch occurs in themiddle of the western Channel (CEC 2002a).Bycatch of porpoises is suspected by analogyin French hake and monkfish fisheries in theCeltic Sea and on the continental shelf edge,and also of a range of cetaceans in the sole,

hake and monkfish fisheries in Biscay.

Spain has a very large fleet of set-netters. In1998, there were over 1,000 small Galicianboats fishing in inshore waters and 535netting offshore (ICES areas VIIIc and IXa).In 2000, 43 boats were recorded fishing inareas VIIIa and b (inner Bay of Biscay) tar-geting demersal species (CEC 2002a). Nocatches of cetaceans were observed inSpanish gillnets during two monitoring pro-grammes conducted in 1994 and between1996-2000. However, a recent study ofGalician fisheries, involving interviews,carcass retrieval and observation, estimatesthat the annual cetacean bycatch is 190animals in the inshore gillnet fleet and 955 in the offshore fleet (López et al. 2003).

Portugal also has a large gillnetting fleet,mainly of small boats fishing in inshorewaters, with over 4,800 netters registered in1991 (Sequeira & Ferreira 1994). Althoughthere is little reliable information on cetaceanbycatches in Portuguese fisheries, consider-able numbers of cetaceans are reported to bekilled incidentally each year, with highestlevels in the gillnet fishery. Commondolphins are thought to be the most affected,particularly in the central zone, but harbourporpoises are particularly vulnerable in thenorthern region. Bycatches of striped andbottlenose dolphins are also reported(Sequeira & Ferreira 1994). A recent analysisof common dolphin strandings data inPortugal suggests that gillnets were responsi-ble for 67% of the bycaught animalsrecorded (Silva & Sequeira 2003). Beachseine nets were the next most prevalentcause, responsible for 11% of the bycatches.

3.3.4 Baltic Sea bottom-set gillnets

Bottom-set gillnets are used by fleets from allBaltic States, targeting species such as cod,turbot, sole, salmon and sea trout. There islittle information available on fishing effortin the Baltic. However, Sweden, for example,has a very large set gillnet fishery for cod and

herring, in which effort increased from173,400 km net.days to 203,000 km net.days(17%) between 1997 and 2000 (CEC2002a). An assessment of bycatch, based onreports from fishermen, produced an estimat-ed minimum catch of five harbour porpoisesper year in Swedish salmon driftnets and codgillnets in the early 1990s (Berggren 1994).

There is also a substantial Polish bottom-setgillnet fishery, targeting cod, herring and otherspecies. In addition, there is a small semi-driftnet fishery for sea trout and salmon.Although there is no independent observerprogramme in Poland, analysis of bycatchesvoluntarily reported by fishermen since 1990shows that the majority of animals (25harbour porpoises and one striped dolphin)were caught in bottom-set gillnets (Kuklik &Skóra 2003). The small semi-driftnet fisheryfor salmonids accounted for more than 40%of all reported porpoise bycatches, most ofthese occurring in the small area of Puck Bay.A further two bycaught porpoises werereported in 2002, one in a Polish coastalsalmon set net and the other in a trawl net(ASCOBANS 2003a). Porpoise bycatches havealso been reported in German bottom-setgillnets in the Baltic (CEC2002b).

In light of the critically depleted state of theharbour porpoise in the Baltic Sea and con-tinued losses through fisheries bycatch (see2.2), a Recovery Plan for Baltic HarbourPorpoises (Jastarnia Plan) has been agreed(ASCOBANS 2002; see also 5.2.2). Amongstother measures, this plan recommends thataction should be taken to reduce the fishingeffort of driftnet and bottom-set gillnet fish-eries in the Baltic and to shift fishing efforttowards alternative, less harmful gear.

3.4 Driftnets

Driftnets are usually deployed at or near thesea surface and are used in a wide range offisheries. The more traditional driftnets, typi-cally using cotton net, are short, small-meshed and used by small boats operating

inshore to target species such as herring,sprat and mackerel. However, as with othergillnets, the emergence of synthetic nylonnetting enabled larger-scale driftnet fisheriesto develop for larger and offshore speciessuch as tuna, squid and swordfish. Driftnetsare also widely used to catch salmon.

3.4.1 Driftnets in the North-east

Atlantic and Mediterranean Sea

Small inshore driftnet fisheries exist in theUK, for herring in the Irish Sea, south-westEngland and the Thames estuary, for sea bassin the Channel and Irish Sea, and for salmonoff north-east England (CEC 2002b).Harbour porpoise bycatch is known or sus-pected in most of these fisheries but notquantified. Norway had, until 1998, asalmon driftnet fishery, in which the rate ofharbour porpoise bycatch was among thehighest recorded cetacean bycatches in a netfishery. This fishery was subsequently closedmainly for reasons of salmon conservation(CEC 2002a). Ireland still has a salmondriftnet fishery that occurs west of Irelandand in the Celtic Sea, in which cetaceanbycatch of a number of species is known tooccur (CEC 2002b).

The driftnet fishery for albacore tuna in thenorth-east Atlantic developed in the late1980s. France introduced the use of driftnetsin this fishery in 1986, followed by Ireland in 1990 and the UK in 1991 (CEC 1993).Initially these driftnets were not restricted inlength, although the French driftnetters had avoluntary maximum limit of 9.25 km (BIM1994). Considerable concern had alreadyarisen by this time about the damage beingcaused to both target fisheries and non-targetmarine species as a result of the indiscrimi-nate and wasteful nature of large-scalepelagic driftnets in other ocean areas. Thisled to the United Nations agreement of aworldwide moratorium on the use of suchnets as from the end of 1992. Similarconcerns resulted in the adoption by the EUof Council Regulation 345/92 which pro-

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hibits the use of driftnets longer than 2.5 kmin the waters of the Member States, with theexception of the Baltic Sea, and, outsidethose waters, to all Community fishingvessels. However, a derogation was grantedunder this regulation, which allowed vesselsthat had operated in the albacore fishery forthe previous two years to continue to usenets of up to 5 km.

This derogation only applied to Frenchvessels and was for one year, only to beextended “in the light of scientific evidence

showing the absence of any ecological risk

linked thereto”. As a result, French scientistsconducted an observer programme in 1992and 1993 to assess the ecological risk associ-ated with the French use of 5 km nets. Thisstudy produced an estimated bycatch in theFrench tuna fishery of 1,700 cetaceans peryear, including 1,200 striped dolphins and400 common dolphins (Goujon et al. 1993).This level represents around 1.6% and 0.6%of the estimated populations of striped andcommon dolphins respectively in the tunafishery area. Considering also the Irish andUK components of the tuna driftnet fishery,the total mortality was assumed to be 30%higher (CEC 1993). The EuropeanCommission’s Scientific and TechnicalCommittee for Fisheries recommended thatbycatch should be kept below half themaximum rate of increase of the population(assumed to be 4%) i.e. below 2% of thepopulation. They concluded that for stripeddolphins the estimated mortality was abovethis level (CEC 1993). The French deroga-tion was not extended.

Subsequent observer monitoring of the smallerUK tuna driftnet fishery in 1995 produced anestimated catch of 165 dolphins in thatseason, comprising 61 common dolphins and104 striped (SMRU 1995). This rate ofdolphin bycatch was almost three timesgreater than the French rate per 100 tunacaught. In 1996 the Irish driftnet fleet wasobserved, recording a mean catch rate of 2

cetaceans per haul (Harwood et al. 1999),considerably above the French or the UK rate.Using this bycatch rate, the total bycatch bythe Irish fleet in 1998 (18 vessels) was estimat-ed to be 964 striped dolphins and 2,522common dolphins (Harwood et al. 1999).

In 1998 EU Fisheries Ministers agreed to a ban on driftnet fishing for tuna, swordfishand similar listed species in the waters ofMember States, with the exception of theBaltic Sea, and, outside those waters, to all Community fishing vessels (CouncilRegulation (EC) No. 1239/98). This bancame into force in January 2002.

Although the phasing out of driftnets seemsto have been adhered to in the north-eastAtlantic albacore fishery, this has not beenthe case in the Mediterranean. The Frenchfleet has continued to operate driftnets,known as ‘thonaille’, to catch bluefin tuna.This fishery is known to catch stripeddolphins (CEC 2002b). There is also increas-ing evidence of a resurgence of illegal driftnetuse by Italian vessels to catch tuna andswordfish. In addition, non-EUMediterranean countries such as Moroccoand Turkey, which are not bound by the EUdriftnet ban, continue to use these nets,despite the UN moratorium on large-scalepelagic driftnets. These fisheries catch a largenumber of cetaceans, mostly striped dolphinsbut also including pilot whales, commondolphins and sperm whales (CEC 2002b).

3.4.2 Driftnets in the Baltic Sea

The restrictions on EU driftnets introduced in1992, restricting driftnet length to 2.5 km,and in 2002, prohibiting the use of driftnetsof any length in fisheries for tuna, swordfishand similar species (see 3.4.1), do not applyto the Baltic Sea, which was specificallyexempted during the negotiations. A substan-tial driftnet fishery for salmon occurs in theBaltic, operated by a number of Baltic states,in which nets of up to 21 km are stillallowed. Bycatch of harbour porpoises in the

Baltic has been recorded mainly in salmondriftnets and bottom-set gillnets, and thesefisheries are considered to pose the majorthreat to the critically small remainingporpoise population in the Baltic Sea(ASCOBANS 2002; see 2.2). Consistent withthe recommendations of the Jastarnia Plan(see 3.3.4 and 5.2.2), the EuropeanCommission has proposed to restrict thelength of driftnets in the Baltic to 2.5 km andto phase out their use completely by 2007(CEC 2003a; see 5.4 below).

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4. Measures to reduce Bycatch

4.1 Why cetaceans get caught

It is important to obtain details of when andwhere cetaceans get caught in fishing netsand also to investigate how and why thishappens, in order to devise effective preven-tative measures. It has been emphasised thateach operational interaction between smallcetaceans and commercial fishing gear islikely to require a solution specific to thatcombination of animals and gear (Read2000). In other words, a mitigation measurethat is effective for one species in a particularfishery may not work for different species.Equally, a measure that effectively reducesbycatch of a species in one particular fisherymay not be effective for that species inanother fishery. It is also worth noting thatin the United States, where bycatch reductionstrategies have been devised and implement-ed since the mid-1990s, these have allinvolved a combination of several measuresto address each bycatch problem (Read2000; see also 5.1.2).

The problem of harbour porpoise bycatch inbottom-set gillnets has been studied in a widevariety of fisheries, as has the behaviour ofthese animals around nets. Most hypothesesabout the mechanisms of their bycatchassume that animals that are foraging nearthe seabed may not detect the nets in timedue to the limited acoustic detectability ofthese nets (Kaschner 2003). Therefore, mostresearch into mitigation measures for thisproblem has focused on methods of increas-ing the acoustic properties of the nets, or

acoustically alerting the animals to theirpresence.

In the case of dolphin catches in pelagic trawlnets there is clearly another mechanism at play.Pelagic trawls are very noisy underwater and itis therefore very unlikely that animals getcaught because they do not detect them.Although little is known about the behaviourof small cetaceans around pelagic trawls,analysis of the stomach contents of bycaughtanimals indicates that, in at least some cases,they are predating on the same fish species asthe fishing vessels are fishing for (e.g. Couperus1997a; Gosselin 2001). It is also possible thatdolphins actively approach and enter pelagictrawl nets for foraging purposes. In this case,the disorientation of animals caused by changesin net geometry that occur during haulingoperations or changes in direction or speed ofthe towing vessels may be a possible reason fortheir capture (Couperus 1996; Connelly et al.

1997; de Haan et al. 1999). Most effort onmitigation to date has looked at how toexclude animals from the trawl net, througheither physical or acoustic means.

Another strategy to reduce cetacean bycatchlevels is to adjust how the problem fisheriesare managed in terms of when and where thefishing takes place, the level of fishing effortand the fishing method used.

The following sections outline some of thekey measures available or under developmentfor the mitigation of cetacean bycatch.

4.2 Technical mitigationmeasures

4.2.1 Exclusion devices

Exclusion devices (also known as selectiongrids or Nordmore grids) are widely used intrawl fisheries to prevent unwanted fish andnon-fish species bycatches. For instance, theturtle exclusion device is used to preventturtle bycatches in many shrimp trawl fish-eries. The device consists of a widely spacedmetal grid (through which fish can pass),placed in the extension piece of the trawl (i.e.the long tube before the cod-end). The angleof the grid deflects large animals, such asdolphins, upwards to an escape hatch in thetop of the trawl net, while fish continuethrough the grid into the cod-end(Northridge 2003b).

In response to the high common dolphinbycatch rate recorded in the UK’s winter seabass fishery in the western Channel, researchto investigate possible mitigation measureswas initiated in 2001 by the Sea MammalResearch Unit (SMRU) in collaboration withthe Scottish Pelagic Fishermen’s Association(Northridge 2003b). Initially, the use ofpingers was trialled in 2001 (see 4.2.2below). However, soon after this fishingseason, work was started on the developmentof a dolphin exclusion device. After develop-ment of a prototype that was tested in aflume tank, an initial sea trial by one Scottishpair was conducted in the spring of 2002.The trial was to be recorded with an under-water camera mounted onto the trawl butthis was curtailed by technical difficulties.However, fish were recorded passing success-

40

The Net Effect?


Repr

oduc

ed w

ith p

erm

issi

on fr

om D

EFRA

200

3.

Figure 2. Schematic model of the exclusion grid

41

The Net Effect?


fully through the grid. In the event, nodolphins were seen during the grid’s four-daytrial in 2002, although a shark was recordedescaping through the hatch apparentlywithout problem (Northridge 2003b).

In 2003, after some modification of thedevice, 42 days of sea trials were conductedand monitored with two cameras, one insideand one outside the trawl (although the latterwas removed for part of the trial) (Northridge2003a). An electronic grid sensor was alsoused to monitor the angle of the grid and thespeed of water passing through the grid.During the trial, observers monitored bycatchin the Scottish pair fishing with the grid, andthe others without it, all of which were fishingin the same general location.

The results from 2003 show that bycatchrates for the three pairs not using the gridwere high, with 37 dolphins caught in 62tows, a mean of 0.6 animals per tow. Thehighest bycatch rate was recorded inFebruary (1 animal per tow). The grid pairwas only operational during March andApril, therefore the total bycatch rates arenot comparable. However, in the 82 grid-tows observed only two dolphins were killed(Northridge 2003a; see Table 3).

The two dolphin fatalities occurred during aperiod when the camera was not functioning.

However, it was evident that one of thedolphins had passed up to the escape hatchand then become caught by its beak in themesh of the cover net (which is a flapdesigned to reduce fish losses). The secondanimal had become trapped behind the first.It was concluded that the two deaths werethe result of using a mesh size for the coverflap that was too large and that the problemcould be rectified by using a smaller mesh(Northridge 2003a).

The very much reduced bycatch rate in thepair using the grid was clearly not achievedby the intended mechanism as no animalswere observed to swim through the escapehatch. Instead, it seems that the experimentalset-up had the effect of deterring animalsfrom venturing too far down the trawl net(Northridge 2003a). Two possible reasonsfor this effect have been put forward. First,the grid sensor, which emits a loud noise attypical dolphin echolocation frequencies,may have caused the animals to turn backbefore they reached the final narrow sectionof the net. Second, the grid itself, which ismade of solid stainless steel bars, would beeasily detectable to dolphins either visually oracoustically and this alone may have deterredanimals from entering the narrow tunnel. Ifthe latter explanation is correct, it is suggest-ed that the simple placement of a large metalgrate further forward in the net, at the start

Table 3.

Comparison of catches between pairs with standard tows and

one fitted with a selection grid and associated experimental equipment

Non-grid No. of tows No. of No. of tows Dolphin tows as Dolphins caughtdolphins caught with dolphin catches % of total tows per tow

February 16 16 3 0.19 1.00

March 29 21 6 0.21 0.72

April 17 0 0 0.00 0.00

Total 37 9 0.15 0.60

Grid pair

March 40 2 1 0.03 0.05

April 42 0 0 0.00 0.00

Total 82 2 1 0.01 0.02

From Northridge 2003a

of the narrow tunnel section, might be suffi-cient to cause dolphins to turn round andescape before they enter the lethal part of thenet. Further trials are planned for 2004 to tryto elucidate how and why the grid appears tobe working, and whether this effect is likelyto present a long-term solution.

Concern has been raised that use of exclusiondevices may lead to the injury of animals thatpass through them, for instance as a result ofimpact with the grid. This has particularlybeen raised as an issue in New Zealand whereexclusion devices are already in commercialuse in the pelagic trawl fishery for squidwhich has a high bycatch of New Zealand sealions. Post-mortem examination of sea lionsthat have passed through the exclusion devicehas found considerable injuries, includingblunt trauma to the head and body (Duignan& Gibbs 2001). However, the cause of theseinjuries is not clear as the animals that passedthrough the exclusion device were retainedwithin a cover net, in which they then died.There do not appear to be significant differ-ences between the injuries sustained by theanimals that were excluded and died in thecover net and those that died in the trawl netitself. Indeed, the injuries recorded in the sealions appear to have been similar to thosefound in common dolphins that are assumedto have been bycaught in pelagic trawl nets in the UK.

However, it is vital that, if the exclusion deviceis found to provide an effective means of pre-venting dolphin bycatch in pelagic trawl nets,it must be clearly demonstrated that theanimals are unharmed by the process. It isalso important that any future use of suchdevices in commercial fisheries is closely moni-tored to ensure that they are being used cor-rectly and are working effectively.

Also, as outlined in 3.2 above, differentpelagic trawl fisheries and fleets use nets withdifferent configurations and operationalcharacteristics. Therefore, it will not neces-

sarily be a quick or simple process to transfera technological adaptation such as this fromone fishery to another. Even within the seabass fishery, further trials may be required toensure that an exclusion device developed forthe Scottish fleet could function effectively inthe larger French fleet, for instance. Althoughthe French industry has shown an interest inthe UK’s research on exclusion devices, andrepresentatives attended a presentation of thepreliminary results in April 2002, the Frenchhave not yet embarked on any collaborativework in this area.


(pingers) in set nets

Acoustic deterrent devices, or pingers, aresmall electronic devices that are attached tofishing nets and emit sounds at the frequen-cies to which small cetaceans are most sensi-tive. The aim of pingers is to produce asound that is either aversive to the animals orthat alerts them to the presence of nets. Thedevices were first developed in the late 1980sto reduce entanglement of humpback whalesin Newfoundland cod traps, but experimentswith them in the Gulf of Maine during theearly 1990s demonstrated that they are alsoeffective in reducing the bycatch of harbourporpoises in gillnet fisheries (Read 2000).

Several different devices are now commer-cially available, with varying physical andacoustic characteristics. It has been empha-sised that it is necessary to test the efficacy of any particular pinger in the context of thecetacean species of concern and the specificfishery (CEC 2002b). Numerous trials havenow been conducted in North America, NewZealand and Europe demonstrating, for themost part, impressive reductions in cetaceanbycatch rates of up to 92% (e.g. Kraus et al..1997; Dawson et al. 1998; Barlow &Cameron 1999; SMRU 2001; Larsen et al.

2002a). As a result, pinger deployment hasbeen introduced as a mandatory managementrequirement in several fisheries (e.g. in theUSA, the Gulf of Maine bottom-set gillnet

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The Net Effect?


fishery and the Californian driftnet fishery).

However, there are serious concerns about theuse of pingers as a bycatch mitigationmeasure. The devices are expensive, requiremaintenance such as periodic batterychanging, are prone to failure and may inter-fere with the setting and hauling of the nets.These factors make them generally unpopularwith fishermen (Read 2000). There are alsoserious problems with monitoring and enforc-ing their use. The efficacy of pingers has beenobserved to decrease substantially whendeployed in a commercial fishery rather thana controlled trial and also over time. Forinstance, porpoise bycatch in nets equippedwith pingers in the Gulf of Maine gillnetfishery was found to increase from 0 porpois-es per haul in 1997 to 0.3 porpoises per haulin 1999 (NMFS 2000). There is someevidence that porpoises may become habituat-ed to pingers after prolonged exposure,showing lessened reactions (Cox et al. 2001).Finally, there is considerable concern that thecontinuous and widespread deployment ofpingers may result in exclusion of harbourporpoises from critical habitats with poten-tially negative consequences for their conser-vation status (CEC 2002a).

In the north-east Atlantic region, trials totest the efficacy and practicality of pingersbegan in the Celtic Sea bottom-set gillnetfishery for hake in 1998. In this fishery,operated by English and Irish vessels, thetrial initially used a UK-manufactureddevice, known as the PICE pinger, whichhad recently been successfully tested inDenmark (SMRU 2001). However, thedevices suffered technical failure and had tobe abandoned. In 1999, the project wasrestarted using American Dukane pingersand continued for six months. The resultsdemonstrated that the porpoise bycatch ratein the pingered nets was 92% lower thanthat in the unpingered nets (SMRU 2001).However, the trial also revealed practicalproblems with attachment of the devices,

observed damage to the pingers (27%) andfailure of some devices as a result of poorconnections. The researchers concluded thatalthough they recorded a substantial reduc-tion in bycatch rate, there are practicalissues associated with pingers, such asattachment and battery changing as well ascost that might make the industry reluctantto adopt them. They also noted that effectivemonitoring and enforcement of pinger usewill be very difficult and that any mandatoryscheme must be accompanied by an inde-pendent observer programme to monitor theefficacy of the pingers (SMRU 2001).

In March 2003 the UK Governmentproduced a consultation document outliningproposals for measures to reduce bycatch ofsmall cetaceans in UK fisheries (DEFRA2003). Amongst other measures, thestrategy proposes the compulsory use ofpingers in UK bottom-set gillnets in thewestern Channel and Celtic Sea area(outside the 6-mile limit), in all UK set-netfisheries using a mesh size greater than 220mm in the central and southern North Sea,and in the North Sea wreck net fishery (onnets up to 300 m long). The development ofthese proposals is still under considerationby the Government. However, an immediateobservation by the fishing industry was thatthey should not be expected to invest inexpensive equipment if it is not clear which,if any, pingers would function effectively intheir fishery. As a result, in September 2003a pinger deployment trial was initiated inthe Celtic Sea hake fishery, to test the prac-ticality and durability of the four devicescurrently available (Airmar, Aquamark,Fumunda and Save Wave). The first phaseof the trial was conducted over the courseof one commercial fishing trip, duringwhich most of the pingers were subjected tofour shooting/hauling cycles. At the end ofthis phase only one of the four pingermodels tested had performed satisfactorily.The manufacturers are planning improve-ments (Seafish 2003).

In Denmark, following various trials in thelate 1990s, the Danish action plan to reducebycatch of porpoises in the North Sea(Ministry of Environment and Energy 1998)was adopted. As part of this, a regulationwas introduced in 2000 requiring pingers to be used in all Danish bottom-set gillnetfishing using nets up to 300m long in theNorth Sea from August to October (Larsenet al. 2002a). In effect, this requirementapplies only to wreck-net fishing for cod, and in the period of highest observedporpoise bycatches. Observations during2000 and 2001 recorded no porpoisebycatches in 129 wreck-net sets with pingers,whereas two porpoises were caught in 11wreck-net sets without pingers during thesame period in 2000 (Larsen et al. 2002a).The researchers conclude that the use ofpingers in the Danish North Sea wreck-netfishery has eliminated bycatch of harbourporpoises, although they acknowledge thateven with functional pingers on the nets theyshould expect to see some porpoise catchesin future. They also note that it is importantto continue monitoring the wreck-net fisheryto assess the efficacy of pinger use and anysigns of porpoise habituation.

Recently there has been some research into interactive pingers, where the deterrentsounds are triggered by the sonar clicks ofthe approaching porpoises (Amundin et al.

2002). This approach aims to address severalconcerns as it reduces noise pollution by onlytransmitting sounds when they are needed,and thus also delays habituation. To date,results of this work have only been reportedfrom trials carried out using captive harbourporpoises in Denmark (CEC 2002a),although sea trials were scheduled forsummer 2002.


(pingers) in pelagic trawls

The potential for pingers to reduce bycatchof cetaceans in pelagic trawl nets has beeninvestigated recently. In response to the high

dolphin catch rate recorded in the UK seabass pelagic pair-trawl fishery, pingers weredeployed during 2001, the first year of miti-gation trials. Dukane pingers were simplyplaced around the mouth of the trawl of onepair with the intention of deterring animalsfrom entering (Northridge 2003b). However,the rate of dolphin bycatch was found to behigher in the 15 tows conducted with pingersthan it was in the 37 tows without pingers.This trial was therefore abandoned. Duringfurther trials in the UK sea bass fishery in2003, Aquamark pingers were deployed, this time placed well back in the trawl inorder to deter animals from swimming intothe rear part of the net. The pingers wereintended to be removed and replaced on adaily basis on two of the observed pairs.However, rigorous trials were not completedbecause in both of the pairs, high catches ofdolphins occurred in the first tow of the trialwhen no pingers were in place (20 animals in two tows with no pingers deployed), and both the skippers asked to have pingersinstalled and kept in place for the rest of thetrial (catching eight dolphins in 32 tows withpingers deployed) (Northridge 2003a).Although the bycatch rate appears to bemuch lower in the pingered nets than in theunpingered nets, dolphins were caught inboth cases and, because the trial was unbal-anced, no conclusions could be drawn on the effect of the pingers on bycatch rates.

Pingers are also being investigated in theIrish pelagic pair-trawl fishery for albacoretuna (BIM 2003). The alarm system beingdeveloped looks at deterring dolphins fromthe vicinity of the trawl when the risk ofcetacean bycatch is believed to be high, i.e.when there is a change in net geometry, forinstance resulting from the vessel changingcourse or hauling the net. A prototypesystem was tested during the tuna seasonfrom July to September 2002, consisting ofa control unit in the wheelhouse of the boatwhich communicates with an underwaterpinger, via a through-water acoustic link.

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The system is triggered manually from thewheelhouse to coincide with high-riskmanoeuvres (BIM 2003), an approach whichis predicted to reduce the risk of habituationof the cetaceans. The trials have also investi-gated the use of Aquamark pingers, whichautomatically emit signals at randomisedintervals. Four pingers were placed round the trawl, about halfway back in the net.

Although the details of the Irish trials havenot yet been published, the results arereported to be encouraging and suggest thatthe devices are effective in reducing cetaceanbycatch (BIM 2003). However, the manuallytriggered device, although technicallyfeasible, is considered to be risky as errorsmay occur. Further work in 2003 is to inves-tigate the possibility of automatic or interac-tive activation of pingers when the vesselstarts to manoeuvre or when an echolocatinganimal approaches (BIM 2003).

4.2.4 Net modifications

Several different approaches to reducingporpoise bycatch in gillnets by modifying thenetting material have been investigated.Attempts have been made to increase theacoustic properties of the nylon used ingillnets by impregnating it with a densematerial (such as barium sulphate). Suchmodified nets, described as “acousticallyreflective nets”, were trialled in the Bay ofFundy. No porpoise catches were recorded in124 strings of modified nets, compared to atleast one porpoise caught in seven of 242control strings, but low bycatch rates in boththe modified nets and the controls preventedany definitive conclusion being drawn aboutthe efficacy of the modified nets (Trippel et

al. 2000). No significant difference wasobserved in the catch rate of the targetspecies in this trial.

A further study of impregnated nets was con-ducted in the Danish North Sea bottom-setgillnet fishery. Here, the netting was modifiedusing iron oxide and described as “high

density net” (Larsen et al. 2002b). The trialrecorded no porpoises caught in the modifiednets, compared to eight caught in the controlnets. However, the sampled effort was insuf-ficient to draw a clear conclusion because thetrial was terminated prematurely. Thisoccurred because of the significantly reduced(20%) catches of the target cod in themodified nets. Surprisingly, the Danishresearchers found that the acoustic propertiesof the ‘reflective’ net were no different to theunmodified net. They conclude that thereduced porpoise catches, and indeed fishcatches, are probably explained by theincreased stiffness of the net rather than itsacoustic detectability (Larsen et al. 2002b).

Whatever the mechanism, if high-densitynetting can be demonstrated to be effective atreducing bycatch, it has the potential to offera simple and inexpensive mitigation measure.However, the heavier and bulkier nets andreduced fish catches are unlikely to make thisan attractive option for fishermen.

The diameter of the twine used in gillnets maysignificantly affect the level of porpoisebycatch according to an analysis of observer-collected bycatch data from gillnet fisheries(Palka 2000). Lower bycatch levels seem to beassociated with thinner twines, although it isnot clear why this would be the case. Theeffect of twine diameter and other net charac-teristics on bycatch is currently being investi-gated in trials conducted by SMRU in the UK(Simon Northridge, SMRU, pers.comm.). Asimilar association seemed to be evident fromdifferences in bycatch rates in monofilamentand multi-monofilament nets (Northridge et

al. 2001). However, when this factor wasinvestigated experimentally, no differences inporpoise bycatch rate were found.

4.3 Management mitigationmeasures

4.3.1 Effort reduction

In general terms, the most direct way toreduce bycatch is to reduce the amount of

fishing effort. However, this approach willproduce the greatest bycatch benefit if theeffort reduction can be targeted at thosefishing sectors or gear types with the highestbycatch rates (CEC 2002b).

Reducing fishing effort is not likely to be apopular mitigation measure. However, wheneffort reduction is being introduced for othermanagement purposes, such as fish stockconservation, the greatest reductions incetacean bycatch could be achieved if sucheffort reduction was targeted at the vesselsusing the gears with the highest bycatch orwithin the times or areas with the highestbycatch. The danger in relying on effortreductions resulting from fish stock conserva-tion measures to gain cetacean bycatchreductions is that, without other precautionsin place, when fish stocks recover and fishingeffort increases, the bycatch is likely toincrease as well.

The European Commission has identifiedpriority measures for the integration of envi-ronmental protection requirements into theCommon Fisheries Policy (CFP), whichinclude the reduction of fishing pressure onfishing grounds to sustainable levels (CEC2002c). It specifies that “this reduction

should target fishing activities having adverse

effects both on the sustainability of fish

stocks and on the favourable conservationstatus of non-commercial species andhabitats”. However, there are as yet noexamples of targeted effort reduction beingintroduced in the EU for the purpose ofcetacean bycatch reduction.

4.3.2 Time and area restrictions

Addressing cetacean bycatch through restric-tion or closure of fisheries over a particularperiod or area is only likely to be effectivewhen bycatch is known to occur predictablyat higher levels at that time or in that areathan at other times or places (Read 2000). Inother words, time/area restrictions will be oflittle use where there is little spatial or

temporal variation in the bycatch rate. Timeclosures need not be on a monthly or seasonalbasis but, if a diurnal pattern of bycatch isevident, could be applied to the time of day ornight that fishing occurs (CEC 2002 b).

There are potential pitfalls with the use ofsuch partial restrictions. For instance, if anarea is closed to a particular gear type eitherpermanently or seasonally, fishermen mayswitch to a different gear type or continuefishing with the same gear elsewhere,possibly in waters adjacent to the closed area(CEC 2002b). The environmental effects ofeither of these outcomes need to be assessedbefore such management measures are intro-duced. This may militate against the intro-duction of such measures, if the conse-quences for either cetacean bycatch or otherenvironmental parameters are found to benegative. Alternatively, it could result in theintroduction of additional safeguards toensure that the measure does not result innegative consequences elsewhere.

In the Gulf of Maine bottom-set net fishery,time/area closures were introduced in 1994that actually resulted in an increase inharbour porpoise bycatches. A review of themeasures concluded that they failed becausethe area and duration of the closure were not adequate to cover the variation in spatialand temporal distribution of bycatches, andbecause of the displacement of fishingactivity and bycatch to outside the closedarea (Murray et al. 2000).

Time/area restrictions can also be combinedwith the use of technical mitigationmeasures. The requirement on the use ofpingers in the Danish North Sea cod wreck-net fishery only in the third quarter of theyear (i.e. the period of highest porpoisebycatch) is an example of this approach.Observer monitoring of this measure demon-strated that porpoise catches were reduced tozero in the pingered fishery during the firsttwo years (Larsen et al. 2002a). However,

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the report of this work does not include anyassessment of the levels of fishing effort inthe wreck-net fishery, or whether the pingerrequirement may have resulted in any redis-tribution of effort into other periods orfishing métiers.

4.3.3 Alternative gear types

Some fishing gear types are inherently proneto cetacean bycatch and in some cases themost effective way to solve the problem is tostop their use and introduce alternative geartypes. For instance, the plan drawn up forthe recovery of harbour porpoises in theBaltic Sea (the Jastarnia Plan), recommendsthat trials of fish traps, fish pots and long-lines should be conducted with the goal ofreplacing gillnets in the cod fishery(ASCOBANS 2002). It also suggests thatdriftnets used in the salmon fishery should be replaced with longlines in areas whereporpoise bycatch is likely to occur.

However, it is important when prohibitingthe use of one gear type that an adequateassessment is made of the alternative gearsthat may replace it and their potentialimpacts. For instance, the EU ban on drift-nets used for tuna and other large pelagicfish was introduced in 2002 largely becauseof the high bycatch of dolphins and otherwildlife species (see 3.4.1). However, oneconsequence of this has been a growth in the use of pelagic pair trawls to catch tuna,which may have a bycatch of dolphins evengreater than the driftnets (see 3.2.4).

4.3.4 Emergency measures

It has been proposed that timetabled defaultmanagement options should be adopted inthe absence of effective implementation ofbycatch reduction measures (ICES 2002).Such measures could include the restrictionor closure of fisheries, for instance wherecritical new bycatch problems are identified,where other mitigation measures are unavail-able or ineffective, or where bycatch reduc-tion targets are not met. In particular, where

there is evidence of a serious threat to theconservation of cetacean populations, suchemergency measures could be introducedunder the provisions of the new FrameworkRegulation on the conservation and sustain-able exploitation of fisheries resources underthe Common Fisheries Policy (see 5.3.1).

4.4 Bycatch managementframework

Experience from around the world hasshown that bycatch reduction can beachieved most effectively if mitigationmeasures are tailored to individual fisheriesand their particular circumstances, and thatthis tailoring is best done by a combinationof relevant fishermen, scientists, managersand conservationists (ICES 2002). However,to achieve this case-by-case approach and toimplement it effectively in the complex,multinational fisheries that occur in EUwaters will require the creation of a formaland strategic management framework andprescribed procedures for identifying andresponding to bycatch problems.

In its 2002 report to the EuropeanCommission on incidental catches of smallcetaceans, the Subgroup on Fishery andEnvironment (SGFEN) of the Scientific,Technical and Economic Committee forFisheries (STECF) concludes that, in orderfor the issue be properly addressed, “abycatch management framework should beestablished at an EU level at the earliestopportunity” (CEC 2002b). The subgroupgoes on to list the vital components of such amanagement framework.

Identification of overall management goals is highlighted as a vital prerequisite for anymanagement scheme. In the case of cetaceanbycatches in the European context, the aimadopted by ASCOBANS of restoring ormaintaining cetacean populations at or above80% of their notional environmentalcarrying capacity (see 5.2.2) has been identi-fied as an appropriate goal (CEC 2002b).

Within the overall management frameworkthere must be a monitoring and surveillanceprogramme to identify fisheries, or timesand areas where cetacean bycatch is aproblem and to quantify bycatch levels.Timely assessments of cetacean populationsare necessary, as is an agreed means ofdetermining the level of conservation threat.A formal institutional framework isrequired in which to devise bycatch reduc-tion plans where these are necessary, withset bycatch reduction targets and time-frames. Further, there must be a means of

implementing bycatch reduction plans,including effective enforcement and continu-ous monitoring and feedback to ensure thatthe overall objectives are met (CEC 2002b).An additional recommendation has beenmade by ICES that timetabled default man-agement options should be applied ifbycatch mitigation is not implemented effec-tively (ICES 2002). In other words,measures to reduce bycatch should beimposed (which could include restriction orclosure of the fishery) if bycatch reductiontargets are not met.

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5. Bycatch regulation

5.1 Regulation of bycatcharound the world

5.1.1 International treaties, conven-

tions and agreements

A large number of international and regionaltreaties, conventions and agreements have abearing on the protection of the marine envi-ronment; many of them cover fisheries or theexploitation of living marine resources, andseveral make specific commitments or resolu-tions on the matter of incidental capture ofcetaceans. The United Nations Convention onthe Law of the Sea (UNCLOS) of 1982 placesa duty on states to make sure that speciesassociated with or dependent on harvestedspecies are not depleted to levels at which they would become seriously threatened. The problem of indiscriminate fishingmethods has also been addressed within theRio Earth Summit (1992), the UN Food andAgriculture Organisation Code of Conduct forResponsible Fishing (1994) and the RomeConsensus on World Fisheries (1995). In par-ticular, the 1995 Agreement for theConservation and Management of StraddlingFish Stocks requires that the catch of targetand non-target species is reported along withcompliance with regional organisations whichhave specific measures aimed at minimisingcatches of non-target species (Gillespie 2002).

The issue of bycatch has become prominentwithin the International WhalingCommission (IWC) which, as early as 1975,recommended that member nations begin torecord the bycatch of small cetaceans. TheConvention on Migratory Species of WildAnimals (CMS) has also taken a seriousinterest in bycatch, passing a resolution(Resolution 6.2) in 1999 which recognisesbycatch as one of the major causes of mortal-ity of migratory species in the marine envi-ronment and requires Parties to theConvention to minimise as far as possible theincidental mortality of migratory species(CMS 1999). This resolution was reaffirmedand reinforced in 2002 when the CMSParties emphasised that bycatch remains one

of the major causes of mortality from humanactivities in the marine environment and rec-ommended a speedy implementation of CMSResolution 6.2 (CMS 2002).

5.1.2 National legislation elsewhere

There are several notable examples fromaround the world of national legislation thathas been introduced specifically, or is beingapplied, to address the problem of cetaceanbycatch. While none is held up as thepanacea, and bycatch still presents seriousproblems in these countries, the process thathas been adopted in the United States andsome of the principles being applied in NewZealand are progressive and provide impor-tant precedents that could be applied in thenorth-east Atlantic region.

In the United States, the incidental capture ofcetaceans is regulated by the Marine MammalProtection Act (MMPA), which was amendedin 1994 to address interactions betweenmarine mammals and commercial fisheries.The Act identifies the following goals:

i) reducing incidental mortality or seriousinjury of marine mammals occurring inthe course of commercial fishing opera-tions to below Potential BiologicalRemoval (PBR, defined as the maximumnumber of animals, not including naturalmortalities, that may be removed from amarine mammal stock while allowing thatstock to reach or maintain its optimumsustainable population) within 6 monthsof enactment; and

ii) further reducing these mortalities andserious injuries to insignificant levelsapproaching a zero mortality and seriousinjury rate by 2001.

The MMPA requires assessments to bemade of the status of marine mammalstocks, including stock structure, abun-dance, trends and levels of anthropogenicmortality. It further requires fisheries to be

categorised according to their likelihood ofcatching marine mammals, which isassessed through compulsory carriage ofobservers (Read 2000). If the magnitude ofbycatches, or other anthropogenic mortali-ty, exceeds PBR for a stock of marinemammals, that stock is deemed to be strate-gic, and the MMPA requires that a takereduction plan be developed. Such plansmust include regulatory and/or voluntarymeasures that will reduce mortality andserious injury levels to below PBR withinsix months of their implementation. Thetake reduction plans are developed byteams of stakeholders, including representa-tives from the commercial fishing industry,conservation groups, scientists, federal andstate officials, and fisheries managementcouncils. If the team cannot reach consen-sus on the plan, the Secretary of Commerceis required by the MMPA to develop a planto reduce takes below PBR. This defaultprovision has acted as an incentive forstakeholders of diverse backgrounds andinterests to work together to developbycatch mitigation strategies (Read 2000).

This system has been implemented in a rangeof fisheries throughout US waters and, whilenot without problems, it has made significantsteps towards reducing bycatch in some of thefisheries addressed (see Read 2000 for individ-ual case studies of four take reduction teams).

In New Zealand, the Government hasacknowledged that increased fishing effortin recent years has resulted in the incidentalcapture of significant numbers of non-targetspecies of marine wildlife protected underNew Zealand law, including Hector’sdolphin. As a response, the New ZealandGovernment introduced in 1996 a schemeto recover from the domestic commercialfishing industry the funding required toinvestigate and mitigate the impacts offishing on protected species of marinewildlife (West et al. 1999). ConservationServices Levies are approved by the Minister

of Conservation, administered by theDepartment of Conservation, and are col-lected by the Ministry of Fisheries. Thelevies are set annually following extensiveconsultation between the relevant govern-ment agencies and stakeholder groups.Levies are primarily used to boost observercoverage in selected fisheries, to monitor thestatus of protected species known to be inci-dentally taken in fishing operations, and todevelop ways of mitigating the bycatch ofspecies protected under the New ZealandMarine Mammals Protection Act 1978 andthe Wildlife Act 1953. These levies give fish-ermen a strong financial incentive toaddress their interactions with protectedspecies and thus negate the need for leviesto be paid (West et al. 1999).

In Australia, the Environment Protectionand Biodiversity Conservation Act 1999 is the primary instrument for actions toprotect and assist the recovery of endan-gered species and ecological communities.Under this Act, endangered or vulnerablespecies can be listed along with key threat-ening processes, for each of which a ThreatAbatement Plan must be prepared. In thecase of bycatch, the plan outlines actions to implement mitigation measures that areknown to be effective in reducing bycatch,provide for the development of newmeasures or improvements to existingmeasures, educate fishermen about threatmitigation and collect information tosupport future management decisions.Threat Abatement Plans are developed inconsultation with the fishing industry, non-governmental conservation groups, scien-tists and government authorities responsiblefor conservation and fisheries management.However, Australia has temporarilyexempted the major fishing operations fromcetacean bycatch assessment under thecurrent passage of the Act and none of theAct’s provisions are being used to mitigatecetacean bycatch.

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5.2 Existing obligations withinthe north-east Atlantic

5.2.1 Regional conventions

and agreements

The Convention for the Protection of theMarine Environment of the North-EastAtlantic (OSPAR Convention), which cameinto force in 1998, addresses the issue ofbycatch, highlighting the need for moreresearch and information on the effects offishing on non-target species such as marinemammals, amongst other impacts, and forimprovements in the monitoring and report-ing of bycatch and discards (OSPAR 2000).Equally, the North Sea Conferences haverepeatedly raised this issue. Most recently, in2002 the Ministerial Declaration of the FifthInternational Conference on the Protection of the North Sea (the Bergen Declaration)included agreement of a precautionary objec-tive to reduce bycatches of marine mammalsto less than 1% of the best available popula-tion estimate. The ministers also agreed todevelop, and adopt as soon as possible, arecovery plan for harbour porpoises in theNorth Sea (Anon. 2002).

However, the fora that probably have mostbearing on the issue of cetacean bycatch inthe north-east Atlantic region are the CMSAgreement on the Conservation of SmallCetaceans of the Baltic and North Seas(ASCOBANS) and the European Union (EU).These are addressed in more detail below.

5.2.2 ASCOBANS

The Agreement on the Conservation of SmallCetaceans of the Baltic and North Seas wasset up under the auspices of the Conventionon Migratory Species of Wild Animals (CMS).It came into force in 1994 and currently haseight Parties (Belgium, Denmark, Finland,Germany, the Netherlands, Poland, Swedenand the UK). Other Range States, includingFrance and Lithuania, are currently in theprocess of accession (ASCOBANS 2003c).

In the text of the Agreement, Parties recog-

nise “that small cetaceans are and should

remain an integral part of marine ecosys-

tems” and that bycatches, along with habitatdeterioration and disturbance, may adverselyaffect populations in the Baltic and NorthSeas. They therefore undertake to cooperateclosely in order to achieve and maintain afavourable conservation status for smallcetaceans. In particular, Parties agree toapply specific conservation, research andmanagement measures which include inter

alia “the development, in the light of avail-

able data indicating unacceptable interaction,

of modifications of fishing gear and fishing

practices in order to reduce bycatches”

(ASCOBANS 1991).

The aim of ASCOBANS was agreed at theSecond Meeting of the Parties (MoP) in 1997as “to restore and/or maintain biological or

management stocks of small cetaceans at the

level they would reach when there is the

lowest possible anthropogenic influence”. A suitable short-term practical sub-objectivewas specified: to restore and/or maintainstocks/populations to 80% or more of thecarrying capacity (ASCOBANS 1997). TheParties also agreed that the general aim shouldbe “to minimise (i.e. to ultimately reduce to

zero) anthropogenic removals within some

yet-to-be specified time frame, and that inter-

mediate target levels should be set”.

The Second MoP defined a level of “unac-

ceptable interactions” as being, in the shortterm, a total anthropogenic removal above2% of the best available estimate of abun-dance (ASCOBANS 1997). However, whenin 1999 the IWC-ASCOBANS WorkingGroup on Harbour Porpoises was taskedwith assessing their status in the North Seaand adjacent waters, it advised that, using abasic population model for harbour porpois-es and assuming no uncertainty in anyparameter, the maximum annual bycatch thatachieves the ASCOBANS interim objectiveover an infinite time horizon is 1.7% of thepopulation size in that year. If uncertainty is

considered, such as in estimating populationsize, maximum annual bycatch must be lessthan 1.7% to ensure a high probability ofmeeting the objective. They further statedthat meeting the objective in a shorter timewill require that annual bycatch be reducedto an even lower fraction of the abundance(Anon. 2000).

As a result, at the Third MoP in 2000 a resolution was passed that “defines, for the

present … unacceptable interactions” asbeing, in the short term a total anthro-pogenic removal above 1.7% of the bestavailable estimate ofabundance”(ASCOBANS 2000b). The reso-lution also notes that in the case of a severelyreduced population, or of species other thanthe harbour porpoise, or where there is sig-nificant uncertainty in parameters such aspopulation size or bycatch levels, then unac-ceptable interaction may involve an anthro-pogenic removal of much less than 1.7%(ASCOBANS 2000b). The Parties called oncompetent authorities to take precautionarymeasures to ensure that the total anthro-pogenic removal of marine mammals in theASCOBANS area and adjacent waters isreduced as soon as possible to below anunacceptable interaction level. The meetingalso identified the intermediate precautionaryobjective “to reduce bycatches to less than1% of the best available populationestimate” (ASCOBANS 2000b).

Although bycatch has been recognised byASCOBANS as being the highest-prioritythreat to the conservation of small cetaceans,it was noted by the Chair of the AdvisoryCommittee in 2000 that least progress hasbeen made by the Agreement with respect tothis factor (ASCOBANS 2000a). Indeed, atthe Fourth MoP in August 2003, in a resolu-tion passed on incidental take, Parties regret-ted “that the recommendations set out [at theThird MoP] to reduce bycatch to below ‘unac-ceptable interaction’ levels have probably notbeen fulfilled” (ASCOBANS 2003b). The

Parties also noted the increasing levels ofstranded cetaceans on coasts of the Celtic Sea and adjacent waters, which may be caused by interaction with pelagic trawling.

However, ASCOBANS has made someprogress with respect to the harbour porpoisein the Baltic Sea. In 2002, the ASCOBANSRecovery Plan for Baltic Harbour Porpoises(Jastarnia Plan) was finalised (ASCOBANS2002), the culmination of considerable politi-cal and scientific effort, managed under theauspices of ASCOBANS since 1997. In brief,the objectives of the plan are to:

a) implement precautionary managementmeasures immediately to reduce thebycatch rate to two or fewer porpoises per year in the portion of the Baltic that was surveyed in 1995;

b) improve knowledge in key subject areas as quickly as possible; and

c) develop more refined (quantitative)recovery targets as new informationbecomes available on population status,bycatch and other threats.

The Jastarnia plan was supported by theParties in a resolution passed at the FourthMoP (ASCOBANS 2003b) and the Meetingemphasised the importance of Parties andRange States now implementing the Plan.

A further significant development at theFourth MoP of relevance to bycatch wasagreement of the extension of theASCOBANS area. The new area encompass-es waters west of the UK and Ireland to lon-gitude 15º W, and southwards to include theBay of Biscay and waters west of Spain andPortugal to latitude 36º N, where it meetsthe boundary of the Agreement on theConservation of Cetaceans in the Black Sea,Mediterranean Sea and Contiguous AtlanticArea (ACCOBAMS). The name of theAgreement is, therefore, changed to theAgreement on the Conservation of SmallCetaceans of the Baltic, North East Atlantic,

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Irish and North Seas (ASCOBANS 2003d).

However, the limited capacity of ASCOBANSto make commitments, or even influencepolicy, relating to fisheries management washighlighted at the Fourth MoP. It was empha-sised in the resolution passed on incidentaltake that the European Community has exclu-sive competence for the conservation, manage-ment and exploitation of living aquaticresources in the context of the CommonFisheries Policy (ASCOBANS 2003b).

5.3 Existing EU legislation

5.3.1 Common Fisheries Policy

The CFP has evolved through a series ofdevelopments, initiated by the signing of the Treaty of Rome which established theEuropean Economic Community in 1957(Coffey 1995). Since this time, new MemberStates have joined the Community andvarious regulations and agreements havebeen introduced shaping policy, for instancewith regard to access to Member States’ ter-ritorial waters, 200-mile limits, and so on. In 1983, the introduction of Regulation170/83 established a twenty-year system forthe conservation and management of fish-eries resources in EC waters. A mid-termreview of the CFP followed in 1992, andresulted in a new system for fisheries andaquaculture under Regulation 3760/92.

In short, under the European Community’sCommon Fisheries Policy (CFP) only theCommunity has competence in fisheriesmatters. This means that only the EuropeanCommission can propose new legislation onfisheries and only the Council of Ministers can adopt that legislation. Member States can(within limits) apply more stringent nationalrules to the activities of their own vessels andwithin their own waters (DEFRA 2003).

In 2002, a major review of the CFP was con-ducted, with an explicit objective to minimisethe impact of fishing activities on marineecosystems, and in particular non-target

species and sensitive habitats (CEC 2002d).This resulted in the adoption in December2002 of a new Framework Regulation (EC)No. 2371/2002 on the conservation and sus-tainable exploitation of fisheries resourcesunder the Common Fisheries Policy. Article 2defines the objective of the CFP as “to ensure

exploitation of living aquatic resources that

provides sustainable economic, environmen-

tal and social conditions”. It further statesthat “the Community shall apply the precau-tionary approach in taking measuresdesigned to protect and conserve livingaquatic resources, to provide for their sus-tainable exploitation and to minimise theimpact of fishing activities on marine ecosys-tems. It shall aim at a progressive implemen-tation of an ecosystem-based approach tofisheries management.”

Among the many new provisions in theFramework Regulation are powers for theintroduction of emergency measures. “If

there is evidence of a serious threat to the

conservation of living aquatic resources, or

to the marine ecosystem resulting from

fishing activities and requiring immediate

action, the Commission, at the substantiated

request of a Member State or on its own ini-

tiative, may decide on emergency measures”

(Article 7). These can last for up to sixmonths (extendable for another six months).Similarly, if there is evidence of such aserious and unforeseen threat resulting fromfishing activities in waters falling under thesovereignty or jurisdiction of a Member Stateand where any undue delay would result indamage that would be difficult to repair, thatMember State can take emergency measures,not exceeding three months (Article 8).

To date, only three pieces of EU legislationhave been introduced under the CFP that relate specifically to cetacean bycatch. In 1992,Regulation (EC) No 345/92 restricted thelength of driftnets to 2.5 km. In 1998, theintroduction of Regulation (EC) 1239/98provided for the phasing out of all driftnets

used to catch tuna, swordfish and similar listedspecies, and their total prohibition from 1January 2002. Both these provisions apply toall EU waters (with the exception of the BalticSea, which is exempt from both provisions)and, outside those waters, to all EU fishingvessels. In addition, Regulation (EC) No973/2001 prohibits the encircling of schools orgroups of marine mammals with purse seines,except in the case of vessels operating with adolphin mortality limit (DML) under the con-ditions laid down in the Agreement of theInternational Dolphin Conservation Programin the Eastern Pacific Ocean.

5.3.2 The Habitats Directive

Council Directive 92/43/EEC on theConservation of Natural Habitats andWild Fauna and Flora (the ‘HabitatsDirective’) was adopted in May 1992.Article 2 of the Directive places a duty on Member States to ensure that anymeasures taken under the Directive aredesigned to “maintain or restore, at a

favourable conservation status, natural

habitats and species of wild fauna … of

Community interest” (which include allcetaceans). Article 11 requires MemberStates to undertake surveillance of the con-servation status of these natural habitatsand species. Article 12 requires MemberStates to establish a system of strict protec-tion for the animal species listed in AnnexIV(a) (which include all cetaceans).

Most specifically, Article 12.4 requiresMember States to establish a system tomonitor the incidental capture and killing ofAnnex IV(a) species. In the light of the infor-mation gathered, Member States are requiredto take further research or conservationmeasures as required to ensure that incidentalcapture and killing does not have a significantnegative impact on the species concerned.

It is evident that Member States are notmeeting their obligations under Article 12.4of the Habitats Directive, and this fact has

been acknowledged by the EuropeanCommission in the ExplanatoryMemorandum accompanying its proposal for a new Council Regulation on cetaceanbycatch (CEC 2003a). This states that “the

Commission has come to the conclusion that

the measures taken so far are insufficient or

lacking in coordination” and that “addition-

al Community action is needed in the fish-

eries sector to improve, in a consistent and

cooperative manner, measures aimed at the

conservation of small cetaceans.”

5.4 Proposed EU regulation onincidental catches ofcetaceans

As part of the 2002 review of the CFP, theEuropean Commission set out an Action Plan to integrate environmental protectionrequirements into the CFP. Part of this was acommitment to introduce a “new set of tech-

nical conservation measures designed to

reduce bycatch of cetaceans to levels guaran-

teeing favourable conservation status of

cetacean populations before 31 December

2002” (CEC 2002c).

In June 2003 the Commission published itsProposal for a Council Regulation layingdown measures concerning incidental catchesof cetaceans in fisheries and amendingRegulation (EC) No 88/98 (CEC 2003a). ThisProposal is based on advice provided by ICES(e.g. ICES 2002) and the Subgroup on Fisheryand Environment (SGFEN) of the Scientific,Technical and Economic Committee forFisheries (STECF) (CEC 2002a and b) andalso on various consultations.

The Proposal consists of three mainmeasures:

1 restrictions on the use of driftnets in theBaltic Sea (Article 9: introducing an imme-diate length limit of 2.5 km, and phasingthem out completely by 1 January 2007);

2 the mandatory use of acoustic deterrentdevices in certain fisheries (Articles 2 and

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3: Annex I specifies the fishing gear, areasand periods in which pingers are compul-sory, including driftnets, bottom-setgillnets and tangle nets in the Baltic Sea,wreck nets and large-mesh bottom-setgillnets in the North Sea and bottom-setgillnets and tangle nets in the Celtic Sea;Annex II sets out the technical specifica-tions of the devices and conditions of use),and

3 coordinated monitoring of cetaceanbycatch through compulsory onboardobservers for given fisheries (Articles 4 and 5: Annex II specifies the fisheries to be monitored and levels of coveragerequired, including driftnets in the BalticSea, North Sea and waters west of the UKand Ireland, pelagic trawls west of the UK,Ireland, France, Spain and Portugal as wellas in the North Sea, high opening trawls,and fisheries required to use pingers aslisted in Annex I; also Article 5 sets out thequalifications required of observers, theirtasks and reporting requirements).

While the Proposal has generally beenwelcomed by conservationists as a good firststep, a number of weaknesses and seriousomissions have been highlighted (e.g. WDCS2003). Broadly, these concern the degree ofemphasis on pingers, the adequacy ofproposed observer coverage levels, the lackof management objectives, targets or a man-

agement framework for bycatch reductionand, more specifically, the absence of anymeasures, or even stated intent, to reducebycatch in pelagic trawl fisheries. Theseconcerns are discussed in more detail inChapter 6 below.

The proposed Regulation will go through a process of scrutiny and negotiations inCouncil Working Groups consisting of civilservants from the Member States, in theFisheries Committee of the EuropeanParliament, and then in the EuropeanParliament itself before the final decision ismade in the Council of Fisheries Ministers.This process is expected to extend well into2004 and possibly beyond, and its outcomeis likely to be affected by the level of publicinterest and concern in the matter.

In the meantime, the European Commissionhas issued a contract for a study, usingtrained observers, of the numbers ofcetaceans bycaught in pelagic trawls in thenorth-east Atlantic (CEC 2003b). The studyis directed to give priority to the winter andspring fisheries of the Western Channel andthe Celtic Sea (various pelagic fish andspawning sea bass), to the summer albacorefishery in the north-east Atlantic, and to theyear-round fishery for anchovy in the Bay ofBiscay. The observation of fisheries isexpected to begin early in 2004.

6.1 Significance of cetacean bycatch

Fisheries bycatch clearly represents a majorproblem for populations of small cetaceans,probably the major problem in many parts ofthe world and in the north-east Atlantic inparticular. Numerous studies have investigatedthe issue in the north-east Atlantic over thepast two decades, albeit in a mostly piecemealand small-scale fashion, resulting in probablyhundreds of publications over many thou-sands of pages. These have been funded byvarious national governments and in manycases by the European Commission. Clearindications of problems have emerged, bothfrom onboard observer monitoring and fromstrandings records, and in some cases goodestimates of the scale of the problem havebeen produced. What is astounding, therefore,is the almost total lack of any policy or, moreimportantly, practical response to the issue ateither national or EU level (beyond thedriftnet ban adopted in 1998).

The cetacean species that are most affectedby bycatch in the north-east Atlantic, interms of absolute numbers, are the commondolphin and the harbour porpoise. Bycatchof common dolphins has been recorded inthe greatest numbers in pelagic trawl fish-eries, and that of harbour porpoises inbottom-set gillnet fisheries.

In the case of pelagic trawls, there has beentoo little monitoring to date to be able toassess total mortality levels. However, thenumber and scale of pelagic trawl fisheriesoperating in the Celtic Sea, Biscay andChannel area, coupled with the number ofstranded bycaught common dolphinsrecorded on surrounding coasts, indicate thatthe total mortality figure is likely to be highand probably unsustainable.

More monitoring has been conducted ofbottom-set gillnet fisheries, at least in someareas, and this has clearly demonstrated largeand unsustainable levels of harbour porpoise

bycatch, particularly in the Celtic Sea andNorth Sea. In areas where porpoise popula-tion levels are very low, such as the Baltic Seaand the southern North Sea/eastern Channel,even a very low level of bycatch is extremelyserious in conservation terms.

For other species, although bycatches may belower in absolute numbers, the impact maybe equally or possibly even more significant.For instance, bycatches in pelagic trawl fish-eries include Atlantic white-sided dolphins,striped dolphins, long-finned pilot whalesand bottlenose dolphins, most of which areconsidered to be far less numerous in theregion than common dolphins. As both pop-ulation and bycatch estimates for thesespecies are at best only partial, the signifi-cance of these mortalities for local popula-tions is unknown, but they are a potentialmajor cause for concern. The bottlenosedolphin, for instance, is only recorded in verysmall isolated populations in the waters offsouth-west England and is also at risk frominshore gillnets. Any incidental capture ofthis species would be highly significant.

It is important to recognise that populationsof many of these species are probably beingimpacted by several different fisheries (aswell as other anthropogenic causes of mortal-ity). For instance, the populations ofcommon dolphins in the Celtic Sea, Biscayand Channel area have already been subject-ed over many years to bycatch in the pelagictuna driftnet fishery (which has recently beenterminated) at levels that were probablyunsustainable. The limited studies of pelagictrawl fisheries to date, combined withevidence from strandings data, suggest thatcommon dolphin mortalities in these fisheriesmay well be unsustainable. In addition,common dolphins are caught, if to a lesserextent, in bottom-set gillnet fisheries (andpossibly others) in this area.

Equally, the harbour porpoise population inthe Celtic Sea is already known to have been

6. Conclusions and recommendations

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subjected to bycatch rates that far exceedwhat could be considered sustainable (over6% per annum) in English and Irish bottom-set gillnets alone, for probably more than adecade. Other gillnet fleets in the Celtic Seahave yet to be investigated. Plus, there is nowevidence from stranded animals in the UKthat this species may also be being impactedby the pelagic trawl fisheries in this area.

Therefore, judgement of whether any individ-ual interaction is ‘sustainable’ must be madein the context of total known or suspectedmortality across the range of fisheries (andother causes of mortality) operating in anarea. It must also take account of the cumu-lative depletion of populations that will becaused by unsustainable mortality levels. Inprinciple, if an unsustainable level of bycatchcontinues unchecked, the significance of thatmortality will become more acute year onyear as the population is gradually depleted.

Current bycatch levels for several species arebeing judged against abundance estimatesthat may now be significantly above the truepopulation levels, given the mortality ratesthat are assumed to have occurred in theyears since population surveys were last con-ducted. Current cetacean abundance esti-mates in the north-east Atlantic are at bestspeculative, as the only major survey wasconducted in the early 1990s, covering theNorth Sea (and eastwards), but only theCeltic Sea to the west of Britain andmainland Europe. For most populationsthere has been no assessment of trends orconservation status. In this respect, the large-scale cetacean abundance survey (SCANS II)planned to cover the North Sea and north-east Atlantic, broadly out to EU fisherieslimits, in 2005 and 2006 is welcome.However, more continuous surveillance ofpopulation trends is also required.

Given all the major areas of uncertainty, it isvital that extreme precaution is applied inassessing the significance of cetacean bycatch

and, in particular, in defining conservationand management objectives. It is recom-mended that the intermediate precautionaryobjective identified by ASCOBANS, toreduce bycatches to less than 1% of the bestavailable population estimate, be theabsolute maximum threshold that should beapplied, and that targets and timeframes toreduce bycatch to below this level, and ulti-mately towards zero, should be adopted.

6.2 Assessment andmonitoring of fisheries

The collection of data on fisheries, includingeffort, gear and location, must be improved,and these data must be comparable betweenfleets, in order to allow the extrapolation ofbycatch rates to individual fisheries and theestimation of total mortality levels within anarea or population. Also, the accessibility ofthese data, much of which are currently onlyavailable for enforcement purposes, needs tobe extended to allow proper assessment ofthe impacts of fisheries.

Routine and ongoing monitoring of fisheriesfor cetacean bycatch is clearly essential inorder to assess the nature and scale of theproblem and also to acquire the informationneeded to be able to devise appropriate miti-gation strategies. This can only be achievedreliably through independent onboardobservers, with alternative monitoring strate-gies only in the extreme circumstances wherean observer physically cannot be carried on avessel. Given the reluctance of many govern-ments to introduce routine monitoring ofincidental capture (despite an obligation todo this under the Habitats Directive), and the refusal of some skippers and even wholefleets to carry observers where this has beenproposed, compulsory observer schemes arethe only way to ensure effective and equi-table monitoring.

Monitoring of fisheries must continue after theintroduction of mitigation measures in order toassess the adequacy of their implementation,

and the efficacy of the measures in terms ofbycatch reduction. Where there is potential forthe mitigation measures themselves to havewider environmental impacts, as in the case ofpingers, it is essential that there is proper inves-tigation and monitoring of these and, ofcourse, withdrawal of the measure if the widerimpact is found to be unacceptable.

While the need to assess the impact ofexisting fisheries is now acknowledged and isbeing dealt with to some extent, no propos-als have yet been forthcoming for the priorassessment of the environmental impact ofnew fisheries or changes in fisheries policy inorder to prevent new problems from arising.While environmental impact assessment(EIA) and now also strategic environmentalassessment (SEA) are routine procedures formany other sectors of industry, the fisheriesindustry has yet to be included. Clearly, untilproper prior assessment is made of new fish-eries developments or the wider implicationsof policy decisions, fisheries managers andpoliticians will continue to be fire-fighting.Dealing with problems after they havebecome entrenched becomes much harderpolitically, and results in greater and unnec-essary environmental impact and also, ulti-mately, in a greater social and economicburden for the fishing communities involved.

6.3 Proposed new EU regulation

The European Commission’s initiative tointroduce the Proposal for a CouncilRegulation on incidental catches of cetaceansis an extremely important and welcomedevelopment, not least for its formalacknowledgement of the importance ofcetacean bycatch as a major conservationthreat and the inadequacy of the measurestaken so far to address it. The proposedRegulation has some significant weaknessesthat must be addressed, but it is importantthat the Regulation is adopted and imple-mented as soon as possible. However, even ifthe Proposal is adopted reasonably intact, itwill not solve the EU’s bycatch problems in

itself. It will need to be built on with furtherand more far-reaching measures and thismust be done quickly if the momentum ofthe initiative and the work that has led to itis not to be lost. Therefore, the followingcomments relate both to the measures putforward in the current proposal and tomeasures that are still required.

The proposed restrictions on driftnets in the Baltic Sea are extremely important. The Baltic population of harbour porpoises is severely threatened and is estimated tonumber as few as 600 animals, with fisheriesbycatch in both bottom-set gillnets and drift-nets presenting the major threat. Theproposed immediate restriction on driftnetlength to 2.5 km brings the Baltic very belat-edly into line with the rest of the EU, andtheir proposed total prohibition by 2007reflects the critical needs of this strugglingporpoise population. These time framesshould not be allowed to slip.

While the potential for effective deploymentof pingers dramatically to reduce harbourporpoise bycatch in gillnets under certain cir-cumstances is acknowledged, seriousconcerns remain over their practicality andefficacy in the longer term, their enforceabili-ty and their potential negative impactsthrough habitat exclusion. Therefore,although compulsory use of pingers mayoffer the best means of reducing the currentunacceptable level of bycatch in the shortterm, they should not be considered or pre-sented as a long-term solution. Indeed, thecurrent proposal places too much emphasison pingers to the exclusion of other potentialmitigation measures and more selectivefishing methods. It should be made clear thatthe pinger requirement is subject to reviewand will be time-limited. In the meantime,the Regulation should make provisions for a)comprehensive observer monitoring of vesselsusing pingers to assess both efficacy ofdeployment and bycatch rates; b) monitoringof cetacean populations in the affected areas

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to investigate any potential exclusion effects;and c) a parallel programme of developmentof other forms of mitigation and alternativefishing methods with an explicit view tophasing out pingers within a set timeframe.

The Commission’s proposed requirement forat-sea observer schemes in fisheries thatpresent a risk of cetacean bycatch is essential.This measure is fundamental to any efforts toquantify and address the bycatch problemacross the broad range of fisheries in which itoccurs. However, the levels of observercoverage set out in the Proposal representonly the minimum levels recommended bythe scientific advisers (SGFEN) and in somecases fall below this. For instance, SGFENrecommended that observer coverage shouldbe a minimum of 5–10% in the pelagic trawlfisheries in the Biscay, Celtic Sea andChannel areas, and “as high as feasible”during the December to March period whenmass dolphin strandings occur. TheCommission proposes only 5% coverage inthese fisheries and 10% during these criticalmonths. While even the proposed levels ofobservation would represent a majorimprovement in most fisheries, political andbudgetary expediency must not be allowed tocompromise the proper assessment of thescale and nature of the bycatch problem.

The Commission states in the accompanyingdocuments that “scientists consider that miti-gation of cetacean bycatch can be primarilyaddressed through an overall reduction infishing pressure” and that this “is expectedas a result of other community measuresaimed at ensuring the sustainability of fish-eries”. While measures being planned andintroduced to reduce fishing effort withinthe CFP are to be welcomed, effort reductiontargeted at those fishing sectors and geartypes causing the greatest impact should bemore actively used as a bycatch reductionmeasure in its own right.

The Commission’s Proposal does not identify

any management objectives or targets forbycatch reduction. Nor are any managementoptions identified in the event that reductionof bycatch levels is not achieved. Althoughthe Commission acknowledges the need for amanagement framework within which acomprehensive strategy can be set up, itcontends that this cannot be put together atthis stage “given the absence of precise infor-

mation on bycatch patterns [etc]”. On thecontrary, a management framework is pre-cisely the tool required to identify monitoringand surveillance requirements, assess the datathat are collected, devise appropriate man-agement responses for each specific fishery orarea (bycatch reduction plans with cleartargets and timeframes), oversee their imple-mentation and enforcement, and evaluatetheir efficacy and impacts. Indeed, the firstand key recommendation in the SGFEN finalreport is that “a management framework …needs to be implemented at an EU and otherappropriate levels if cetacean bycatch is to beaddressed adequately” (CEC 2002b). Thismust be introduced without delay.

6.4 Pelagic trawl fisheries

Although the Commission acknowledgesthat gillnets and pelagic trawls appear tocontribute most cetacean bycatch inEuropean fisheries, the proposed Regulationmakes no provisions regarding the pelagictrawl sector beyond observer monitoring.To date, only a limited number of thesepelagic fisheries have been monitored in anydepth, so the compulsory observer monitor-ing provisions are extremely important.However, high dolphin bycatch rates havebeen recorded already in the Dutch mackereland horse mackerel single-trawl fishery, theIrish albacore pair-trawl fishery and the UKsea bass pair-trawl fishery. The Communitymust make clear its intention to introducewithout delay measures to reduce bycatch inthose pelagic trawl fisheries where bycatchlevels are found to be problematic.

While the UK’s work to develop an exclusion

device may show promising early results, theseare currently only based on a very smalldataset. There is still considerable uncertaintyas to why the device appears to be workingand whether this effect will continue in thelonger term and without detriment to thedolphins. Therefore, there should be a parallelprogramme of research to investigate possiblealternative mitigation measures or fishingmethods for these fisheries.

In the absence of any other effectivemeasures for the mitigation of bycatch inpelagic trawls, the Community must beprepared to introduce management measuresincluding the suspension or closure of fish-eries where necessary. In particular, wherethere is evidence of a serious threat to the

conservation of cetacean populations, theCommission should introduce emergencymeasures, as provided for by Article 7 of thenew Framework Regulation of the CFP ((EC)No 2371/2002).

Finally, the proposals put forward to dateapply only to fisheries that operate within EUwaters. However, there is evidence of substan-tial cetacean and other protected speciesbycatch occurring in the EU’s considerabledistant water fisheries such as the pelagictrawl fisheries off Mauritania. It is therefore,essential that provisions made for bycatchmonitoring and mitigation (as well as the req-uisite provisions for surveillance and enforce-ment) are also reflected in the Community’sregulation of its distant water fleets.

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Acknowledgements

We would sincerely like to thank Marie-Pierre Gosselin for her assistance in researching thisreport. We are also grateful to Kristin Kaschner and Simon Northridge for their valuableinput and to Henrique Cabral, Marina Sequeira, Carina Vonk, Stella Turk, Jan Haelters andAlfredo López for providing much useful information. We would like to thank many WDCSstaff for their assistance, particularly Mark Simmonds, Jo Clark, Simon Keith, KateO'Connell and Gina Davies. We also thank Doug Parr and others at Greenpeace for theirsupport of this project.

This report was funded by Greenpeace Environmental Trust.

The Net Effect?

A WDCS report for Greenpeace62

Reproduced with permission ICES 2003.

Appendix 1ICES Fishing Areas in the north-east Atlantic

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Appendix 2Breakdown of the French pelagic fleet for 1992

1992

Quarter 1 Quarter 2 Quarter 3 Quarter 4

Northern Biscay Total: 147 boats, working Total: 150 boats, working Total: 137 boats, targeting Total: 79 boats, targetingin pairs targeting horse in pairs targeting sardine, anchovy and sardine. anchovy.mackerel or hake. hake and horse mackerel.

(Also small activity in theCeltic Sea.)

77 boats, pair trawlers 78 boats, working in pairs 90 boats, working in pairs, 34 boats, working in pairs,with mesh size >20mm, and targeting hake and targeting small pelagic targeting anchovy.targeting hake, sea bass horse mackerel (with species such as anchovy,and horse mackerel. some trips to the sardine and horse

Celtic Sea). mackerel.

62 boats, pair trawlers 42 boats, targeting 47 boats, working with 17 boats, working in pairs, working with several sardine and mackerel. panel trawls (one trawl targeting sardine and herring.gears, targeting horse /single boat), targetingmackerel, cephalopods anchovy.and pollack.

33 boats, working in pairs 32 boats, targeting anchovy,using various types of using panel trawl.trawls, targeting cuttlefishand pollack.

Southern Biscay Total: 103 boats, targeting Total: 108 boats, targeting Total: 131 boats, targeting Total: 48 boats, targeting tunaanchovy and occasionally sea bream, squid, anchovy, tuna and swordfish. species and swordfish. Alsowhiting. hake, Norway pout and (Also offshore.) capture other species

other species. including squid. (Sometimes work offshore.)

16 boats, targeting sea 22 tuna boats, working 16 boats, targeting horsebream and bass, and offshore, targeting mackerel, swordfish, tuna,also capture herring tuna and swordfish. squid and hake. (Some and mackerel.* offshore trips for tuna

species)

35 boats, working in pairs, 49 boats, targeting tuna 13 boats, targeting Norwaytargeting horse mackerel, and hake. pout and other species,sea bream and hake. using several trawls.(They sometimes usesmall-mesh trawls foranchovy.)*

37 boats, targeting various 60 boats, targeting Norwayother species with several pout, mullet, bass, squid,trawls for a single boat. cuttlefish, sea bream(Fisheries of Norway pout, and others, using variouswhiting and squid also types of trawltake place.)* (including bottom trawl).

Western English Channel 44 boats with several 15 boats, targeting sea breamtrawls for a single boat, (and targeting tuna andtargeting sea bream. swordfish offshore).(Also targeting of whitingin the Bay of Biscay, withcaptures of Norway poutand other species).

Notes 250 boats used pelagic 258 boats used pelagic 268 boats used pelagic 127 boats used pelagic trawlstrawls during this quarter. trawls during this quarter. trawls during this quarter. during this quarter.67 boats, targeting anchovy 17 boats, targetingin the Bay of Biscay, anchovy in the Bay ofworking in pairs. Biscay with panel trawl.

* These boats also workin the English Channel.

Common Name Scientific Name

Cetaceans

Atlantic white-sided dolphin Lagenorhyncus acutusBottlenose dolphin Tursiops truncatusBlue whale Balaenoptera musculusCommon Dolphin Delphinus delphisFin whale Balaenoptera physalusHarbour Porpoise Phocoena phocoenaHector’s Dolphin Cepalorhynchus hectoriHumpback whale Megaptera novaeangliaeMinke whale Balaenoptera acutorostrataOrca (also known as killer whale) Orcinus orcaPilot whale (long-finned) Globicephala melasPilot whale (short-finned) Globicephala macrorhyncusRisso’s dolphin Grampus griseusSei whale Balaenoptera borealisSperm whale Physeter macrocephalusStriped Dolphin Stenella coeruleoalbaVaquita Phocoena sinusWhite-beaked dolphin Lagenorhyncus albiostris

Fish

Albacore Thunnus alalungaAnchovy Engraulis encrassicolusBigeye tuna Thunnus obesusBlack Bream Spondyliosoma cantharusBlue whiting Micromesistius poutassouBluefin Tuna Thunnus thynnusBogue Boops boopsCod Gadus morhuaDogfish Scyliorhinus caniculaGobies GobiidaeHake Merluccius merlucciusHerring Clupea harengusHorse mackerel (also known as ‘scad’) Trachurus trachurusLantern fishes MyctophidaeLumpfish Cyclopterus lumpusMackerel Scomber scombrusNorway pout Trisopterus esmarkiiPearlsides MaurolicidaePilchard (also known as ‘sardine’) Sardina pilchardusPlaice Pleuronectes platessaPoor cod Trisopterus minutusRays Raja spp.Saithe Pollachius virensSalmon Salmo salarSandeels AmmodytidaeSea bass Dicentrarchus labraxSilvery pout Gadiculus argenteus ssp. thori Skate Raja batisSkipjack tuna Katsuwonus pelamisSole Solea soleaSprat Sprattus sprattusSwedish pollack Pollachius pollachiusSwordfish Xiphias gladiusTrout Salmo truttaTurbot Psetta maximaWhiting Merlangius merlangusYellowfin tuna Thunna albacares

Other species

Grey seal Halichoerus grypusNew Zealand sea lion Phocarctos hookeriSpider crab Maia squinado

Appendix 3Table of scientific names of species referred to

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Cover photo: Greig/Greenpeace Harbour porpoise, Boswinger Beach, Cornwall, January 2004

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