Norway and Russia

009

Report on the joint researchonGyrodactylus salaris

in the northern region ofNorway and Russia

Bjørn Ove JohnsenEvgeniy P. leshko

Andrej KarasevArne J. Jensen

I. Schurov

NINA. NIKU Foundation for Nature Research and Cultural Heritage Research

Report on the joint researchonGyrodactylus salaris

in the northern region ofNorway and Russia

Bjørn Ove JohnsenEvgeniy P. leshko

Andrej KarasevArne J. Jensen

I. Schurov

Foundation for Nature Research and Cultural Heritage Research

nina.niku Project Report 009

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ignature pers I responsible:

2

Johnsen, B.O., leshko, E.P., Karasev, A., Jensen, A.J &Schurov, I. 1999. Report on joint research on Gyrodactylussalaris in the northern region of Norway and Russia. -NINA-NIKU Project Report 009: 1-20.

Trondheim, april 1999

ISSN 0807-3082ISBN 82-426-1039-8

Management field:Environmental monitoring

Copyright (C):Foundation for Nature Researchand Cultural Heritage Research (NINA•NIKU)

The report may be quoted when the source ismentioned by name.

Editor:Tor G. HeggbergetNorwegian Institute for Nature Research, Trondheim

Layout and designSynnøve Vanvik

Stock: 300

Contact address:NINATungasletta 27485 TrondheimTlf: 73 80 14 00Fax: 73 80 14 01

The Norwegian Directorate for Nature Management

© Norwegian institute for nature research (NINA) 2010 http://www.nina.no Please contact NINA, NO-7485 TRONDHEIM, NORWAY for reproduction of tables, figures and other illustrations in this report.

AbstractJohnsen, B.O., leshko, E.P., Karasev, A., Jensen, A.J& Schurov, I. 1999. Report on the joint research onGyrodactylus salaris in the northern region of Norwayand Russia. - NINA-NIKU Project Report 009: 1-20.

Concerns about parasites and diseases amongsalmon in Russia and Norway, especially G. salaris inthe White Sea basin, have necessitated this project.

Atlantic salmon presently spawn in 16 rivers along theKarelian White Sea coast. Reliable data on the condi-tions of these rivers and their spawning statistics isrequired in order to solve the problem of restorationand conservation. In 1990, the Karelian ResearchCentre began an examination of the salmon rivers. By1998, the rivers Pulonga, Keret, Kem, Vyg (lower part)and Kuzreka had been examined fully, and the riversVonga, Pongoma, Kuzema, Gridina, Kalga, Suma andShuya examined partially. The data available definitelyindicates a constant decrease in fish caught along theKarelian coast of the White Sea. Recommendationson solving these problems are discussed.

Today, two hatcheries in Karelia are engaged insalmon breeding. Hatchery-reared parr are released at2 years of age. The total number of parr released hasnot exceeded 200 000-250 000 individuals. The returnmakes up less than 1 %.

Investigations on the parasites of salmon parr in theWhite Sea basin were reported by several authorsfrom 1935 to 1985. Their analyses showed significantquantitative and qualitative differences in fauna invarious areas of the region. In the River Keret investi-gations have continued every year since 1992. In1992, G. salaris was found infecting fins, skin and gillsof salmon parr. The parasite had not been recordedpreviously on salmon parr in rivers of the White orBarents Sea basins. G. salaris is believed to havebeen introduced via stocking from the Vyg hatchery.The density of salmon parr in the River Keret was verylow in 1992-98 compared to 1990 and 1991.

On the Kola Peninsula there are 37 main salmonrivers draining to the White Sea basin and 28 salmonrivers draining to the Barents Sea basin. The KolaPeninsula rivers have a considerable reproductivepotential. The total area of spawning/breeding groundsof all salmon rivers is 3 857 hectares, 1 104 hectaresin the Barents Sea rivers and 2 753 hectares in theWhite Sea rivers. During the period 1986-91, theabundance of spawners running into the Barents Searivers fluctuated from 20 000 to 41 000 (32 000 onaverage) and between 110 000 to 215 000 fish (152000 on average) were found in the White Sea rivers.

3

ninaeniku Prolect Report 009

At present, four hatcheries in the Murmansk regionproduce juvenile salmon for further release into naturalwater basins. One hatchery releases juveniles into therivers of the Barents Sea basin, while the three otherhatcheries operate on the White Sea basin rivers.Average release from all the hatcheries is about 450000 juveniles at age 2+.

In 1993-98, several rivers in the Kola Peninsula weresampled by electrofishing and salmon parr wereexamined for occurrence of Gyrodactylus. G. salariswas not found.

Landlocked Atlantic salmon occur in several hydro-logical systems in European freshwater bodies. Nineof the lakes (Ladoga, Onega, Kuito and others) arelocated in Russia, one in Finland (Saimaa), one inSweden (Vånern) and one in Norway (Byglandsfjord).Parasite studies of salmon parr from these lakes arescarce. However, the lakes of the Kamennaya riversystem, which are situated in the upper tributaries ofthe Kem river, have been studied and no G. salariswere found in the landlocked salmon parr. A riverpopulation of landlocked salmon lives in the upperparts of the river Namsen in Norway. In 1997 and1998, a total of 41 specimens from the river Namsenwere studied, but no G. salaris was found.

In 1993, G. salariswas found on rainbow trout in a fishfarm in Siskili at Lake Enare in northern Finland. Thefish in the fish farm were slaughtered and the farmwas disinfected. One monogenean was found onpectoral fin of a rainbow trout less than 1 km down-stream from the infected fish farm in 1996. There aresome concerns about the parasite spreading down-stream in the river Pasvik, but the river was notinvestigated in 1997 or 1998 due to lack of financialsupport.

G. salaris is most probably a recent introduction toNorwegian rivers, and its distribution is associatedwith stocking of fish from infected salmon hatcheries.In Norway, the primary goal is to prevent the furtherspread of G. salaris and to exterminate the parasite inas many infected rivers and hatcheries as possible. Inthe period 1981-97,25 Norwegian rivers were treatedwith rotenone in an attempt to exterminate the para-site, and so far 13 rivers have been stated healthyafter the treatment. The parasite has turned up againin the rivers Skibotnelva, Rauma and Steinkjervass-draget.

In Russia, the Gyrodacty/us-situation is complex be-cause the parasite occurs naturally where the Balticsalmon occur (Ladoga lake, Onega lake), but notwhere Atlantic salmon occurr (The White Sea area,and the Kola Peninsula). The development of theGyrodactylus infection in the Atlantic salmon popula-tion of the river Keret resembles the development in



Norwegian rivers, with epidemics in the salmon parrpopulation resulting in very low densites of parr andfew adult salmon ascending the river. Further spreadof the parasite from this river to other rivers in theWhite Sea area wiU constitute a great danger tosalmon populations in the area. Actions should there-fore be taken as soon as possible starting with abarrier in the lower part of the river Keret to preventsalmon from ascending the river. Some years after thebuilding of the barrier the parasite should be exter-minated from the river by treating the area down-stream of the barrier with rotenone.

Key words: Atlantic salmon, Gyrodactylus salaris,Norway-Russia.

Bjørn Ove Johnsen and Arne J. Jensen, NorwegianInstitute for Nature Research, Trondheim, Tungasletta2, N-7485 Trondheim, Norway.Evgeniy P. leshko and lgor Schurov, KarelianResearch Centre, Russian Academy of Science, 11Pushkinskaya St., Petrozavodsk 185610, Karelia,Russia.Andrej Karasev, Knipovich Polar Institute of MarineFisheries and Oceanography, 6, Knipovich Street,183763 Murmansk, Russia

4

PrefaceIn a letter dated 25 June 1992, The NorwegianDirectorate for Nature Management (DN), referring tothe Russian-Norwegian Environmental Commission,invited the Polar Institute of Marine Fisheries andOceanography (PINRO) to participate in a Russian-Norwegian joint research programme on anadromousfishes. The Norwegian Institute for Nature Research(NINA) was proposed as the Norwegian institutionresponsible for the scientific work in the joint project. AProtocol of Intents between PINRO and NINA wassigned in the same year, and a proposal for a jointresearch programme was written and sent to DN forfunding. The aims of this project have been: 1) to ex-change knowledge and technology about surveys inAtlantic salmon rivers, and handling of material,including harmonising of methods and equipment, 2)to survey selected Atlantic salmon populations tocollect information about changes in population sizeand composition, which may indicate changes in theenvironment and 3) to obtain information about para-sites on Atlantic salmon, especially Gyrodactylussalaris and salmon lice.

Since 1993 this joint programme has been within theRussian-Norwegian Working Group on the marineenvironment of the Barents Region, which is one ofthe working groups which are within the Russian-Norwegian Environmental Commission. The main partof this programme has been a comparative study oflife history of Atlantic salmon in four rivers, twoRussian and two Norwegian. Included in this studyhave been growth, density and heavy metal analysesof parr, strategies during smolt migration, and growthand age structure of adult salmon (Jensen et al. 1997,1998).

In 1994, an agreement of intent for the joint researchprogram about salmon management in Norway andRussia, was made by the Norwegian Directorate forNature Management (DN) and the Russian Academyof Science, Karelian Research Centre (KRC). Themain goal of the research project was studies con-cerning parasites and diseases among salmon,especially G. salaris in the White Sea basin, and NINAwas asked to manage the project. In 1995, theGyrodactylus project was included in the program onanadromous fishes.

The results from the Gyrodactylus project is presentedin this report. The project has been financed by DN,PINRO, KRC and NINA.

April 1999

NINA, Trondheim KRC, Petrozavodsk PINRO,Murmansk

Bjørn Ove Johnsen Evgeniy leshko Andrej Karasev


ContentsAbstract 3Preface 4

1 Introduction 5

2 Material and methods 6

3 Results and discussion 63.1 Atlantic salmon rivers in Karelia 6

3.1.1 Reproductive potential of theAtlantic salmon in Karelia 6

3.1.2 Atlantic salmon catch in Karelia 83.1.3 Artificial salmon reproduction in

Kareha 93.1.4 Plans for conservation and

enhancement of salmon stocks inKarelian rivers 10

3.1.5 Investigations of parasites on Atlanticsalmon parr in Karelian rivers 10

3.1.6 Investigations of salmon parr in theRiver Keret 11

3.2 Atlantic salmon rivers in theMurmansk region 123.2.1 Reproductive potential of the Atlantic

salmon in the Murmansk region 133.2.2 Atlantic salmon catch in the

Murmansk region 133.2.3 Artificial salmon reproduction in the

Murmansk region 133.2.4 Investigations of Atlantic salmon

parr in Murmansk rivers 133.3 Landlocked salmon populations 143.4 G. salaris in Lake Enare and in

the River Pasvik 153.5 Investigations in Russian hatcheries

regarding G. salaris 153.6 G. salaris on Atlantic salmon parr in

the River Vefsna, northern Norway 163.7 Parasite fauna of the European grayling

in the River Vefsna, northern Norway 17

4 Measures against G. salaris 18

5 References 19

5

1 Introduction


Biological investigations of rivers in northern Norway in1975-79 coincidently led to the discovery of theectoparasite, Gyrodactylus salaris, as a serious pro-blem for Atlantic salmon populations in Norwegianrivers (Johnsen 1978, Heggberget & Johnsen 1982).G. salaris is most probably a recent introduction toNorwegian rivers, and its distribution is associatedwith stocking of fish from infected salmon hatcheries(Johnsen & Jensen 1986). Populations of salmon parrand catches of ascending salmon have been severelyreduced in infected rivers.

In Russia, Gyrodactylus salaris occurs naturally in thepart of the country where the Baltic salmon occurs(Ladoga lake, Onega lake), and not where Atlanticsalmon occurs (The White Sea area, and the KolaPeninsula).

G. salaris was found on salmon parr in the river Keretin 1992 (Bristow et al. 1994, leshko et al. 1995). Thiswas the first registration of G. salaris in rivers drainingto the White Sea.

In 1993, G. salaris was detected in a rainbow troutfarm in Lake Enare, Finland. The fish farm was disin-fected, but there is still some concern about theparasite spreading downstream in the river Pasvik.

The main goals of the Gyrodactylus project are:

1. To report on the status of Atlantic salmon popula-tions in rivers draining into the White Sea Basin

2. To map the distribution of G.salaris in the drainagearea of the White Sea

3. To survey some selected rivers regarding densityof salmon parr

4. To investigate hatcheries regarding G. salaris5. To discuss measures against G. salaris



2 Material and methodsThe parasitological studies of fish in the Russianrivers were made according to Dogiels method(Bykhovskaya-Pavlovskaya 1985) and include studiesof all organs. The number of G. salaris was countedon each fin and on the body of each fish. The termsprevalence, intensity and mean intensity are used asrecommended by Margolis et al. (1982). Density esti-mates of salmon and trout parr in the rivers weremade with electrical fishing equipment according tothe removal method (Zippin 1956, Bohlin 1984).

6

3 Results and discussion

3.1 Atlantic salmon rivers in Karelia

On the Karelian coast, the rivers are of mountainousor semi-mountainous type. They have extreme rapids,usually on the lower sections. One of the main charac-teristics of the rivers in this region, is the large numberof lakes that occurr along their course. The fish com-munity of the Karelian coastal rivers include 15 speci-es, with the most common species being: Atlanticsalmon (Salmo salar), brown trout (Salmo trutta),grayling (Thymallus thymallus), whitefish (Coregonuslavaretus), pike (Esox lucius), perch (Perca fluviatilis),roach (Rutilus rutilus), burbot (Lota lota), minnow(Phoxinus phoxinus), bullhead (Cottus gobio), stickle-back (Gasterosteus aculeatus), ten spined stickleback(Pungitius pungitius) and flounder (Platichthys tlesus).

3.1.1 Reproductive potential of theAtlantic salmon in Karelia

According to available data, Atlantic salmon presentlyspawn in 16 rivers of the Karelian White Sea coast(Figure 1). The length of the rivers Keret, Vonga,Kem, Vyg, Suma and Nyukhtcha ranges from 100-200km. The remaing rivers, Pulonga, Gridina, Kalga, Sig,Kuzema, Pongoma, Letnaya, Shuya, Kuzreka andKolezhma do not exceed 100 km. The rivers Kem andVyg are both regulated for hydroelectric purposes, andthere are five dams along the river Kem. The data pre-sently avalable on the size of the spawning/breedinggrounds (SGA) and spawning beds is displayed inTable 1. It should be mentioned that examination ofthe rivers was conducted in the late 50's. Many riverswere not fully examined at that time and there arediscrepancies in the assessment of the SGA sizes.Since that time, the situation in many of them haschanged dramatically and for most of the rivers dataon the SGA does not exist.

Reliable data on the conditions of the rivers and theirspawning statistics is necessary in order to solvethe problems of restoration, conservation, abundanceand growth of the salmon populations. Therefore theInstitute of Biology of the Karelian Research Centre ofthe Russian Academy of Sciences began a newsurvey of the salmon rivers in 1990. By 1998, therivers Pulonga, Keret, Kem, Vyg (lower part) andKuzreka had been examined fully and the riversVonga, Pongoma, Kuzema, Gridina, Kalga, Suma andShuya had been examined partly.


Sapadnaya LitsaTitovka

Pechenga

\ffivaLuvengaKolvitsa

PilaPorja

UrnbaChernaya

0 25 50 75fams==~~

Malaya sapadnaya LitsaUra

TulornaKola

SprednyayaTyuva

ZarubikhaKlimkovka

DolciayaTeriberka Barents SeaMuchka

VoronyaOfenka

RindaZolotaya

KhadovkaVostochnaya Litsa

SidorovkaVarzina

DrozdovkaChernaya

IvanovkaSavikha

lokanciaKadialovka

SapadnayaChernaya

LumbovkaKamenka (I)

Peschanka

DanilovkaGlubokaya (1)

SnezhnitsaSosnovka

Glubokaya (II)Babya

eZ3 Kuzreka Likhodeevka,Khlebnaya Pulonga

Pulonga I Bolshaya KumzhovayaKeret I PialitsaOlenitsa ChapomaSalnitsa* Jugina

Varzuga StrelnaKamenka (II)

Gridina ChavangaKalga deInra

Sig-reka

VongaKuzemaPongomaLetnjayaKem

ShujaVyg

Figure 1. Atlantic salmon rivers in the Murmansk region and in Karelia.*: mainly sea trout.

7

Kuz-rekaSuma

KolezhmaNjukscha

WhiteSea

nina.nlku Project Report 009

KachkovkaOrlovka

Ponoy



Table 1. Length of river access for salmon, size of spawning area and size of spawning/breeding grounds(SGA) for salmon rivers in the Karelian region of the White Sea basin. The "Length" data originate fromthe examination of the rivers in the late 50's, while the "Corrected length" data give the length of the riveraccess for salmon today.

Main river

PulongaKeret

Total for Keret watershed

GridinaKalgaSigVongaKuzemaPongoma

LetnayaKemShuyaVyg (Low Vyg)KuzrekaSumaKolezhmaNyukhtchaTotal for Karelian rivers

Note: * preliminary data

Tributary Length (km) Corrected Size of spawning Size of SGA, (m2)length (km) area (m2)

-ChernayaEletLouksa

52110384813

725959

10662.5

86

7719485

18846

16487

106

3.1.2 Atlantic salmon catch in Karella

Salmon fisheries on the White Sea developed a longtime ago. Catch data are available from the secondhalf of the 19th century. Salmon was then caught inmany rivers and along the White Sea coast as well.The fishery was especially intensive in the lowerreaches of the rivers Kem, Vyg and Keret. Variousfishing modes existed then: the garva, the peremetand the poesd (Russian names for different fishingtools). The most commonly used methods were byzabor and zakol (fences or racks with traps). In 1860,the lower reaches of the Kem contained 158 zaborand zakols (Korablev 1974). In 1880, 265 zabor andzakols were observed along the Karelian coastal area,including 169 on the river Kem.

In the early 1880's, the number of zabors started de-creasing because of the rapid growth in wood raftingon the rivers of the Karelian coast, and by 1897 there

5210638*48*

9*

8*49*

no data106*no data86*

no data4

26*

7no datano datano data

8

166 060 3 703 880

were only 136 left. In the period from 1875 to 1889,the mean annual salmon catches were 28.8-30.4 tons.In 1890-95, the annual catch increased to 35.2 tonsand in 1895-99 it increased further to more than 48.0tons (Korablev 1974). However, since 1900 a gradualdecrease in catch has occurred.

Possible reasons for the reduction in catch are anexcessive catch rate the previous decade and theeffect of massive wood rafting. Unfortunately, no com-plete statistical data base exists that would allow for areview of a continous series of observations. How-ever, what is available definitely indicates a constantdecrease in fish catch on the Karelian coast of theWhite Sea (Table 2).

The value of fishing in specific areas has varied fromplace to place and also with time. Early in the 20thcentury the main salmon fishing areas were con-centrated close to the river Keret, although large


amounts of salmon were also caught near the riversGridina, Pongoma and Vyg. In the 1920's the riverKem became the most important river, and in theperiod 1920-33 nearly half of all the salmon catch forthe western coast of the White Sea was obtainedhere. Presently only one river - the river Keret retainsits significance for the fishery. A decline in the catch ofadult salmon has been observed in later years in theriver Keret (Table 3).

Table 3. Number of salmon esti-mated in the trap (1 day closed, 1—2 days open) in the river Keretduring the period 1985-98.

Year Number of salmon

Table 2. Average yearly catch (tons) of Atlantic salmon inKarelian rivers (White Sea basin)

1985 3 940 The hatcheries decided to work with eggs from other1986 3 230 sources, because the native stocks were very low in1987 2 427 both rivers. Eggs for the Vyg hatchery were collected1988 3 294 from Kem salmon until 1965. Fry incubation and1989 3 531 rearing was conducted in Vyg water, and the young1990 2 520 fish (parr) were released into several rivers including1991 690 the Vyg, Pongoma, Kuzema and Kalga. During 1965-1992 536 68 eggs from Kola river salmon (Kola Peninsula) were1993 687 delivered to the Vyg hatchery, with the fry being1994 753 released into the rivers Vyg, Kem and Pongoma. Later1995 1 066 (in 1970) the Vyg hatchery started to collect eggs from1996 391 Keret river salmon and release the fry into the same1997 180 river. Only in particular cases were small batches of1998 607 fry released into the rivers Vyg, Kem and Pongoma.

Kem hatchery obtained eggs from Kola river salmon,and released the fry into the rivers Kem, Pongomaand Shuya. Hatchery-reared parr were released at 2years of age. The total number of parr released did notexceed 200 000-250 000 individuals. The return fromthese releases made up less than 1 % of the adultpopulation.

9


3.1.3 Artificial salmon reproduction inKarelia

Today, two hatcheries in Karelia are engaged insalmon breeding. A third, the Petrozavodsk hatchery,which began operating in 1977, was closed in 1990 fora number of reasons, principally an excessively lowegg and fry survival rate.

The Vyg hatchery was built in 1956 on the river Vyg,23 years after the construction of the Belomorsko-Baltiiskiy channel and 3 years after the Matko-nezhskaya hydropower station was put into operation.By that time, the salmon in the river Vyg were on theedge of total extinction. The Kem hatchery was builton the river Kem in 1971, 5 years after Putkinskayahydropower station, when the salmon were almostexterminated.


nina.niku Protect Report 009

3.1.4 Plans for conservation andenhancement of salmon stocks inKarelian rivers

Atlantic salmon production (both natural and artificial)in the Karelian area of the White Sea basin must beconsidered as extremely unsatisfactory. The reasonsfor such a situation have been discussed many timesin several publications. The salmon stock develop-ment strategy in Karelia involves: 1) the possible fulluse of natural spawning stock coupled with the artifi-cial reproduction and restocking of depleted stocks; 2)regulating industrial activity in the basins of thespawning rivers; and 3) the conservation and protec-tion of spawning beds. Well-founded recommenda-tions on solving these problems can only be given onthe basis of a modern detailed inventory of existingspawning stocks to evaluate the present situation. Formost of the rivers such data are not yet available. Thefollowing tasks are of primary importance:

- Certification of the salmon riversEvaluation of the size and condition of the spaw-ning stocks.

-

Organization of regular surveys of salmon parrdensities in the rivers and number of spawningredds. This will allow for the forecasting and for themodification of salmon escapements.

In addition the organization of complex investigationson the Keret river requires full accounting of down-stream-migrant salmon. Results of current investiga-tions on the Keret (1990-98) indicate an alarmingsituation. A steep decline in abundance of adultsalmon has been observed. During the same periodthe density of young salmon decreased dramatically.The presence of the monogenean parasite G. salarisis the most probable cause of this threat to the Keretriver salmon stocks. The parasite is believed to havebeen introduced via stocking from the Vyg hatchery.

The information obtained in these investigations willform the basis for identifying the potential productivityof salmon rivers and for the elaboration of measuresto optimize the Atlantic salmon catch. In addition, dataon the status of natural reproduction is necessary foroptimizing enhancement.

It would be advisable to include the following mea-sures in the plan for the development of salmonenhancement in Karelia:

1) Kem hatchery should work only with Kem riversalmon.

2) To construct a hatchery on the River Keret, whichshould utilize only Keret river salmon. The primaryresearch goal shou(d be to determine the optimumcapacity and location of the hatchery on Keret andto work out the most efficient scenario for the

10

operation of the Vyg hatchery based on the use ofVyg river salmon (brood stock capture and holdingand locations and form of parr release into theriver).

3) To study the possibility of building hatcheries onthe rivers Gridina, Pongoma, Kuzema and Shuya,which are the most promising for salmon enhance-ment. To achieve this task the investigationsasessing the salmon population, and size andcondition of these rivers SGA's need to becontinued.

4) Taking into consideration that the aforementionedsuggestions will require financial investment andtime, as well as solving other problems (e.g. lack ofhigh-quality, locally produced food for salmon pro-duction), special attention should be given to in-crease the efficiency of the existing hatcheries.

3.1.5 Investigations of parasites onAtlantic salmon parr in Karelianrivers

The first notes on parasites of salmon parr in theWhite Sea basin came from Dogiel & Petrushevsky(1935) who reported 12 freshwater species. Thesedata were supplemented by Malakhova (1972) whostudied salmon parasites in the river Keret. The para-site fauna of salmon parr consisted of five freshwaterspecies which have complicated life cycles. Mitenev &Shulman (1985) reported 27 parasite species onyoung salmon parr from the rivers of the Barents andWhite Sea basins. Their analyses showed significantquantitative and qualitative differences in fauna fromvarious areas of the regions. They also noted that thefauna is very impoverished in the southern part of theregion (Karelia, Arkhangelsk region), primarily due tothe disappearence of species.

The parasites of salmon parr in eight rivers flowinginto the White Sea basin were studied in July-August1992-97 (Table 4).

Fish were collected from spawning/breeding areas byelectrofishing. The sampling localities were in thelower rapids of the rivers near the river mouths.However, in the river Keret 3 localities in the Varatsky,Sukhoi rapids, and upper reaches were also sampled.

In 1995, the rivers Gridina and Kalga were investi-gated. The average salmon parr abundance in therivers Vonga, Pongoma, Gridina and Kalga in 1993-95was about 0.4-1.5 parr/m2.


3.1.6 Investigations of salmon parr in theRiver Keret

The river Keret is situated in the taiga zone of northernKarelia. The river Keret begins at Lake Petri and flowsthrough four lakes. Total length of the river is 110 km,and the length of the lake section is 34 km. The totaldrop in river elevation is 90.6 m and mean flow rate is23.3 m3/s. There are 18 rapids in the river Keret.Normal smolt age in the river Keret is three years.

In the river Keret, investigations of young salmondensity began in 1990, while parasitological investiga-tions have continued every year since 1992. Thefigures in Table 5 are based on samples of 15 salmonparr from each site.

Table 4. Number of salmon parr collected for parasite examina-tions in rivers tiowing into the White Sea in the Karelian region (in1994 and 1996 only G. salaris infection was studied).

11


In 1992, G. salaris was found infecting fins, skin andgills of all salmon parr in Varatsky. In the lower part ofthe river no parasites were found. The parasite hadnot been previously recorded on salmon parr in riversof the White or Barents Sea basins (leshko et al.1995). In 1993, only the Varatsky region was investi-gated. Fifty-seven percent of the salmon parr wereinfected and the mean intensity was lower than in1992. In 1994, almost all salmon parr in the Varatskyand Sukhoi regions were infected, but the meanintensity was quite low in the Sukhoi region. In 1995,the prevalence and mean intensity in the Varatskyregion were the same as the year before, while G.salaris was not found in the upper parts of the river.As the data of 1996 shows, all locations sampled inthe river Keret had G. salaris (Table 5). In 1997, onlytwo

Table 5. Occurrence of G. salaris on salmon parr (prevalence (P) andmean intensity (I)) from different years and locations in the river Keret."Lower part" is the section between the outlet of the river and thesalmon trap. Varatsky is situated 20 km from the sea, while Sukhoi andthe "Upper part" are situated 80 km and 105 km from the sea,

River 1992 1993 1994 1995 1996 1997 1998

Keret 30 30 30 15 60 55Pulonga 15 16Vonga 15Pongoma 15Gridina 25Kolezhma 0Kuzema 0Kuzreka 0ShuyaKalga 15Kem 5VygSuma 15

respectively.

1992 1993 1994 1995 1996Locations PI PI PI PI PI

Lower part 0 0 - 100 75Varatsky rapid 100 226 57 13 100 399 100 313 100 314Sukhoi rapid - - 93 6 - - 100 66Upper part 0 0 80 7



salmon parr were found, and both were infected.Investigations carried out in 1998 showed that theintensity of the infection of the parr was much higherin September than in July (Table 6). It can thus beassumed that heavily infected parr die when the riverbecomes covered with ice. Moreover, infestation washighest in the river stretches inhabited by both secondand first year fish (Table 6).

G. salaris is believed to have been introduced viastocking from the Vyg hatchery. In the period 1986—89, landlocked young salmon were transported fromthe Petrozavodsk hatchery to the river Shuja (Onegabasin) by helicopter. During one of those years, thishelicopter also transported young salmon from theVyg hatchery to the river Keret the same day. Theyoung salmon from the Vyg hatchery were transportedin the same tank as the landlocked salmon. G. salarishad probably survived in the tank after the transport ofthe landlocked salmon and was introduced via salmonfrom the Vyg hatchery to the river Keret.

The density of salmon parr in the river Keret in theSukhoi and Varatsky rapids was very low in 1992-98compared to 1990 and 1991 (Table 7).

Table 6. Seasonal dynamics of salmon parr infestation by G. salaris in the river Keret in 1998.

Table 7. Density of salmon parr (n/100 m2) in different locations andyears in the river Keret.

12

3.2 Atlantic salmon rivers in theMurmansk region

In the Kola Peninsula there are 37 main riversinhabited by Atlantic salmon that drain to the WhiteSea basin (Zubschenko et al. 1991). The passableriver stretch for Atlantic salmon in most of these riversis rather short. In many of the rivers the salmonmigrate up 20-30 km, and in some rivers only 5-10 kmfrom the mouth because of impassable waterfalls.Favourable hydrological conditions and large areassuitable for spawning and breeding, however, com-pensate for the short lengths. It should be noted thatthe Varzuga river, one of the richest salmon rivers onEarth, flows here. The total spawning area for Atlanticsalmon in this river is more than 1.500 ha (Kazakov etal. 1992), and estimated parr densities in 1994 and1995 averaged 28.8 ± 12.0 and 19.3 ± 5.9 individualsper 100 m2, respectively (Jensen et al. 1997).

There are 28 salmon rivers on the Kola Peninsuladraining into the Barents Sea. In two rivers (Tulomaand lokanga) can Atlantic salmon migrate morethan 200 km, while in six other rivers (Pechenga,Bolschaya Zapadnaya Litsa, Teriberka, Voronja,Harlovka, Vostochnaya Litsa) they can migrate morethan 100 km. All the other rivers are much smaller, butstill rather productive.

JULY SEPTEMBERLocality Age

groupNumber Prevalence Intensity (mean) Number Prevalenceof fish of fish %

Intensity (mean)

Morskoi 0+ 5 100 1-139 ( 33) 9 100 15-2 531 ( 801)Morskoi 1+ 2 100 144-340 (242) 3 100 3 037-5 895 (4710)Sukhoi 0+ 15 20 1- 13 ( 5) 15 46.6 1- 144 ( 35)


3.2.1 Reproductive potential of theAtlantic salmon in the Murmanskregion

The Kola Peninsula rivers have a considerable repro-ductive potential. The total area of spawning/breedinggrounds for all salmon rivers combined is 3 857hectares, with 1104 hectares in the Barents Sea riversand 2 753 hectares in the White Sea rivers. During1986-91, the abundance of spawners running into theBarents Sea rivers fluctuated from 20 000 to 41 000(average 32 000), and that the White Sea riversfluctuated from 110 000 to 215 000 fish (average152 000) (Zubschenko & Kuzmin 1991).

3.2.2 Atlantic salmon catch in theMurmansk region

Since 1922, nearly complete records of salmoncatches in rivers of the Kola Peninsula and its coastalareas exist. In the period 1922-90, the catch variedbetween 130 tons (1932) and approximately 750 tons(1937, 1938). Berg (1935, 1948) considered that theabundance of salmon is subject to natural fluctuationswith a 9-11 years periodicity. 1n fact, the lowestcatches were registered in 1921, 1932, 1942, 1951,1963, 1972 and 1982. Azbelev (1960) remarks that asa rule the minimum catches are registered in the firstdecades, and long-term depressions in salmon abun-dance always begin in the middle or the end of adecade and continue until the middle of the followingone. Such depressions were registered on the KolaPeninsula in 1921-32 and in 1963-72 (Zubscenko &Kuzmin 1991).

3.2.3 Artificial salmon reproduction inthe Murmansk region

The Murmanrybvod has been artificially breedingAtlantic salmon in the Murmansk region since themiddle of 1930's. The main purpose of which was toincrease salmon stocks and to compensate for thedamage to salmon production caused by the buildingof hydropower stations. At present four hatcheries,which produce juvenile salmon for further release intonatural water basins, are operating in the Murmanskregion:

- Taibola (Barents Sea basin)- Kandalaksha (White Sea basin)- Umba (White Sea basin)- Knyazhaya Guba (White Sea basin)

One hatchery releases juveniles into rivers of theBarents Sea basin, while the other hatcheries releasefish into the White Sea basin rivers. The average

13

nina.nlku Project Report 009

release from all the hatcheries combined is about450 000 juveniles at age 2+.

Eggs for the hatcheries were collected from wildAtlantic salmon. Egg incubation and breeding of juve-niles took place under natural water temperatures.Rearing technology of juvenile salmon is designed tomimic natural conditions as closely as possible.During two years of rearing, their weight reaches 10-12 g, on average. They are stocked in rivers at an ageof 2 years. At that time the bulk of juveniles were parr,and 10-15 % of them were close to smolting.

The hatcheries release their juveniles in spring afterthe spring freshet at river temperatures of 3-5 °C. Themajority of juveniles live in the river for one yearbefore running to the sea. After one year in a riverreared juveniles do not differ in their physiological andbiological characteristics from the wild ones. Thereturn as spawning migrants averages about 1 %(Kuzmin & Zubschenko 1991).

3.2.4 Investigations of Atlantic salmonparr in Murmansk rivers

There is a danger of the further spread of G. salarisfrom the river Keret to other White Sea rivers.Specialists from PINRO therefore, monitor the mostimportant salmon rivers within the Murmansk region.

Annual parasitological investigations are carried outon the following White Sea rivers: Kovda, Virma,Kanda, Lubche-Savino and Niva, as well as theUmba, Kandalaksha and Knyazhegubsky hatcheries.G. salaris has not been found.

In 1993-98, several rivers were sampled by electro-fishing, and salmon parr were examined for invasionwith Gyrodactylus (Table 8). Gills, skin and fins of livefish were examined. G. salaris was not found. Fullparasitological dissections of caught fish were con-ducted, and material on parasite fauna was collected.

In 1997, monitoring continued in the basin of theTuloma river. Wild young salmon were sampled in theinflows of the Tuloma. No evidence of gyrodactylidswas found. In 1997, parasitological investigationswere carried out in the Baltic sea rivers originating inthe Murmansk region: Sallajoki, Kuolajoki andTennijoki. G. salaris was not found. The dominant fishspecies in these rivers were brown trout and grayling.Young Atlantic salmon were absent. In 1998, themonitoring continued in the index rivers of the WhiteSea basin (Kovda, Virma, Kanda and Niva).


nina.niku Protect Report 009

Table 8. List of rivers where samples were taken by electrofishing and salmonparr were examined for occurrence of Gyrodactylus in 1993-98 (Murmanskregion).

Year River

The White Sea basin1996 Kovda

KandaVirinaLubche-SavinoValasNivaBezimeni

1997 KovdaVirmaKandaNiva

1998 KovdaVirmaKandaNiva

The Barents Sea basin1993 Kola1994 Kola

199319941996

The Tuloma RiverinflowsPechaPechaPechaShovnaPakKertcha

The Baltic Sea basin1997 Sallajoki

KuolajokiTennijoki

3.3 Landlocked salmonpopulations

Number of salmon Age compositionparr examined of sample

52110

no salmon parr in samples

11

11

2510112020

71520

(0+):5, (1+):20(1+):1, (2+):7, (3+):14

11

11

19 (1+):7, (2+):6, (3+):5, (4+):123 (0+):1, (1+):8, (2+):13, (3+):1

21 (1+):8, (2+):11, (3+):216 (0+):4, (1+):1, (2+):5, (3+):613 (1+):3, (2+):9, (3+):110 (0+):1, (1+):4, (2+):3, (3+):211 (0+):6, (2+):518 (1+):11, (2+):4, (3+):1

no salmon parr in samples

11 11

Kazakov (1992) summarized the current status ofAtlantic salmon in European freshwater bodies whichcomplete their whole life-cycle in fresh water. Hementions nine lakes in Russia (Ladoga, Onega, Kuitoand others), one in Finland (Saimaa) and one inSweden (Vånern) with populations of landlockedsalmon. In addition, one exists in Norway (Lake Byg-landsfjord). This population was saved from extinctionin the 1970's. "Småblank" is a river-dwelling land-locked salmon living in the upper regions of the RiverNamsen in Norway. Most of the lakes and rivers drain

14

into the Baltic, White or Norwegian Seas (Kazakov1992).

According to Kazakov (1992), five lakes with popula-tions of landlocked salmon drain to the White Seabasin. The lakes Segozero and Wigozero belong tothe watershed of the river Vyg and the lakes Kujto,Kamennoe and Njukozero belong to the watershed ofthe river Kem (figure 1 in Kazakov 1992). The salmonpopulations in the Kujto lake have not been investi-gated for Gyrodactylus. The lakes of the Kamennayariver system which are situated in the upper tributariesof the Kem river, were investigaed by leshko et al.(1982). In the specimens of landlocked salmon thatwere studied, no G. salaris was found (leshko et al.1982).


A total of 41 specimens of "Småblank" from the upperparts of the river Namsen collected in 1997 (11specimens) and 1998 (30 specimens) were examinedfor the occurrence of G. salaris, but no G. salaris wasfound. All specimens collected in 1997 and 15 speci-mens collected in 1998 were studied parasitologicallyaccording to Dogiels method. The results are given inTable 9 and Table 10.

The parasite fauna resembles that on landlockedsalmon in rivers in the Onega lake system.

Table 9. Parasite fauna of 11 specimens of land-locked salmon collected in the river Namsen inSeptember 1997.

Parasites

Myxidium sp.Chloromyxum sp.Myxobolus sp.Capriniana pisciumApiosoma sp.Crepidostomum farionisDiplostomum volvensIchthyocotylurus erraticusApatemon annuligerumContracoecum sp.

No. infected Min-max

14344

118312

Table 10. Parasite fauna of 15 landlocked salmonfrom the river Mellingselva, a tributary to the riverNamsen, in August 1998.

Parasites

Chloromyxum sp.Myxobolus sp.Capriniana pisciumApiosoma sp.Diphyllobothrium dendriticumCrepidostomum farionisPhyllodistomum conostomumDiplostomum rutiliDiplostomum sp.Ichthyocotylurus erraticusCystidicoloides tennuissiamaAcarina

No. infected Min-max

106761 1-16 1-251 1-13 1-18 1-33 1-41 1-11 1-1

15


3.4 G. salaris in Lake Enare and inthe River Pasvik

In 1993, G. salaris was found on rainbow trout in a fishfarm in Siskili at Lake Enare in northern Finland. Allfish in the fish farm were slaughtered and the farmwas disinfected. Later the fish population in the farmwas rebuilt from disinfected eggs. One monogeneanwas found on a pectoral fin of a rainbow trout lessthan 1 km downstream from the infected fish farm in1996 (reported by Dr. P. Koski, National Veterinaryand Food Research Institute, Regional LaboratoryOulu, Finland during the third meeting in November25, 1996 on G. salaris in the Barents Region).

Lake Enare drains into the river Pasvik in Norway.Investigations in the River Pasvik below Boris Glebwere conducted in 1993 by the County Governor inFinnmark, Environmental Department. Atlantic salmonfry and parr (1+ and 2+) were found, clearly indicatingthat spawning had occurred in this area (Memorand-um from a meeting of the Norwegian-Finnish BorderCommission 20.-22.9.1993). No Gyrodactylus wasfound.

Parasitological investigations were planned, but notcarried out in the river Pasvik in 1997 and in 1998,because of lack of financial support.

3.5 Investigations in Russianhatcheries regarding G. salaris

Every year salmon parr from hatcheries in theKarelian region are studied. G. salaris was found onlandlocked salmon parr in the Petrozavodsk hatcheryin the middle of the 1980's (E. Rumjantsev, personalcommunication).

In spring 1995, 25 young salmon from each of the fourhatcheries in the Murmansk region were examined byPINRO. G. salaris was not found.

In Murmansk region, three small freshwater rainbowtrout farms exist. In February—March 1996, PINROinvestigated the largest of these fish farms. A total of67 specimens of rainbow trout yearlings from cageslocated in the basin of the Tuloma river were examin-ed. Four specimens of Gyrodactylus were found onfins of two fish. They were fixed and studied, and allmaterials including preparations were sent to Dr. G.Malmberg in Stockholm for final identification. As aresult, it was stated that the parasites belonged to thespecies, Gyrodactylus lavareti. In addition to G.lavareti, 11 other parasite species were identified.



Salmon parr from the Kandalaksha hatchery havebeen investigated every year since 1995 by PINRO.Hatcheries and fish farms in the Murmansk regionhave been inspected every three months by theIchthyopathology Service of the Murmansk RegionalVeterinary Laboratory (cfr. Kalinina 1996). G. salarishas not been found.

3.6 G. salaris on Atlantic salmonparr in the River Vefsna,northern Norway

G. salaris was probably introduced into the riverVefsna by stocking of Atlantic salmon smolts frominfected hatcheries in 1975 and 1977. An outbreak ofthe parasite was registered in 1978, and within twoyears the parasite had spread throughout the wholewatercourse. There was a rapid rise in prevalence rateand degree of infection. The density of salmon parrdecreased from a high level before the Gyrodactylusoutbreak to close to zero after the outbreak (Johnsen& Jensen 1988).

In 1992, the fish ladder in the waterfall Laksforsen wasclosed in an attempt to prevent the ascension ofAtlantic salmon. In spite of this, some specimens

ascended in 1992, but from 1993 the ascension waseffectively prevented.

In September 1996, 19 salmon fry (0+) with a sizevarying between 29 and 40 mm, were collected belowLaksforsen and the number of G. salaris was countedon each fish. The number of parasites varied from 90to 693 on each fish with a mean intensity of 245parasites per fish (Table 11).

The number of parasites seems to increase withincreasing length of the fish (Figure 2).

In 1997, no salmon fry or parr were investigated,because of high water flow in the river Vefsna duringSeptember. On 21 August 1998 electrofishing wasconducted in one location sited approximately 500 mdownstream from the waterfall Laksforsen. We founda density of 32.5 0+ salmon/100 m2 and 17.5 1+salmon/100 m2. The mean intensity of G. salaris onthe 0+ and 1+ salmon was 21 and 1325 respectively.The 24 specimens of fry (0+) which were investigatedvaried in size between 25 and 34 mm. They were allinfected and the number of parasites on each fishvaried from 1 to 95. The investigation in 1998 tookplace three weeks earlier than the investigation in1996. The difference between the intensity of infectionamong the 0+ salmon in 1996 and 1998 was probablydue to the different sizes of the fish in the two years.

Table 11. Number of G. salaris on fins and body of 19 Atlantic salmon fry (0+) collected below thewaterfall Laksforsen in the river Vefsna on 12. September 1996.

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•

3.7 Parasite fauna of the Europeangrayling in the River Vefsna,northern Norway

The Directorate for Nature Management plans to treatthe river Vefsna with rotenone in an attempt toeradicate G. salaris from the watercourse and thus,restore the salmon population. Therefore, the river hasbeen closed since 1992 for ascending salmon at theLaksforsen waterfall. All salmon parr upstream fromthe Laksforsen waterfall will smoltify and migrate outof the river. The parasite G. salaris is very species-specific and will die out when the salmon parr dis-appear, if it cannot find another host. The grayling isknown to be a host for G. salaris under experimentalconditions, and it is, therefore, important to find outwhether the grayling can be a host for G. salaris undernatural conditions in the river Vefsna. Based on this,we started investigations of the parasite fauna of thegrayling in the river Vefsna.

ln the period 1995-97, a total of 55 grayling werecaught upstream from the waterfall Laksforsen. ln1998, 37 specimens were caught just downstream ofthe waterfall, where the salmon still have access andspawn each year.

All specimens of grayling were investigated for theoccurrence of Gyrodactylus, and in addition, parasito-logical studies according to the method of Dogiel wereconducted on 39 specimens of grayling. There wereonly small differences in the parasite fauna of graylingcaught upstream or downstream from the waterfallLaksforsen. The paucity of the parasite fauna is dueprimarily to the low abundance of grayling in the river,the low number of fish species inhabiting the river, andthe paucity of plankton and benthos, as well as

17

•

•

•

•

Length of fish (mm)

•

• ••

28 30 32 34 36

•

presumably the absence of a whole complex of smallrelict crustaceans.

No Gyrodactylus was found parasitizing the graylingfrom the river upstream of the waterfall Laksforsen.Downstream of the waterfaH, one specimen of Gyro-dactylus was found on 3 grayling. These results indi-cate that grayling are not an important host for G.salaris.

For further details see leshko et al. (1999).

nina•nlku Prolect Report 009

•

38 40



4 Measures againstG. salaris

G. salaris is almost certainly a recent introduction toNorwegian rivers, and its distribution is associatedwith the stocking of fish from infected salmon hatcheri-es (Johnsen & Jensen 1986). In 1986, the NorwegianDirectorate for Nature Management published a planfor "measures to be taken against the Atlantic salmonparasite, Gyrodactylus salaris" (Anon. 1986). Theprimary goal of this plan is the prevention of furtherspread of G. salaris and its extermination in as manyinfected rivers and hatcheries as possible. Theseprimary goals were later repeated and underlined innew action plans presented in 1995 (Direktoratet fornaturforvaltning 1995) and in 1998 (Anon. 1998).

In the period 1981-97, 25 Norwegian rivers weretreated with rotenone in an attempt to exterminate theparasite. The treatment has so far been a success in13 rivers, which now (per April 1999) have been statedas healthy after the treatment. The parasite has turnedup again in the rivers Skibotnelva, Rauma andSteinkjervassdraget.

In Russia, the Gyrodactylus situation is complex,because the parasite occurs naturally where the Balticsalmon occur (Ladoga lake, Onega lake), and doesnot occur where Atlantic salmon occurr (White Sea,and Kola Peninsula). The development of the Gyro-dactylus infection in the Atlantic salmon population ofthe river Keret resembles the development in theNorwegian rivers, with epidemics in the salmon parrpopulation resulting in very low densites of parr andfew adult salmon ascending the river.

The Gyrodactylus situation in the White Sea area wasdiscussed in a meeting of the Russian-NorwegianWorking Group on the marine environment of theBarents Region, ("Havmiljøgruppen") in Tromsø 29-31October 1996. This is a working group within theRussian - Norwegian Environmental Commission. Inthe protocol from the meeting, the working groupstates: "The working group points out that a furtherspread of the parasite G. salaris will constitute agreat danger. This parasite is registered in a Russianriver that drains into the White Sea (the river Keret,Karelia). Taking into consideration the real dangerfor the further spread of this parasite in theregion, the working group recommend that theRussian/Norwegian Environmental Commission strait-en out the possibility of treating the river Keret withrotenone and thereby removing the possibility offurther spread of G. salaris in the White Sea basin".

Based on this a survey of the river Keret was arrangedin July 1997. Participants in this survey were repre-sentatives from the Karelian Research Centre in

18

Petrozavodsk, the County Governor in Møre ogRomsdal, Norway, who has played an important partin the actions taken against G. salaris in Norwegianrivers and the Norwegian Instiute for Nature Researchin Trondheim. Actual attempts to remove the parasitefrom the river Keret were discussed after an inspectionof the river. The possibilities of removing G. salarisfrom the river Keret are discussed in a report from theCounty Governor in Møre og Romsdal dated 26September 1997. It is concluded that actions shouldbe taken as soon as possible beginning with theconstruction of a barrier in the lower part of the river toprevent salmon from ascending the river. The parasiteshould be exterminated by treating the river withrotenone downstream from the barrier several yearsafter its erection.

This report was submitted to the Directorate for NatureManagement along with a letter from NINA dated 2October 1997. In the letter it was underlined that theoccurrence of G. salaris in the river Keret must beconsidered seriously. There is a possibility for thespread of the parasite to other rivers in the area. In thelong run, this will be a disaster for the salmon popula-tions. An extermination of the parasite from the riverKeret will put an end to such a development. It wasrecommended that the Directorate contact theRussian authorities as soon as possible with theintention of building of a barrier in the river Keret.


5 ReferencesAnon. 1986. Handlingsplan for tiltak mot lakse-

parasitten Gyrodactylus salaris for 10-års period-en 1987-1996. - Direktoratet for naturforvaltning,Trondheim. 1-27 (in Norwegian).

Anon. 1998. Forslag til handlingsplan for tiltak motlakseparasitten Gyrodactylus salaris - Direktorat-

et for naturforvaltning og Statens Dyrehelsetilsyn.

1-52 (in Norwegian).Azbelev, V.V. 1960. Materialy po biologii semgi

Kolskogo poluostrova i ee vyzhivaemosti. - Trudy

PINRO, vyp.12: 5-70 (in Russian).Berg, L.S. 1935. Materialy po biologii semgi. -

lzvestiya VNIORH, tom 20: 1-113. (in Russian).

Berg, L.S. 1948. Ryby presnykh vod SSSR i sopre-

delnych stran. - 4 izdanie, M-L, chast 1: 1-466 (in

Russian).Bohlin, T. 1984. Quantitative electrofishing for salmon

and trout - views and recommendations. - In-formation från Sötvattenslaboratoriet No. 4: 1-33

(in Swedish with English summary).Bristow, G.A., leshko, E., Shulman, B. & Berland, B.

1994. Salmon parr parasite from river entering

the southern White Sea. - The eighth internationalcongress of parasitology, lzmir, Turkey, October

10.-14., 1994. Abstracts, Volume 1: p. 54.Bykhovskay-Pavlovskaya, I.E. 1985. Parasites of fish.

Manual for study. L. - Nauka: 1-121.Chubb, J. C. 1970. The parasite fauna of British fresh-

water fish. - Symp. Brit. Soc. Parasitol., v. 8: 119-144.

Direktoratet for naturforvaltning 1995. Forslag tilhandlingsplan for tiltak mot lakseparasitten Gyro-

dactylus salaris for perioden 1995-1999. - Ut-redning for DN nr. 1995-2: 1-96 (in Norwegian).

Dogiel, V.A. & Petrushevsky, G.K. 1935. Opyt eko-

logiceskogo issledovanija parasitofauny belo-morskoi sel'gi. - Voprosyekologii i biocenologiee.

L., (in Russian).Heggberget, T.G. & Johnsen, B.O. 1982. Infestations

by Gyrodactylus sp. of Atlantic salmon Salmo

salar L. in Norwegian rivers. - J. Fish Biol. 21:

15-26.leshko E.P., Malakhova R.P. & Golitsyna, N.B. 1982.

Ecologicheskie osobennosti formirovaniya fauny

parasitov ryb ozer sistemy r. Kamennoy. (Ecolo-

gical peculiarities of the development of the river

Kamennaya system's lakes parasite fauna). -

Ecologia parasiticheskih organismov v biogeo-

cenozah Severa. Petrozavodsk: 5-25.leshko, E., Berland, B., Shulman, B., Bristow, G. &

Shurov, I. 1995. On some parasites of salmon

parr (Salmo salar L., 1758) (Pisces, Salmonidae)

from rivers of the Karelian White Sea Basin. -

Abstr. Fourth International Symposium of Ichthyo-

parasitology, Munich, Germany 3-7 October

1995, p. 100.

19

ninaontku Project Report 009

leshko, E.P, Johnsen, B.O., Shulman, B.S., Jensen,

A.J. & Schurov, I.L. 1999. The parasite fauna of

an isolated population of grayling, Thymallusthymallus (L.) in the River Vefsna, northern

Norway (in manus).Jensen, A.J., Zubschenko, A., Hvidsten, N.A.,

Johnsen, B.O., Kashin, E., Kuzmin, 0. & Næsje,

T.F. 1997. A comparative study of life histories of

Atlantic salmon in two Norwegian and two

Russian rivers. - NINA-NIKU Project Report 007:

1-44.Jensen, A.J., Zubchenko, A., Hvidsten, N.A., Johnsen,

B.O., Kashin, E. & Næsje, T.F. 1998. A five year

study of Atlantic salmon in two Russian and two

Norwegian rivers. - NINA-NIKU Project Report008: 1-38.

Johnsen, B.O. & Jensen, A.J. 1986. Infestations of

Atlantic salmon, Salmo salar, by Gyrodactylus

salaris in Norwegian rivers. - J. Fish Biol. 29:233-241.

Johnsen, B.O. & Jensen, A.J. 1988. Introduction and

establishment of Gyrodactylus salaris on Atlantic

salmon, Salmo salar L., fry and parr in the River

Vefsna, northern Norway. - Journal of Fish

Diseases 11: 35-45.Kalinina, N. 1996. History of development of ichthyo-

patological service in the Kola Peninsula. - P.

43-47 in Larsen, T., ed. Report from seminar onfish diseases and organisation of the fish health

service in the Finnish, Norwegian and Russian

parts of the Barents region. Høgskolen i Finnmark1996-12.

Kazakov, R.V. 1992. Distribution of Atlantic salmon,

Salmo salar L., in freshwater bodies of Europe. -

Aquaculture and Fisheries Management 1992,23: 461-475.

Kazakov, R.V., Kuzmin, 0.G., Schustov, Ju. A. &

Shurov, I. 1992. Atlantic salmon of the Varzuga

River. - Hydrometpress, Leningrad. 108 pp. (in

Russian).Korablev, N.A. 1974. lz istorii rybolovstva v Karelskom

Pomorie (vtoraya polovina 19 veka). Biologic-

heskie resursy Belogo moryai vnutrennich

vodoemov Evropeiskogo Severa. Petrozavodsk.

s. 286-288. (in Russian). (From the history of

fishery of Karelian region ofWhite Sea (the second half of 19 century). in

"Biologycal resources of White Sea and inland

waterbodies of European North". Petrozavodsk.

p. 286-288 (in Russian).Kuzmin, 0.G. & Zubschenko, A.V. 1991. Artificial re-

production of Atlantic salmon in rivers of the

Murmansk region - Materials to the meeting of

experts on anadromous fishes, Trondheim 27.10-

3.11.1991.Malakova, R.P. 1972. Parasitofauna semgi Salmo

salar L., kumzi Salmo trutta L. gorbuchy

Onchorchyncus gorbuscha (Walb.) i siga

Coregonus lavaretus pidchian n. pidchianoides



Pravdin v bassejne Belogo Morja. Lososevye(Salmonidae) Karelii. - Petrozavodsk 1: 21-26 (inRussian).

Margolis, L., Eshc, G.W., Holmes, J.C., Kurtis, A.M. &Schad, G.A. 1982. The use of ecological terms inparasitology (report of an ad hoc committee of theAmerican Society of Parasitologists). - Journal ofParasitology 68: 131-133.

Mitenev, V.R & Shulman, B. 1985. Ekologichskieosobennostiparasitifauny molodi semgi Salmosalar L. Evropesjskogo Severa. Eklogisja ivospproizvidstovo proshodnych Isososevych rybv basssejnach Belogi i Baraeceva morej. - Sb. tr.PINRO. Murmansk. 149-159 (in Russian).

Zippin, C. 1956. An evaluation of the removal methodof estimating animal populations. - Biometrics 12:163-169.

Zubschenko, A.V. & Kuzmin, O.G. 1991. Atlanticsalmon stock status in the rivers of the KolaPeninsula. - Materials to the meeting of expertson anadromous fishes, Trondheim 27.10-3.11.1991.

Zubschenko, A.V., Kuzmin, 0.G., Novikov, O.N. &Sorokin, A.L. 1991. The salmon recreationalcatch on the Kola Peninsula. - Polar Institute ofFishery and Oceanography (PINR0). Murmansk.150 pp. (in Russian).

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