Ecologyof fheBenng Sea: A Rewcivot RussisrrLiterature
Distributionand Trophic Relationships of AbundantMesopelagic Fishes of the Bering Sea
Ye,l.Sobolevsky MarineBiology Institute, Russian. Academy vf Sciencesof theFar Fast V/adivostok, Russia
T.C.Sokolovskaya, A.A. Salanov, anti I.A. Senchenko Sakhalin ResearchInstitute of Fisheriesand OceanographyrSakhZ'INTRO! Sakhali n, Russia
1NTRODUCTION determinedby weight beforefixation. An index of Previous research in the pelagic realm of the Bering fullness and degreeof digestionwere estimated vi- Sea has clarified distribution and migration pat- suallyy. terns, and resolved some questions concerning the For purposesof discussionin this paperthe epi- abundanceof important commercialfishes Shunt- pelagiczone is the surfacefishing horizon,at 0-200 ov et al. 1988, KVespestadand Traynor 1988, Daw- rn; upperrnesopelagic zone, 200-500 rn; and lov'er son 1989,Bulatov and Sobolevsky1990, Groot and meso pelagic,;i 00-1,000 rn. Margolis 1991,Radchenko 1994, Sobolevsky et al. 1994!, At the same time, these studies showed the RESULTS necessityof conductingsnore detailed researchon the mesopelagicichthyofauna, including questions Mesopelagicfishes in the Bering Seaslay scattered of abundance and many poorly known aspects of at different depthsand do not, f'orm fishable concen- biology. trations. The meso-and bathypelagic fish fauna in- Mesopelagicfishes const,itutea large biomass cludesat least 62 speciesfrom 54 genera and 85 in the Bering Sea1 Shuntovet al. 1993,Radchenko families iBalanov and Il'inskiy 1992t The most 1994!and play an important role in the pelagicfish abundant, families are Myctophidae and Bathy- assemblyas foodcompetitors to commercialfishes, lagidae:Sterrobrachius leucopsarus, S. nannochir, while serving as food objects themselves. Leuroglvssusschmidti, Lampanictus jordani, L. regalia, Bathylagus pacificus. Pseurl<>bathvlagus mi lleri, Lipolagus ochotensis.and Diaplrus tAeta. MATERIALSAND METHODS These two families constitute about 92 ic of the to- For this study we analyzed the results of trawl sur- tal biomass of mesopelagic fishes Table 1 t veysconducted by the PacificResearch Institute of The dominant species is Stenobrachrus leucop- Fisheries and Oceanography TINRO i. Surveys were sarus, with 64": Table1. Biomassand percentageof dominant familiesand species of mesopelagiefish- es in the Bering Sea -1,000 m!. Biomass Thousands Family, species of tons Family: Myctophidae 10,940 75.1 Bathy 1agidae 2,340 16.1 Chauliodontidae 300 2.1 137 0.9 Scopelosauri dao 5.8 Other families 845 100.0 Total 14.562 Species; Stenobrarhi us leucopsarus 9,354 64.2 8 ten obrachr us nannochi r 1,430 9.8 Bothylogus poerftcus 812 5.6 Pseudobrrthylcrgusmilleri 572 3.9 Lcuroglossus schmi dti 535 3.7 Lipolagusochotensis 420 2.9 Chauli odus macouni 300 2.1 Other species 1,138 FigureL Distributionof catchesof northernsmooth- 14,561 100.0 tongue,Leuroglossus schrnidti, in themeso- Total pelogiczone of theBering Sea. An increasein catcheswas obvious over the con- twophases during the day in theupper and lower tinentalslope in thenorthwestern part of the Corn- levelsof the mesopelagiczone Sobolevskyand manderBasin Figure 1!. Thedistribution of catch Sokolovskaya1993!. These are present with certain modificationsfor othermesopelagic species that rise for otherspecies followed a similarpattern Figure to theepipelagic zone at night.Catches usually in- 2h Mostmesopelagic fishes of the BeringSea mi- creasein the upper mesopelagiczone in the morn- gratedaily between meso- and epipelagic zones. As ing anddecrease in the afternoonin the lower a rule,mesopelagic fishes are caught in smallquan- mesopelagiczone, Such variations in thecatch are tities in the epipelagiczone in the eveningand at probablythe resultof thevertical migratory char- mght.This is commonfor L. schrnidti,S. leucops- acterofL. schmidti,S. leucopsorus, and some other arus, L. ochotensis. species. Scrutinyof the daily migrationsrevealed some However,it shouldbe noted that in thedeepwa- detailsof the verticalmigration structure. For ex- ter basinsof the Bering Seain the spring-summer arnple,L. ochotensisrose only to the lower level of period,when the daylightstays much longer, the theepipelagic zone in theevenings. The catches of verticalmigrations have a smalleramplitude arid are not as distinct.This is especiallyobvious for L. schrnidtiwere small in the uppermesopelagic speciesthat migrateto the epipelagiczone: L. zone. l isuallyin the eveningand at night thereis an schmidti,S. leucopsorus,and L, ochotensis.During increasein epipelagiccatches due to migrantsris- this periodthey prefer the upperand lowerrneso- ingto this level. In the second half of night the catch- pelagiczone for mostof the day. esdecrease in theepipelagic zone. The amplitude of Followingare some characteristics of thebiolo- catchesfor differentspecies is high and is deter- gy anddistribution of the moreabundant mcsope- minedmostly by the lengthof verticalmigrations lagic fishes. and availability of food organismsat different Stenobrochius leucopsarue is the mostabundant depths.Catches of L. schmidtr Figure 3! display speciesin the mesopelagiczone of the BeririgSea. Fcolagyof theBering Sea: A Reviewot RossiatiLiterature Figure2. Distributionof metopelagicfishes other than Leurnglnsstts schmidtt, Btesohrachtus leitcopsarus,and B. natinoehrrhart ested itt theBering Beo. In the westernBering Seaits biomassis morcthan tions of L. echmidti are comnion in the areas bor- 9 million tons Table I!. Even though this species dering the continentalslope. Here the catchesare doesnot aggregateto coinmercialfishing concen- largerthan in i,heother parts of'the Bering Sea '.Fig- trations, its catchesincrease significantly overthe ure I!, continentalslope areas, where all sizesare caught In the opensea, fish of all sizesare found in the -13 cm!. The portion of fish migrating to the epi- catches,but the nuinberof feinalesamong large fish pelagiczone at night is not great,and most of the is greater than for males Figure 4i. In areasclose fish rising io this level are small onesmeasuring 8 to the shelf break i.here is a greater percentage of cm or less, Larger fish are caught inostly in the small fish, and this is especially common in the epi- meropelagiczone during the night. pelagiczone Figure hh In the deepwaterareas, how- Stenobrachi its nannochi r has a somewhat scat- ever,the percentageof sinallerfish decreasesand tered distribution. Unlike 8, leucopsarus, they do the catch of mature individuals increases. not rise to the epipelagiczone at night and stayfar- Lipolrtgusochotensia is mostlyfound in the up- ther away from the continentalslope. This species per mesopelagiczone and. partially,in the lower is consideredto stay at depthsof 300-700m Pearcy inesopelagiczone. As all Bathylagidaedo, it hasdis- et al. 1979,Parin andFedorov l981!, sinceall sizes tinct, daily migrations, and doesnot forin concen- are found there -13 cin!. trations, Sinall catcheshave beenregistered in the Leuroglossusschmi dti is distributedevenly over deepwaterareas. The sizes of fishin thecai,ches fluc- the deep parts of the Bering Sca.Local concentra- tuate between 6 and 18 cm. 162 DistributionenclTrophi< Re4 ior Pseudobathylagizsmilleri doesnot rise to the probablybecause most, of the mesopelagic fishes it epipelagiczone. It is mostlya meso-and bathype- feedson gatherat this levelin the daytime. lagicspecies Ress and Kashkinal967!. The larg- Thetrophic relationships of mesopelagicfishes estcatches have been registered in the Commander havebeen studied mostly during the summerand Basin. k'ishes7-20 crn long arefound in the catches; faH Balanovet al, 1994,1995!. Vone of the dataon they most commonlymeasure 13-16 cm. feedingduring the venter has been published, so ChrttLltodus macottru' is a typicalpredator with wethought it necessaryto describe t.he winter food a inuchsmaller biomass than the restof thelisted spectrumin detail, species.Its sizeis larger,ranging from 9 to26 cin In t.he winter, 8-12 groups of food organisms and with inost.individuals ineasuring 14-18cm, havebeen found in the stomachsof the abundant mesopelagicfish species Stertobrachi usleucopsarus, Migrationsfrom the lower to the upper incsopelag- S. nantzochir, and Leuroglossus schmidti !, Thcdiet ic zoneare often observedduring the day.This is of L. schmidti Table2! is morediverse than the dietsof S. leucopsarusand S, nannochir Tables 3 and 4!, In the sumtner,stomachs of S. leucopsarus andS. nannochircontain a largevariety of foods. Thisis a resultof a highamplitude of' daily inigra- 3.0 tionsby those species Pearcy et al. 1979,Gorbaten- ko and Il'inskiy 1991!.These fishes' diets include 24 interzonalspecies of planktonorganisms along wit h epipelagicspecies. The least diversity of food objects in the summeris a characteristicof S. nannoc/iir 1.8 andP. milleri, with four and three prey species,re- spectively Balanov 1994!; these fishes typically in- c 1.2 habitdeep water Willisand Pearcy 1982!. Calanoidaplay an importantpart in thewinter 0 0.6 nutrition of I.. sthmidti, S. leucopsarus,and S. nan- nochir.This has alsobeen observed in the summer. Significantdifferences are found inostly at various depths.Diversity of food items is greatest at depths 00:00 04:00 06:00 12:00 16:00 20:00 of 200-500m Tables2-4!. This is especiallyobvious Time of day in the winter nutritionof I.. schmitfti.Individuals caughtin thecpipelagic zone had the narrowest food Figure3. Dieli ariattun nf Leurngl 40 o 3p 0 20o EOe 10 to 4 5 6 7 6 9 10 11 Length em! Figure4. Size< rimpust'tionofcatches ofLeuruglussas schmidti t'nthe pelagic zone ufthe Bering Sea. kcofog>oi the BeringSt+i A ReviewoF Russi.in Li erature 16! Continental slope 20 -.e 08 DE tp N tn Deepwaterregions a 20 O k 10 4 6 6 10 t2 14 16 4 6 8 to 12 14 t6 Length cm! Length cm! Figure5. Sizecomposition of Leurngloseus schmidti in continentalslope and deepuater regions of the Bering Sea. sopelagiczone with 17items andthe lower mesope- 500 in, and smallest for L. schmidli at all depths lagic zone with 12 items not counting items found Tables 2-4!, The percentage of empty stomachs for in trace amounts; Table 2!. The basic foods for L. L. schmidti was high 4'k! in the upper and lower schmidti in the epipelagiczone are Calanoida,and mesOpelagieZOnes. S enObrnchiualeuCOpsarusfrOm in the upper mesopelagiczone are Calanoida,Ku- the lower mesopelagiczone had the lowestnumber phausiidae, Hyperiidea, and Coelenterata.. of empty stomachs i 18'A!. The diet of S. leucopsartts in the winter is inost diverse in the epi- and mesopelagic zones Table 3!. DISCUSSION Calanoitla from 34.7'7r in the epipelagic to 84.2'7r in the lower mesope]agic!and Euphausiidae 2,5'7r in As the research shows. rnesopelagic fishes do not the epipelagic zone and 42.5% in the upper mesope- aggregatein harvestable concentrations in the lagic zone! are most important.. Bering Sea. Consequently,ii. is difficult to obtain Calanoida, specifically Calattus cristatus, play largecatche~ of them, With pelagictrawls not built an iinportant part in the nutrition of S. nannochir, for deepwatertrav, ling of small-sizedfishes, in the At depthsof 500-1,000m Calanoidaare nearly the processof trawling most of the fish probablyescape only foods eaten 99.3'/ !. At 200-500 m, stomach from the trawl; if so, estimates of abundance are contents also include species of I',uphausiidae, Hy- biased low. However, basedon the trawl catch analy- periidea,Decapoda, Gammaridea, and Coelentera- sis. we can inake some generalizations about distri- ta. The amount of Coelenterata i 15.6 ir ! in the diet. bution, The catch analysis showsthat the deepwater is substantial, but the other prey contribute little parts of the Beriiig Sea,including the Commander trace to 3.3'< ! to the diet Table 4 L Basin and i,he Shirshov Ridge, are areas v here Among the examined species,in the fall-winter mesopelagicfishes are situated. Usua!ly the maxi- period the index of storiiach fullness was greatest mum catches are recorded over the northern part of f'or S. leucopsarusand S. nrtnnochir at depths of 200- the Shirshov Ridge and the continent,alslope off DistributionandTrophta Relatiarrships ofAbuntl ant it Table 4. Food spectrum for Stenobrachirtsrstrn- rnesopelagicfishes. The first two families are the nochir in the Bering Sea, November 1991- most abundant. Sincethe spatial structure of rneso- January 1992. pelagicichthyofauna is determinedby the distribu- tion of the abundant species,those two play the most "k of stomachs with food at idepthr important part in the functioningof this group. Food items 200-500 m 500-1,000 rn A comparisonof the diversityof mesopelagicfish species Balanov and Il'inskiy 1992irevealed sig- Calanoida 78.6 99.3 nificant similarities and dominance of a small nurn- Calanus cristutus 45.3 3?.3 berof specieswith most of the biomass. In theBering C. plumchrus 1.6 4.0 Sea,S. leucopsaruscontributes about 640r to the Pan uchaeta elongata 0.2 2.2 biomass. In the Okhotsk Sea, L. schmidti accounts Candacta columbia 0.5 10.0 for 70% of the 14.6 million ton biomass, Thus, in Metridia pacifica 0.5 the rnesopelagicichthyofauna a smallgroup of spe- Gaidius sp. 0 2.1 1.2 ciesare dominant.An analogoussituation has been noted in subarctic waters for Lampanycf usj ordarri Eucalanus bun gii 0.2 0 and some other specieslKass and Kashkina 1967, Pleuromamma scutullata 0.8 0,1 Parin and Fedorov 1981l. 0 Heterorabdus tonneri 0.3 Researchshows that vertical distribution of fish Each acta marina 1.3 0 hasits specificfeatures typical for most rnesopelag- Other Calanoida 27.0 44.0 ic fishes that perform active vertical migrations in Eo.phausi idae 0.7 0 northern latitudes Gj@saeterand Kaw aguchi 19801 Thysanoessalongiper 0.7 0 Thc character of the daily vertical migrations de- Hyperiidca 0.3 0 pendsa loton the abundanceof food organisms. es- Parathemisto paci fica 0.2 0 peciallyabundant species like euphausiidsand Scina sp. 0.1 0 calanoids.Species that have a high amplitude rif Decapoda 3,3 0 vertical migrations,such as S. leucopsarrtsand L Garnmaridea 1.0 0 schmidti, have a morediverse diet including epipe- lagicand interzonal food objects, For deepwater spe- Ostracoda 0.5 0.7 0.5 0.7 cies S. nanriochirand P. millerii migrationsusually Conchoecia sp. occurin the upper and lower rnesopelagicregions, 15.6 0 Uoelenterata where there is a much smaller number of food items Mean index of fullness 10. 8 6,2 in their diet. Number of stomachs 298 125 Analysisshows that for abundantrnesopelagic % of stomachs with food 39 62 fishes of the Bering Sea,the dominating food ob- Mean weight of fish Ig> 9.2 9,7 jectsin all seasonsare Calanoidaarid Euphausi- Mean length of fish cm! 9.7 10.0 idae,Other groups Hyperiidea, Ostracoda! are of lessimportance. In the summerperiod Appendicu- laria gain importancein the dietsof Bathylagidae L. schtrridti and L. ochoterrsis!,whereas in the win- CapeOlyutorsk and the CommanderBasin, IIow- ter they consumemore Coelenterata. A similar pat- ever,no significantconcentrations have been dis- tern of feedinghas been notedfor Bathylagidaein covered, This shows that in the Bering Sea the other areas of the Pacific Adams 1979, Gordon et spatial distribution of mesopelagicfishes is more al. 1985 i. even than that of the commercial species walleye All of the foregoingshows hov distinctthe food pollock,herring!, which form aggregations that en- specializationis for the examinedspecies of'meso- ablethe fishing fleet to work efficiently. pelagicfishes, The extracted differences in distri- In the Bering Seafour families Myctophidae, butionand especially in the exterit.of dailyvertical Bathylagidae, Chauliodontidae,and Scopelosau- migrationscertainly affect the diversity of thefood ridae make up the major portionof the biomassof spectrumand choice of dominatingfood objects. 166 Distributionand Frophic Relationships ofAbunc!ant ittesopelagic Fishes orrhe Bering 5ea Parin,N.V and VV. Fedorov.1981 Comparison of REFERENCES deepwaterpelagic ichthyofaunas of the north- Adams,A,E. 1979. The food habits, age and growth westernand northeastern Pacific, In: Biologiya of three midwater fishes Stenobrochius leucop- bol'shikhglubin Tikhogo okeana lBiology of the sarus,S, nannochir,and Leuroglossus schnrid- greatbasins of the PacificOcean j. Vladivostok. ti! from the southeasternBering Sca.M.S. DVNTS [Far Eastern Branchj Akad. Nauk thesis,Univ. Alaska, Fairbanks, 302 pp. SSSR,pp, 72-78. In Russian,! Balanov,A.A. 1994.Nutrition of prevailingrnesope- Pearcy,W,G., II.V. Lorz, and W. Peterson. 1979. Corn- lagicfishes of the BeringSea. Vopr. Ikbtiol, parisonof thefeeding habits of migratoryand 34 !:252-259. In Russian.! non-migratorySrenobrachi us eucnpsarus Myc- tophidae!.Mar. Biol. 51<1i:1-9. Balanov,A.A,, K.M, Gorbatenko,and T.A. Gorelo- va, 1994.Daily dynamicsof nutrition for meso- Radchenko,B.I. 1994. Sostav, struktura i dinamika pelagicfishes of the BeringSea during the nektonnykhsoobshchestv epipelagiali Beringo- surnrnerperiod. Vopr, Ikhtiol, 34 !:534-541, In va morya Composition,structure, and dynarn- Russian. ! ics of nektonic cornrnunitiesin the epipelagic zone of the Bering Seaj. Avtoref. kand. diss. Balanov,A.A., K.M. Gorbatenko, and A.Ya. Efrmkin. ICandidatethesis', Vladivostok, 24 pp. In Rus- 1995.Daily dynamicsof nutrition for mesope- lagic fishesof the BeringSea during the fall sian.! period.Biol. Morya 21! 2!;125-131, In Russian.! Rasa,T.S,, and A.A. Kashkina, 1967. Bathypelagic Balanov,A.A., and Ye.V. Il'inskiy. 1992. Species com- smelts Pisces,Bathylagidae! of the northern positionand biomass ofrnesopelagic fishes of the partsof thePacific Ocean. Tr. Inst. Okeanol. Okhotskand Bering seas. Vopr, Ikhtiol. 32 !;56- Akad. Nauk SSSR84:159-208. In Russia~.! 63. In Russian.! Shuntov,V P.,A.F. Volkov, and AYa, Efrmkin. 1988. Bulatov,S.A., and Ye.I. Sobolevsky. 1990. Distribu- Compositionand abundanceof pelagicfish tion,abundance, and future perspectives of pol- groupsin thewestern Bering Sea. Biol. Morya lockfisheries in the openBering Sea. Biol. Morya 2:56-65. In Russian.! 5:65-72. In Russian,! Shuntov,V.P., V.I. Radchenko, V.I. Chuchukalo, and Dawson,P,K. 1989. Stock identification of Bering others,1993, Composition of plankton and nek- Seawalleye pollock. In: Proceedingsof the In- ton groupsof the upperpelagial of thc.western ternationalSyrnposiurn on BeringSea Fisher- BeringSea and Pacificwaters of Kamchatka ies,July 19-21,1988, Sitka, Alaska, U.S. Dept. duringanadroinous migration of salmon.Biol. Commerce,NOAA Tech. Memo, NWFS F/NWC Morya 4:19-31. In Russian.! 163: 184-206. Sobolevsky,Ye.I., V.I. Radchenko, and A,V. Startsev. Gjissaeter,J and K. Kawaguchi,1980. A reviewof 1994, Distribution and food of churn salmori, the world resourcesof mesopelagicfishes. FAO Oncorhynchuskenya, in thefall-winter period in Fish, Tech. Pap. 193 Rome, 151 pp, the westernBering Sea and Pacificwaters of Kamchatka.Vopr. Ikhtiol. 34 !:35-40. In Rus- Gordon,J.D.M., S. Visida, and T, Nemoto. 1985. The sian,! diet of mesopelagicfishes from the Pacificcoast of Hokkaido.J. Oceanogr.Soc. Jpn. 41 !:89-96. Sobolevsky,Ye.I., V.P. Shuntov, and A.F. Volkov. 1989. Gorbatenko,K,M., and Ye.N,Il'inskiy. 1991.Food Thecoinposition and present state of pelagicfish communities in the western Bering Sea. In: Pro- of abundant.mesopelagic fishes in the Bering ceedingsof the InternationalSymposium on Sea.Vopr. Ikhtio!. 31!5!:816-821. Sobolevsky,Ye.l and T.G, Sokolnvskaya, 1993. New data on northern smoot!itongue, Leuroglossus schmidt Bathylagidaei,biology in the north- westernPacific. Vopr. Ikhtiol. 33 !:780-784,iln Russi an. ! Wespestad,V.G., and J.J, Traynor,1988. Walleye pollock. In: Condition of groundfish resources of the easternBering Seaand Aleutian Islands regionin 1988,Int. N. Pac,Fish, Comm. Doc, 3345, pp. 17-40. Willis,J.M., and W.G. Pearcy, 1982. Vertical distri- bution and migration of fishesof the lower zone of Oregon.Int. N. Pac. I"ish, Comm.Bull. 70 !:87-98. Ecologyot theBarite S< at A Reviewot RussianLiterature StockDynamics ofWestern Bering Sea Herring N.I. Natjmenko KamchatkaResearch Institute of Fisheriesand Oceanography KarnchatiVIROJ Petropavloosk-Kamchatski,Russia. ABSTRACT thesepopulations were divided into three groups; This work examinesthe distribution, dynamicsof Northern,Central, and Southern Barton 1978, abundanceand catches, and the fluctuationsof year- Friedand Wespcstad 1985, Rowell 1980, Walker and classstrength of the Korf-Karaginherring. Schnepf1982, Rogers et al, 1984,Rogers and Theentire life cyde of herring occurson the con- Schnepf 1985!. tinental shelf of the westernBering Sea, where they In addition to the above populations, another spawn,forage, and undertake wintering migrations. stockof marine herring reproducesin the Gulf of Thesize of the Korf-Karaginherring year classesis Anadyr.The biomassof this stockis noticeably subjectto substantialfluctuations with a dominant smaller than the other two. periodicityof years. Herring reached their maximum Several lake-lagoonherring stocks have been biomassin the late 1950s.At that time, the biomass observedin the Bering Sea Prochorov1965, Mak- of inature fish exceeded400,000 tons. Stockshave sirnenkov1979!, They inhabit baysand lagoonsbe- been depresse.din the last 30 years. tweenCape Olyutorsk and Cape Navarin, including Anastasia,Dezhnev, and Expedition bays, and Uzh- naya Lagoon. INTRODUCTlON Severalpopulations of Pacificherring Clupeapal- MATERIALSAND METHODS /asi! inhabit the far-easternseas of Russia.Biologi- cally,they are divided into lake-lagoon herring and Since 1958,many interdisciplinary observations marineherring. Lake-lagoonor coastalherring win- havebeen carried out to elucidatethe biologicalcon- ter andreproduce in lagoonsand salt, lakes. They ditionof' herring and estimate their stocksize. The feedin neighboringbays and do not migrate very researchwas conducted in spring,summer, and fall. Spawningwas monitored during May from hr.- far. Marine herring, on the other hand, spendmost licopters.The spawningdates and areaswere de- of their lives far from shore. The coastal portion of terrnined,and sizeof'the spawmngareas estimated. their life cycleis limited to the spawningperiod. Duringlow tide immediatelyfollowing major repro- Marineherring undergo prolonged spawning, feed- ductive events, the substratum with eggs was ran- ing,and wintering migrations. Soinetiines they mi- domlysampled. The sample area is 20crn x 20cm. grate500-900 miles from their spawninggrounds, At least, 10 such samples were collected in each Thereare two particularlylarge stocks of ma- spawningarea. The number of eggs in the samples rine herringin the BeringSea: the Korf-Karagin was countedand the density of depositionon each andeastern Bering Seastocks, The former is a sin- spawningsite wasestimated, along with the aver- glepopulation, without any discrete local or seasonal agedeposition density on all spawningsites, taking groupings Panin l950, Prochorov1965, Kachina their size into consideration.The total number of 1981!.The structure of the easternBering herring eggsspawned by all femaleswas determined by mul- stockis muchmore complex. There are ninemajor tiplyingthe averagedensity hy the total spaivning spawningpopulations managed for commercial fish- area. erieson the easternBering Seacoast of Alaska Row- Concurrentlywith the abovestudies, rneasure- ell 1991!. Based on a number of characters scales rnentsand biological analyses were done on herring andage structures, growth rate, spawning dates! taken in seinesset near the spawning grounds. 170 Stock Dynsniics of LVesternBering Sea Herring These collections allowed us to determine size, age, and sexcornposit.ion of the spawningstock, and es- timate the average fecundity and weight of the fish. The number of feinales was estimated by divid- ing thetotal amountof eggsat. the spawninggrounds by the averagefecundity per feniale,after whichthe total number of spawners were estimated from the sex ratio. Seven days after the major hatching event usu- ally between 1 June and 20 June!, larval surveys were done.These surveys allowed us to estimate the number of larvae and determine herring survive.l during embryogenesis and during the first seven days following hatching. Standard biostatistical data were collected from commercial catches in Olyutorsk Bay during the fall fishery. In addition, trawl surveyswere undertak- en in the Karagin and Olyutorsk regions in Novem- Figure I. Distribiition and migrationsof Korj'-Karagin ber to estimate the strength of the current year class. herring in the yearsof high Ai and loie tB! This permitted us to estimate survival during the year classstrength. I! spau;ningarena, !2! transition from larval to 0 age cia.ssjuveniles ap- spaiuning migrations, i feedi ng mi gratinn ~, J u!i nteri ng migrations, J feeding areas,!6'! proxirnately 5 months!. wi nteri ng areas. Herring abundance and the age class before 19o8were estimated by virtual population analysis VPA!. m. The major purse seine fishery occurs at this time. The schools move to greater depth in late Novem- RKSUITS AND DISCUSSION ber-earlyDecember and continue moving westward. They usually reachtheir traditional overwintering Distributionand migrations area to the southeast of Cape Goven by the middle Spawningmigrations of the Korf-Karaginherring of Deer mber. usually beginin the secondhalf'of April. In yearsof Juvenile Korf-Karagin herring do not co-occur high spawningstocks, they movedto the spawning with adult firh. They spend the first two years of groundsin three major migration routes.In years their lives in Karagin Bay and the third year in the of low abundance, they moved in two major migra- Olyutorsk Bay, tion routes Figure 1!. Spawningoccurs in May,in the shallowbays and Conditionand stock dynamics lagoonsof nort,bernKaragin Bay and in KorfBay. The numberof' spawning areas has significantlyde- Spawningstocks and commercialstocks are regu- clined in the last 25 years, The herring use prirnari- lated annually in the western Bering Sea, The ly Zosteraas a substratumfor eggdeposition, former consist of all the mature fish; the latter in- Right after spawning, the mature fish leave cludes all the fish, including juveniles, that have Karagin Bay and migrate to the foraginggrounds reached a length of 25 crn 126 crn according to the between Cape Olyutorsk arid Cape Navarin, The Smith measurement technique!, the recruitment duration of the migration dependson the sizeof the length established by Russian Federation Fishery stock: as the number of the spawners increases,the Regulations, Cornrnercial stock are believed to con- area of the foraging zoneextends eastward. In some sist of fish that are 4 years old and older. yearsthe Korf-Karaginherring reach 178'E, Her- The spawning stock was estimated by the egg ring stocksforage in OlyutorskBay during periods survey method in all the spawmng areas. Commer- of extremely low abundance.The foraging period cial stock were estimated from spawning stocks, usually last,s4 to 5 months. taking recruitment, mortality, maturation and I'he winter migration moves in the opposite di- growth rates into consideration. rection,usually in September-November.Returning The observations encompass 57 years, from I9S7 to OlyutorskBay, the herringspend 20-50 days in to 1993. Substantial variation in size of the spawn- the eastern area at relatively shallow depths, 40-90 ing stocks has occurred over these years, ECO/OgyOfthe Bering5ea A RevieivOt RuSSian literature 171 and 1,5 x 10s Kachina 1981 k The decline in repro- ductive potential to less than half of the optimum has caused a disruption in the stock-recruitment ratio, All the above featurer of spawning stock dynarn- ics arealso present, in the commercialstocks. They reached rnaxirnum size in 1956-1957, The overall CI commercial stock is 1.7 times greater than the 2 c spawning stocks. I~ 50 I ala '~ 55555459555 Yearclass strength Z Somevariation in year class strength is inherent in aII the marine herring inhabiting the North Pacific. Most researchers have documented a periodicity of about 5 years and longer, equivalent to two solar cycles Prochorov1965; Birman 1973;Turnin and Yelkin 1977; Kachiria 1981; Naumenko 1984, 1990; Naumenko et al. 1990!. Similar periodicity has been observedin both 040 5550 lj560 5lln 5'~ 550 Italo the Bering Sea and Okhotsk Sea herring. Never- rIR1 theless, short-term cycles are unstable and can be broken. The common feature of all three of the above Figure2, Commercial A anrt sporoiring BJ stocks of herringstocks is a relativelystrict 5-yearperiodici- Korf-Karagi n herring. ty in yearclass strength in yearswith high and av- eragespawning potential and the absenceof stable cyclesin years with low potential, Thefirst 18years 937-1954! canbe considered Estimates of recrriitrnent to the Korf-Karagin a periodof averageabundance Figure 2!, charac- herringfishery is basedon abundanceof age4 fish terized by relatively stable age-sizecomposition, sex i.e., the ageat which they enter the fishery!. The ratio, abundance, and biological condition of the entire researched period can be dixdded into four s pawnera. The total numberof spawnersduri ng this intervals, baserl on year-class strength in the popu- periodvaried from 7 x 10'to 1.5 x 10'individuals, lation under study. and their biomass was 2 to 5 x 10' tons, The first intervaL covers 18 years from 1928 During the next ten years 955-1964! the Kara- through 1945.It is characterizedby averageyear gin herring stockabundance remained at, a highlev- class abundance and moderate amplitudes in year el. In these years, the population experienced class fluctuations, In the first, three years 928- significant changes,Due to a few exceptionally 1930i the number of 4-year-old fish was fairly low, strongyear classes,the numberof spawnersrapid- 7 x 10' to 1.7 x 10' Figure 3 t In the f'ollowing 15 ly increasedand by 1957reached the historical rnax- years 931-1945! the year class strength stabilized imum, 3.4 x 10" fish or 735,000 tons. Fluctuations at 2 x 10' to 1,2 x 10" fish. Already during this 18 in biologicalfactors becamemore obvious.Strong year period a.definite five year periodicity in year differences in year class strength occurred. Except class strength was noted, Highest year class for the last two years of this period, the number of strengthoccu.rred during the followingyears: 1931- spawnersexceeded 10" individuals. 1932,1937-1939, and 1943-1945.However, strict pe- From 1965 to the present, western Bering Sea riodicity was not observedduring this period.The herring stocks have been low. The distinguishing averagenumber of 4-year-oldrecruits during the feature of this period has been a maximum ampli- first research interval v'as about 6.25 x 10'. tude in the fluctuations of all biological indices char- The next 1» years in the history of the Korf-Kara- acterizing reproductionpotential. The number of gin herringfishery represent a classicexample of a spawnersduring this 29 year period has varied from strict cyclicrecurrence in year-classstrength. The 2.4 x 10' to 6 x 10', and their biomass has ranged periodicitywas as follows: strong year classesoc- f'rom 6,000 to 175,000 tons. curred in the 1st-3rd and 6th-8th years of a decade, The optimum number of mature fish in the stock pooryear classes occurred in the 4th, 5th, 9th. and for expanded reproduction is somewhere between 1 10thyears, i,e two v eakyear classesfollovved three StockDynam!cs of WesternHt ring Sea Herring oe o u u o u E Z 0 Figure3. Ahundanceof the 4-year-oldcohort of Korf- Karogin herring. ! strongyear class, ! ao- erage, ! ueak year c/ass. strongones. In additionto the strict periodicityin 1946-1960, the absolute maximum year class strengthwas achieved, averaging about 1.1 x 10'fish. Year In 1961the populationstarted to declineand wassoon quite depressed. For 11years 961-1971, Figure4. Russiancatches ufherring in the.Far-Easterri 3rd interval! the stockretained its 5-year periodic- seas. I! Sakhatin-Hokkaido, ! Okho sk, ! ity of strongyear classes alternating with weaker KorfKaragi n, ! Ciizhiginsky-Kamchatka, I ones. However, the stronger classesappeared once EaSternBering, ! Peter the Great Bay, ! or twicein five yearsand absoluteabundance was Dekastrtnsky. nothigh, 3.6 x 10"to 1.0x 10'individuals. The aver- agerecruitment, to the commercialstock was a lit- tle over 2.5 x 10 individuals. From 1972to the present th pcriodl, the re- Beringmarine herring!, and relativelylow Peter productiveoutput has been low. The 5-year cycle of the Great Bay and Dekastrinsky!,The averagean- strongyear classes has also been broken. Year class nua] harvest from the erst category was 90,000- strengthof over2 x10' fish occurredwith a period- 120,000tons, the secondwas 21,000-34,000 tonr, icity ofeight years during the 1970sand 1980s. The and the third was 6,000-7,000 tons Figure 1!. averagenumber of recruitsduring the last interval Froin 1921 to 1992 the total annual herring has decreasedby 1.7tiines comparedto the preced- catchin the far-easternseas has fluctuated greatly ing interval,and was only 1.5x 10'fish. Figure4!. Twice,in 1931and 196S-1969,catches exceeded500,000 tons. In the first case,the high commercialtake was due to increasein catchesof Fishery Sakhalin.-Hokkaidostocks, and in the seconddue Amongmarine herring stocks inhabiting the Japan, to rnaxiinurncatches of Okhotskherring. But there Okhotsk,and Bering seas, the followingsustained havebeen years when the domesticcommercial fish- a significantfishery for Russia: Petro Velikogo Bay ery tookless than 100,000tons; 1937-193S, 1946- herring, Dekastrinsky, Sakhalin-Hokkaido, 194S,1976-1982, and 1989-1990. Okhotsk. Gizhiginsky-Kamchatka,Korf-Karagin, Beginningin the 1960s,the total catch of Pacif- and Eastern Bering stocks. ic herringhas depended on the Okhotsk stock. which Basedon commercialstatistics, these popula- makeup an averageof 70%of the annual catch. tions are clearly separatedinto three categories: During the entire 72 year observationperiod populationswith abundance,bioinass, and conse- 921-1992 l, the Russian fishery has taken about quent.catch levels t,hat are high Sakhalin-Hokkaido16 million tons of Pacific herring, averaging 221,000 and Okhotsk', medium Korf-Karagin, Eastern tons annually. ECOIOgt:of the eri g Sea:A RC'VieWOtRt 5!a L tera urn 773 Table 1. Russiancatches of herring in the Par-Eastern seas Figure 1! 1921-1992 in thousandtons!. Totalfishing period lntensive fish> ng period Total Avg.yearly hfarr.catch Total catch Avg. yearly catch, catch, Years No yrs. Years No.yrs andyr. intensiveyrs. catch all vrs. all yrs. Sskhslrn-Hokkaido '?-1992 72 1921-1959:39 595 931! 6,511 167 6,657 Okhotsk 1945-1992 48 1945-1992 48 380 9691 5,716 119 5,716 119.1 Eorf-Karagin 1939-1968, 46 1953-1968 16 196 961 1,217 76 1,549 :3'3.7 1977-1992 Gizhiginsky- 1937-1973, 44 1955-1973 19 161 9581 740 39 911 20.7 Karrrchatka 1986-1992 Ea atern Ber i ng 1959-1980 22 1959-1976 18 92 9691 556 31 572 26.0 Dekastrinsky 1926-19'36, 46 1926-1936 11 26 9291 161 16 287 6.3 1965-1971, 1982-1992 Ycter thc Great 13ay v-1936, 46 7-193o 107 25 926! 190 19 246 7.0 1965-1969, 1975-1988 Coinmercial exploitation of the Korf-Karagin herring began in 1939, In the first year of fishing about 5,000 tons were taken Figure 5!. Over the next 15years, through 1953, herring was taken only with passivegear herring weirs! during the short sr r period when the spawners were near shore for spawningin KaraginBay, Catches slowly grew and IO in 1953 the catch was 21,500 tons, .illnetting on 0 foraging schools was introduced to the fishery in O 1954,the fall purseseine fishery was begun in 1958, IO and the winter trawl fishery v as started in 1959. ~ oa Japan also joined the Korf-Karagin herring fishery in 1961.The Japanesecaught pre-spawni ng herring with nets, putting enormous amounts of gear in the path of the spawning migrations. The Korf-Karagin herring fishery was the most valuable in the northwestern Pacific in 1960-1966. ISIS lsar rssrr iszo % r I99 r The total annual catch USSR and Japanl during Year this period exceeded100.000 tons, with the maxi- rnum in 1961 at 268,000 tons, During the eight year Figure 5, Total USSR und Japan! catrhes nf Korf- period from 1959 to 1966, herring fishing was done Kuragin herring. !3! rSSIK, sernes, hy, ! all year long, In the late 1960s the herring catch USSR, seiries, Sep ,-¹r., r'3! USSR, gr'linet, rapidly decreased,despite thc constant increasein 3 USSR, trarols, iVot.-Afar<.h, J Japan, fishing effort, and by the end of the decadethe fish- gil/rte , Apr. Vay. ery was suspendedfor economicreasons. Fishing was suspended in 1970 and was not completely re- opened unt.il 1986. Exploitation of Karagin herring at much lov er levels began again in 1977, Low catch quotas re- mained in efIect in the 198Os;only 8,000-32,000 tons were caught. The fishery was closed in 1992 and 1993 for two reasons: the relatively low reproductive potential StockDynatnics oi tVesternOenng Sei Herring 174 Fried,S,M., and VG, Wespestad.1985. Productivi- andto protectthe juveniles of two strong year cl ass- ty of Pacificherring Clupea horengus pailasi! es, 1987and 1988,from the fishery. in the eastern Bering Sea under various pat- terns of exploitation.Can. J, 1'ish,Aquat. Sci. CoNCI USION 42 Supp.1!:181-191. Overa half-centuryof researchon herringin the Kachina,T.F. 1981, Seld' zapadnoy chasti Beringo- westernBering Sea allows us to concludethe fol- va morya.lThe westernBering Sea herring.J lowing: Pishch. Prornst., 121 pp. 1. Theentire bfe cyde of herringoccurs on t,he con- Maksimenkov,V V. 1979. Differentiation of juvenile tinentalshelf. They undergo spawrung, feeding, Bering Sea herring Clupea pa tlasi paltosi' Val.!. and wintering migrations.The durationand rangeof the feeding migrations depends on the TINRO, Vladivostok 10:111-118. size of the stock. Naurnenko,N.I. !984,Numerical dynamics of the easternBering Sea herring, Candidate's thesis 2. Herringabundance has varied greatly through- in biologicalscience. VNIRO, Moscow, 23 pp. out the yearsof observations,from the average levelin the 1940s,to highlevels in thelate 1950s Naurnenko,N.I. 1990,The reasonsfor Long-term andearly 1960s,and low in the last 30 years. depressionofKorf-Karagin herring stocks. Bio- Thelargest spawning stock was observed in logicheskieresursy shel'fouykh i okrainnykh 1957when there were 3.4 x 10'fishes or 735,000 rnoreySSSR. [Biological resources ofthe shelves tons.The smallest stock levels were recorded in andmarginal seas of the UhSR,] Nauka Press, 1969 at 2.4 x 10' fish or 6,000 tons, Moscow,pp, 139-148, 3, Five-yearalterations of strongand weak year' Naurnenko.N.I., P.A. Balykin, Ye,A. Naumenko, and classesoccurred in yearsof averageand large E.R.Shaginyan. 1990. Long-term changes in the stocksize. This cycle was disrupted in yearswith ichthyofaunaof the westernBering Sea, Izv, depressedstocks and a neweight-year cycle Tikhookean,Nauchno-Issled. Inst. Rybn.Khoz, developed. Okeanogr, TINRO! 111:49-57. 4. Russiancatches of herringin the far-eastern Panin,K,I, 1950.Materials on the biologyof her- seasin the 1920s-1980svaried from 40,000to ringgon the northwestern Kamchatka coast, Izv. 520,000tons. They werehighest in the Late Tikhookean.Nauchno-Issled. Inst, Rybn.Khoz. 1920s-early1930s and in the late 1960s.In Okeanogr. TINRO! 32:3-36, termsof the sizeof the catch,the Korf-Karagin herringis third,aA,er the Okhotsk and Sakha- Pravotorova,E,P, 1965. Biological data on Gizhigin- lin-Hokkaidostocks, During the entire history sky-Kamchatkaherring related to fluctuations of the commercialfishery 939-1992!,over 1,5 in abundanceand changes in feedingarea. Izv. million tons has been harvested, averaging Tikhookean.Nauchno-Issled. Inst. Rybn.Khoz, 34,000 tons per year. Okeanogr. TINRO! 59:102-126. Prochorov,V.G, 1965, Topatsky herring. Voprosy RFFERENCES GeografiiKamchatski 3:115-116. Barton,L.H. 1978,Finfish resourcesurveys in Norton Soundand KotzebueSound. U.S. Dept. Rogers,D E.,and K.N. Schnepf. 1985. Feasibility of Commerceand U.S. Dept.Interior Environmen- usingscale analysis methods to identifyBering talAssessment ofthe Alaskan Continental Shelf. Seaherring stocks. Fisheries Research Institute Final Report,Biological Studies 4;75-313, Univ. Washington,Annual Report FRI-UW- 8501, Seattle. 48 pp. Birman,I.B, 1973.Solar-hydrographic interactions asa basisfor long-term stock predictions in com- Rogers,D.E,, N.N, Schnepf, and P,R. Russell 1964. mercialfisheries e.g.salmon and herring!, Vopr. Feasibilityof using scale pattern analysis meth- odsto identifyBering Sea herring stocks, Fish- Ikhtiol. 13 I!:23-37. Ecologyor the BeringBed: A Revicvvo Russianliterature eries Research Institute Univ. Washington, An- nual Report FRI-UW-8402, Seattle, 47 pp. Rowell,K.A. 1980,Separation of spawningstocks of Bering Sea herring basedon scalegrowth patterns,In: Proceedingsof the AlaskaHerring Symposium.Univ. Alaska SeaGrant Report80- 04, Fairbanks, pp. 262-263. Rowell, K.A., H.J. Geiger, and B.G. Rue. 1991.Stock identification of Pacific herring in the eastern Bering Seatrawl bycatch and in the Dutch Har- bor food and bait fishery. Proceedingsof the In- ternational Herring Symposium. Univ. Alaska SeaGrant Report 91-01, Fairbanks, pp. 255-278. Tyurnin, B,V and E.I. Yelkin. 1977.Some biologi- cal factors regulating the Okhotsk Sea herring fishery. Rybn. Khoz. 4:14-17. Walker, R.V and K.Ã. Schnepf. 1982. Scalepattern analysisto estimatethe origin of herring in the Dutch Harbor fishery, Fisheries ResearchInsti- tute Univ. Washington, Final Report FRI-UW- 8219, Seattle. 47 pp. Ecologyof thi BeringSea; A Reviewof RussianLiterature Dynamicsand Abundance ofWestern 6eringSea Walleye Pollock P.A.Balykin KamchatkaResearch Institute of Fisheriesand Oceanography KamchatNIRO! Petropai:/oisk-Kamchatski, Russia, ABSTRACT ing ground locatedat about the samelatitude as This paperreviews and summarizesinformation on DezhnevBay. Reproduct,ionstarts at the end of pollockabundance, catch, and year-class strength March,and the peakof egg-depositionis in early to within the Russian exclusive econoinic zone in the mid-May, depending on the water temperature Bering Sea.Western Bering sea pollock stocksin- Figure1. Walleye pollock spaioning areas ! in the uestern Bering Sea,and most feeding migration rouiee !. 3rtodi- fiedfrom Bhuntsvet al. 1993. 3-year-oldslarge enough to betaken by thegear av- catchva.ried from 271,000to 383,000tons Table1!. eraging23.5% and 35.3% of their year class strength The catch ratio of Americanand Asian pollockvar- respectively!.Spawning stock is calculatedfrom the iedgreatly over the years. The latter averaged 47ok. numbersin eachage group and the ratesof sexual maturation. For comparison,we presentdata from ESTIMATIONOF STOCKSIZE trawl surveysin 1986and 1987,when pollock hio- Virtual populationanalysis VPA! is usedto esti- rnasswas estimated at 1.3 and 1.6 million tons rnatepollock stocks in thewestern Bering Sea i Gul- Shuntovet al. 1993!,which is very similar to esti- land 1969i, lt applies coefficientsof natural mated size of commercial stocks Table 3!. mortalityby age group and fishing mortalii,y by year It is knownthat pollockabundance in the west- andage group, Natural mortality is determinedby ernBering Sea in the 1950sand 1960s was not high i,hemethod of Tyurin 962! Table2!, andfishing Kachina1979, Naurnenko et al, 1990!.Throughout mortalityis computedby the Savillemethod Pope the 1970sa significantgrowth of pollockbiomass andShepherd 1983!. Informal.ion onabundance and wasnoted. Hy the beginningof the 1980sthe bio- biomassof pollockin 1970s-1990sis presented in rnassincreased several times and exceeded3 rnil- Table3. Theentire stock includes fish 2-9years of lion tons Table3 !.The resource stayed at high levels age.The commercial stock includes 4-year-old pol- for5 years.Stocks began to declinestarting in 1985, lock,the ageat whichjuveniles are fully recruited andby 1990the biomasshad decreased io 1.8mil- to thefishery iHalykin and Naksimenko l990!, and lion tons.According to our information,the decrea.se olderindividuals. The fishery also includes 2- and in stockshas continuedto the present. The stock Ecologyof theHr ring Sear A Reviewof Russianl.fferature 179 Table 1. Harvest of pollock in the western Bering Table 2. Natural mortality rate factors for poHock Sea. M!. Total catch Catch to west of 176sE Age in years Year thousand tons! thousand tons! 2 '3 4 5 6 7 8 9 1970 40 22 55 0.87 0.45 0.34 0.36 0.42 0.54 0. 73 1.04 1971 89 60 1972 141 76 54 1973 77 66 86 fl 9 1974 114 90 population,we can use the 'parent,-progeny"rela- 1975 188 176 94 tionship of Ricker 954!: 1976 549 83 15 R = 3 494e' ~~s' Figure 2 i 1977 265 8o 32 where R = number of recruits at age 4, 10" individ- 1978 417 161 39 261 48 uals; 1979 546 S = numberof spawners,10' individuals. 1980 825 419 51 1981 1133 279 25 Year class strength calculat.edby this equation 1982 976 356 36 is the solid line plotted in Figure 2, One can distin- guishyears when the year class strength was greater 1983 1006 353 35 +! or less f than the predicted values. 1.984 755 376 50 1985 662 278 42 + 1973-74, 1978-79, 1982, 1984-85 1986 867 271 31 1975-77, 1981, 1983, 1986-90. 1987 812 300 37 Analogousinforination aboutfavorable and un- 1988 1327 324 24 favorable years for the reproduction of eastern 1989 1029 309 30 Bering Seawalleye pol!oclr is availablein Wespes- 1990 814 383 4n tad 989, 1991, 1994!; 309 61 1991 504 + 1972-73, 1978-80,1982, 1984, 1989 281 47 1992 597 1975-77, 1981, 1983,198,>-88, 1990. 1993 677 363 54 Apparently,in mostcases the signof the anoma- lies in pollockyear-class strength in the easternand westernBering Sea is the same.which is a resultof the common cliinatic and oceanographic regime. Wespestad 991! concludedthat there is a def- declines are related to climatic cooling, Increases in inite connection between year class anomalies and pollockabundance in the Bering Seaare not likely water temperature:as a rule, strong year classes before the end of the century Shuntov 1993!, occur in warm years. One exception was 1972, when a very strong year class occurred I Wespestad19911 Comparisonof pollockyear classstrength in the YEAR ClASS STRENGTH w'estern Bering Sea to year type classifications ac- Apparently,inl,erannual variations in pollockstock cording to Davydov 984, 1991! were inconclusive are caused by fluctuations in year class strength Figure 3!: strong year classesoccur iii both warm Table 4, Figures 2, 3!. In the absenceof complete and cold years, and so do weak ones.Possibly, the information on the fishery in the early 1970s, year abiotic conditions themselves only increase or de- class strength from 1966 to 1970 is assumed to be crease, to a certain degree, the influence of other low. With the aboveassuinption, the 1971 year class forceson pollock year class strength in the given was the weakest 43 million fish! and the 1978 year periodof tiine. Thisconclusion agrees wit h published class was strongest .107 billion!. Adjacent year reports.Thus, Khen <1987!showed that given low classes can differ froin each other by two times. pollockspawning stocks in the easternBering Sea, Fluctuations in year-class strength are caused warmer temperatures result in up to a 25" Table4 Abundance RJof pollock year classes atage 4 millionfish!. 1973 1974 1975 1976 1977 1978 1966 1967 1968 1969 1970 1971 1972 1,116 1,156 791 H94 1,093 2,107 241 283 397 563 364 543 '767 19791980 1981 1982 1983 1984 1985 19861987 1988 1989 1990 R 1,894 1,175794 1,4781,0S1 1,3lS 1,434 1,049 795» 686" 720* 993» ' Theseestimates are >>rehmir arrane! meampleia tions leadto recruitmentanomalies of up to 15%-, influenceof populat,iondensity on year cLass Thedegree to which a yeartype warm-cold! influ- strengthis estiinatedat a minimumof 54'i'rusing enceswestern Bering Sea pollock recruitment is dispersionanalysis Balykin 1992!. l Editor's note: estimatedat 14% Balykin1992!. Since the influ- m =P and t =+in Ricker's spawner-recruit mode].j enceof abioticconditions on yearclass strength is AccordingtoWespestad 989, 1991,1994!, the notgreat, inl.eractions at the population level are correlationbetween the productioncoet7icient RJS ! probablysignificant. This assumption isconfirmed andbiomass of pollockin theeastern Bering Sea is: byhigh correlation between the reproduction index r = 0.710,ri = 28, m = 0.094,t = 4,36.Therefore, R/S!and abundance r = O.S01, >r = 21,m =0.078, yearclass strength of easternBering Sea pollock is t =4.66! and biomass r = 0.811, m =0.075, t =4.78! primarilyinfluenced by density factors at thepopu- ofall pollock stocks in the western Bering Sea. The lation level. otologyo the BeringSea: 8 Reviewof RussianLiterature R ll C C r Et' u t6 1.6 ti n 9 n 9 ti ft4 g a 4 0HI 60 <99$ srr0 i975 SUMMARY REFERENCES 1. Pollockof Asian origin make up an averageof Balykin,P.A. 1981, West Bering Sea pollock distri- 47% of the western Bering Sea harvest. bution during feeding and wintering periods. Ekologiya,zapasy i promysel mintaya Ecology, 2. Pollock stocks in the western Bering Sea in- stocks,and the pollockfishery]. Vladivostok, pp. creasedfrom the early 1970sthrough the mid- 57-62. 1980s. The maximum abundance of 2 to 9-year-oldfish reached 13.1-14,3 billion fish and Balykin, P.A.1992. Year class strength and recruit- the biomass reached 3.1-3.4 million tons, At ment of the west Bering Sea pollock TFteragra present,pollock stocks are declining. chalcagromm.o.Vopr, Ikhtiol. 32 !:185-188. 3, The direction of changesin pollockyear class Balykin, P.A,1993, Variability in the spaivningpe- strength in the westernand eastern Bering Sea riod and developing egg mortality in ivcstern in most casescoincides, thus indicating a single Bering Seawalleye pollock. Research on the bi- climatic regime, ologyand populationdynaniics of cornrnercial fishes on the Kamchatka shelf. No. 2, Petropav- 4. In this study, formation of pollock year class lovsk-Kamchatski, pp. 166-176. strength was influencedprimarily by density factors at the population level. Balykin, P.A.,and V.P.Maksimenko. 1990. Biology and conditions of pollock stocks in the v,estern BeringSea. Biologicheskie resursy shel'fovykh i okrainnykh morey SovietskogoSoyuza [Bio- logical resources of the shelfand bordering seas of'the Soviet Union]. Vauka Press, Moscov, pp. 111-126. Oynamicsand Abund~n<.e at'Western !3eri n gSeaW'a//eye Poi roc:k Davydov,I,V. 1984. Oceanographic conditions in the Tikhookean. Nauchno-!ssled. Inst. Rybn. Khoz. majorfishing regions of the far-eastern seas. Izv, Okeanogr. TINRO! ll 1;49-57. Tikhookean, Nauchno-lssled, Inst, Rybn. Khoz. Okeanogr, TINRO! 109:13-16. Pope,J.G., and J,G, Shepard. 1983. Comparison of the perforinanceof variousmethods for tuning Davydov,I.V. 1991.Hydrometeorologicalconditions VPA'susing effort data. ICES Doc.9, 33 pp. for reproductionof certain fish populationson the Kamchatka shelf in 1991and predictions for Ricker,W,E. 1954.Stock and recruitment, J. Fish. 1992, Manuscript. KamchatNIRO archives, Res. Board Can. 11:559-623. Petropavlovsk-Kamchatski, 35 pp. Serobaba,I.I. 1977.Information on population struc- Fadeev,N,S. 1988.Distribution and migrationsof ture of the Bering Sea pollock, Vopr. Ikhtiol. pollockin theBering Sea. Manuscript, TINRO 17 !;247-260, archives, Vladivostok, 69 pp, Shuntov,V,P., A.F. Volkov,O,S. Ternnych,and K.P. Fadeev,N.S. 1990.Distribution and inigrationsof Dulepova. 1993. Mintay v ckosistemakh pollockin the BeringSea. Rybn. Khoz, 7:46-47. dal'nevostochnykhxnorey [Pollock in the ecosys- tems of the far-eastern seasj. Vladivostok, 426 Flusova,G.D., and I .V,Bogdanov. 1986. Population pp- structure of pollockbased on geneticresearch. Treskovyedal'nevostochnykh morey Gadidsof Ternnykh,O.S. 1994. Morphological differentiation the far-eastern seasj. Vladivostok, pp. 79-88. in pollockof thewestern Bering Sea and Pacific waters of Kamchatka. Vopr. Ikhtiol. 34 !:204- Guiland, J,A. 1969.Manual of methodsfor fish as- 211. sessment.Part 1.Fish populationanalysis. FAO Man. Fish. Sci. 4. 154 pp, Tyurin,P.V. 1962. The natural inortality factor and its significancein regulating fish catches.Vopr. Kachina,T,F. 1979.Population dynamics of herring Ikhtiol. 2 !:403-427, and pollockin the far-easternseas. Rybn. Khoz. 3:7-9. Wespestad,W.G, 1989. Abundance and yield of wall- eyepollock on the easternBering Seaand Aleu- Khen, G.V.1987, Intcrannual changes in watertem- tian Basin. Proceedings of the International peraturesin the southeasternBering Sea and ScienceSyinposiuin on Bering Sea Fisheries, its role in oscillation in year class strength of Sitka, Alaska, July 1988. Seattle, pp 348-375. eastern Bering Sea pollock, Populyationnaya struktura, dinamika chislennosti i ekologiya rnintaya [Populationstructure, numericaldy- Werpestad,W,G. 1991. Pacific herring population nainics and ec.ologyof pollock], Vladivostok, pp. dynamics,carly life history and recruitinent variation relative to eastern Bering Sea ocean- 209-220. ographicfactors. PhD. Dissertation, Urriv. Wash- Moiseev.P.A. 1967,Rybolovstvo Yaponii [Fisheries ington, 237 pp. in Japanj. Pishch.Promst., Moscow, 199 pp, Wespestad,W.G, 1994. Walleye pollock, Report and Niaumenko,V.I., P.A.Balykin, Ye.A. Naurnenko, and data submitted for the Third International Pol- E.R,Shaginyan. 1990. Multi-year changes in the lock Stock Assessment Workshop. Seattle, pp, ichthyofauna of the western Bering Sea.Izv. 11.9-143. Ecologvot theHeririg Sea:.4 teleview ot kassi in Literatitre 1tf3 PacificCod Gadusmacrocephalus! of the WesternBering Sea Andrei V. Vinnikov KamchatkaResearch Institute of Fisheries and Oceanographv KamchatIVIRO! Petropai lo ask-Kamcha tski,Russia BRIEFHISTORY OF RESEARCH hydrologicalregime of the far-easternseas, and the The first mention of cod as a commercial fish of distributionand biologyof commercialfish, includ- Kamchatka was in 1755 in Krashennikov'shook ing Pacificcod iDyeryugin 1933a, 1933b: Bhmit Descriptionof Kamchatka 949!, The very sinall 1933,1936; lUIoiseev 1934; Suvorov and Shchetini- populationof the far-eastern region of Russia, which na 1935;Andriyashev 193o, 1937, etc.!, Most of the in the late eighteenth-earlynineteenth century con- scientistsbelieved that the failure of the trawl fish- sistedof mostly natives, did nottake cod or any oth- erywas caused by poororganization and iinproper er marine fish cominercially.Cominercial fishing gearconfiguration. At the sametime, they empha- requiredgoing into the opensea with specially sizedthat codstocks were large enoughfor a profit- equippedvessels and fishing gear, Salnion fishing able fishery. in the rivers waspr eferred, for it requiredtnuch less lii 1950-1952 the TINRO expedition led by V.D. f'ordeev discoveredhuge concentrationsof cod by eA'ort. Biologicalresearch on codis directlyrelated to CapeNavarin in thenorthwestern Bering Sea. Pub- its commercialexploitation, which began in the lishedworks basedon material collectedduring that westernBering Sea in the 1920s,as the Russian perioddealt with coddistribution tGordeev 1954!, fishingindustry was established and, at first, pri- size.age structure, nutrition twrdeeva1952, 1954 i, vate enterprises were created, andsystematics Pyetrova-Tychkovs 1948, Tikhonov In 1927-1928the Japanese company Luri orga- 1955}, It was concluded that cod stocks in the re- nized an experimental hook-and-linecod fishing gionwere very high, but dueto the remotenessof event in the southwestern Bering Seanear the Com- the area, coinmercialexploitation was st.ill not ini- inander Islands and Karagin Island. Navozov- tiated. Collection of data on the biology of western Lavrov,who took part in this expedition,observed BeringSea cod was resumed in 1966.and in 1967 the behaviorand feedingof cod,and alsoconclurled several commercial t,rawlers were sent to the Cape that their stockswere quite substantial Navozov- Navarinregion for experimentalcod fishing. The Lavrov 1927, 1928!. resultsled t,o the organizationof a specialcodfish- The initial successof the cod-fishing schooners ing expeditionin 1968.Systematic research in the led to the developinentof a Russiantrawl fishery 1970s-1980sresulted in the publication of a nurn- aimedspecificaRy at codstocks. However, due to or- ber of works on the biologyand fisheriesof Anadyr- ganizationalflaws and the limitedscale of the ex- Navarin cod lVershinin 1975, 1976, 1981, 1983, ploratoryfishery, the catch per unit effortof the trawl 1984,1987; Vershinin and Maksimenko1984!. fisherywas solow that it wasconcluded that cod In addition, several publications on eastern fishingin theFar East was not cominercially viable. Kamchat,kacod refer to the biologyand fisheriesof Marine scientists in the Far East played an im- thesouthwestern Bering Sea cod Karagin, Korf, and portantpart in fisheriesresearch. In 1929-1939,the Olyutorskbays! Bogayevsky1948; Polutov 1952, Pacific Research Institute of Fisheries TIRKh, in 1970;Moiseev 1953; Fyodorov 1973; Polutov and 1934renamed TINRO! organizeda numberof ocean- Tokranov 1978; Vershinin and Tokranov 1983; ographicexpeditions. The collected data were pub- Tokranov1986; Borets 1989;Tokranov and Vinni- lished in the first Russian reports characterizing the kov 1991a, 1991b i. !'acitic Cod oi tht 1Ve~teni Bering Sr s COMMERCIAL FISHERIESDISTRICTS: MATERIALSAND METHODS After introduction of commercial fishing regions, stock monitoring and harvest quotas were donesep- arately by region:western Bering Sea and Karagin subzones of the eastern Kamchatka Commercial FishingDistrict southwesternBering Sea!, The Karagin subzone 1.02.1! includes the southwestern Bering Sea with Ozernoi Bay, Kara- gin andOlyutorsk bays, and inner Korf Bay Figure 1!, The western Bering Sea zone 1,01! includes the coastalregion of theKoryak uplands from Cape Olyutorskto CapeNavarin and the Gulfof Anadyr Figure 1!, This regionis alsoreferred to as the Anadyr-Navarinarea in tbe northwesternBering Sea. This work is based on materials collectedin the westernBering Sea in 1966-1993.The field research and trawl surveyswere doneuntil 1990on vessels of the PacificDepartment of the Commercialand Scientifi.c ResearchFleet TURNIF!, and in some yearson vessels of thecommercial fisheries depart- ment of Kainchatka Kamchatrybprom KRP!. In 1991-1993the surveys and collection of the biostatis- tical data were done on small- and medium-sized boatsequipped with Danishseines. The study area included the continental shelf and the upper conti- nentalslope to 500-meterdepth. During spring and summerof 1991-1992a bottom-setlongline survey was donein the southwestern Bering Sea. Biological analysis of cod and measurements weredone by standardichthyological methods. The AC lengthwas takenfrom the tip of the snout to themiddle rays of the caudalfin in centimeters,The Figure 1. Fishing regionsin the westernBering Sea. stepof the lengthfrequency distribution was 5 cm. Karagin suhzone61.02.i and westernBering The bodyweight was measuredin grams.Age of Sea zone 61.01. Anadyr-Navarincod was determinedby otoliths in 1968-1985,and in subsequentyears by scales.In the southwestern Bering Sea in 1984-1993age was determined only by scales. We would also like to thank KarnchatNIRO re- Trawl surveys,on a standardstation grid on re- searcherA.M, Tokranov for his help in writing the searchcruises and at random sites on commercial sections"Reproduction" and "Nutritionaland Tro- fishingcruises, were done to assesscod distribution phic Relationships," in the western Bering Sea from 1966 to 1988.The catchper hour of trawling in hundredsof kilograms LIFECYCLE AND BASICBIOLOGICAL was acceptedas an arbitrary unit of fishing and surveyeffort andbecame the standardquantitative f EA+URES measure of cod distribution. Differentiationwithin the species In this work we used the un.published materi- als of Ko TINRO scientist B,G. Versbinin, who stud- The shelf zone and the upper continental slope of ied the biology and cornrnercial exploitation of the Bering Sea are within the extensive range of Anadyr-Navarincod, and we dedicatethis work to Pacific cod, Cod in the study area are typical mem- his memory, bers of the northern boreal zoogeographiccomplex Ero/ogyof theBerirttf Sea: A Reviewof Rossitn l.iter,irore of the world'socean Vinogradov1948, Andriyashev arate, sometimes adjacent, areas. The crucial fac- 1954 1 tor influencingthe distribution, migration, and be- Sharpdifferences in geomorphologicalfeatures havior of cod is epibenthic water temperatures, andhydrological conditions of someareas inhabit.- whichalong with other abiotic factors,influences a edby Pacific cod result in a numberof distinct,eco- species'inetabolism, reproduction, and juvenile de- logically isolated stocks with relatively small velopment Moiseev 1960!. ranges,undergoing limited migrations Moiseev A tagging study of cod migrations in eastern Kamchatkabays did not producereliable results due 1953, 1960!, Geographicallyseparate and temporally stable to a verylow numberof return~. But they did dis- winteringand spawning areas indicate the presence provethe contention of Polutov 937! thatcod from of a number of independentpopulations. Gordeev different bays do not mix I e.g.,one fish taggedin 954! postulatedthat Navarincod wintered on the Kronotski Bay was caught two years later in Oly- continentalslope of the easternBering Sea. utorsk Bay!. The studies also indicated that such Analysis of thc populal,ionstructure of western migrationsare not possiblein coldyears, when low BeringSea cod Vershinin1984, 1987! revealed ac- water temperaturesaround the capesserve as nat- tual differencesin morphologicalcharacters which ural barriers,preventing migration from onebay to indicate that the groupsunder comparisonare in- the next tl'olutov 1952!. In the early 1970s977 fish dependent,populations. Similar habitat conditions weretagged in an attempt to determinecod migra- imposedby thegeographic proximity of theAnadyr tions in the CapeNavarin region, but only three andsavarin regionsresults in relatively high mor- taggedfish. were recoveredin practically the same phologicalsimilarity among the codpopulations in locationwhere they were taggedafter 11, 19, and the region,Substantial differences were observed 20 days.The study was thercf'oreinconclusive. only in thosemorphometric characters inost sub- The results of winter trawl surveys in the Bering ject to environmentalinfluences. When comparing Seain 197 5 through 1980 showed the discreteness the codsfrom more remote areas, the magnitude and of the codwintering areas.Every year, November number of the differences increase. This indicates throughApril, concentrationsof winteringcod oc- that a distinct population exists in t.henorthwest- cur at depthsof 150to 410 m, wherebottom water ern Bering Sea. temperaturesare -0.5 to 3.6'C.As a rule,the larg- We were unable to determine the status of the est catchesoccurred between the 180 and 250 m iso- Korf-Karaginand Olyutorsk cod populations south- baths,where bottom temperatures were 1 to2,5"C. westernBering Sea!,because the availableinateri- Oxygenconcentration in the waterduring the sur- al was not representative enough. They are veyswas high everywherei not less than 90-95'rr' presumablya singlestock, sinceexchange of indi- saturation!,salinity variedinsignificantly 2.6-33.0 vidualrbet,ween populations is less limited there pptt, Codconcentrate in shallowerregions where than between other regions, The above conclusions warm,deep water moves up ontothe shelf.In t,he areindicated by the relativelywide shelf near the Gulfof Anadyr catchesof 30-500kg at depthsof 170- natural boundaryof Cape Govenand the general 180 rn were recorded. circulation pattern of the water masses Leonov In the southwesternBering Sea Karagin and 1960!. Korfbays I, codoverwinter primarily at. the edgeof The absenceof an accepted point of view about the continental slopeat depths of 180-300m between thepopulation structure of westernBering Sea cod CapeGoven and the northernend of KaraginIs- complicatesthe solution of several management land,where catchesof'up to 500kg have beenre- questions,especially those related to fishingregu- corded. In some years, in late November and lations. Decemberlow concentrations of cod v'ere observed; catchesof' up to 50 kg were taken in Litke Strait and Korf Bay, where bott,om water temperat.ures Generaldistribution and migrations were already subzero i as low as 0.5'!. Moiseev 954! emphasizedthat cod migrationsin Overwinte ring schoolsof codoccur at 170-410m the far-eastern seas are strictly seasonal.In the fall depthin OlyutorskBay, the Navarinregion, and far- andwinter they migrateto the wintering andspawn- ther southeast..Catches in the Navarin area did not inggrounds on the continentalslope and in spring usuallyexceed 50 kg; however,near 172E a few andsummer they move to shallowshelf waters for catchesabove 1 tonper trawl wererecorded in No- thesummer feeding. This typeof migration, in his vember-December of 1976. The largest concentra- opinion,is causedby marked differences in geomor- tions of cod have been found in the upwelling zone phologicaland hydrologicalconditions between sep- to the south-southeastof CapeNavarin. Catchesof Paciiic Cud of the ltestern Oerir>gSea Table1. Codcatch per unit effortin the BeringSea for winterand summer. Catch ikg! per hour of trawling Limits Average Winter Summer Winter Summer 60 Karagin, Korf hays 1-80 2-2.5 80 60 Olyutorsk Bay 20-600 2-600 150 640 Anadyr-Navarin region 30-3,500 30 9,000 170 over 1 ton per trawl havebeen obtained there at Seawater in 1966-1988;catches in the central Gulf depthsof 180-250m, wherebot tom water tempera- ofAnadyr were usually 60-300 kg but oftenexceed- tures did not exceed 2.1-2.5'C. Some catches were ed 1 tonper trawl. In someyears, incidental con- upto 3.5tons. Catches were usuaHy much lower at centrations of codwith catchesup to 50 kg per trawl greater depths to 350 m!, wherethe temperature wereencountered by researchvessels in the north- is above 3.0'C. The limited data indicate that cod ern part of the gulf, alsooverwinter directly withini,he boundaries of the Thecatch of cod per unit effort in the studyarea Gulf of Anadyr; however,severe winter conditions tluctuated widely,because during the surveysthe preventa inoredetailed study. Cod also enter the trawls were taken not only within denseschools, iced-overharbors of the Chukchi Peninsulain Oc- but also outside of them Table 1!. Therefore aver- tober-December Andriyashev 1937!.Apparently, in- agecatch per unit effort statisticsare not high. trusion of warm Bering Sea water into Provideniya, Catchesper effort.in winter arc somewhathigher Lavrentiya, and other harborsprovide the neces- than in summer due to a decreasein the total area sary conditionsfor overwintering, wherewater temperatureir optimal for cod,thus Codspawning has been observed over all regions producingan increasein schooldensity. of the western Bering Sea at depths of 150-370rn, Winter and summer distributions within each with bottom temperatures of 0.5 to 2.3'C, study area showthat cod migrate to deep water in Feedingmigrations to shallowregions begin in the fall and to shallow areas in spring. May-June.The exact time is related to water tern- perature.Shelf waters in the southern regions warm Reproduction up to positivetemperatures by mid-Mayand cod appearin the catchesat depthsof less than 100m. After the feedingperiod summer-fall! the gonads Warmingis slowerin higherlatitudes where cod arein a resting stageat maturity stagesII, II-III on remain longerin wintering areas.For example,rni- a 6-pointscale; they are underdevelopedand have grationsto shallowwaters in theAnadyr-Navarin low volume and weight. Gonads in mature fish of region begin in early June. both sexesundergo intensive development; females Foragingschools wit,h catchesabove 500 kg oc- developfast,er than males.From early Novemberto cur mostlyon the relativelywide shelves, where nearlythe endof February mostfish reachmaturi- eddies and nutrient enrichment from continental ty stageIV {IV-V! January-February!,very near runoffproduce regions of elevated productivity. Such spawning condition, foragingschools are observed annually in thesouth- Codspawn practically simultaneouslyin coast- western Bering Sea,in Litke Strait and Korf and a] waters of the western Bering Sea. Prespawning Olyutorsk bays. andspawning fish maturity stagesIV-V andV iare Cod arc ubiquitousin the Navarin areain the found at the depths of 130 to 370 m, where bottom summer but highest concentrationsoccur on the water temperatureis 0,5 to 2.3'C mostly above shelf from 174 'K to Cape Navarin. This region has zero!. Bottom sediment in the catch locations is pri- unusuallyhigh productivitydue to upwcllingof marily sand mixed with pebblesand small rocks. deepwater ontothe shelfand has been an irnpor- Descriptionof spawning conditions are given in Moi- tant commercial fishing region since 1968. The seev 953!, Vershinin 984!, and Tokranov and Vin- southwesternpart of the Gulf of Anadyr is similar, nikov 991a!, where in the early 1970s catches by an average- Cod tend to form prespawning and spawning size vessel could reach 6-9 tons per trawl. Cod also schoolsin the epibenthic layer. Spawning happens formed schoolsin regions occupiedby warm Bering only once,as indicatedby the presenceof onepor- &CafogyOf he HerfngSear 8 Keview OI Krraxrafrfi r-nr ftrre 187 Table 2. Percent females in Bering Sea cod populations by region and study period. Age, years Region Period 2 3 4 5 6 7 8 9 Avg Navarin 1966-1990 48.1 47.3 5i0.4 51.3 59.5 5 i 7 67.9 66,7 50,9 Anadyr 1966-1990 46.1 49.5 49.4 52.2 o1.2 57.0 46.7 Hl.H 50.1 Table 3. Maturation rates of the Anadyr-Navarin cod. Region, Age, years year ofcatch Sex 2 3 4 5 6 Navarin Females ! 44 4 i 18i 49.2 f246! 75.0 iGH! 92,,'3 31 100.0 i 71 1971 Males i! ;35.4 i 311 51.3 36! 69.6 561 71.4 i 85.7 ! Anadyr Females ! I 27! 9,5i 84! 60.6 i 33! 62.5 i16! 100.0 f 3! 1971 Males ! 51 44.4 99! 72.0 51 75i 0 5i! 87 5 i16! Anadyr Females 131 721 21 16.0 5! 66.7 i 100.0 13 1975 Males ! 5,3 511 18.3 [82! 27.3 i221 20.0 ! 100. 0 61 Navarin Females 4! 1 6'3.6 1 ! 68.6 f11 ! 75 0 l3! 100.0 1 1977 Males 1.4 0! 11.1 91 80.6 I;311 100.0 fl;31 85.7 f7! 100. 0 Anadyr Females 4! 1I 50 0 1 72.8 11 85.7 f 80.0 i 41 1977 Males 85! 4 3 31 100 0 1 89.5 i191 100.0 ! I2 I ! nparentheSeS, Oital numberOr rish examined tion of mature oocytes along with immature oocytes Note that males also predominate in older. rna- in the ovaries of mature females. The entire mass ture age groups in strong year classes of Anadyr- of gonads in prespawning males were mature dur- Navarin cod, This feature of the sex ratio of strong ing the study period. year classes apparently has a profound impact on Males are smaller than females due to their ear- reproduction, since elevated numbers of males in lier maturation, Therefore males are significantly the spa vi ning stock enhance fertilizatiori. more abundant than females in the spawning stocks, Since most of the material on Anadyr-Navarin but they have shorter lives and slower growth rates cod was collected during the feeding period, rnatu- after reaching maturity than do females, ration rates were deter mined from data taken only At time of spawning there are two or three males in May- June of 1971, January-February of 1975, and for one female in the spawning st,ock, but the sex October of'1977 Table 31. ratio is close to 1:1 for the entire population, Proba- Maturation rates varied significantly over the bly, successful fertilization of the large amount of years, hut some general tendencies v.ere observed eggs produced by each female requires several males. f'or all years. Most cod are mature at 5-6 years of There is a certain regularity in the size-and-sex age, and males mature earher and when they are structure of cod in practically all the areas exam- smaller than females. ined. Females make up about 50~c of the 65 cm long Mature cod are present in the Bering Sea in fish; however, their portion rapidly increases among January through May Moiseev 1953; Tokranov and larger fish, and fish 95-11M cm long are 10f3~/cfemale. Vinnikov 199la!. although incidental specimens The sex ratio of Anadyr-Navarin cod in 1966- have been taken even in August. The dates of egg 1990 averaged 1: l. Age differences were clearly seen: deposition differ and depend on the geographic lo- males were predominant, in the younger age groups, catiorr of the spawning bed spawning tends to shift and females were predominant in the older ones to later dates in northern areas I, and also or>hydro- Table 23, meteorological conditions of a particular year. Patrie Cod or the ptesrernBering Sea 188 Table4. Spawningdatesfor cod in different regions ofthe western Bering Seaand adjacent waters. Peak Source Spawning regions Beginning-endof rpawning Moiseev 1958 January-March Feb 1 Kamchatka, Kronot,ski bays Moiscev 195;3 February-April May! Mar 2 Karagin Bay Our data February-April Mayl Mar :3 Ozernoi Bay Bur data February-Apxil May! Mar 4 Olyutorsk Bay Our data M arch-April May! 5 Navarin region Our iota March-April I May! 6 Gulf of Anadyr Svyetovidov 1948 7 Northern Bering Sea January-February March! Feb-Mar Moiseev 195;3 8 Commander Islands January-May Table5. Codfecundity in OlyutorskBay. Absolute fecundity Relative fecundity- I million eggs! eggsper g ofgutted weight! I.irnits Average Limits Average No.of fish 27 1.15 - 5.65 2.0+ 0.1 584- 858 640~ 17 havenot beenresearched at all becausethe larvae As a rule,the peakof cod spawning occurs in the southwesternBering Sea in lateMarch early andeggs are not taken by gearused for ichthyo- plankton surveys, April,and in t,henorthwestern Bering Sea in April Catchesof larvae in thc Bering Sea werexnen- Table 4h tionedby Moiseev 953!, Mukhachcvaand 7vyagi- Accordingto ourinformation, at theend of the na <1960!,Musienko 970!, and Bulatov 986>. second10 days of April 1991 only incidental mature Therewere usually not morethan six eggsin t,he codwere in bottom-setlongline catches in Olyutorsk samplesand few samples were taken. Cod larvae Bay,mostly males, and in lateMay no spawning werefound in catchesnot earlier than June 11, cod were foundin catchesin the southwestern catcheswith larvae occurredat four stations over BeringSea KaraginBay and Ozernoi Hay t depthsof 160-1,300rn and temperatures of 1.7- Thereare practically no dataon fecundity of 2,2'C,and their size varied from 10 to 15.6mm Bu- BeringSea cod, except a brief'report on Olyutorsk latov 1986!.The sizeof larvaein the catchesof Bay Table 5!. BeringSea cod eggs are colorless orwhitish-yel- 1945-1955in differentareas of the westernBering lowwith a smalllipid drop.They are small, round, Seavaried during May-July from 5.4 to 32mm, and not very sticky Moiseev1953l, According to Musienko 970!, "matureovarian eggs have a di- Size artd age structure ameterof 0.77-1.00mm averaging0.94 mm!," the Trawland Ds.nish seine catches in theAnadyr-Va- diameterof fertilizedeggs varies between 0,95 and varinregion in 1966-1990contained cod of 18to 1.11mm averaging0.98!, and the incubationperi- 118cm length, rnaxirnum weight of 20.7kg, and od variesfrom 10 to 20 daysdepending on bottoxn rnaximuxnrecorded age 12-13 years I 0.2 crn 40.4 ttom seining 7,8 20 anish seine! = 55,5 ttorn seining 4.8 anish seine! = 62.1 < 2O C CO V QV V CJ CL ~ t0 bottom seining 20 1.9 Danish seine! 20 M = 47.3 longline M = 69.8 JUtv! bottom seining 20 48.9 Danish seine! M = 48.8 November! 49,2 bottom gillnet M=76,3 i 00 Lert gt'h t:rrt! Figure2a. Sizeoomposition of rod in eatehestaken with different fishing devicesin the northuesternBering 8ea rAnadyr-Kaoarra region! in 1984-1993. Pacific .od of the l4r sternBering Sea 190 20 4o 20 40 ia 30 C dt 20 at L + <0 «0 20 10 20 20 to Age Figure2b.Age eninpoeition ofcod incatches takenu ith different fishing deuieeein thenorthwest- ern.Bering Sea Anadyr-iVavarin region! in 1984-1998. I'acrfic Cod of Iht WesternBc ring Sea 989 i0 20 c 20 c O 50 c2 <0 CL 40 20 10 60 20 Age Figure3b.Age conlposition ofrodin Danish seinecatches inthe southuestern BeringSea in 7984- 1993, Fcologyoi tlie Bering.4r a. A Reviewot' Russian Literato'' Table6. Averagelength cm! and body weight g! of BeringSea cod by age and areas of fishing. 10 Region 1 2 3 4 5 6 7 8 9 Southwest Length 36.5 46.0 54.4 62.2 68,9 75.6 80.6 85.9 89.6 Weight 153 517 996 2,077 3,262 4,230 5,237 6,449 7,773 9,457 Northwest Length 21.4:32.4 43.9 54.1 62.0 68.9 74.7 80.2 84.7 89.3 We! ght 96 470 1,121 2,090 3,108 4.261 5,418 6,630 7,983 9.197 Table7. Factorsof the ratiolength:weight of body a and b!and parametersof VonBertalanffy's equa- tion for Bering Sea codfrom different regions. Ratio lengihiweight Paramne.err of Von Bertalanffy's equations Region Research period L cm! 3V Igi rA Southwest 1986-'1990 0.0089 3.0975 164.3 60,364 -2.35 0.0338 Northwest 1968-1976 0.0126 3.0100 119.9 22,250 -0.15 0.1477 1985-1990 125.6 24,320 -0.20 0.1430 the strong 1962year class were doininant in the eludeinsignificant numbersof fish over 70-80crn catches.The portion of fish 25-40cin longin the 1969 length.The major concentrations of large fish prob- catchesincreased rapidly due to recru.itmentof a ably occuroutside the traditional suinmer fi~hing strong1967 year class, and fish froin ths.t year class groundsin 20-100m of water.Habitat preferences comprisedthe modalsize groups for the next4-5 s.rethe inajor factorinfluencing the seasonaldistri- years.After 1972,the nuinberof fish that reached bution of ageclasses. Juveniles are moreeurybath- cornrnercial size was apparently not great because ic and prefer shallow waterswhile larger fish t,hemodal peaks were broad, and in somecases there migratefroin the summer habitat at 50-200m depth were two modes Vershinin 19871. The 1978 year to overwinter at 200-400 m depth. Therefore, the class can be i.raced on the age-size graphs clear size distribution of cod in the catch record depends through to 1986,The dominanceof juvenile fish in on i,he bathymetry of the fishing region. the 1985 and 1989 catches also indicates elevated Gearselecti>dty also influences size and agedis- recruitinent. Thus, the dominance of some year tribution in the catch records Figure 2a!, The bot- classes in the catches for several years shows that tom-setlongline is the most selectivegear: as the cod abundance can be determined by the size of a catch records indicate, it selects for the largest and singleyear class,and the differencesin sizesof oldest fish 1mostly 5-7 year olds!, modal groups during those sameyears indicates Weight of codduring the study period changed asynchronousdynamics of codyear classstrength in conformity with changesin length Table 6!. in the study area. Length-weightrelationships conforin t,othe expo- Size and age structure in each study area re- nential equationW' = aL,'where W isweight in g, I flects not only the dominanceof fish froin specific is length in cin, and rr and b are paraineters;b is yearclasses, but alsothe catchcharacteristics ofthe approximately 3. The regression equation fishing gearand seasonalityof the commercialfish- log W! = logta 1+blogtL1 ery and trawl surveys. Thespecialized Danish sein.c cod fishery is liin- relatesthe logarithmsof the weightand length and ited to coastal regions during summer due to severe b is the rate that the weight increases with respect winter weather conditions in the western Bering to length.Therefore it is an indexof the gravimet- Sea.The fishery concentrateson small and medi- ric growth rate of cod Table 7!. um sized fish, it does not include large fish, and The VonBertalanffy equationwas used for ana- thereforethe size age curvesfroin the fishery in- lytical analysesof growth in lengthand weight.The Pyritic Cr!rt >tthe 14'externBering Sea TableS. Poodcontent for cod %by weight!in 8!,even though the species compositio~ of thesetwo Karaglnand Olyutorsk bays southwest- foodgroups is subjectto significantseasonal varia- ern Bering Sea! in 1976-1988. tion in every region. Someof the first publicationson codnutrition, Researchperiod Gordeeva 952, 1954!,examined cod diets in the Total Anadyr-Navarinregion. The diet of Kamchatka cod May-Sept Nov-Dec period in 1976-1988and its positionin the foodweb of the Compo ! ent southwest.emBering Sea Karaginand Olyutorsk 0.1! 1! Algae. 0.1 ! bays!were examined in detail Tokranov1986, s- ! Spongia + ! Tokranov and Vinnikov 1991b!. + ! Hydrozoa + ! Pollock,Z'heragra chcrlcogramma. is the dorni- + ! Anthozoa + ! + ! nantfish in thediet of southwesternBering Sea cod + !1> duringwinter upto 90-97'kby weight!.The pro- Priapulida + ! 4.0 9! portionof pollockdeclines in summerdue to con- Polych acta 6.0 9! 0.4 ! 1.3 ! surnpt.ionofsand lance, Ammodytes hexapterus, and Echiurida 2,1 1! 0 1 !1! 1.1 ! otherfish. Among decapods, the portionof shrimp Sipuncu! id a 1.7 I 1! + in the diet.increases while that of crabdeclines. C op epode. + ! 0,2 ! Themajor food iten!a less than 20 cm in length '.umacea 0.2 ! duringsurnrner inthe southwestern Bering Sea con- + ! I sopoda + ! sist of smallcrustaceans: Arnphipoda, Nysidacea, !.2 ! Amphipoda 0.3 ! 0.1 .4! Euphausiacea upto 71-91%by weight!. Their im- + ! %1ysidacea + ! + ! portancein thediets of fish of 20-30 crn length rap- + .'1! Eup hans iacea + ! + ! idlydeclines and thc majorfood items of 20-50cm 22.3 3! Decapoda 28.6 3! 10.7 I.t!! longcod are decapods 8-69% by weight!; the small- 0.6 ] ! Gastropods 0.9 1! + I! er fish take mostlyshrimp, the larger onestake 1.1 ! brachiuran and herinit crab. In additionto decapods, Bivalvia 1,6 ! 0.1 ! 3.9 ! smallschooling fish arean importantcomponent of 0ephalo poda 6.0 1! + ! 0.1 i 1! the diet of 20-50cm cod,including sandlance, cape- Asteroidea 0.1 1! lin MaltotusI illosus !, andjuvenile pollock. Cod over Ophiuroidea + ! + ! 0.6 I '! 50cm length feed primarily on various fishes, espe- Holoturoidea 0.9 ! 0.3 ! ciallypollock, and cod that are70-90 cm long con- Ascidia 0.4 ll sumeincreasing amounts of cephalopods up to 88.5 ! 64.0 5! Pisces 50 7 5! 22-24% by weight!. 0.2 ! Fish eggs 0.2 ! Arnphipods,euphausiids, and mysids 5-74% 87 Total number 31 byweight! are still the main food for cod under 20 cm of species lengthduring winter but the ratio of the above taxa 271 Index of st.omach changes.Cod 20-50 crn long consume mostly deca- fullness, pprn pods,and, as during summer, larger cod take pri- 247 1,193 rnarilypollock and other fishes. Number of fishes 946 Aseast Kamchatka cod grow, they consume few- mrani Ieaathan O is of f~xl. n parentheses= number oi specter idvorh p-"up found in theatomarh er invertebratesand morefish Tripolskayaand Andriyevskaya1967, Tokranov 1986!. Cod 40-50 crn longtake roughly equal amounts of fish and inver- tebrates;their diet includesmaximum amounts of equationparameters Table 7! weretested by com- all foodtaxa and therefore has the greatestspecies putingpredict,ed stock size estimates and compari- diversity. As cod grow, somecrustacean taxa are replacedin thediet by others. sonwith catchdata on westernBering Sea cod. Sincedifferent size groups of codconsume dif- ferentfood taxa, their foodcompetitors change v ith Nutritionand trophic relationships age.Cod diets in the Korf-Karaginregion are very Thediet of the Pacificcod is quitediverse in all re- stable Andreev1987!, Their main food competitors gionsof the Bering Sea, and each area includes 90- aresculpins, although in somecases the dietsof cod, 100inembers of varioussystematic groups. But most saffroncod, and halibut overlapped. of the codbiomass about 86-96"rr ! is produced prac- Thediets of saffroncod and juvenile Pacific cod ticallyeverywhere from fish anddecapods Table in shallowregions of the CapeNavarin area are very Fcotogyotthe BeringSea: 4 Revieivo RussianLtterature 195 similar Nikolotova 1954! and include amphipods, 1992 showed that the main factor determining the cumaceans, and polychaetes. amount of the annual harvest was the fishing in- The above indicat,esthat Bering Sea codare fac- tensity number of fishing days!: r = +0,75, n = 10,p ultative predators,whose diet is very flexible with = 0.01 Kuznyetsov; VNIRO, unpublished, Figure highnumbers of potential food species. Although the 5!, Kuznyetsov pointed out. that all values for 198R- speciescomposition and degreeof use of somein- 1992 catches are above the regression line because vertebrate and fish taxa by cod in different. areas the catch per efTortin those years was aboveaverage. vary seasonallyand by life history stage,adult cod, The Danish seine fishery in the Anadyr-Navar- at the third trophic level, pt'oducemost. of their bio- in region is done annually on seiners under favor- massat the expeiiseof fishesand decapodaat the able weather conditions from May or June through secondtrophic level. Membersof the intertnediatc September.Over this period,the entire recommend- trophic level, including herbivoresand consumers edcatch quota for the year is obtained.I 'sually.35'»- of zoobenthos,are taken by juvenile cod up to 40 cm 40% of the annual catch is taken in June, and t,he length,but they usually makeup not morethan 5'% remainder is taken in the third quarter of the year. of the diet by weight. Preliininary estimatesindicate that 1 to 1.5tons of codare taken as bycatchby the v.int,erpollock fish- ery,which takes groundfish anddeepwater fish in FISHERIESAND STOCK ABUNDANCE the region. But,establishing a strict recordingsys- tem of the amount taken is diflicult. In recent years, Seasonaland annualcatch dynamics since the far-eastern fishing fleet started purchas- Results of the TINRO expeditions in the Bering Sea ing boats equippedwith longline gear, cod fishing in 1930-1933 and 1950-1952 showed that the trawl in the Anadyr-Navarin region is sometimes done fisheryfor codcould be quite effective,especially in with bottom-set longlines. In 1989-1990 the catch the northwestern Bering Sea Moiscev 19531 How- by Russianlongline fishing boatswas 1,000t.ons per ever, due to organizational flaws and the remote- year. Sincejoint ventures wereestablished, some ness of this region, coinmercial exploit,ation was Japaneseand Americanlongline boats contracted postponed. to take cod using quotasoutlined in the contracts. The Anadyr-Navarin region has been a cornmer- The total catch by longline fishing boats in the west.- cial codfishing district since1968, and later, in the ern Bering Seain 1993reached 41,000 tons of cod. late 1970s carly 1980s, trawls were replacedby Unfortunate]y, until recently the catch statis- Danish seine s. ticsfroin the Karaginsubzonc have been pooled with A relatively small area of large stock densities, the total cod catch taken from the eastern Kamchat- favorable bottoin conditions for trawling, and con- ka coast.Annual catcheswere stated specifically for sistently high catchesled to a rapidincrease in fish- this area only after a distinct Karagin subzone ing intensity, a measureof fishing effort bythe fleet t61.02.1! was established in the southwestern catchcapability of the different gear types times Bering Seain 1984 Figure 4!. As in the northwest- fishing time in days!. This ineasureof the fishing ern Bering Sea,the Danish seinecod fishery in thc district is a reflection of the effective area harvest- 1970s-1980s was done during favorable weather edin a givenyear, Before 1971,the fishing intensi- conditions May-Octoberi by a fleet of sinall boats ty increasedat substantiallygreater ratesthan the alongthe northeasterncoast of the KamchatkaPen- total harvest. Both factors reached their maximum insula,and mostof'the annual catchwas taken dur- during the 197l fishing season 51/c and 91,600 ing the spring-suinmerfishing season.%Cost of the tons respectively.In folio@rinyears the fishing in- cod is harvested in Karagin and Olyutorsk bays. tensity decreasedand stabilized at a lowerlevel OzernoiBay is practically untouchedby the fish- 25% to 31%. The total catch of cod in this area ery.At present,,the a.nnualcatch of codin this part Figure 4! started decreasingrapidly in the early of the Bering Sea is about 15,000-25.000tons. 1970s; in 1977-1979 cod was harvested only as a supplement to pollock. The catches started increas- Stock abundance ing again in 1980due t,o a warming in the Bering Sea and an increase in the number of cod. Froin the Codhave a relativelyshort. life cycle,small number late 1980s to the present., the annual harvest of of year classesin the commercialstock, and signifi- Anadyr-Navarin cod stabilized at 40,000-50,000 cant fluctuations in year class strength. They arc tons. therefore vulnerable to unfavorable en~dronmental Correlation analysis on data from the Danish conditionsand exploitation regimes.For example, seinecod fishery in the western Bering Seain 1983- two strong year classesi1966 and especially1967i PacificCi!ri of the tl'esterriH ringSea J96 00 ioo 50 sa oa 80 50 0 0 0 ~+60 00 E 50 5oo c0 ~ 4Q 200 150 100 ]970 Year Biomassof 3 and> agefish using V PAmethod: Catch: ~ Northernpart of western Bering Sea, 1988-1994 Northernpart ot westernBering Sea, 1978-1 994 EB Southernpartof western Bering Sea, 1984-1994 Southernpart of wes1emBering Sea, 1978-1994 ~ Prejeoted biemaSSin t 995-1997 'i Projectedcatch in 1998-1998 r Figure4. Catch rinthousand tons!andbiomass ofcommercial codstock fish at the age of3yrs and older!, computed bythe oirtua/ populations analysismethod VPA!in the uestern Rering Seaby regions inl968-1994 dicatedthat, about 68% were from the 1978year led to increasesin stockabundance of Anadyr-Na- classand 16,4'7 Yearclass strength Therelatively short life cycle the maximumage in the populationis 12-13years!, high growthrates, and early maturat.ion most codmature at 5 years of age!,followed by rapid increasesin naturalmor- tality, all conf,ributeto the fact that cod10-12 years ofageusually do not make up morethan 2~ii ofcorn- inercial catches.At the saine time, high growth rates CO result in early recruitinent. They reach 3D-35cm CI lengthin their secondyear andare a substantial portionof the catchesin someyears. Anadyr-Na- Ost varin cod are coinpletelyrecruited to the cominer- 0 cial stockin four years.The abovefeatures indicate a high turnover rate. Recruitsare very important to the fisheries;therefore commercial stocks under- gosubstantial annual fluctuations, and stocksize is determinedby the strength of singleyear classes l Figure 6!. Accordingto datafrom coinniercialfisheries, the yearclass strength of Anadyr-Navarincod for 1962- 1977fluctuated between 0.2 and 55.8 million indi- viduals.The long-termaverage i14 million fish f was Total fishing effort exceededby the 1962,1966, and 1967year classes. Highcatches occurred when t,hese year classes were Figure5. Dependenceofcod catches in thousandtons! in the fishery; however, catches started declining in byDanish sei ne in thewestern Bering Sea on 1971, The decline was caused by both removal of fishing intensity numberof fishing days!in thestrong year classes and weak year classes after 1983-1992 V, V. Kuznyetsou, VIVIRO, unpubl.h 1967.Year classstrength remainedlow for 1969- 1976,but in 1977the stocksbegan increasing. Sensitivity of the annual catch to recruitment indicates that the decreasein harvests after 1971 1968-1993are depictedby fishing regionin Figure was caused primarily by low recruitinent due to 4 the cominercial stock biomass for fish 3 yearsand weakyear classes. Createst fishing intensity in the older is calculatedusing virtual populationanaly- early1970s coincided with a naturaldecrease in the sis!.Also depicted are forecasted values of optiinal Anadyr-Navarincod abundance. Intense fishing had allowable catch and stock bioinass for 1995-1997. a negativeeffect on the populationand worsened Peaksin the Anadyr-Navarincommercial cod stock the depression.Spawning stocks in the late 1970s abundance occurred in 1971 and after 1985, and were extremely low which is probably the reason stocksare quite high at present,Harvest dynamics that the size of 1977-1979year classdid not reach generallycoincide with changes incommercial stock that of the 1966-1967year class,in spite of l'avor- abundance.The high abundanceof commercial able environmental conditions. Therefore, following stocks in 1990-1993 was the result of strong 1986- recruitment, the 1977-1979year classescould not 1989year classes Figure 6!. The biotnass of Anadyr- increasecommercial landings to the levelof theearly Navarin cod, according to regular ground 1970s, trawl Danish seine surveys, was 98,900 tons in The fisheriesof the early 1980shad a shghtly October of 1987 in Navarin region only!, 766,000 different character. Stocks increased due to consec- tons in July-August of 1989,and 142,300tons in utive recruitmentby the strongyear classesof 1977- July of 1991. 1980.The year class strength from 1977 to 1980was Rightnow northwestern Bering Sea cod abun- less variable than that of the late 1960s. The 1979 danceis decreasingdue to the absenceof strongyear yearclass had the maximum abundance and at age classes.The increasingportion of longline catches 5 it madeup thebulk of the 1984commercial catch. to the total harvest of cod is also of concern because The 1978 year class at age 6 was still important, the effectsof the longline fishery on the spawning contributing2.93 million fish to thetotal catch, sim- structureand reproductive potential are not known. ilar to that of the 1979year classi 3.09million fish!. 1 '36 Pacific Cod of Ihe Wt'sterrt RerirtgSea o 4Q E 1962 65 70 Year Figure6. Codyear class abundance in the northu,estern Bering Bea t'n 1962-1993 according tothe fishery yielil inforniation. Black indicates year classes still in thef'ishnig stock. ln 1985 the Anadyr-Navarinst.ock abundance that ice cover is a good predictor of year class decreased a little; however, becausethe 1978-1980 strength in cod Vershinin 1983,1984, 1987!. yearclass cod were still in the commercialstock, or actually becauseof the increaseof their biomass, Fishingand natural mortality the catchesstayed at a high level. Data from the regularground trawl surveyin July-August,of 1989 Based on mortality rates, stock abundanceand in the Anadyr-Navarinregion demonstrated that a maximum sustainable yield are determined. Then, substantialnumber of the 1987year classremained followingthe well-knownfisheries convention that in the catches and made up 629. of total cod catch commercial mortality should not exceed natural duriiig the survey.The 1987 year class recruited to mortality Zasosov 1970!, the total allowable catch the commercial stock in 1991.Year classesbetween is computed. 1987 and 1991 were of averageabundance and kept Several methods have been used to estirnat.e the the cod stock stable until 1993. t.otal cod mortality coefficient.sfor both the Anadyr- Theyear class strength of theAnadyr-savarin Navarin region and the southwesternBering Sea. cod stock is inversely proportional to ice cover in Calculations using the "integral method" Beverton the first 10 daysof April time of the majorspawn- and Holt 1958! showed that total mortality coeffi- ing eventin the area! r = 0.72!, The relationship cients in the Anadyr-Navarin cod fishery varied is valid at the 95% confidence level, thus indicating annually within a large range between0.75 and ECO/agyat the Hering Sea: 8 Reviewat RuiatanLit rittire / otal Table9. indicesof totalmortality rate and decline from fishing for Anadyr-Navarin codby years of catch 968-1984!. 19681969 l970 19711972 1973 1974 !9 5 1976 1977197tt 1979 1980 1981 1982 t983 19H4 Total 1.13 1 19 1.20 0.81 0.72 0.93 0.92 0.59 0 63 060 1.14 1.30 1.50 0.97 0.75 0.67 1 16 Fiahlog0.45 0.480.49 0 17 o.130.33 0.32 0.060.10 0.07 0 ts 0.54 0.62 0.3fi0 ss 0.290 47 Table10. Natural mortality rate /yr! for Anadyr-Navarin cod I! andsouthwestern Bering Sea cod III, calculated by different methods. Method Age, years Region ref'erence 1 2 3 4 5 6 7 8 9 10 11 0.39 0.52 1.73 1.05 1.65 'Pjrurin 1962 0.78 0.35 0.24 0.25 0.30 0.25 0.26 0.29 0.33 0.38 Zykov- 0.79 0.51 0.37 0.30 0.26 0.25 Slyepokurov 1982 Tryetiak 1984 124 065 029 0.15 030 078 166 300 461 0.37 0.51 0.71 1.03 1.63 Tyurio 1962 0.97 0.49 0.28 0.22 0.24 0.29 0.34 0.38 0.43 0.50 0.58 Zykov- 0.61 0.41 0.33 0.30 0.29 0,31 S!yepokurov 1982 Tryetiak 1984 1.27 0.71 0.36 0.24 0.37 0.78 1.47 2.53 3.91 1.35!.Maximum valuesoccurred in 1970-1972and varin and southwestern Bering Sea cod using dif- were1.21, 1,35, 1.11 respectively; average for 1968- f'erentmethods on recent data Tyurin 1962, Zykov 1976was 1.03 Table 9 l.Also, the mortality rate was and Slyepokurov1982, Tryetiak 1984!tTable 10!. determinedby age composition, where the numbers Minimum values of the instantaneous coefficient of of fish from different year classesin the catches naturalmortahty occuramong 4-6-year-old fish, the normalized l.o the fishing effort were used as an age at which roost fish mature. abundance indicator for different age groups, The slopeof thestraight line in a leastsquares fit ofthe Methodsof stockabundance prognosis natural logarithmof'abundance for fish 4-9years of ageis an estimateof thc total mortalitycoefficient To estimate cod stock abundance in the v;estcrn .14!. The averagevalue from the first and second BeringSea and predictthe total allowablecatch two methodwas 1.09,and the resulting annual rate of' yearsahead, both direct counts and mathematical decreasewas 0.67. The instantaneous nat,ural mor- models are used. tality coeflicientwas determinedby the agecontent Direct counts are done using regular ground in the population before recruitment, assuminga trawl surveyson standard station grids, However. linear relationshipbetween total mortality andfish- in the last severalyears the surveyshave not been ing intensity.Tbe instantaneous natural mortality doneregularly, and the vesselsand fishing gearare coefIicient and the annual rate of decreasein stocks not the sameas previously.Therefore the results wereequal to 0,53 and 0.41respectively, The aver- arenot strictly comparable,The surveys are usual- ageinstantaneous mortality coefficient from fish- ly doneunder favorableweather condit.ious in sum- ingwas found by subtractingthe naturalmortality mer and fall, coefficient from the total mortality coefficient; the Based on the results of the trawl Danish seinel valuefor the Anadyr-savarin regionwas 0,56 t0.54 surveys,cod stock abundance is estimated by a rnod- for the southwestern Bering Scab The annual rate iftcation of the areatechnique Leonov,A.K. 1960.Regional oceanography. Gidro- Pyetrova-Tychkova,M.A. 1948. Meristic characters of the far easterncod. Izv. Tikhookean.Nauch- meteoizdat,Leningrad, pp. 62-184. no-Issled.Inst. Rybn.Khoz. Okeanogr. TINRO I Moiseev,P.A. 1934.The temperatureregime of 28: 127-137. BeringSea cod. Rybn. Khoz, Dal'n. Vast. -2k94- Pyetrova-Tychkova,M.A. 1954,Materials on the 97. biology of cod of the Navarin region. Izv. Moiseev,P.A. 1953. Cod and flatfishes of the far-east- Tikhookean.Nauchno-Issled. Inst. Rybn. Khoz. ern seas.Izv. Tikhookean. Nauchno-Issled. Inst. Okeanogr. andits placein the foodweb in the coastalwa- theapplied science conference onfisheries pre- tersof Kamchatka.Vopr. Ikhtiol. 31 !;253-265. diction],Murmansk, 26-28 Oct. 1983, p, 27, Tripolskaya,V.N.. and L,D, Andriyevskaya. 1967. Vershinin,V.G. 1984. The biology of cod and the cod Feedingof codin AvachinskyBay. Izv. Tik- fisheryin thenorthwestern Pacific. Candidate's hookean. Nauchno-Issled.Inst. Ryhn. Khoz. degreedissertation. DVVTs Akad. Nauk SSSR, Okeanogr. TINRO! 57;122-134. Vladivostok, 21 pp. Tryetyak,V.L. 19S4. Method of estimatingthe nat- Vershinin,V.G. 1987, Biology and current stock ural mortalitycoefficient of fishesof different abundanceof codin the northernBering Sea, ages for example ofthe Arctic cod!. In; Ekologiya In: Biologicheskieresursy Arktiki i Antarktiki biol. resursovSev. basseyna i ikh promysl [Biologicalresources of the Arctic andAntarc- ispol'zovanie[Ecology of the biological resourc- tic].Nauka Press, Moscow, pp, 207-224, esof the northernbasin and their exploitation] Vershinin,VG., andA,M, Tokranov.1983. Repro- PINRO, Murmansk, pp. 85-102, ductionof cod Gad@amacrocephalus Tilesius, 1810!near the coastof easternKamchatka. In; Tyurin,PV. 1962. Natural mortality of fish and its Problemyrannego ontogeneza ryb, tezisy dokla- significancein fisheriesmanagement. Vopr, dov[Problems in earlyontogenesis of fish,com- Ikhtiol. 2,3 4!:403-427. pendiumofreports], AtlantNIRO, Kaliningrad, Vershinin,V G.1975. The dynamics of somebiolog- pp. S2-84. ical indicesfor Anadyr-Navarincod in 1967- Vershinin,V.G., and V.P. Maksimenko. 1984. Meth- 1973,Biologicheskie resursy morey Dal'nego odsfor determiningthe recruitment agein com- Vostoka[Biological resources of the Far East]. merical fish population for example the Tez,Dokl. Vses.Soveshch., Vladivostok, Oct. Anadyr-NavarinCod!. Rybn. Khoz. 9:17-18. 1975, p. 45, Vershinin,V,G. 1976, Biology and the commercial Vinogradov,L.G. 1948. Zoogeographic regions of the fisheryon Anadyr-Navarin cod.In; Research on far easternseas, Izv. Tikhookean,Nauchno- fish biologyand commercial oceanography, Issled.Inst. Rybn.Khoz. Okeanogr. TINRO! TINRO, Vladivostok7:122-128. 28: 162-164. Vershinin,V.G, 1981. Stock composition of codin Zasosov,A,V. 1970. Teoreticheskie osnovy rybolo vst- the Anadyr-Navarinregion, Rybn. Khoz. 3;39. va [Theoretical basesof fishing]. Pishch, Promst.,Moscow, 290 pp. Vershinin,VG. 1983.The possibility of predicting codyear classstrength in the northwestern Zykov,I..A., and VA. Slyepokurov.19S2, The equa- BeringSea from ice cover. In: Tezis dokladov tionfor estimating natural inortality: Using the nauchno-prakticheskoykonferentsii po metoda LakeYendyr Peled as an example.Rybn. Khoz. promyslovogo prognosi rovaniya [Proceedings of 3:36-37, E«!f<>LIyr>ithe' Berir>g Sea. A Renoirot Rus!ian Literature 203 Distributionand Biological Indices of YellowfinSole Pleuronectesasper! in the SouthwesternBering Sea S.V.Kupriyanov KamchatkaResearch Institute of Fisheriesand Oceanography Kamcha PIRO! Petropavlovsk-Kamchatski,Russia i NTRODU CTION nifrcanceof vellowfin solefor coinmercialfishing in Theyellowfin sole Pleuronectesasper! is the most this area,regular studies of the stockshave been commonspecies of righteyeflounder family Pleuro- conducted since 1978. nectidae!inhabiting continental shelf waters of the Russian Far East. As membersof the subarctic- IVLATERIALSAND METHODS borealgroup of fauna Fadeev1970k yellowfin sole arewell adaptedto severeenvironinental conditions. Asthe informationalbasis for this work, I useddata Consequently,in certainparts of their rangethey collectedfrom catcheswith the Danish seineMRS- formlarge concentrations that providethe basis of 225during standard surveys conducted from 197S intensivecommercial fisheries, Up i.o8,000 tons of through1992, and temperature and salinity rnea- flounders are harvested annually in the shelf wa- surernentstaken at standarddepths during hydro- ters of northeastern Kamchatka, and 90% of thein logicalsurveys conducted from 1980through 1989 by weight! are yellowfin sole, 'igure ll. The averagewater temperaturefroin The distribution of yellowfin sole along the east- surfaceto bottomwas usedas a ineasureof the heat ern Kamchatka coast is patchy Moiseev 1952, content of the water, and calculated as follows: Fadeev 1987!. To the north and sout.hof Korf, Kara- gin,and Olyutorsk bays they are scattered among rock sole Pleuronectesbili neatus and Alaska plaice P,quadrituberculatus!. A number of scientists Po- wherei is the st,ratumdesignation, t, and t are lutov 1967,Tikhonov 1969,Fadeev 1970 relatethe temperaturesat the levelsnext to eachother; P is differences in distribution and biology of demersal the vertical distance between adjacent strata; and speciesto specifichydrological conditions. For ex- 8 is total depth. ample,in examiningt,he distribution of yellow+in The dynamicmethod was usedfor calculating sole in the North Pacific, Fadeev 970a! noted the surfacewater currents Zubova and Mamayev 1956k connectionbetween stock dispersal and the reinains Levelingof the dynainicamplitudes was doneoff of river systeins.ln studiesof the distributionof hydrologicalstations 14 and 44 Figure 1!. yellowfinsole over the westernKamchatka shelf, Ichthyologicalmaterials were collected using Tikhonov 969! andDavydov 971! pointedout the standard methods Pravdin 1966! during the bio- dependenceof the stock on environmentalfactors, logicalsumnier, in Augustand September. Due to primarilywater teinperature at thebottom. Fadeev the peculiaritiesof heatexchange and water circu- 9S7 > summarizedthe results of research on floun- lationin the yearsstudied, the analysisof biologi- ders in the North Pacific, and noted the preference calindices for yellowfinsole emphasized relatively ofBering Sea stocks for the surfaceand intermedi- warm and relatively coldyears. To estimatediffer- ate layersof the sea.He emphasizedthat the larg- encesamong biological indices, the KaraginBay est concentrations usually form close to coM spots studyarea was divided along latitude 59'10'N into that remain from t,he winter. Considering the sig- two sub-areas Korf Bay and the southernregion, foologvof heBering.Sf.a: A Review nf RussianLiters urf 205 Table 1. Correlation coefficients r! for 1982 Isolherms the catch of yellowfin sole per catchesof Danish seine cast and bottom 6032 water temperature in Karagin Bay in August, 1980-1989 5965 ts Year r Number of casts D 59.62 + 5938 1980 0.043 20 te C 5915 1982 0.35 34 r 0 1983 0.07 15 Z 58.82 1984 0. 16 50 5868 1985 0.226 49 58ss 163'l3 163.5116389 16427 16465 164.0316541 16579 166t7 1986 D.036 44 1987 0.292 46 1985 1988 0.25 44 I sothe fms catchesol 1989 D.71 12 yeyowfthSOie ~ 60.57 6005 5953 peraturegradient Figure 2i. Forinstance, in 1982 5901 a steeptemperature gradient was recorded in the regi on o f 1 ati tu des 59 50'-60'20'N, l ongi tu des 5649 165'40'-166'10'E,with a differenceof 0,5 C permile. 5797 In this region, catchesranged from 0.2 to 0.9 tons o 57,45 Z per cast, and averaged G.23tons, 56.93 The distribution of fish is determined by the heat storedin the water,which is expressedthrough the 56.4118008 16089 161.70162 51 16333 l64 'l4 16495 16576166 sf averagewater temperature from the surfaceto the bottom. The horizontal temperature distribution in 1988 June Figure 3! shows that the amountof water IsoIhetms catchesol which moved to the continental shelf of the study yellottrtihSole IWR regionvaried during the researchperiod. The area 6022 of warm coasl,al water s also varied, so the 1.5'C iso- .97 therm is considered the conventional borderline et ~ 59 73 betwee~ these waters. It is obvious from Figure 3 that the smallest amount of warm water movedonto est5948 the continental shelf by currents occurred in 1987, 5924 and as a result the shelf in tha.t year was occupied 0 by waters with temperaturelowered to O'C. The 5699 warmest water was found in 1982. There were sirn- 5675 i lar differences in distribution of yel lowfin sole con- 16328 16363 16398 164.33164.68 165 02 165.'3716572 166.01 centrations Figure 2!. In 1962,concentrations that East longitude yielded catches larger than 0.5 tons per cast were locatedin the southernregion of Karagin Bay,and Ff'gure 2. HOrf'runral dier rf7Iritioff Ofdefffersal Fr'gure3,HOTlzorttal distrrbutionof the arernie temperrrture fromsurfare tobottom rnJune i to the shallow parts of the bays. In those years sev- eral closed cir culations with different directions of water movement were present. The existence of vor- ticeshas an important practicalmeaning, because, as Natarov t 1963! pointed out, in a cyclonic vortex water rises in the center and falls in the periphery. In an anticyclonic vortex, there are inverse process- es.Such processes of upwelling insure the aeration of the bottom levels, and also the rising of the abys- sal waters, rich with biogenic eletnents, to the sur- face,forming zonesof high biologicalproductivity, High concent,rationsof commercialfishes are usu- ally associatedwith suchzones. As a rule,there is a steeptemperature gradient in theseregions. There- fore, the large concentrationsof flounder that oc- curred in 1982 in the region werc probably caused by creationof a zoneof high productivity. A different pattern of water circulation forined in 1987,when the presenceof two vorticesprevent- ed water movementfroin the opensea to the shelf. As a result, the heat, content of the water was creat- edby warming through radiation. An analogoussit.- uation occurredin 1989,but the causewas a lackof currents. Closed vortices also exist in the southern region of Karagin Bay Figure4!. Sincethe rates of water moveinentinside thosecirculations can be differ- I"tgure 3. continued,J Horizontal distribution of tbv ent,the areasof highproductivity are alsodiffer- averagetemperature from. surfaceto bottom ent, which is reflectedby the densityof concent,ra- in June 1989. tions of yeliov F!pure4. Surfacecurrent.i nts tn Juneune 1982and 1987-1989. Ecologyo the Bering Sea. A Reviewot RussianLiterature 209 Table2. Averagecatch tons!per Danishseine Males Litke Strait castof yellowfinsole in KaraginBay by 3.0 type of year. Southern 2.0 Year Korf Bay region 'I 10 9-term 1982 Relativelywarm 0.65 0.085 C era9es 1985 Intermediate 0.32 0.083 1988 Relativelycold 0.17 0.029 82 84 86 88 90 92 Fernale Q thetrophic relationships ofyellowfin sole andAlas- ka plaicein the southwesternBering Sea. Ananalysis of stomach fullness of yellowfin sole ce 2.0 ona long-termbasis did not indicatean increase in «C feedingactivity after spawning,which allows onc to assumethat feedingcontinues to the endof bio- to logicalfall, Tokranov 1 1989! carne to similar conclu- sionswhile comparingthe durationof feedingby yellowfinsole in thesouthwestern Bering Sea and 1978 80 82 84 86 88 90 92 thewestern Kainchatka shelf OkhotskSea!. Con- Year sideringthat the cold period in northwesternBering Figure5, Auerogestontctch fullness , entpty,to4, full! Seabays lasts more than half the year, it isclear for yeltoufrn soleat theage of 8+ in Iittce thatyeBowfin sole continue feeding to the endof Strai t and Korf Hay from 1928to 1992. fall in.order to restorethe energylost in winterand during spawning. Variationsof stomachfullness indices within the saineage groups are related to bothgerider and re- gionof inhabitance Figure 5!. High indices of full- sincethe intensiveness offeeding by females exceeds nessoccurred in maleyellowfin solein both regions that of the males Figure 6!. in 1978-BOand in 1985;but for femalesthe index Similar analysesof long-termvariation in the indicateda contraphasepattern with asynchronism. patternof feedingby yellowfinsole during the Higher-than-averagestomach fullness of femalesin spawningand feeding periods were reported by 1VIikulich 954! andTokranov 989!. Togetherwdth Litke Strait in thoseyears f 1982,!987, 199f!!coin- certainpreference forsome food species, the authors cidedwith high indices for KorfBay feinales, with a pointout the differencein thefood spectrum. Ac- 2-year l ag. Comparisonof stomachfullness shows t,hat in cordingto Tokranov's inforinatioii t 1989!, during the yearswhen the thermalregime and water circula- examinedyears the food content of yellowfinsole tiondiffered, stomachs of'yellowfin sole of KorfBay stomachsvaried, and only in 1985,which is consid- duringthe biological surnrner were ful ler thanthose eredan intermediateyear, was the food coiitent the in Litke Strait Figure6!. Weassume that females sainein bothregions 0% consistedof polychaetes!, in Korf Bayfed longerthan thosein Litke Strait, In 1982the proportionof echinodermsincreased, whichmight be due to differencesin thermalregime. whereasin 1986they were practically absent from In the listedyears, the warmthin Korf Baycame thediet. Judging from stomach contents, the diet of fromthe openBering Sea and from heatingof the yellowfinsole in 1982.a warmyear, was broader waterby radiation.Because of this.probably, a rel- than in 1987and 19SS,which were relatively cold ativelyeven food base was formed in this region. Table 3!. Nikolotova11979!, studying long-termvariation in Consideringthe differences in feedingintensive- stomachfullness of western Kamchatkashelf yel- nessand preferencesbetween the sexes,it is rea- lowfinsole, noted a zig-zagpattern of the curve,and sonableto comparethe sex ratio dynamicsof explainedit bythe fact that fish havecertain food yellowfinsole in thestudy region sub-areas l Figure preferences.Such selective ability for foodorgan- 7!.The data indicate that femalesdominate in Lit- ismshas to havean efTecton the fullnessof the fish, ke Strait, and in 1985and 1991their proportion Dtstrihotionencl!3io!ngica/ Indicts of Yegotvtin Solei n the .8outhtvestern Bering.Sea 210 Litke Strait Stomach Stomach Stomach tullhess3 Stomach tallness2 tallness0 fulthesst so 40 ~1 2o V C V 4+ 7+ 84- 44. 7+ ct Korf Bay ttt too 0! U 4+ 7+ 8+ 4+ 7+ Age Figt4re6.Stomach fullness , empty, to4, full! forfernale andmale yellou finsole atages 4+,7+, and 8-in Iitke Straitand Korf Bay iayearsuith differert t patterns ofu~ater circulation tl982,1987, 7988!. inalesin differentmaturity stagesranged from 25 decreasedto 40~re,Observations shov ed that the to35 cm in KorfBay, and from 19 to 33crn in Litlce spawningofyellowfin sole in thestudy subareas Strait.During 1988 cold year! the sizes were equal, takerplace at different times. It endsearlier in Lit- at 25-35cm and 23-35 cm, respectively. Long-term ke Straitthan in KorfBay. Comparing the curves datashowed that. within the Korf-Karagin area, the Figures5 and7!, it is obviousthat the high stoin- numberof immaturefish increasedwith distaiice achfullness index for 9-year-old fernale fish of Korf south.At thesame time, as noted by Fadeev 97Qa! Bayin 1937 was probably due to their stronger dom- andTikhonov l 981!, the proportion ofyellowfin sole inancecompared to Litke Strait., femalesincreased in yearsof smallerstock size. Thesex ratio is a specificstock parameter. Anal- Fromthe information available we can conclude ysisof the curves describing thevariations ofthe that the yellowfinsole stocks in bothregions repre- sexratio as fish grow size and sex structure! al- sentone entity, but that fish migratefrom onere- lowsone to draw a conclusionabout the stable char- gionto another in differentyears due to changes in acteristicsof someregions and the distinct differencesamong such characteristics fordifferent watercirculation and therinal regime. regions.Iiowever, comparison analysis ofthe size- Analyzingthe feeding intensiveness <>fthe wesr.- and-sexstructure curves for yellowfin sole females ern Kamchatkashelf yellowfin sole, Yikolotova ofthe two regions in yearswith different thermal 979! associatedthe difference in feedingintensive- conditionsdid not, show any significant differences nessbetween females and males with the maturity Figuretlh The variability ofsizes of maturing fe- of the gonads,In her opinion,females feed inten- malesin I,itkeStrait was greater during relatively sivelyuntil the third stage of sexual mat.urity, where- coldyears, whereas in Korf Bay it wasgreater dur- asmales feed intensively only until the secondstage. ing1982 warm year!. At that time, the sizes offe- Theinterest of the fish in fooddeclines with rapid fco ogyof iheHr ring Sea. A Reviewor R'ussiar Literature Ts bie3. Foodspectrum %! of northeastern Kamchatka yellowfin sole in August and September of1982, 1987, aud 1988. 1982 ]987 1988 Age group 4+ 7+ 8+ 7+ 8+ 7+ 8+ Food Sex M F M F M F M F M F M F N F Korf Ray Echiur da 17. 2 22.2 Polych acta ]6.7 12.5 15.4 42.9 11.8 31.0 100.0 42.8 Oph iu roide a 16 7 12 5 7. Scutellidae Gammaridae 33 3 25 0 38 o 23 5 10 3 Decapoda 12.5 .6 23.5 10.4 14. 3 50.0 Bivalv>a 33.3 37.5 30.8 14.3 23.5 24.1 Molluscs Pisces 14.3 25.0 Fish eggs Hydrozoa Pl ant remains 100.0 66.7 100.0 25.0 Digested food 28.5 17.7 14.3 Litke Strait Echiuri de 4.0 16.7 83.3 66. 7 Polychaeta 14.8 16. 0 ] 7.0 21.4 50.0 83.3 55.6 40.0 100.0 Ophiuro idea 18,5 12.0 12.8 14. 3 Scutell id as 14.6 14.9 Gamm arid ae 18.5 32.0 17.0 Decapoda '3.7 6.3 16.7 Bivalvia 29. 7 28.0 12.8 14.3 33. 3 60.0 Molluscs 6.4 Pisces 4.0 4,3 Fish eggs Hydrozoa Plant, remains 4.0 Digested food DistributionandBiologicai indices o Yellowftn Solein the Southisrstern BeringSea 2J2 Lltke Strait developmentofthe ovaries and testes. For the north- too' Korf Bay - easternKamchatka yellowfin sole, this assumption Males doesnot hold true for the same age groups, One of 80 themorphological and physiological indices is the Fultoncondition index, which connects two other factors:growth and sexual maturity, For9-year-old ycllowfin sole, in bothregions the elm coultoncondition index of females was greater than es thatof males Figure 9!. The greatest value of the conditionindex occurred in 1985.In 1988,the con- dition indexv as the sameas in 1985in Korf Bay, c 1979 90 82 94 86 ss 90 92 andin Litke Straitit waslower than average. Since 1987,annual variations in thecondition index have c too Females occurredin LitkeStrait: in evenyears the condition O BO indexis greaterthan in oddyears. For KorfBay fish, suchvariations are lessapparent. Nikolotova 979!noticed similar variability in Lang-term thelength of western Kamchatka yellowfin sole, and 40 Averages statedthat in evenyears fish fed more actively than in oddyears. While characterizing annual variabil- ityin thefood spectrum, she noted a greatergain formaturing flounders in evenyears, relating it. to 1978 9O 82 84 86 99 90 92 increasedconsumption of amphipods. Such prefer- Year encesfor certain food organisms are related to their caloricvalue. Table 4 liststhe caloriccontents nf Figure7. Proportionoffemale and male yellou fin sole someorganisms consumed byyellowfin sole, in Litke Strait and Korf Bayfrom l978 to 1992. ~Male [ Fernale~ Litke Strait Kerf Bay 90 at O 60 0 40 C ta 20 LL 4+ 7+ 4+ 7+ 8+ Age Figure8. Sex ratio ofyellotufin soleatages 4+,7+, and 8~ in Lit!re Strait and Korf Bay in years uithdifferent patterns ofutater circulation 982, 1987, 1988!. Ecologyof hr 13ring Sea:A Reviewof kussianf.i eruture 213 1.6 Table 4. Average caloric content of food organ- isins per grani of wet weight Nikolotova 1979!. Organism Calories Sources 1.4 Amphipoda 1,240 G,S. Karzinkin, 1.29 A.M. Makhinedov 1 24 Deca poda 750 V.M. Strel'aikova 12 Cumacea 940 B.N. Bokova Eu phausiacea 1,050 V,I. Shershneva Mollusca 280 G.S. Karziokin, A.M. Makhmedov 1,0 1978 80 82 64 66 88 90 92 Verin.es 700 A.M. Makhmedov, K.A. Vioogradov C .2 1.6 Fchinodermata 200 A.M, Makhinedov, K.A. Vinogradov C 0 O Pisces 1,500 Paodiao 1.4 1.3 Comparing the data we have on the stomachcon- tent.s of yellow the continentalshelf due to warmingby radiation Ages 8+ or movement of heat by currents. 7+-- ~ Theborderline of the currentsentering the shal- 4+ --. Kort Bay lowbays can be the 1.5'C isotherm that character- 32 izesthe average water temperature from surface to 30 0 30 bottom.In yearswith a well-developedcurrent sys- 27.s 28 tem 982!, thereare cyclonic vortices on the shelf 26 with variousdirections of watermovement. High 24 concentrationsof flounders in Augustoccur at the 22 21 5 peripheryofthe anticyclonic vortices, in theareas E wherehigh biologicalproductivity and steeptem- 1978 80 82 84 86 as 90 9 peraturegradients form. gr Whenthe current system is weak '1988-1989!, itke Strait theheat content of the water is determinedby warm- 29 5 ingby radiation; such periods are characterized by 28 the absenceof closedcirculations and a relatively Longterm 26 Atrerages evendistribution of fish overthe shelf. 24 Analysisof the long-tenn research data on the 22 dietof yellowfin sole showed its contraphasechar- i 978 80 82 84 86 88 90 92 acterwith a 2-yearlag of the stoinachfullness in- Year dexfor Korf Bayfemales coinpared to Litke Strait femalesof thesame age groups. Such asynchronisrn Figure10. Average length ofyeilou fin sole at ages 4+, 7+, is a resultof the developmentof the foodbase in ortd8+ i ri Lithe Strait and Korf Hrxyin 197A- northeasternKamchatka influenced by hydrologi- 7992. cal conditions.The spectrumof foodorganisms con- sumedby ycllowfinsole is broaderin relatively warmyears than in intermediateand cold years, Duringthe examined period the stomachfull- whilethe largest males were caught in Litke Strait nessindex for females of Korf Baywas greater than. mean= 30.6cm!. For immature fish ofboth regions, that for same-agefemales of Litke Strait,.In cold theproportion ofsmall-sized indivdduals hasbeen andintermediate years, females dominated in Lit- growinginrecentyears f1981-92! due to the ret~ keStrait but not in Korf Bay.Their lower abundance mententering the commercialstock. Overall, the in Korf Bayis causerlby migrationof' fish fromone averagesizes of yellowfin sole in KorfBay are larg- regionto anotheras hydrological regimes change. er than in I itke Strait, given the sameage groups. Theaverage body length and weight of yellow- This is relatedto the formationof hydrologicalre- fin soleare greater in KorfBay than in LitkeStrait. gimes,vrhich depends both on dynamics and the amountof freshwaterrunoff, which directly affects developmentof the foodbase. REFERENCES Sincethe growthof fishis, in mostcases, iso- Fadeev,N,S. 1970a Fisheries and biologicalchar- metric asthe lengthof the bodyincreases, the acteristicsof the easternSering Sea yellowfin weightincreases in a cubicproportion!, changes in sole.Tr. Vses.Nauchno-Issled. Inst. 5!orsk. weightwithin a giventime period will be more ap- Rybn.Khoz. Okeanogr. VNIROI 70 Izv. parentthan changes in length. In ouropinion, the food base in KorfBay is rnost- Tikhookean.Nauchno-Issled, Inst. Rybn.Khoz, lyformed through movement ofwater from the open Okeanogr, TINRO! 72:327-390, In Russian,! sea,and in LitkeStrait through freshened water. Fadeev,N.S, 1970b. The main patternof distribu- This explainsthe variousfeeding patterns among tionofyellov fin solein the northern Pacific. Izv. theyellowfin sole of the Karagin sub-areas and, Tikhookean,Nauchno-Issled. Inst, Rybn,Khoz. therefore,the dynamicsof the biologicalindices. Okeanogr. TIÃRO! 74:3-21. { InRussian.! CONCLUSIONS Fadeev,N.S. 1984. Promyslovye ryby sever noy chasti Thedistribution of yellowfinsole in theKorf-Kara- Tikhogookeana [Commercial fishes of the north- ginregion of northeastern Kamchatka isrelated to ernPacificj. DOTS [FarEastern Branch] Akad. thethermal regimes that form in marinewaters over Nauk SSSR,Vladivostok, 269 pp, In Russian.r Ecologyof theHering Sea: A Revieivaf RussianLiterature Fadeev,N,S. 1987. Severo-tikhookeanskie kainbaly western Kamchatka shelf bottom fishes]. Diss. [Northern Pacific flounders]. Agropromizdat, kand. biol. nauk [Candidate thesis in biologyI, Moscow, 174 pp. In Russian.! 24 pp, In Russian.! Lakin,G.F. 1980. Byometriya [Biometry]. Vysshaya Polutov,I.A. 1967.Abundance of floundersand de- shkola, Moscow,352 pp. In Russian.! mersal fish in Kamchatka waters and the de- velopment of commercial fishing. Izv. Mikulich, L,V. 1954,Food of flounders along the Tikhookean. Nauchno-Issl ed. Inst. Rybn. Khoz. coast of southern Sakhalin and the southern Okeanogr. TINROi 57:98-121. In Russian,! Kuril islands. Izv. Tikhookean. Nauchno-Issled, Inst. Rybn.Khoz. Okeanogr. TINRO! 39. In Pravdin, I.F. 1966. Rukovodstvo po izucheniyu ryb Russian,! [Manual on fish research],Tushchevayo Prom- ishlennost, Moscow. In Russian.! Moiseev,P.A. 1952. Some specialfeatures of the benthic and demersal fishes distribution in the Tikhonov,V,I. 1969.Biology and fisheries of yellow- far-eastern seas. Izv, Tikhookean. Nauchno- fin sole off the western coast. Diss. kand. biol. Issled,Inst. Rybn. Khoz. Okeanogr. TINRO! 37. nauk [Candidate thesis in biology]. Petropav- Englishtranslation 1968, pp. 297-307 in: Sovi- lovsk-Kamchatski, 22 pp. In Russian.! et fisheries investigationsin the northeastern Pacific,I'art I, National TechnicalInformation Tikhonov,V.I. 1981.Sex composition of the western Service, TT 71-50127. Kainchatka yellov;fin sole stock. Izv. Tikhookean. Xauchno-Issled. Inst. Rybn. Khoz. Natarov,VV. 1963.Water inasses and currents of Okeanogr. TINRO! 10o, In Russian.! the BeringSea. Tr. Vses.Nauchno-Issled. Inst. Morsk. Rybn.Khoz. Okeanogr. VNIRO! 48, Izv. Tokranov,A.M. 1989.Food of yellowfin solein the Tikhookean, Nauchno-Issled, Inst. Rybn. Khoz. southv'.estern Bering Sea. Vopr. Ikhtiol. Okeanogr, TINRO! 40 !;111-135. In Russian,! 29 !:1003-1009. In Russian.! Nikolotova, L.A, 1979.Pitanie i nckotorye cherty pischevykhvzaimootnoshcheniy donnykh ryh Zubov,N.N., and I.O. Mamayev. 1956. Dynamic zapadno-kamchatskogoshel'fa [Diet andsome method of calculating elements of sea currents. characteristicsof trophic relationshipsof the Gidrometeoizdat 115. In Russian.! Ec BiologyofSmelt Osmeridae! inthe Korf-KaraginCoastal Area of the SouthwesternBering Sea V.l.Karpenko and P.M. Vasilets KamchatkaResearch Institute of Fisheriesand Oceanography Kamchat VIRO} Fetropavlousk-Kamchatski,Russia ABSTRACT different species:H, olidus Pallas!, occurring in Thispaper presents data on the biology of three spe- freshwater; H. pretiosus Girard! and Hjaponicus ciesof smelt Osmerusmordax dentex, Hypomesus Brevoort!,both coastal; H. nipponensis McAllis- ofir1us,and H. japonicus frommaterials collected ter!, anadromousand coastalilake-river or lake in the surnrner and fall of 1975-1993in coastal wa- forms!;and H transpacificus McAllister!, known ters of Karagin Bay, southwesternBering Sea. onlyfrom the lower reaches of Californiarivers, The Smeltsgather in river estuariesof the studyarea mostrecent researchon the speciesconfirmed this duringpre-spawning, spawning, and post-spawning classification Gritsenko arid Churikov 1983t periods.The maximumage of Arctic smelt , m. The earliest surnrnaryof data.on smeltsof the ctentex!was 9+ years,and of silver smeltsor rnal- RussianFar Eastis by Petrov 925!, who analyzed orotayakorioshka H. olidus and Hj apunicusI was themorphological features of Osmerusin thediffer- 5+years; maximum length and weight were 33 cm entregions of Russia.Sakhalin Island smelts have and.25G g, and24,8 cm and 158 g, respectively. beenthe subjectof numerousstudies i Ivanova1955: Smelts do not feed during spawning, and they Tagmaz'yan1974; Churikov 1975, 1976, Churikov feedvery little beforeand right after spawning. and Gritsenko 1983;Grit.senko and Churikov 1964; From then until the end of August, Arctic smelt con- Gritsenkoet al. 1984a,1984b; Dudnik and Shrhuki- sumea greatamount of youngPacific salmon pink, na 1990;SakhTINRO 1993!. Less research has been chum,and sockeye! migrating fromthe rivers. Con- doneon smelts in other region. of the RussianFar versely,larval and juvenile smelts constitute a large East;Amur {Soin 1947;Kokhmenko 1964: Podush- portionof the foodof youngsalmon and other corn- ko 1970a,1970b, 1971!; Prim orie Pirozhnikov19oG, mercial fishes. It is conceivablethat smelt compete Zadorina 1980i; western Kamchatka Dobrynina et with salmon,herring. pollock,and other fishesfor al. 1988;Maksimenkov and Tokranov1993a, 1993b i; and eastern Kamchatka Belousova 197 i, Naumen- food. ko et al. 1990!. The presentpaper summarizes the available INTRODUCTION materialson the biologyof smeltsin the southwest- Thefamily Osmeridaeincludes t,wo important gen- ernBering Sea, describes the species, defines their era, Osmerusand Hypomesus,with sevenspecies rolesin the ichthyofauna,and identifies the major Klyukanov1969, 1970, 1975; 1VlcAlhster 1963!. Os- questionsthat warrant further research. merusconsists of two speciesof rainbow smelt: O. ln the southwestern Bering Sea,there are three eperlanus L.! andO. mordax Mitchill!, Basedon speciesof smeltsin tw:o genera: silver smelts or mal- differences in skull structure and the number of orotayakorioshka, H. olidusand H japonirus;and vertebrae,some workers recognizetwo subspecies Arcticsmelt. O. rruirdaxrien te~. Because of their high of O. mordax: the western Atlantic form, 0. m. abundanceand constant presence in coastalwaters, mordax Mitchill!; andthe arctic form, O. m. dentex theyplay an important part in the ecosystemoi'this Steindachner!,Hypomesus is representedby five area. BiologyotSme rn tthe Kort'-Karagin 'oastalArea ot tt!c' Suutt!v!:cstern BeringSea 27B 0-N 59' 66- 56 162' 163" 164= 165' 166'E 162' 1 F'figure1. Sampling locations ofArctic srnett, Osmerus mordant rlentex. eriesstatistics. The total nuniber of smeltsin river MATERIALSAND METHODS estuarieswas determinedby the method of areas Weused m aterialcollected in the 60-mile-longcoast- IMesyatsevct al. 1935,1VIayskiy 1940!, which had al zoneof the Korf-Karagin area I Figure1! during beensuccessfully tested by ShershnevI 1971, 1975.i the summersof 1975-1993.We used fishing gear and Churikov 975!. While studying the diet. we appropriateto the differentzones of thesea. The determinedthe frequency of animalsin food,index- basicgear types were beach seine, small-meshed esof fullnessand consumption, and the amountof drift nets I12-40 mm mesh!,and purse seine youngsalmon eaten by onesmelt. To calculate the I Karpenko1992!. amount of salmon consumedwe used Churikov's Mostof thematerials were obtained from beach formula I 1975!: seinecatches. In 2,698beach seine casts, 17,200 X= Sxn xn,xtj/S smeltswere caught. The silver smeltswere not sep- aratedby speciesfor biologicalanalysis, but in the where S is thc area of research, in square meters: n catchesbefore 1982 the predominantform was H, is the averagenumber of fish caughtin onecast; n, oiidvsI Karpenko1982b, 1983b! and after 1982 was is the averagenumber of salmonin onestomach; t I3.juponrcvs IChurikov and Karpenko 1987!. Bio- isthe length of the feeding period in days;and S, is logicalanalysis was performed on 681 Arct.ic smelt the seine area 75 m'!. and438 silver smelts from beach seine catches, and The estimated numbers of downstream mi- 273Arctic smelt from drift gillncta.nd trap net catch- grant~of pinksalmon ,Oncorhynchrts gorhuscliu! and chum salmon O. ketu! were obtained by ex- es !Table 1!. Biologicalanalysis was done using standard trapolationof dataon youngsalmon tagged by methods: the condition factor was calculatedby KamchatNIROscientists in the Kyaylyulya River Fulton'smethod; for ageand size, we used the meth- I Karpenko1994!. For calculating averagetemper- odsdescribed by Chugunova 959!, Pravdin 966!, atures,we used temperature estimations from sur- andBryuzgin 969!. To estimate the abundance of facewaters of the littoral zonewhere beach seine smelts,we used the results of observationsand fish- casts were performed. cacologyof the Hen'ng.Sea. A Reviewor RussianLiterature Table 1. Number of smelts caught and numbers used in the analyses. Number of specimensused in analyses Arctic am.e1t Silver smelts Osmerus mordox derr ex! Hypomes us spp.! Number Bio- 92o- Year caught, analysis Food Age analysis Food Age 1975 5,240 1976 2,072 62 41 60 1977 12 100 100 100 1978 748 144 144 144 84 84 1979 693 9 1980 357 89 89 89 32 32 32 1982 278 95 95 15 15 15 1983 703 139 139 139 51 51 51 1985 543 91 91 gl 109 109 109 1986 2, 147 21 21 21 85 85 85 1987 507 12 11 12 28 1 28 1988 1,795 1989 1,612 167 105 28 1991 186 1992 210 1993 93 20 25 Total 17,198 954 861 785 438 379 410 The data were processedusing standard statis- Regular observations were made in the Korf- tical methods Lakin 1990!. Karagin area in estuaries of 11 rivers from 1975 through 1986,and in estuaries of 17 rivers from 1987 through 1993.Arctic s~elt werefound in estuaries ARCTIC SMELT of 13 of those rivers, most often near the Dranka Distribution and Belaya-Kichigarivers Table2!. On 14 and 30 Arctic rainbow! smelt Osmerus morris r derrtex! feed July 1978they werecaught with drift gillnets about in coastal waters and spawn in rivers Churikov and 300-400 m away from shore near the mouth of the Gritsenko 1983,Dudnik and Shchukina 1990,Grit- Rusakova River. In the open part of Korf and Kara- senko 1990!. In the summer they are scattered in gin bays, sinelt were found everywherewithin,'3 ! the warm shallow waters of Sakhalin and the Kuril km of shore in August and September 1978 Fimrre Islands to a. maximum depth of 40 m. As the water 1!. cools off, the fish migrate to deeper waters and by Thus, in summer Arctic sroelt were found November-Decemberthey locate in the 90- to 100- throughoutthe studyarea: in the littoral zone,small m-deepareas of the shelf, concentratingin places bays and gulfs, and open waters of Korf and Kara- where the water temperature at the bottom is 1- gin bays. 3'C. In January and February they move close to shoreagairi. In April mature fish movetoward the Reproduction main spawning rivers. YoungArctic smelt stay sep- arate from adults in fall and winter at depths of 70- Arctic smelt spavn in rivers, which they a.cendfoi. 80rn, where bottom v.ater temperatrrresare 0-3'C. distances from 100 m to 10 km, depending on thc As it gets warmer they move to shallow areas size of the river and distance from the mo~th to SakhTINRO 1993!. In Karagin Bay, according to adequate spawning grounds. In 1980 school:-of trawl survey results, smelts are found in approxi- spawning smelt were seen 2-3 km above the rnatelyequal quantities at depthsto 50 and 50-100 Makarovkaestuary. Time spentin the river varied m Naumenko et al. 1990!. from several hours to 10-15 days, during w hichthey HiOtogyOt.Sme inthe tKOrf-Katagt'n COSStalAredOt tht SO0thwe Rusakova Dranka Makarovka Vytv irvayam Relays-Kichiga Virovayam Anapka + Gnunvayam + n/d n/d n/d n/d n/d n/d n!d Ku1 tush nay a n!d n/d n/d n/d n/d Olyutorka n/d n/d n'd n/d n/d n/d n/d Yeuvayam n/d n/d n/d n/d n/d n/d n/d n/d n/d Asigivayam n/d n/d n/d n/d n/d Tnskbyvnytvayam n/d n/d OecvTreiire:+, presenn . ~bshent; n/d,ao daLv. Table4. Dateof first catch of Arctic smelt larvae Table3. Agecomposition ofArctic smelt at matu- ritystages 4-6 in estuariesofthe Korf- in estuariesof Ksragin Bay. Karaginares, June Year "4 of fish at sge yearsi 8 9 No. fished 2 3 4 5 6 Beach seine 144 1978 7.6 73.6 16.7 2. 1 9 1979 44.5 22.2 33.3 89 1980 24.7 11.2 56.3 6.7 95 1982 6.3 4 r.4 32.6 8.4 1.4 1.4 139 1983 3.6 18.0 33.9 26,6 15. 1 91 ]985 659 275 44 21 1986 23.8 4.8 23,8 38.1 9,5 12 1987 33.3 58.4 8.3 26 1993 4.0 88.0 8.0 Drift gi linet 1976 3.3 19.7 26.2 34.4 14.8 1.6 61 1977 2.0 40.0 18.0 22.0 11.0 4.0 2.0 1.0 100 did not feed ;hurikov and Gritsenko 1983, gin Hayon 19July, and young fish startedappear- ingin purseseine catches in earlyAugust Figure 11. SakhTINRO 1993k Arctic smelt may spawn on stony substrate,as in the riversof Sakhalin Churikovand Gritsenko Age 1983!,or onplants, such as the Obsmelts that lay eggson set.tied or floating grassy or arboreousplant.s In the littoral zone,in beachseine catches, Arctic Amstislavskiy1969. Amstislavskiy and Brusynina smeltwere up to 7+years of age and more than two- 1963,Venglinskiy et al. 1967!.There are no data on thirds were 3 to 4 yearsold Karpenko 1983al.In the character of spawning for Arctic smelt of the theopen waters of Karagin Bay, in drift gillnetcatch- Korf-Karagin area. es,the smeltwere 2-9+ years of age Table5!. Arctic smelt in the southwestern BeringSeajoin In the Dranka River estuarythe averageage of' the spawningstock during their third year.Most Arctic smeltcaught in the first seiningwas older spawners > 76%!are 3-4 years old Table3!. Spawn- than that of t,hefish caught in the secondseining, ing startsin June,and the periodof eggdeposition several weeks later Figure 2!. This could be ex- is quitelong, For example, in 1988in the estuaryof plainedby a highermortality rate among the older the Dranka River,inature fish with gonadsclassi- agegroups an d bythe younger f ishcoming closer to fied as 6-2 were recorded on 29 June 97.6~x! and 27 shore.It is interesting to note that in the littoral July 9.1m!.Based on the first appearanceof smelt zone there were hardly any age 1+ smelt, even larvae in estuaries,spawning in the northern part thoughi.his group is the largestin the population. ofKaragin Bay started earlier than spawning in the Oneexplanation is that fish ofthis ageusually feed south,and in KorfBay it startedearlier than in farther from shore,The absenceof'age 1+ smelt in KaraginBay Table4k The reasonis that watertem- drift net catchesin the open part of Karagin Bay peratureincreases earlier in the north. Fecundity probablyis due to their smallsize. which allows is unknown. thornto escapethrough the drift net mesh, The length of the larvae at hatching is 7-8mrn. In the small rivers, along with the downstream rni- Lengthand weight grationof thehatched larvae, the developing eggs probablyalso get carried to the sea,as in Sakhalin Arctic smelt reacheda maximumlength of 33 crn wa.ters Churikov and Gritsenko1983!. The larvae andweight of 250g. Theaverage length over the quicklymigrate to the openpart of the bay,where yea.rsvaried from 1.6.3 to 22.5cm Table6k theysoon develop into youngfish. In 1993Arctic Theaverage annual gain in lengthfor smelts smelt larv~e were found in the open waters of Kara- was 3.54cm. The rate of linear groivth in the first 2 Biolr>gyofSmelt inthe Kort-Karagin CoastalArea of the SoL thwestHer Sea.rnr e 222 K3US 8 UR'2 9P 80 70 60 >> c 50 Qu 40 a. 30 20 10 0 8 Jul80 25Jul BO 21Jon 83 13Jul 83 29Jun 85 23Jul 85 Fit>2, >re Agecomposition ofArctic smelt, Osmer mordox sden collectedex, fromthe Dranka Riier estuary. Table6. Length composition ofArctic smelt inbeach seine catches inKaragin Bay,June-July 1978- 1 993. Yearfished 9-10 11-12 13-14 15 -1617-18 ~v19-20offish 21-22stlength 23-24 cmi 25-26 27-28 29-30 31-32 33-34 No. length Mean 125 19.1 08 64 344 35>2 9.6 5. 6 7.2 0.8 1978 11.1 9 1S0 22. 2 33.3 11,1 22.2 1979 1.1 S9 20 0 ! 4.6 10. 1 2.2 4.4 38.2 20.2 7.8 1. 1 1980 1.4 1.4 139 21.0 2 8 14 93 107 79 23,7 22 3 15.1 3 6 1983 3.3 91 22.5 7.6 50.5 20 8 15.3 1.1 1985 4,7 21 19. 1 9.5 9 5 4.7 9.5 14.2 23.8 4.7 4.7 1986 14.2 1.2 167 20. 2 4,1 16. 17.3 7,7 11.3 28. 1 10.7 2.4 1989 25 163 4.0 4.0 1993 8.0 8.0 40.0 16.0 20,0 forother fishes Bryuzgin 1969 l. It canbe explained yearswas above average. From 2 to5 yearsofage it bythe fact that after spawning the large fish die off stayedpractically the same. and after 5 yearsthe firstbecause they develop faster and join the spawn- rateof growth decreased fFigure 3!. The total an- ingstock earlier. Thus, by August large fish of ages nualgain of weight in thefirst 5 yearsincreased 5+and 6+ died and the average size of fish decreased from 16to 44 g. Xo differenceswere found in the comparedtothe size of fish caught, inJune and July lengthand weight of malesand females. v ith thebeach seine. The larger size of age3+ smelt Theaverage size of Arctic smelt aged 2+ and 3+ fromdrift netcatches compared to fish caughtwith yearswas smaller in the beach seine catches than beachseine is easy to explain considering the growth in the drift gillnetcatches tTable 7!, Fish4+ years of agelacked these differences, and at 5+and 6+ processand fishing efficiency of the nets. yearsthe average size of ~melt caught by beach seine At equallength the averageweight and there- exceededthe size of smelt caught with drift gillnets. forethe conditionof fish in Augustare considerably Thedifferences between the fish of 3+,5+, and 6+ higher,which is completely reasonable because this yearsof age were significant atthe probability kv- is thetime when intensive feeding occurs in theopen elof 0, l~r. Such a growthpattern has been described waters of the bay. EtOlogynt' the Bering Sea: .0 Revit w GtRuSSian I itt'ratttre 45 12 40 10 35 E t! 30 ~c!! 8 o! t! 25 c t: 6 20 c! ! 0! V! 15 ct! i: 10 4 Age in years Figure,3 Annualgro ottof Arctic smelt, Osmerus mordaxdcntex. Table 7. Length, weight, and condition factor by Table 8. Fullnessof stoxnacbsof Arctic smeltand ageof Arctic smeltin beachseine and percentagefeeding at differentmaturi- gi linet catches,Korf-Karagiu area. ty stagesof the gonadsin beach seine catches, June-.July 1978-1993. Age Length cm1 Weight i gi Condition factor years l Mean Mean s! Mean s' No. Stomach '.» of fish at gonad inatoritv stage fullness" 6 6 2 2 3 Beach seine 70.6 92 9 100 75 9 85.5 1 11.0 1.0 10.0 3.4 0.858 0 130 10 2 15.3 1. 6 26.8 8.4 0.870 0.090 47 59 14 3.e 15.0 0.833 0.110 187 3 19.0 2. 2 50.0 14 8.3 3.6 2.9 16.0 G. 767 0.090 90 4 226 1.4 76. 5 29 105 23 4 3 27.2 0 752 0.100 14 26.4 1.6 120.6 17.6 1.55.4 11 4 6 28.7 0.3 140.0 .1 0 693 0020 3 storeache 17 69 4 133 220 70 Drift g!linet exaroined N l 2 17.4 0,6 39.0 6.0 0.861 0.060 2 Fish '29.4 7.1 24 1 14.5 24.3 3 204 0. 7 75. 7 12.0 1.037 0.120 40 feeding i ~»i 4 22. 5! 1.3 105. 0 17. 8 1.065 0, 110 23 C«1CSorie«t! romp;yi io S ~full! 5 249 0.9 134,3 18 4 1.014 0.090 36 6 263 0. 7 158,2 15.7 1.0925 0.100 18 7 28»2 0.5 198.0 14.2 1.013 0080 4 8 307 227.5 22 5 0 907 0030 2 9 315 0 5 222 5 7.r! 0 867 0.010 2 '24 Biolopv of Smeltin he Kort-KaraginConsist Arcs of th» SoorhivesrerriSering Sea Table L Frequency of food items iri stoniachs of Arctic smelt from the littoral zone beach seine catches! and percentage of fish feeding, June-July 1978-1993. % of stomachs with food item in ivear! Food item 1978 1980 1982 1983 1985 1986 1989 1993 Polychae tee 22.2 26.4 Mysids 20.5 32. 1 1.9 50.0 21.7 Gem marids 20.5 25.0 15.1 33.3 Euphausids 2.9 Shrimps 5.9 insects 17.0 Young smelts 11.8 7,1 18.9 Young pink salmon 23.5 14.4 4.3 Young chum salmon 8.8 10.'7 1 7.0 26. 1 Young sockeye salmon 10.7 3.8 33.3 Young acul pins 3.6 77.8 Threespine stickleback 5.7 Nine spine stickleback Sand lance 20.6 21.7 Atka mackerel 2.9 Fish, unidentified 8.8 7.5 50.0 17.4 11. 1 Stomachs examined No i 144 89 139 91 21 167 25 Fish feeding %! 23.6 31.5 959.5 38. 1 3.3 28,6 13.8 36,0 able 10. Average length of Arctic smelt consum- Feeding ing different foods, from beach seine catches ia the Korf-Karagin area The intensity of Arctic smelt feeding varied signifi- cantly during the year. As they matured, the amount Smelt length cm i of food consumed decreased, and during spawning Food items Mean lVlin. Max. the smelt stopped feeding Table 8!. After down- stream migration the fish started feeding. Older fish Young salmon 20.8 3,6 12.7 29.0 that had spawned several times started feeding lat- Mysids, gammarids 16.9 3.8 10.0 29,0 er than younger fish Churikov and Gritsenko 19831 The amount of food consumed reaches maximum in open waters during August and September. Of 161 Arctic smelt from gillnet catches of August 1976and 1977, the stomachs of 6.2' were fullness category G empty!, 3.7% category 1, 10,6/c category 2, 18.0% category 3, and 61.5%category 4 fuHh In all, 93.8' had been feeding. The diet of Arctic sinelt in the littoral zone in- cluded polychaetes, mysids, garnmarids, euphausi- ids, shrimp, insects, and young fishes Table 9!. Some benthic crustaceans, polychaetes, and fish were the most important part of the diet, Young salmon were the main component in the diet of the larger smelt,. whereas the smaller fish ate mostly mysids, gam- marids, and polychaetes 'Table 10!. The differences were significant at the 0.1% probability level, The basic food of Arctic smelt in the open wa- ters of Karagin Bay was young fishes, mainly sand Ecr>k>gyr>/ thr RcrrngSea> / R Table ll. Frequency of food items in stornacits of lance, pollock, capelin, and flatfishes Table 11!. Arctic smelt from offshore waters gillnet Young herring, saffron cod, pink salmon, sculpins, catches! and percentage of fish feeding, and Atka mackerel were not found as often, appar- August-September 1976-1977. ently due to the low abundance of these species, Among the crustaceans, shrimps and mysids were '4 of stomachsunth foodItem on idate] most important. 11 Aug 8 bep 18 Aug 20 Aug 29 Aug Fooditem 1976 1976 1977 1977 1977 S/LVER SMELTS Polychaetes 22.6 28.9 Mysids 16.1 .0 100 22.2 HypO»teSusgri/>Onicusare the largeSt Speciesof Hy- Cumaceans po>>tesus.According to Hainada, they spawn in April Hyperiids and May in freshwater areas of the coast with a Shrimps 9.7 37.5 48.9 sandy bottoin and salinity of 28 ppt, and in sotne Crab larvae 20 67 cases they enter lagoons with a salinity of 4-6 ppt Squids 20 Gritsenko and Churikov 19835 ln early May they Youngherring 84.4 have been observedto enter Tunaycha Lake in large Youngpink numbers, and at the end of the month, Busse La- salmon goon Sakhalin! Gritsenko and Churikov 1983!, Youngpollock 12.9 12.5 17.8 Hypor>tesus otidus can be nonanadrornous lake Youngsaffron cod 48.9 and lake-river! or anadrotnous. The nonanadronious Youngsand lance 85 12.5 60 75 6 fish differ from the anadromous forin by t.heir srnall- Youngatka er size, earlier maturity -2 years old!, and more mackerel intensive piginentation SakhTINRO 1993!. The Youngsculpins 22.6 typical lake-river form of H. olidus inhabits the Young halibut 125 20 4 4 Amur River watershed. Thc anadromous form is Cape!in 25.0 20 4 4 common in eastern Sakhalin rivers Gritsenko and Stomachs 27 9 5 73 Churikov 1983 !. examined b o.! Fish feeding !9 ! 100 74.1 88.9 100 61.b Table 12. Occurrence of silver smelts, Hypomesusgaponfcrsa and H. oh- dsss,in river estuaries oi Karagin. Bay, 1878-1889. River 1978 1979 1980 1982 1983 1985 1986 1987 1989 Rusakova U ranks Makarovka Vytvirvayam Belaya-Kichiga Virovayarn Anapka Gnunvayam Mamikinvayam Olyutorka n/d o/d rU'd n/d n/d rr/d n/d Occurrence:+, present;-, absent;n/d, no data. 226 Ricrlogyo! Smeltin he Kort-KaraginCoastal Area of th» SouthivesiernSeri rig Sea Table 13. Age composition of silver smelts at ma- Table 14, Age composition of silver smelts in beach turity stages4-6 in beach seine catches seine catches, Korf-Karagin area, June- from estuaries of the Kerf-Karagin area, July 1&78-1986. June- July 1978-1987. Year ~~of fish at age ycars I % of fish at age years! fished 0 1 2 3 4 5 Ao. Sex 3 4 Ão. 1978 6,0 63. 1 30.9 84 Fernale 0 70 30 10 1979 66. 7 33. 3 6 Male 33 63 4 24 1980 3.1 25.0 65.6 6.3 32 Both sexes 23 65 12 34 1982 73.3 26.7 15 1983 43.1 35.3 17.7 3.9 51 1985 43. 1 33.9 23.0 109 1986 3.5 34.1 38.8 22.4 1.2 85 Table15. Lengthcomposition of silversmelts in beachseirie catches in Karagin Bay,June-August 1978- 1989. Year '7~of fish at length eml Mean fished 7-8 9 10 11 12 13-] 4 15 16 17--18 19 20 21-22 23 24 25 26 . Jo. length 1978 1.1 13.1 29.7 22.6 20.2 13.1 84 14.8 1980 6.2 3.1 28.1 46.8 12.5 3.1 32 16.3 1982 33 3 46 6 13 3 6 6 15 17 2 1983 21.5 43. 1 13. 7 5.8 13.7 1.9 51 18.2 1985 29.3 14.6 17.4 28.4 10.0 109 16,7 1986 8.2 22.3 '2.3 37.6 22.3 2.3 85 17.8 1989 46.4 42.8 10.7 28 14.4 Distribution Age Over the study period silver smelts were found in Few smelts caught in the littoral zone were 5 years the estuaries of 10 of the 17 rivers examined in the old; inore than 90'ic were 2-4 years old Table 14!. Korf-Karagin area Table 12!. They ivere seenmost The low percentage of 0+ and 1 year-olds is typical often in the estuaries of the Dranka, Belaya-Kichi- for silver smelts, and for Arctic smelt, even though ga, Makarovka, and Anapka rivers. Possiblybecause these age groups must be the most numerous in the of their small size, silver smelts were not found in population. drift gillnet catchesfrom the offshorewaters of Korf and Karagin bays. Lengthand weight The length of silver smelts ranged from 7 to 24.8 Reproduction cm, and fish 12-18 cm long made up half of the catch Silver smelts of Korf and Karagin bays enter the Table 15!. The average annual increase in length spaivningstock during their third year of life. The was 3.12 cm, The rate of linear growth at 1 and 2 majority of the spawning stock 5ti 'I consisted of yearsof agewas somewhatabove average, and then fish at the age of 3 years Table 131.Spawning starts gradually declined lFigure 41. The total annual in Junc and the period of egg deposition is relative- weight gain during the first 5 yearsincreased from ly long. Thus, in 1985at the mouth of' the Dranka 7 to 52 g Table 16!, The maximum weight was 158g, River there v'ere fish at t.he maturity stage of 6-2 V'e did not find any difrerence in the size of males on 29 June and 23 July. and females, Ecologyof tltt 8 ritterStd; A Reviewof Russia >l ilcr tture 77 10 60 50 E 8 40 g C L r 30 4 20 a~~i c 3 t C 2 10 3 Age in years Figure 4. Artrtuol growth uf silver smelts. Hype>mesuanl duart tdH japoaieus. Table 18. Length, weight, and condition factor by Table 17. Fullness of stomachs of silver smelts and age of silver smelts in beach seine catch- percentage feeding at different gonad es, Korf-Karagin area, June-July !978- maturity stages in beach seine catches, 1989. June July 1978-1987. An L~ht i ~Wei ht t Condition facto Stomach fi of fish at onad maturity stag . tyearS! Mean Sd Mean si Mean a-' No. ful lneas 4 5 6 6-2 2 7.5 0.4 2.3 0.5 0.740 0.140 3 93.2 66.7 100.0 73.3 62.8 64,tI 10.0 1.2 9.0 2 4 081li 0 140 6 3.4 9.5 9 1 9.7 14.5 1.7 25.9 97 0984 0.160 164 9.5 6 7 9 5 9.7 9.5 13.3 11.7 9. 18.4 1.3 54.4 17.8 0.992 0.160 11 4.8 6. 6.9 6.9 20.6 1.5 79.0 25 7 1 025 0.160 51 23. 1 1.1 131.0 295 1218 0 3 Stomaohs Vo. i 29 9 15 281 examined Fish 6 33.3 0 26.7 37.2 36 0 feeding t'» t eC ttegoriestt emptyi to 4 if 1! 228 Biologyof Smeltin theKorttKaragin Coastal Area of theSorjthiiestern Bering Sea Table18. Frequencyof fooditems in stomachsof silver smeltsfrom the littoral zone beach seine catches! and percentage of fish feed- ing, JuneQuly 1978-1988. % of stomachs wit,h food item in year! Food item 1978 1980 1982 1983 1985 1986 Gastropod s 25.0 Copepods 88.9 90.9 Mysids 62 Cumaceans 2.1 Isopods 25.0 Gamrnaride 89.6 62.5 Shrimps 20. 8 Crab larvae 78.3 Midges 4.3 Young smelts 2.1 90.9 Young pink salinon 20.8 Young s colpins 21 3.7 Fish, unidentified 18.7 96.3 Stomachs examined No. ! 84 32 15 51 109 28 Fish feeding '7nI 57 1 25.0 60.0 21.6 24.8 82.1 Feeding flect the abundance equally. For example, even if smelts are not frequentlyfound, but their catches In the processof maturing, the amount of foodre- are still large, asin 1986,then the averagecatch in quireddecreases, and smelts do not feedat all dur- the area will still be higher than is the case with ing spawning Table 17!. After the downstream the regular catchesof average size, as in 1989 Fig- migrationthe fish startedeating mails, copepods, ure 5!. This is why we used both of these values, mysids,curnaceans, isopods, gammarids, shrimp, In the beach seine fishing, the minimum catch- crab larvae, midges,and youngfish i Table 18!. The es of smelts along with a low frequency in the estu- widest food spectrum was noted in 1978,as opposed aries of the area'sri vers happened in 1981and 1991. to 1982 when the sinelts only consumed copepods, During June andJuly of 1981,129 beach seinecasts or 1983 when they only consumedcopepods and were made in the mouths of ll rivers of Karagin young smelts. Bay.and one mature smelt was caught only once, eventhough the youngfish were practically every- ABUNDANCE OF SMELTSIN THE where. One of the reasons for such a phenomenon could be the abnormally high water temperature by KORF-KARACHIW AREA the coast Figure 6!. In 1991the averagecatch and The abundance of smelts in the Korf-Karagin coast- frequencywere higher than in 1981,and the tern- al area fluctuated considerably.We usedour own ob- peraturewas closeto average.It is interesting that servations as well as commercial fishing statistics the cornrnercial harvest in those years was relative- to estimate stock size. In both cases we lumped the ly large Figure7!. The minimumharvest of smelt data on Arctic and silver smelts, but in the commer- occurred in 1980 and 1990. In addition, the harvest cial catches the proportion of silver smelts was con- of these fish was low in 1987, as were the beach siderablysmaller than in the beachseine catches in seine catches, even though the frequency was high the river estuaries. This is causedby the use of trap that year. The maxirnurn commercial catchesof netsto catchpre-spawmng smelt near the estuaries. smelt occurred in 1976-77, 1982, 1988, and 1992, To estimate the abundance of smelts from the and do not coincide with the abundance peaks on results of the beach seine fishing we used the aver- the graph constructedfrom beachseine catches in agecatch and frequency,which do not alwaysre- river estuaries Ecologyof the GeringSe,i: A Revie~of RussianLiterature 229 18 16 30 14 0 U 25 12 20 0 10 0 8 6 15 e 0 2 1978 79 80 81 82 83 85 86 87 88 89 91 92 93 Year Figure5. Frequencyand CPUE samples! of srne tsinthe Korf Karagin coastal area. 25 20 IO O p 15 0> ~ 10 E Q I 0 1978 79 80 81 82 83 84 85 86 87 88 89 90 91 9 Year Figure 6. Atteragewater temperatureat thesurface in July '30 6iOIOgyc>fSir reit in IheKore'-Karagin Coasfaf Area lot tire Snufhcvesterrr Br*ring SC a 60 CD 40 IO o 30 ce cr 20 10 0 ccr cCrC cCr a> Cr ccr cn N Irl c0 i ccr Ol cD cv cn 'cl ccl cCl N cU1 I0! cn Cr w Ix! ccl ccrco co cc>cD ccl c! cc al Cb CD cD>cD cD I I R 8 X al crl cclcD cDlcD al Dl CD CCICD! Ol CD cD o> cD Q! cr! Dr al CD Year Figure 7. Dynarnccsofsmelt catchesinthl. KnrfKarngin area. Period of oafch I - June 1-15 II - June 16-30 Ill - July1-15 I IV - July16-31 V - Aug»sf1-15 I rSS Hrr rrQg ritS rg HrNH Anapka HAH' @HAH HH 8 8 HS Virovajam 15O H8J HH ESSE Srtt HH 8 H $1$ Belaya-Kictriga HHH HH Marke!ovskaya D 1OO HHS g gHZ H > > Mamikinvayam r H Hrr S 8SH HH Gnunvayam 0 SH SWS S HH + HH Makarovka 5' HS JHOW 8 rs s er Dranka HeSeS Hrra Rusakova ~niH~r S Srr HratarSuerSrSrH Khaylylulya I I ' I I I I i I I I ' ll ,I I I I I I I I » I» IV I» IV» lrl IV II Ill IV Irl IV V Ir I» IV»»r IV II iil IV II III ri I» I » III IV»»l IV II »I lri 1978 1979 1980 1981 1982 1983 1985 1988 '1987 r988 1989 199I 1998 1993 Figurcg. Frequencyfrfsnrelts rn estuaries of 10ri»ers/lrrui ng to Karagi n Bay,Juneilugust 197tf-198'l. Erologyot the Heririg>Sea: A Reriew of Rrrssi~rrLiterature Table 19. Estimated riumber in millions! of juvenile salmon Orrcorhynehus spp.!consumed by smeltsin someriver estuariesof Karagin Bay,1978- 1993. Number millions! of young salmon consurnrd Salmon Be! aye-Kichiga Dranka Makarovka Rusakova Year species l2.06 km'! .4 km'-'! 2.86 km'-'! i1.03 km-'! Arctic smelt 1978 0 gnrbuschn 0.30 1980 0 gorbuscha 0.49 0 keta 0.56 0.41 0 serka 0.72 1983 0 keta 0.63 0. 13 0 rrerka 021 1985 0 ketn 0.34 0 nerkn 0.15 1989 0 gorbusr ha 0.49 0 kata 1.82 Silver smelts 1978 0. garbuscha 0. 26 0.97 The dynainics of smelt abundance in June-Au- the effect of predatory fishes i n Kamchatka waters gust 1978-1993in estuariesof 10 rivers flowing to Arctic char, Siberian char, and Arctic smelt on KaraginBay are representedin Figure8. Theabun- youngsalmon, and estimationof the value of salrn- danceof smelts in the estuar'y of each river changed on consumed in some generations. In this paper, we significantly during June and,July, but no consis- only touch upon some problems concerning the tency was observed in those changes. In Karagin smelts' predation pressureon salmonstocks, and Bay, sinelts were found most frequently in the the placeof smeltsin the coastalecosystem of the mouths of the Dran ka and Belaya-Kichiga rivers and investigated area. in Korf Bay in the rnout,hof the Kultushnoye River. During the study period, consumption of young The ratio of smelt speciesin catches varied sig- salmonby smeltsand other pred.atorswas not sig- nificantly. Judging by the ratio in the samples nificant every year. Consumptionof youngsalmon taken from beach seine catches for biological analy- by smeltsin thc river estuarieswas noted in 1978, sis,Arctic smelt made up about 70%of the total catch 1980,1983, 1985. and 1989 r Karpcnko 1982a, 1994t in 1975-1993. The commercial fishing statistics lack andin openv, ater s ofKaragin Bayin 1976I Karpen- the requiredinformation and do not allowus to draw ko 1982b!, Out of 17 river estuaries examined, con- even a tentative conclusion about this, sumption of young salmon was noted in only 4: Summarizing, the abundance of smelts in the Rusakova, Makarovka, Dranka, and Relaya-Kichi- exaininedarea is subjectto signiticant.cyclical Ruc- ga. In the Rusakova and Makarovka estuaries it was tuations, and we do not, have evidence that would observedonly once each, in 1983 and 1980. respec- confirm its decline. In recent years the values of tively; and in the Dranka and Belaya-Kichigariv- catches and frequency in survey fishing have been ers it occurred relatively constant.ly.In thc estuarv below average,but the commercial catch of1992 was of the Dranka River smelts consumed juverdle chuin one of the highest. salmonand sockeyesalmon in 1980,1983, and 1985. In the estuary of the Belaya-KichigaRiver smelts EFFECTOF SMELTON YOUNG fed onjuvenile pink salmonin 1978,1980, and 1989, andon youngchurn salmon in 1980and 1989 Table PACIFIC SALMON 19l.Juvenile pink salmonwere most.ly consumed in In several papers Karpenko 982a, 1982b, 1982c, the yearsof strongdownst,ream rnigrat:ion. The larg- 1983a, 1983b, 1991, 1994a, 1994b! examined pre- est number of juvenile pink salmonconsumed dirr- dation by smelt. on young Pacific salmon, including ing the seasonby oneArctic smelt v as65, notedin 23 i t3io ogyof Smeltin theKorf-Keratin Coasra Area of theSouthivr str rn Orri rig Sea 1978; of churn salmon was 20, noted in 1983; and ot diet of youngsalmon during the early stageof their sockeyesalmon was 4, in 1980,The total numbers sea lives. In her oral report in August 19'93, L.V. of juvenile salmonconsumed by smeltsover the en- Piskunova noted that young smelts made up 22,8% tire periodof researchwere: pink salmon.,80.8 rnil- by weightof the foodof youngpink salmonand 3.5'Pr. hon; churn, 30.5 million; and sockeye,2.4 million, of thc food of young chum salmon, arid such situa- Smelts consumed 10.9-17.0% of the pink salmon tions are not unusual. However, this question, along year-classesin 1978,1980, and 1989while feeding with evaluation of smelts as food competitors, re- in the littoral zone. These numbers are much smafler quiresadditional research. than those determined by Shershnev 975! and Churikov 975! for the coastal waters of southwest- REFERENCES ern and northeastern Sakhalin. However, Arctic smeltkeep feeding on young salmon after theymove Amstislavskiy, A.Z. 1959. Reproductivebiology of to the open waters of Karagin Bay, where the prey Asian smelt in the southern Gulf of Ob. 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