Natural History of Sharks, Skates, and Rays

Conservation & Management

MARE 380Dr. Turner

Fisheries ManagementInvolves regulating when, where, how, and how much people fish to ensure that people will be able to fish in the future

NOAA's National Marine Fisheries Service (also known as NMFS or NOAA Fisheries Service) is the Federal Government agency responsible for fisheries management in the United States

You Down With EEZLaw Of the Sea – established 200-mile-wide Exclusive Economic Zones (EEZ) – granting coastal nations exclusive rights with respect to natural resources

US EEZWaters 3 to 200 miles offshore (or 9 to 200 miles offshore in western Florida and Texas)

US EEZInternational shortages and disputes over fishing rights were solved the establishment of the Exclusive Economic Zone (EEZ), a 200-mile national fishing zone

Actually led to overfishing by U.S. domestic fishing fleets

Western Pacific EEZ

Fisheries ManagementFederal fisheries management in the United States is driven primarily by the Magnuson-Stevens Fishery Conservation and Management Act (MSA) - 1976

Set up a democratic form of fisheries management in which stakeholders of fisheries resources held important roles in their overall management

Magnuson-Stevens Governs the conservation and management of ocean fishing

Establishes exclusive U.S. management authority over all fishing within the EEZ

Foreign fishing within these areas prohibited unless permitted - only with reciprocity to U.S. fishing vessels

Establishes 8 Regional Fishery Management Councils responsible for management plans

National Standards of the Magnuson-Stevens Act Conservation and management measures shall:(1) Prevent overfishing while achieving optimum yield

(2) Be based upon the best scientific information available (3) Manage individual stocks as a unit throughout their range, to the extent practicable; interrelated stocks shall be managed as a unit or in close coordination

(4) Not discriminate between residents of different states; any allocation of privileges must be fair and equitable

(5) Where practicable, promote efficiency, except that no such measure shall have economic allocation as its sole purpose

Magnuson-Stevens

(6) Take into account and allow for variations among and contingencies in fisheries, fishery resources, and catches

(7) Minimize costs and avoid duplications, where practicable

(8) Take into account the importance of fishery resources to fishing communities to provide for the sustained participation of, and minimize adverse impacts to, such communities (consistent with conservation requirements)

(9) Minimize bycatch or mortality from bycatch

(10) Promote safety of human life at sea

Magnuson-Stevens

In Hawai‘iWestern Pacific Regional Fishery Management Council – (WPRFMC)

Decision-making body to develop and recommend specific management measures

Fishery management plans (FMP), subject to approval and implementation by NOAA Fisheries

Shark LegislationShark Finning Protection Act – 2002 - amendment to MSA to prohibit and person:1) aboard a US vessel from finning a shark2) possessing shark fins aboard a US vessel w/out the carcass3) landing fins w/out carcass4) from a foreign vessel w/in US EEZ from landing, possessing, or shipping fins w/out carcass5) selling or purchasing shark fins taken in volation

Shark Finning Protection ActAims are to:1) prevent unsustainable levels of shark catch due to demand for shark fins2) prevent waste of shark meat

Led to localized regulations by states or Regional Fishery Councils

Shark Protection in Hawai‘iObserver program – both swordfish & tuna

100% coverage shallow-setting swordfish

20% coverage deep-setting tuna

Shark Protection in Hawai‘iTo most fishermen in Hawai‘i – sharks are a nuisance/not desirable as they:

1) wreck gear2) are not very marketable – only mako & thresher (meat or fins)3) risk of injury4) risk of overfishing5) negative stigma6) tainting of catch in hold - urea

Fishing TechniquesBottom trawlPurse seine

LonglineGill net

Bycatches and Discards

The aim of most fishers is to capture species that have financial or energetic value – target species

Target species are often associated with non-target species (organisms not intended catch of that fishery)

Can become part of the catch known at incidental catch

All Longlines not Equal

International RegulationsFew countries (Canada, New Zealand, Australia, South Africa, United States) have fishery management plans for shark fisheries

International cooperation and coordination of existing and development of new sharkmanagement plans are needed

Wide range of shark distributions require cooperation, assessments, and agreements to understand and manage sharks sustainably

International RegulationsNo international management mechanisms effectively addressing the capture of sharks

Number of international bodies:

International Commission for the Conservation of Atlantic Tunas (ICCAT)Northwest Atlantic Fisheries Organization (NAFO), Inter-American Tropical Tuna Commission (IATTC)

Initiated efforts to encourage member countries to collect information about shark catches

International RegulationsInternational management initiatives:

Guided by:Atlantic Tunas Convention ActAgreement for the Implementation of the Provisions of the United Nations Convention on the Law of the Sea relating to the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks

International RegulationsNinth Conference of the Parties to the Convention on International Trade in Endangered Species ofWild Fauna and Flora (CITES) adopted a Resolution on the Biological and Trade Status of Sharks, requesting that: (1) The United Nations Food and Agriculture Organization (FAO) and other international fisheries management organizations establish programs on shark species(2) all nations utilizing and trading specimens of shark species cooperate with FAO and other international fisheries management organizations

International RegulationsFAO Committee on Fisheries: develop Guidelines for a Plan of Action for the improved conservation and management of sharks

International Plan of Action for the Conservationand Management of Sharks (IPOA)

Code of Conduct for Responsible Fisheries: encompasses all elasmobranch fisheries (commercial and recreational) - calls on all member nations to implement IPOA through own national plan

Shark Catch from Hawai‘i Longline Data

Got Sharks?

Year #Caught #Retained Fins only Whole sharks %Retained %Finned

1994 114,656 98,119 15,374 1,163 14.4 13.4

1995 101,292 67,760 32,842 690 33.1 32.4

1996 100,992 57,254 43,109 629 43.3 42.7

1997 85,838 36,496 48,552 790 57.5 56.6

1998 99,919 39,062 60,083 774 60.9 60.1

1999 87,576 29,308 57,286 982 66.5 65.4

2004 74,917 71,857 0 3,060 4.1 0

Changing Attitudes

Changing Latitudes

Fisheries ModelsTo produce a good fisheries model, we must account for all contributions to reproduction, growth, and mortality, throughout the life cycle of the fishery resource species

MortalityRecruitment

Reproduction

Growth

(Nursery Area)

Fisheries ModelsSimilarly, population biomass depends upon growth, reproduction, natural mortality, but also includes the implications of fishing mortality

Population Biomass

Reproduction Growth

Fishing mortality

Natural mortality

Models!

Constructing Fisheries ModelsInitial goal to to determine maximum sustainable yield (MSY)

Complex calculations based upon several life history parameters, including:

Surplus population models – used to search for the largest fishing mortality rates that can be offset by increased population growth, normally measured in changes in population biomass per unit time

population densitypopulation biomasspopulation growth rate

** Equilibrium – point at which processes balance one another

Oh, I forgot to er, carry the one“I first observed this technology at the airport gift shop” – Professor John Frink

Logistic population growth

Populations grow most quickly at intermediate sizes up to a maximum total biomass Bmax

MSY in biomass occurs at a level of fishing mortality that places the population at an

intermediate size

Bmax

MSY

Bmax Bmax

Applying Fisheries ModelsSince MSY is a small target (an actual number) and is also a moving target (due to temporal changes in productivity), actual catch controls are first gauged by simulations of high and low quotas.

If quota set too high:yield would exceed the surplus population so the population would be driven to extinction

If quota set too low:if the population is larger than BMSY – will stabilize and yield lower than BMSY

if population is smaller than BMSY – will become unstable and either increase to equilibrium at the higher population size or crash

Evaluating Fisheries ModelsThe choice of production quotas is minor compared to the procedure of fitting these models to real data to estimate MSY and the level of fishing effort at which it occurs

Several to choose from:e.g., - delay-difference, virtual population, statistical catch-at-age

Yield-per-recruit models – seek fishing mortality rates that achieve the best tradeoff between the sizes of the individual caught, and the number of individuals available for capture

The logic of yield-per-recruit models is based upon the trade-off between growth

and mortality of individuals

A = optimal age at which to catch fish

A

Fisheries Models in ActionIf fishing mortality rates are set too high, too many individuals will be taken before they have had a chance to grow – growth overfishing

Yield per recruit (Y/R) and population biomass per recruit

(B/R) for a single cohort of fish, for various potential fishing

mortalities, F

Y/R

B/R

Fishing mortality - F

Overfishing!

If fishing mortality is too low, although individuals will be large when captured, the total yield will be low

Fisheries ManagementFisheries are managed because the consequences of uncontrolled fishing are undesirable

e.g., - fishery collapse, economic inefficiency, loss of employment, habitat loss, decreases in abundance of rare species

Primary goal – maintain maximum biologically sustainable yield (MSY or BSY)

Recently a mixture of biological, economic, social, and political objectives

MultiplicityCurrent thinking: - concept of MSY may not be useful in fisheries management since overfishing has caused major alterations in the trophic structure of marine food webs

Individual species do not live in a vacuum – they eat each other and may compete for food and space

Biological interactions – mean that population dynamics of different species are inevitably linked