A Review of Russian Literature

01 C2

t.6lN COPYON V

F !ital hy Ole A, Mathisen and kenneth O. C i@le ~B-96 OO1 C2

LGAMCQi'Y ONLY Ecologyof the BeringSea

A Review of Russian Literature

Edited by Ole A. Mathisen and KennethO. Coyle

AlaskaSea Grant ReportNo. 96-01

AlaskaSea Grant College Program University of Alaska Fairbanks Fairbanks, Alaska 99775-5040

Fax {907! 474-6285 E-mail l- YVU BSO~aurora, alaska.edu Elmer E. RasmusonLibrary Cataloging-in-Publication Data

Ecologyofthe Bering Sea: a reviewofRussian literature / Ole A, Matbisen and KennethO. Coyle,editors,

AK-SG; 96-01! 1,Marine ecology Bering Sea. 2. Marinemammals Bering Sea Ecology. 3.Fishes Bering Sea Ecology,I. Mathisen, Ole Alfred, 1919- II, Coyle,Kenneth 0, IIl. Alaska Sea Grant CollegeProgram. IV. Series: Alaska sea grant report; 96-01,

QH95.26.E27 1996

ISBN 1-56612-037-3 Citationfor this volume is: O,A, Mathisen snd Kenneth O. Coyle Editors!. 1996. Ecologyof the BeringSea; A Reviewof RussianLiterature. Alaska Sea Grant CollegeProgram Report No. 96-01, University of Alaska Fairbanks.

ACKNOWLEDC MENTS Thisbook is the result ofwork sponsored by the U.S.Department of State,award no.S-OPRAQ-93-AH-016. Production work on the publication was sponsored by theUniversity ofAlaska Sea Grant College Program, which is cooperativelysup- ported.by the U,S.Department of Commerce, NOAA Offjce of SeaGrant, grant no.NA46RG-0104, project A/75-01; and by the Universityof Alaskawith state funds.Cover designis by SusanGibson. TheUniversity ofAlaska is anafhrmative action/equal opportunity eznployer and education.al institution, SeaGrant is a uniquepartnership with public and private sectors combining research,education, and technologytransfer for publicservice. This national networkof universitiesmeets changing environmental and economicneeds of peoplein our coastal, ocean,and Great Lakes regions. Contents

Preface

OceanographicDescription of the BeringSea V.K. Pavlov awardP. V. Pavlov.

Zooplanktonof the BeringSea: A Reviewof Russian-Language Literature K.O. Coy/e, VG. Chavtut;and A.l, Pinchuk 97

SpeciesComposition and Distributionof Squidsin the WesternBering Sea Ve.l.Sobolevsky.

Long-TermFluctuations in the Ichthyofaunaof the WesternBering Sea N.l. Naumenko 143

Distributionand TrophicRelationships of Abundant MesopelagicFishes of the BeringSea Yr.k Sobolevsky,T.Ci. Sokolovskaya, A.A. Balanov,and 1.A.Senchenko .... 159

StockDynamics of WesternBering Sea Herring N.I. Naumenko

Dynamicsand Abundanceof WesternBering Sea Walleye Pollock P.A.Balykin ., 7

Paci6cCod Cadusmacrocephalus! of the WesternBering Sea Andrei 'V. Vinnikov.

Distributionand BiologicalIndices of YellowfinSole P/euronectesasper! in the SouthwesternBering Sea .S.V. Kupriyanov . 203

Biologyof Smelt Osmeridae!in the Korf-KaraginCoastal Area of the SouthwesternBering Sea V.l. Karper>koar>d Plvt. Vasileft . Distribution,Biological Condition, and Abundance of Capelin Maflohrsvillosus socialis! in the BeringSea f.A. h'aumenko. 237 Developmentand Distribution of theYoung of Northern Smoothtonguegeurogjossus schrnidti! in the Northwest PacificOcean arul Western Bering Sea Ye,l.Soholevsky and T C Sokolovskaya. 257

Distribution,Abundance, and Trophic Relationships of BeringSea Cetaceans Ve.l. Sobolevskv and OJ'eA. Mathisen. 265

Statusof the Northern Fur Seal Ca/lorhinusursinus! Populationof theCommander Islands A, I. Bol toe v . 277 Distributionand Seasonal Feeding Behavior of SpottedSeals Pbocalargha! in the BeringSea Ye.l,Soho/evsky. 289

HistoricalTrends in Abundanceof Steller Sea Lions Eurnetopiasjubatus!in the Northwest Pacific Ocean A.l, Boftnev and O,A. Mathisen 297 Preface

Thepurpose of this bookis to makeavailable results of Russianstudies of the BeringSea ecosystem to North Americanscientists not conversantin the Rus- sianlanguage. The book is the resultof a contractsigned in July 1993between the U.S.Department of Stateand the Schoolof Fisheriesand OceanSciences, Universityof AlaskaFairbanks. Dr. O,A. Mathisen became the principal investi- gator of this Joint U.S. RussiaBering SeaStudies project,

RESEARCHNEEDED FOR RESOURCE MANAGEMENT Utilization and managementof marine resourcesin the Bering Sealargely have beenon a species-by-speciesbasii;.As a result,less attention has been paid to the non-commercialgroups of organismseven though the largest biomass is foundin groupssuch as mesopelagicfishes, A newtrend is to lookat the ecosystema.s an entity with broadinteractions between the trophiclevels. As our knowledgeof migrationsby fish, marinemammals, and birdsis expanding,it becomesvery clear that the eastern and western parts of the Bering Seacannot be treated as separateunits. They are linked acrossnational boundaries by oceancurrents and trophic connections. For the Bering Sea there is a reasonablehope of developingan ecosystem approachto management,provided there is a unifiedresearch approach. This wouldprimarily be between institutions in the RussianFar Eastand the United States,as the principalusers of the resourcesof the BeringSea, in additionto research institutions in Japan, Korea, and China.

HISTORY OF RUSSIAN RESEARCH Despiteongoing economic problems, Russian marine institutions have maintained collectionsof oceanographicdata and field samplingfrom the Bering Seaecosys- tern. These institutions include TINRO, KarnchatNIRO, SakhTIVRO, the Insti- tute of Marine Biology,the Acadcrnyof Sciencesof the Far East, the Institute of FyydrbbiOIOg,the Far EasternState University, and smallerunits, Studiesbe- ganeven before World War II andincreased rapidly as the Russianfishing fleets expanded into the Bering Sea. Some scientific results have been published in journals of TINRO and the Academyof Sciences,Proceedings of the many meetingsand workshopsheld in the Far East have beenproduced in such low numbers,from 200 to 400 copies, that supplieswere immediately exhausted. In addition,the publishedarticles arebrief andincomplete, Prepared manuscripts remain unpublished because of a several-year lag in the publication schedule. COMPILATION OF THIS BOOK The writing of this bookwas accomplished by makingcont, acts with Russian ex- pertsin selectedresearch fields. Faculty members of the UAF Schoolof Fisheries and Ocean Sciences made short visits to institutions in Russia, and Russian sci- entistswere invited for lengthy visits to UAF in Juneauand Fairbanks.While mostresulting papers summarize contemporary Russian knowledge in the se- lectedfields, some papers are entirely new and original, For someauthors who had nearly coinpleted manuscriptson hand, this book has provideda welcome publishingopportunity. While ideally all organismsin the ecosystemwould be treated,grou ps including birds and salmon are notincluded in this book. For a review ofRussian salmon research see V.I, Radchenkoand A.I, Chigirinsky,1995, Pacific salmonin the Bering Sea, ¹rth PacifiicAnadromous Fish Commission Doc. 122, 80 pp.! The task of translating the papersinto English wasaccomplished by Univer- sityof Alaska School of Fisheriesand Ocean Sciences research associate Kenneth Coyle,University of AlaskaFairbanks student, Alexey Isakov, and University of Alaska Southeast student Lisa Valetsky. The translations, tables, and figures were corrected,redrawn, and retypedby professionaleditorial staff of the Alaska Sea Grant College Program Sue Keller and Carol Kaynor!,Point Stephens Press Kitty Mecklenburgand TonyMecklenburg!, Catherine Franklin Desktop Pub- l.ishing,and Heid.i Olson. In the referencesections, editors abbreviated journal titles accordingto Serial Sourcesfor he BIOSIS PrevieivsDatabase. Expertswho reviewed the papersin this volumeinclude Karl Banse,Jeff Breiwick,Robert Elan,er, Lew Haldorson,Dick Merrick,Keith Pahlke,Brian Paust, AndreiProshutinsky, Terrance Quinn II, Kathy Rowell,William Smoker, Grant Thompson,Thomas Wilderbuer,and Ann York. In the contributionby Coyle et al, all reviewercomments were addressed;in other papersreviewer comments were addressedby the editorswhere possible.The mandateof the U.S. Depart- ment of State making availableEnglish translations of Russianresearch on the BeringSea ecosystem is fulfilledin this volume,The mandate, coupled with the difficulty ofcommunicating with Russian authors in a reasonabletime, precludes standard peer review. Also, it shouldbe notedthat. some of the paperswere writ- ten without accessto new North American literature. It is hopedthat tbe contributionsin this bookwill be usefulas background material in planning future joint studies. Ecologyof the Bering Sea.A Revteivot RussianLiterature

OceanographicDescription of the BeringSea

V.K. Pavlov and P.V. Pavlov Arcti c and Antarctic Research Institute St. Petersburg, Russia

CONTENTS 1 G EOGRAPMIC-MORPMOLOC ICAL Geographic-MorphologicalDescription DESCRIPTION The Bering Sea is one of the bordering seas of the 2. HistoricalBackground Pacific Ocean. Its shape is like a sector-circle; the 3. ClimaticFeatures: Meteorological top is pointed north and the bottom parallels the Regime latitude lines. The Bering Sea washes the coast of' North America in the east arid northeast and the Waves coast of Asia in the west and northwest. The Aleu- tian-Commander archipelago bordersthe sea to the S. Water Cir culation south, separating it froin the Pacific Ocean. 6. Circulationand Water Exchangein the The Bering Sea is connected with the Chukchi Straits Sea and Arctic Ocean through the Bering Strait, which separates the Chukchi Peninsula from the 7. Freshwater from Rivers Seward Peninsu]a. Numerous straits through the 8. SurfaceHeight Aleutian-Corninander archipelago connect the Bering Sea with the Pacific Ocean Figure 1.1!. 9. Water Structure and Water Mass The extreme geographicpoints of the Bering Sea Characteristics are at the north end of Krest Bay f'u]f of Anadyr, 66'-24'N!, on Amchitka Island to the south A]eu- 10. Light and Water Clarity tian Islands, 51"-15'N!, in Karagin Bay in the west 62'00'E!, and the end of Kvichak Bay Bristol Bay, 11. Ice 156'55'' ! '! in the east. The greatest lengths of' the 12. HydrochemicalFeatures Bering Sea are 909 mi]es from north to south, and 1,290 miles from east to west, There are many islands in the Bering Sea The Aleutian-Commander a.rchipelago extends for 1,220 miles along the sout,hem edge of the Bering Sea and inc]udes more than 150 islands Table 1.1, Figure 1.2, Figure 1.6!. The A]eutian-Coznmander archipe]- ago is divided into six island groups by Buldir Strait, Amchitka Strait. Amukhta Strait, and Samalga Strait: Cominander Islands, Near Islands, Rat Is- lands, Andreanof Islands, Islands of the Four Moun- tains, Fox Islands; the Is] ands of t.he Four Mountains are included in the Fox Island group. Other important is]ands include the Karagin and Verkhoturov islands in Karagin Bay, the Di- ornede Islands Ratmanov and Kruxenstern islands i in the Bering Strait, St. Lawrence Is]and, Araka- inchechen and Ittygran in the Chirikov Basin, Stew- OceanographicDescription vt the HeringSea

Figure1.1. BrLthymetric map of theBering Sea. Ecology

Table1.1. Morphometrlc characteristics of the straitsin theAleutian-Commander archipelago Udintsev et aL ltt58!.

Peninsulas Width Depth rn! Cross sectionalarea and islands Strait or pass i es In aximum era~ ~m-

Kam ehatka Kamchatka 103.0 190.8 4,420 1,768 335.34 45.89 Bering Commander 46.3 105 '76 3.53 0.4B Medniy Copper! Near 196.0 363,3 2,000 658 238. 96 32.70 Attu Semichi 16.0 29.6 122 71 2.10 0.29 Al aid, Shemya 8hemya 1.7 3,2 0.01 0.01 Shemya, In genstrernRocks Buldir 67.7 125.4 256 32.05 4.39 Buldir 59.8 110.8120 74 8,22 1,12 Kiska South 22.2 0.01 0.01 Cape Kiska Tanadak 20.0 37.0 59 31 1. 16 0,16 Rat Oglala 11.5 21.3 51 1.08 0.15 Amchitka Amchitka '74.5 138.01,082 398 54.'94 7.52 Unalga Kavalga 7.0 13.0 82 51 0.66 0.09 Kavalga Ogliuga 5.6 0.03 0. 01 Oglinga Skagul 0.5 0.9 3.6 0,01 0. 01 Skagul Tan aga 17.5 32.4 377 144 0. 64 Tan ago Ksnag a 3 6.8 49 28 0.19 O.03 Ka usga Adak 7.0 13.0 0 59 0. 08 Adak Kagal asks 0.5 0.9 29 0.01 0.01 Kagalaska Cape Tanaga 55 29 0.07 0.01 Cape Tanaga Umak 0,7 0.01 0.0l Umak Chttgul 0.60 0.08 C hugoI Tagalak 1,5 2.8 18 0.03 0.01 Tag alak Fenimore 6.0 0.02 1kigi oak Okhudak 1.0 1.8 Okl iudak Atks 4.0 7.4 28 0. 2] 0.03 Fcologyot theBering Sea: A Reviewof kussianLiterature

Table1.1. continued.!MorphoInetric characteristics ofthe straits in theAleutian-Commander archiyeb ago Udintsev et a1 l959!.

Peninsulas Width Depth rn J Cross sect>ona area and islands Strait or pass Miles km Maximum Average km'-

At.ka Arnlia 1.0 1.8 26 16 0.03 0.01 Amlia Seguam 59 29,4 177 82 2.40 Seguam Amukta 40. 0 74.1 314 23.28 Amukta Chagulak 7,2 64 0,25 0.03 Chagulak Yunaska 10.0 18.5 499 314 0.80 Yunaska Herbert 14.1 26. 1 635 268 7.01 0.96 Herbert, 101 0 58 0.08 Chu gin adak 2 Chuginadak Samalga 17.4 300 139 4.48 0.61 Samalga 0.01 Sagak 19 3.5 2.6 0.0 Urnnak Umnak 5.9 53 39 O.23 0.03 Unalaska Un alga 51 36 0.10 0.01 Unalga Chaicbi Baby! 1.0 1.8 37 22 0.04 0.01 Chaichi Baby! Akutan 2.7 5.0 28 0.14 0.02 Akutan Akun 2.0 22 10 0.02 0.01 Akun Avatanak 3.0 110 0.29 0.04 Rootok Rootok 1.2 2.2 18 0.04 0.01 Avatanak Dcbrinski 1.4 2.6 42 0. 11 0.02 Tigalda 0.01 Kaligagan 29 18 0.02 Kaligagan 0.03 Ugamak 3,2 5.9 70 Aiktak Aiktak 0.5 0.9 16 0.10 0.01 Jgamak Unirnak 10,6 19.6 60 1.18 0.16 Unimak Izanotski 1.5 2.2 1.7 0.01 0.01 Alaska

Total 773.2 ],431. 7 730 92 Oceanographi

E E C> ID o 8 E OJ O chatka

g I.

Iy I.

naga I.

a I.

rnnak I,

laska I.

Unimak I,

Figure t.3. A longitudinal section of the Figure 1.2. Mop of Aieutian- Aleutian- Commander Comma nder Ridge. Ridge. ECOIOgyOf he Bering Seal A Revietvof Ru>Sianl i erafure

Table1.2. Important morphosnetric characteristics Table 1.3. Morphological characteristics of the of the straits in the northern Bering Sea. Bering Sea Gorshitov19BO» and 1980b!. Udintsev et al. 1959!. Total area, thousands of km' 2,3 l 8 Depth m! 1;ross section Area of the islands, km' 44. 4 Cape Sl,reit Width Max, Avg. km' rx Aleutians 377 Pevek St. Lawrence 4.9 Bering 88.2 58 38 3 38 Nttnivak 4.5 Prince of Kat agin 2.1 Wales Commander 1.8 Chukotsk 3,796 Chirikov 71.5 51 3fv 2.58 33.16 Volume of the sea, thousand~ of km' Norwastern Greatest depth, rn 4.097 Southeastern Shpanberg 222.2 38 23 5.20 66.84 Average depth, m 1,640 Rumyantsev Total for Chirikov 293.7 and Shpanberg straits

Table1.4. Morphological characteristics of the BeringSea Leonov1960!.

Area of sea Areaof' 4 ea Volumeof !oyer Summaryof relieftate ones VoI time Ave 7telie f Depth within i sohath betweenteobaths betweenisnb*t.hs km' km' Il depth Im. ca togory m km' km'

Continental 0 2,292,205 101!.0 shelf 2.112,543 91.7 179,662 8.3 55,219 1.5 50 1,833,934 96 278.609 121 49.33 1 13 75 1,603,176 69.6 2;10,758 100 42,964 1.2 46 6 8,0 Itt 2 64 100 1,438,667 628 164,509 7 1 38,023 92 0 1,066357 Continema1 150 1,293,916 56.2 144.751 tl 3 68.314 1.8 elope 200 1,238,649 53.8 55,267 2.:1 63,314 1.7 300 1,20?.610 52 5 31,D39 1.3 122,312 3.4 600 1,166,G14 50.6 41,596 18 237,362 6.4 750 1.133,324 49 2 32,690 1.4 287.2tt7 8.0 1.00D 1,037,645 4i.l 95,679 44 2if371 i6 393 458 17 711.326 1 i 1.80o 1!ea p basin 1,500 999.635 434 38,010 16 509 345 14 1 2,000 920,590 40.0 7th045 34 480,056 13.3 2,500 845,191 36.i 75 399 3.3 443,945 122 3,0DO 772,118 33 5 73,073 32 404 327 11.2 3,500 629,926 273 142,192 62 350,511 98 4,000 45,210 25 564,i16 24.8 168.784 4 tt 81 3.331 > 4,000 45,210 25 25,6I3 0.8 R-t5,191 37 2,791,593 1 00.0 3,562,919 1tl0.0 2,292.205 100 3,562.I919 10G 1.554 Oceanr>graphicDescription of the8ering Sea

2. HlS'TORICALBACKCROUNO ericanexpedition on the Albatross Table 2.1!. Sub- The BeringSea was discovered in 1642when Cos- sequently,other nations gradually became involved sackSeinen Dezhnev crossed the strait dividing Asia and the volumeof researchpeaked in the 1950sand from North America Dobrovolskiy 1959!. Almost 1960s,when various regions of the seawere being threecenturies passed from the timeof the discov- studiedby up to tenvessels at onetime. The research eryuntil theinitiation of systematic deepwater ob- included not only basic hydrological observations servations. temperature,salinity! but alsoa widerange of hy- An increasein geographicstudies for the pro- drochemicaland biologicalstudies. It was during ductionof navigationcharts began in the earlynine- this periodthat themajor concepts of the hydrolog- teenth century.During the first 60 yearsof the ical, hydrochernical,and meteorological regimes of n.ineteenthcentury descriptions of the BeringSea the BeringSea were forinulated.Table 2.2 and coastlinewere made by manyRussian expeditions. Figure2.1 have data on the quantitative and tem- Theyalso collected much hydrographic data, and poral-spatialdistributions of hydrologicaland hy- tooksome meteorological measurements and hydro- drochemicalobservations in the Bering Sea.This logicalinformation. material is basedon a seriesof fundamentalworks The first systematichydroineteorological re- on thehydrology of the BeringSea Dobrovolskiy searchin theBering Sea was undertaken by an Am- 1961a,1961b; Ivanenkov 1964; Arsenev 1967!. Lco!ogyof theBering Sea: A Reviewof RussianLiterature

Tahle 2.1, Researchexpeditions in the Bering Sea.

Months Working region Vessel name V~ation Year Southern Taskarara USA 1874 July, Aug. July, Aug. Vega Sweden 1879 1888 July 1890 May June July Aug Southern, Eastern Albatross USA 1693 July, AugSep, 1894 July, Aug. 1895 Junc, July, Aug. 1896 July, Aug. 1900 June 1906 Junc Northern Fedor Litke USSR 1929 June, July Southwestern Krasniy Vympel USSR 1929 July, AugSep. Northern USSR 1930 June, Julv. Aug., Sep, Western Dalnevostok USSR 1932 July, Aug., Sep. Southwestern Krasnoarmeets USSR 1932 July, Aug., Sep. Southwestern Paltus USSR 1932 May, June Northern Sovet USSR 1932 AugSep. Western, Northern Krasnoarrneets USSR 1933 July, Aug., Sep. Southern Janet UtSA 1933 June, Aug. June. Aug. Southern Catalyst USA 1933 Northern Krasni USSR 1934 Sep., Oct. Eastern, Northe rn Chelan USA 1934 July, Aug. Southern Southwestern Komakasi Japan 1934 July, Aug. Northern Krasni USSR 1935 July, Sep. Northern USSR 1935 Feb., July Southern, Southwestern Komakasi Japan 1935 July, Aug., Sep. Southern Itukusi ma Japan 1935 July Southern, Southwestern Komakasi .Japan 1936 July, Aug. Southwestern USSR 1937 July, Aug. Eastern Northr astern northland USA 1937 June, July, Aug.. Sep. Eastern, Northeastern USA 1938 Aug., Sep. Western Vilyay USSR 1939 July, Aug. Japan 1939 Aug., Sep. Southern Nort.hem Smolni USSR 1941 June 1941 July Sout,hero Southw e stern Dalnevostok USSR 1942 May Northern Temp USSR 1942 June, July, Ort. Nort,hem Smolni 1rSSR 1942 June,,luly. Aug., Sep. C-2 USSR 1942 Aug. Western Northern Ost USSR 1943 June, July, Aug., Sep., Oct.. Vorthern Snmlni USSR 1943 June, July, Aug., Oct. USSR 1944 July, Sep., Oct,. Northern Northern Tetnp USSR 1945 Aug., Sep., July, Oct. USSR 1946 Aug., Sep., Oct, Northern USSR l947 July. Aug., Sep. Northern USSR 1948 June, July, Ort. Northern OceanographicDescription of theBering Sea 10

Table2.1. continuetl!Research ezpetbtiorss in the Bering Sea.

Months Working region Vessel name Nation Year June Southwestern Vi lyiiy USSR 1948 Northern USSR 1948 Jan. June July Northern Temp USSR 1949 Northern Sidaruud 1949 Western Vityaz th cruise! USSR 1950 Ailg., Sep, Southwestern Toporok USSR 1950 Aug., Sep., Oct. May June July Aug , Sep. Southwestern Ostyak USSR 1950 Western Vityaz 8th cruise! USSR 1951 Sep., Oct. Western DK-106 USSR 1951 June, July, Aug. Northern Aysberg USSR 1951 July, Aug. Northern Bertan Is and USA 1951 Feb. Western Vityaz 0th cruise! USSR 1952 May June July Western Vityaz 3th cruise! USSR 1952 Dec. Northwestern Western Izumrud USSR 1952 July, Aug., Sep. June, July, Oct, Northern Terllp USSR 1952 June, Hep., Oct. Western Arnetist USSR 1952 Western, Southwestern Vi.tyaz3th cruise! USSR 1953 Jan. Southwestern Vityaz 4th cruise I USSR 1953 June Southwestern Vi tyaz .16t h cruise! USSR 1953 Oct Nov Dec Northern, Northwestern Lomonosov and Donets USSR 1953 June, July, Aug., Oct. June Southwestern Anreti st USSR 1953 Sep. Western Lotos USSR 1953 Oct. Western Akudem,ik Knipooich USSR 1953 May, July, Aug., Sep., Southwestern Os!ioro h5a ru Japan 1953 May, June July, Aug., Oct. Southern Lomonosoir USSR 1954 Northern Krytatka USSR 1954 AugSep. Aug., Sep., Oct. Southwestern Ameti st USSR 1954 Southwestern Akadcrnik Knipovick USSR 1954 May, June June Southeastern Oskoro iMaru Japan 1954 Southwestern Vityaz 0th cruise USSR 1955 May, June May June July Aug Central Southern sherpa USSR 1955 July, Oct,. Northern Lomonosoo USSR 1955 May-Dec. Southwestern Met st USSR 1955 Southwestern Akademi k Shuteykin USSR 1955 May Southern Tereza Canada 1955 Aug. Southwestern Oshoro %'arii Japan 1955 June, July FebMar. Northern 1Vorth Wind USA 1955 July, Aug., Sep.,Oct. Western, Central ¹rpa USSR 1956 July. Aug., Sep., Oct. Northwestern Lomonosov USSR 1956 Southwestern Akude mik Sh ataykt n USSR 1956 Aug., Sep. June, July Southwestern Okean USSR 1956 1956 June Southwestern Val USSR ,lu!y Southern Bard USA 1956 Aug, Southern Xcu: Ctassgo USA 1956 June, July Southern, Central Os!toro i~faro Japan 1956 Dec. Western Ametist USSR 1957 Jun.e, July Western SRT-V 347 USSR 1957 Eeo!ogyof theBering Sea; A Reviewot RussianLiterature

Table2,1. continuedJ Researchexpeditions in the BeringSea.

Working region Vessel name Nation Year Months Southern Brou.n Bear USA 1957 Aug. Southern Horizon USA 1957 Aug. Southern Ait tu USA 1957 June, July 1957 July, Aug. Southern Paragon USA Saut,bern Pioneer USA 1957 June, July, Aug. Southern Oshoro tiara Japan 1957 June, July Southeastern Vi tyuz i 29th cruise! USSR 1958 Oct. Southern, Southeastern Zhemchug USSR 1958 July, Aug., Sep. Westera Abakan USSR 1958 July Western SRT-I 037 USSR 1958 Aug. Sep Oct. Southern Attu USA 1958 June, July, Aug. Southern Pioneer I.ISA 1958 June, July, Aug. Southern Vaitrot Canada 1958 July, Aug. Central Oshoro Maru Japaa 1958 June Southern Snyo ltrfaru Japan 1958 Aug., Sep. Southwestern Hokasey Maru Japan 1958 May, June Eastern, Western, Centra! Pervenets USSR 1959 July, Aug., Sep. Southeastern, Central Alaseya USSR 1959 Mar., Apr. Sout.hem Oshoro Maru Japan 1959 June, July Northern Brown Bear USA 1959 Aug., Sep. Northern Brotvn Bear USA 1960 luly, Aug. Northern ¹rth Wind USA 1962 Oct., Sep. Northern North Wind USA 1963 Aug. Northern Forth Wind USA 1964 Aug. Northern IVorth Wl'nd 1 JSA 1967 July Northern Thompson USA 1967 J lily Northern North Wi nd USA 1968 Feb. Northern Staten Island USA 1968 July Northern Staten Island USA 1969 Mar., Apr. Northern tVIorth Wind USA 1969 Apr. Northern North Wind USA 1970 Aug. N orth em Olaci er USA 1970 Sep., Oct. Northern Oshoro Maru Japan 1970 July, Aug. Northern Thompson USA 1973 Sep.. Oct. Akademik Shokal'skiy IJSSR 1984 Northern Akademik Shokal'skiy USSR 1985 Northern Akademik Shokal'ski y USSR 1986 Northern Akademi k Shak al'ski y USSR 1987 lKditcr'cootc:t974-I9sa teata pzodttcttve perioditi Russian cceaiivltraphic stvdictMany etpcditioos toohplace iii the Benos Bcccciit thctigh theytire tict listedhare ] OceanographicDescription of theBering Sea

TableML Distributionof hydrological observatioas in the Bering Sea Arseaev1967!.

Avg. density No. one-degreecells with Number oi' stations No. onein cells observation a t dc p th m ! 500 1,000 2,000 > 3,000 Month Temperature Salinity degreecells temp./sah 14 January 79 79 2/2 February 2 6 92/1 45 42/2 19 March 68 66 April 5 5 1/1 3/1 35 25 4 Slay 215 97 70 165 115 31 June 818 711 303 3/2 167 140 31 4 July 1,342 1,068 329 4/3 4/3 135 121 32 16 August 1,234 873 313 63 21 6 September 771 641 211 4/3 83 82 65 10 October 407 364 147 3/2 141 45 33 1 November 110 105 54 2/2 15 4 December 104 82 56 2/2 Er;ologyot th -'Bar>ng Sos: 8 Reviewof RussianLiterature

Figure2. I. Distributionofhvdrologi col observations in the Bering Sea, Digits denote the number of hydrologicalstotalons in eachsquare; block triangles denotesquares u ith 20 and moreobsarr.otions. OceanographicDescription of the br ring Sea 14 Thecyclonic circulation over the Bering Sea is 3. CI.IMAT1CFEATURES: producednotonly by low pressure cells right over METMROI OPTICALREGIME thesea itself, but also by low pressure cells displaced to the northand south. Low pressure areas can pre- Factorsaffecting the Bering Sea climate dominatefor months at a timeover the Bering Sea Figure 3.1!. TheBering Sea climate is determinedprimarily by Onaverage, about six to nine low pressure cells atmosphericcirculation and currents. The warm passover the Bering Sea in a month, However, their Alaskacoastal current causes the climate in the numberscan vary from 3-4 to 11-14 per month Bur- easternpart of thesea to be inuch more mild than rninstrova1956!. The maximum frequency of lows in thewest, where a relativelycold current runs is infall andspring. The highest intensities are in along the coast. winter,when the frequency oflows with minirnuni Therelatively free exchange of waterbetween thePacific Ocean and BeringSea along with the pressurereadings 960 rnb or lower! is maximum restrictedflow betweenthe BeringSea and Arctic TableFigure 3,1!. 3,2 illustrates eight typical trajectories Basincauses different dimate conditions in the forlow pressure systems influencing Bering Sea northcompared with the south.

Figure3.7. tfean morsthty pressure fieldzuoer thesen from mulliyeer data. Eeoiogyof thcBeri ng Sea: rl Reviewof RussianLiterature

Table 3.1. Number of low pressure cells passing weather. In about 7G% of the cases, lows over the over the Bering Sea Karpova 1963!. Bering Sea are producedby cycloniccirculation of marine origin. The rnaximurn frequencyof marine Pressure lows is observedduring winter, and continental lows in mb Jan. Feb. Mar. Apr. May June are more common in spring and fall, The most corn- mon trajectory among the marine lows is trajectory 960 1.15 0.58 0.43 0. 14 IV; trajectory II is most commonamong the conti- 3.89 3 31 3.46 4.18 2 88 1.01 961-980 nental lows. Trajectory I is least frequent, occurring 981-990 1.73 1.73 3.03 1 73 2,16 1.15 only during summer, 991-1,000 1.30 1.44 1.44 1.87 2.02 2.16 ! 1,000 1.01 0. 70 1.01 1. 01 1.30 1.87 Total 9.08 7.78 9 37 8.93 8.36 6.20 Meteorologicalcharacteristics during winter

Winds Pressure Total For Northern winds dominate in the western and north- in mb July Aug, Sep. Oct. Vov. Dec. yr easternregions of the sea;their frequencymay reach 81-90'1c Table 3.2!. Northern winds predominate in 960 058 1.01 101 490 the southwestern region of the sea, but their fre- 961-980 0.14 0.86 3.17 2.59 3.17 4.03 32.7 quencyis somewhatlower, from 26%%ucin the westto 981-990 1.01 3.02 1.44 1.15 2.31 2.16 21.61 73% in the east. Northeastern winds predominate 991-1,000 3.31 2.31 1.87 3.17 2 02 1 87 27.78 over the openregion of the sea7-69%! andsouth- ! 1,000 3.60 2.45 0.86 0.86 1.01 0.29 15.99 eastern and northwestern winds predominate in the Total 8.07 7,64 7.35 8.36 9.51 9.27 100.00 Aleutian Islands. %'ind speedsin the opensea and over the central Aleutian Islands are 15-2G misec, and in the coastalregions they do not exceed1G mfsec. Calm periods occur from 0 to 28'7r,of the time.

Air temperature Averageannual air temperaturedecreases over the ocean from 2' to 4'C in the south to 8'C in the north Figure 3,3a!. Average monthly temperature in thc north can range froth -14= to -22.C Figure 3.3b!; minimum temperatureis 49'C. The severe climate results from strong northerly winds carry- ing coldair southward Karpova 1963!.

Precipitation Figure 3.2. Typiccd trajectories of cyclonesaffec ing the The averagemonthly precipitation on the northeast- u cather oner the Bering Sea. ern coast does not exceed 30 mm, and on the western coast it does not exceed 55 mm. The maxirnucn average monthly precipitation is observedin the Aleutian Islands: 145-2GOmm Figure 3,4!.

Meteorologicalcharacteristics during stjmmer

Winds Southernwinds predominateover the entire Bering Seaduring summer,but wind directionduring summer over the southeastern region is not always constant. Averagewind speedsdo not exceed5-7 m/sec. The frequencyof calmperiods is 1G-24'rcfor most coastal regions, but for someregions it can reach 16 OceanographicOescrfption of the BeringScs

Table $4. Fretlneney of wind speeds %! by dirae. tion for regions of the Bering Sea.

Speetl Direction Season m/sec! N NE E SE S SW W NW

Northern Bering Sea Spring < 6 7 7 4 3 6 4 2 2 5-12 18 12 3 3 3 4 1 1 12-16 6 3 2 1 1 1 > 16 2 1 Summer < 6 5 7 7 7 7 9 6 5 6- 12 4 4 4 4 8 9 4 3 12-16 1 1 1 > 16 Fall <6 6 4 4 2 4 4 5 5 6-12 12 8 5 3 3 4 4 7 12-16 4 3 2 1 1 1 3 > 16 1 1 Southwest Bering Sea Winter < 8 4 5 3 4 2 1 1 3 6-12 8 9 7 o 3 2 3 5 12-16 3 5 4 2 2 1 1 2 > 16 2 4 4 ! 3 <6 7 6 5 4 4 3 3 6 6-12 7 7 7 4 3 2 3 7 12-16 2 2 2 1 1 1 2 > 16 1 1 2 1 2 Summer < 6 4 7 7 10 10 7 5 6-12 3 4 4 5 5 7 4 3 12-16 1 1 1 1 > 16 Fall < 6 6 6 5 3 3 4 6 5 6-12 8 7 5 3 3 3 5 6 12-16 2 2 2 1 1 1 1 2 > 16 2 1 1 1 1 Central Bering Sea Winter < 6 3 2 2 2 2 6-12 jo 6 3 3 3 3 12-16 5 3 2 1 2 > 16 2 2 1 1 1 1 1064323 3 5 3 2 4 3 Spring < 6 6-12 7 5 5 6 9 5 12-16 3 2 2 2 3 3 > 16 2 1 ! Summer < 6 4 5 6 8 6 5 6-12 24852316 6 6 10 9 5 7382 12-16 1 2 1 1 1 >16 Figure 3.X A. Afean annual air temperatures; 8. 3 3 3 3 3 4 < 6 mean monthly oir temperatures in 6-1 2 3 6 6 8 January; C. mean monthly ai r terr pera- 12-16 2 2 1 2 2 3 tures in August. >18 1 1 1 2 1 Ecotogyof the Berm@Seat A Revtewof Russianliterature

40 33-42 k Cross Sound, Dutch Harbor!. The frequency of calm periodsin the opensea does not exceed6%.

Air temperature The highest temperatures in the northern region 25 are observedduring July -11'C!, and during Au- gust,in the southernregions 0-12'C!, Highestval- 20 ues in the central regions can reach 20-31=t., minimum values are around 7' Figure 3,3cx 15

10 Precipitation Precipitation increasesduring summer over the entire BeringSea, with the except,ionof the Aleu- tian Islands, where it is minimal during summer Ol00 Ol DO IS IS Dl IN 00 IO II IO DlIS 00DI IS IS OI DS 00 ID II 'l0 0-100 mm/month!. Average monthly precipitation Cape Nome Adak Island in the north ranges from 25 to 65 mm; in certain coastal areas it can increase to 80-90 mm/month

35 Nome! Figure 3.4!.

OlOD Dl OO I ~ 00 Dl IS IS 10II ID OlNl 00 Dl 00 OO IN 00 S IOI'I IO St. Paul Cape Weller

Snow

Figure 3.4. l0tean annual distribution of precipitation. OceanographicDescription of the Berittg .Sea

%able4.1. Waveheigbt frequency <%! and period for 4. WAYEs tbe Bering Sea. TheBering is oneof the stormiest seas adjacent to Wave Wave height I mt Russia.High waves result from intensestorm ac- 2-4 4-6 6-8 > B tivitydue to the high frequency oflow pressure sys- Season period sec! tetns,the large ates encompassed bythe sea, and Winter <5 10 31 6 2 thegreat depths. High waves are especially com- 5-7 B 4 2 monin thesouthern and central regions. Ice in the 2 3 1 northernregions has a strongmoderating effect on 7-9 9-11 5 1 waves,as well as the smaller regions of open area 1 1 and the broad shallowshelf. 11-13 Wavesare observedonly in the southernand 13-15 centralregions of the sea during December through > 15 May,since the entire northern region isice covered. Spring <5 27 21 2 Winter is the stormiest period. The highestwaves develop in the opensea, 14 7-9 6 2 1 ~herethe frequency ofwaves in excessof 6 mis 8% 2 1 duringwinter an.d falls to 1.5%during summer 9-11 Table4.1!. The frequencyof waves over 6 mhigh 11-13 1 1 furthernorth is 3-4%in the fall andwinter and 1.5% 13-15 duringsummer. The strongest wave activity is dur- > 15 ingfall. Waves can reach heights of 16m during 26 2 1 unusuallystrong storm surges about once in 30 Surnraer <5 3B years.Waves predominantly travelfrom a norther- 5-7 7-9 ly direction. Thesea is relativelycalm during summer; the 9-11 frequencyof 1-2m highwaves is 40-60%.Waves 11-13 travel predominantlyfrom a southernor eastern 13-15 direction. >15 Swellsin the BeringSea are most cominon in fall andspring. Swells can also develop from local Fall <5 27 7 2 stormsin theBering Sea. SweMa of S tnheight can 5-7 12 4 2 occurat i'requenciesof 4-5% Polyakova 1976!. 7-9 6 2 1 Swellsfrom the Pacific Ocean are broken up by t;he 9-11 1 1 Aleutianarchipelago, Wind waves and swells break 11-13 in theshallow regions of theAlaska coast, forming 13-15 bandsof intense breakersand surf. > 15 Ecologyof the'Beritig Sea: A kev>ewot' kussian literature !9

5. WATER CIRCULATION Thefirst mapsof surfacecirculation for theBering Seawere produced at the endof the nineteenthand earlytwentieth century Dali 1881, Makarov 1894, Shmidt1904!. They were based primarily on the way the current carried ships,The first diagram of currents basedon the compilationof a broadset of hydro-rnetcorologicalobservations was producedby Schulz 911!. Accordingto his diagram, the surface currents were determined primarily by winds. In 1937 Ratmanov 937a! produced a current map Figure5.1! which was considered most com- pleteduring the two subsequentdecades. Accord- ing to Ratmanov,one of the major forcesdriving currents in the Bering Seais the flow of water into the seathrough the AleutianIsland passes. Most important to this systemwas the strong flow throughNear Strait, forminga strongcurrent in a northeastern direction. This current produces two Figure5.1. Scheme of iurrents in the Bering Sea largegyres in the deepregions of the sea;one with Ratmonoi t987aJ. its center at about 57 N, 175 F,,and with a counter- clockwisecirculation; the secondcentered at about 55'N,176 W, and with a clockwisedirection of flow. The author consideredthe speedsto be aboutthat of the Kuroshio.Observations from the shallowopen regions were completelylacking, so the area re- mainedpractically unknown. A more detailed inap of surface currents was producedby Leonov 960! Figure5,2! and Dobro- volskiyand Arsenev 959! Figure 5,3!.However, a morecomplete investigation of currentswas done by Arsenev967!. Theauthor produced computation of both geostrophicand drift currents for the entire sea.The coinputations were basedon numerous observationsof temperature and aalimty and also on measurements of current speed and direction.

Geostrophiccurrents Figure 5.2. Scheme of currentsin the Bering Sea

Figure5,3. Scheme ofcurrents ntthe Bering Sea DobroUoteteiy andArseneo 19591 surfacelayers, the monthly maps of dynamic topog- Surface Aowbetween the Kamchatka Peninsu- raphywere constructed notfor the very surface but la andBering Island carries water primarily from forthe 10 db layer Figure5.5, 5.6!. theBering Sea into the Pacific. Although a counter- Themaps constructed for thewarm half of the currentis presentin theeastern part of Kamchat- yearwere quite similar. This is very important, since ka Strait, it is weaklydeveloped. the similarityin themays constructed using inde- Waterentering the BeringSea through the Al eu- pendentdata confirm the accuracy of thecomputa- tian archipelagoruns eastward along the islandarc tions.The maps of geostrophiccurrents for winter in the Beringcurrent system and a portionof it re- and summerare show'nin Figure5.7. enters the Pacific. Accordingto thesemaps, a constant,almost Thelargest transverse current system in terms uninterruptedcurrent flows westward along the of area occursto the north of 54-55'N, The trans- southernside of the Aleutian-Commander archipel- versecurrent bends near the lower edge of the con- agoto NearStrait. Water carried by theAlaskan tinental margin.This currentdivides the BeringSea Streainenters the Bering Sea primarily through the into twomajor sections with respectto water flow: eastern half of Near Strait, thedeep southwestern region with a well developed Evenbefore reaching Near Strait, the Alaskan cycloniccirculation and a shallownortheastern re- Streamproduces branch flows into the Bering Sea, giondominated byelements ofanticyclonic circula- Thelargest branches forin persistent anticyclonic tion. circulationaround the largest island groups. There- Analysisof the surfacegeostrophic current map fore,counter-currents are formedto the eastand andcomparison with independent ca.lculations t Na- westof the Andreanofisland group in broad arear, tarov 1963!indicate that winter circulation doesnot includingthe largest straits in theeastern Aleutians, substantiallydiffer frorusummer circulation, This Amchitkaand Amukhtu, and also in NearStrait the doesnot, however,pertain to current speeds,which sinai!islands do not influence the major circulation are about 1.2-1,7 times greater in all areas during winter than summer Tables 5.1, 5.2!. patterns t Ecnlogyot theBering Sea: 8 Revieweroi Russian Literatttre

Figure5.4. Grtd ofsquares foraeeraging thenbseruatiarr data. Labels tcithin squares, resreferred tvin thispaper, are a 6 c d 22 OceanographicDescription of lheBering Sea

Figure5.5. Dynamic relief vf 10 db surfacerelative to Figure5.6. Dynamic relief of 10db surfacerelative to 1,000 db Arsenev 19671. 1 000 db Arsenev 1967! cacologyof the f!eri

I t more noticeable Figure 5. 10!. However, even at 500 p i i i r m thespeeds are fairly high. Theyare 2-3 cm/secin ar I the centralregions, but reach10-15 cm/sec at the ~l edgesof the cyclonicgyres. Speeds are about4-7 I J / cm/sec near the transverse current at the eastern edge of the gyre, At greater dept.hsthe differencesbetween the spe.edsin the centraland peripheral regions slowly 1 I f diminish, and almost disappear at 1,000 m depth. / I I I I Averagespeeds at 1,000 m depth are 1-4 cm/sec. I 'I 'I Speedsat 2,000m depthdo not exceed1 cm/sec,

Drift currents The observations of currents in the Bering Sea indicate the Eckman theory can be applied to the computationof wind-drivencurrents Arsenev1967!. Wind-driven current speedsare computedby the equation:

where: W = wind speed next to the ground A = constant empirical coefficient tp = latitude

Numerous measurements indicate that A is 0.0127 Shuleykin 1953!.The angleof deflectionof the wind-driven current from the wind direction i s about 45=. Accordingto the map Figure 5.11!, drift cur- Figure5.7. Geostrophiccurrents at the surface.Above: rents in the Bering Sea are inainly to the west,or Summer, Beiouit uii uter. Current rpeed tr m/ northwest during most of the year. Northwestern seve I is less than 1, 2 is from I to 5; 3 is from drift currents are established in November and con- 5 to 10; 4 is from IO to 20; 5 is from 20 to 85; 6 tinue until March-April. Current speedsare maxi- is from 35 to oO;7 ts more than 50 /Arsenev inum during the aboveinterval, reaching10 cm'sec, i967!. The velocity fields during winter are fairly constant. Subst.antial differences occur only in currents in the verysouthern regions of the sea,where speeds are very small. Oeepwater circulation The transition to summer is characterized by a A seriesof dynamicmaps at various depthsbased changein the directionof wind-drivencurrents. Due on monthly and averageddata were constructedto to a disturbancein the persistenceof the wind fields elucidatedeep circulation Figure 5.8-5.10!.Com- characteristic of this time of year, one would expect. parisonof thesemaps with bathymetricmaps indi- that current direction would be variable. Speerls catethe strong influence of bottom topographyon during June-September over nearly the entire deepcirculation. The isolines of dynamicheight over BeringSea do not exceed 2-3 cm/sec Arsenev 1967 !. the entire basin correspond well with large scale They noticeablyincrease only in October.when the bathymetricfeatures, resulting in the formationof wind fields are reestablished over the sea. closedgyres over the central and western basins. Thecurrent speedsfrom the surfaceto the deeplay- Resultant currents ers diminish gradually without distinct discontinu- ities. Speedsat 100-200m are similar to surface The resultant currents Figure 5,12! are computed speeds.At greater depths the differencesbecome as the vector sums of the gradient tin geostrophic OCeanOgraphiCf!CSCriptivn Ofthe Her!nit Sea 24

Table 5.1. Averagegeostrophic and resultant cur- Table 5.2. Averagegeostrophic and resultant currents at the surface of deep regions of rents at the surface of shallow regions the Bering Sen Arsenev 1967!. of the Bering Sea Arsenev 1967!.

Resultant current, Geostr'ophic Resultant current Geostrophic currertt ~ct d Measured t t ~Cm t.d Measured A' V ctn/sec! Menth A' V lean/sec! A' V em/sec! A' V cnLJsec! Month A' V cm/sec! A' V crn/sec!

23 5 19 6 Kamchatka current 85 6 76 6 10 Augu st. 214 30 211 29 10 5 8 6 220 50 226 57 232 62 May 258 2 282 2 August 267 16 202 15 210 15 August 330 2 359 2 221 15 235 329 297 10 302 109 2 98 3 70 1 63 2 285 10 285 20 240 4 206 2 254 16 253 17 276 19 July 89 5 76 7 240 6 251 6 40 6 57 8 48 JLLne 232 7 267 14 Transverse current 350 5 5 5 300 6 293 146 333 6 344 326 August 315 7 309 143 327 3 350 333 8 318 154 315 4 335 305 7 304 145 305 5 320 330 9 3!L8 16 Current at. the center of the main cycloniCcirculstLon feature 340 2 16 2 302 3 300 10 294 3 319 2 354 2 299 8 316 3 345 3 344 4 309 9 8 2 35 3 45 3 322 7 100 4 94 6 122 October 188 14 191 13 32 6 41 7

Figure6.8. Dynamic relief of different surfaces,Above: 300dbrelatiue to 1,000, December. Below: 300 db relnttue to 1,000, June Arseneu 1967r. &cokrgy of theBering Sea; A Reviewof Rttssiari1 te i rat ure

Figure5.9, Dynamtc relief vf differentsurfares, Above: 500 db relative to 8,000,from meunannual characteristics. Belotvt 500 db relative to Figure5.10. Dynamic relief of differentsurfbces, friiin mean nnnual characteristics. Above: 1,000 1,000, December Arsenev 1987!. db reluti ce to 3,000, Below@:2.000 db relu- tive to 8,000. Purely drift currents i.%reevedi. 1961!

approximation,Figure 5,7! and drift Figure5.11! currents are to the northwest only in the regionof cotnponents.Comparison of the resultantcurrents the Transverse :urrent. The average speed. of the for July Figure5,12! and the suinmermap of geo- resultant current, are about twice t,hat of the geostrophiccurrents at the surface Figure 5,7a! dern- strophiccurrent Table5.1!. The resultant currents onstrates that the incorporation of the drift computedfor the deepregions of the seaare con- componentdoes not producesubstantial changes in firmed by actual observations Figure 5.1!. the surfacecurrent pattern, The resultant currents 'omputedspeeds were lower than measured aresimilar in directionand speedto the geostrophic speedsin theshallow regions in themajority of cases currents.Incorporation of the wind-drivencurrents wherecomputed directions most closely correspond- for winter result in substantial alterations in the edto measureddirections Tab]e5.2!. A similarcon- generalwater circulation at thesurface. The result- clusion can be made from examining the map of ant currents are to the northwest in most of the icc- surfacecurrents in the northern Bering Seai Fig- free regions of the sea, while the geostrophic ure 5.13! Tiguntsev 1976!. OceanographicDescription ot the HcrirtgSea

Figure 5.1! Purely drif'f eurreiits Arsenev 1967!. Foologyot the BeringSea: A Reviewof Russianf fterafure 77

I f g

f/it f f q//r~w ~~ I I f f f -/ t f /

r/ t! f t / f ~i/t f f f r rCC M / f f K K ~ / X r f I I f h~/v' f >4 r 4 t C f f t CC / I/- 92 If I jC1 r t C~i / r r // // t lf f I lk tf f r q~ f / / t ~~q q' f, ~/ / //~~~~~/ / %a- r~ > f~ ~r v'/ -f f 3 fr g l 'I /

I // NIfew ~

Figure5.12. Resulting currents ot the surface.Above: Summer; Below: uinter. Current speed cm /sec>: 1is lessthan 1;2 fs from 1 to5; 8 isfrom 5 to 10,'4 is from 10 tn 20; 5 is from 20 to 85; 6 isfrom 85 to 50; 7 is more than 50. 28 OceanographicDescriptiort oi theBering See

Figure 5.13. Currents of the northern Bering Sea from instrumental observations 'Bguntsev 1976'J. !9 Ect>logyot theHaring Sea: A Reviewof RussianLiterature

westernregions of the strait,and it canbe traced to 6. CIRCULATIONAND WATER the southernshores of the Chukchi Peninsula,es- EXCHANGEIN THESTRAITS peciallyduring lail. The important feature of the Pacific Current is BeringStrait the seasonalchanges in its intensity: transport in TheBering Sea is uniquein that it connectsthe August-Septeinberis 3-4 times greater than in Feb- Pacificand Arctic oceans.Therefore, water exchange ruary-March. at its boundariesare important not only for under- Difl'erentopinions have been expressed concern- standingconditions in theBering Sea itself, but also ingthe nature of the PacificOcean Current. Accord- for understandingconditions in the entireArctic ing to Zubov945k the current"is neithercoiivec- Basin. Data indicate that, Pacific Ocean water can tive nor drift. lt is a compensatorycurrent caused betraced in the Arctic Oceanclear to the Canadian by flow from the Arctic Basininto the Greenland Archipelago Belyakov and Rusanov 1970!. The flow Sea."However, hc did not address the following con- of waterthrough the BeringStrait into the Arctic tradiction;speed of the EastGreenland Current iii- Oceansnakes up 22%of the input portionof the creasesfrom summerto winter,while the speedof water balance in the Arctic Basin Antonov 1958!. the current in the Bering Strait increasesfrom win- Manyinstrument observations have been inade ter to summer. in the BeringStrait, sincetransport through the A similar view was held by Leonov947 i. Iie strait is central to understandingthe influenceof indicated that wind forcing was very important. Pacific water on the Arctic Ocean.The average an- However,Leonov was not ref'erringto localwinds nual transportthrough the BeringStrait as esti- but to atmosphericcirculation encompassing the matedby a numberof authorsis presentedin Table North Pacific and Arctic basins. 6.1,These estimates are similar to eachother, with Shtokman 957! raised the hypothesis that the exceptionof Sverdrup934!, The differences transportthrough the BeringStrait andchanges in canbe explainedby two factors:errors in instru- transportduring the yearwas caused by meridion- ment observations or long-term variations in trans- al differencesin water density betv cen the Arctic port through the Bering Strait. Elucidating the causeof' the diflerenceswill re- quirean understanding ofthe nature of flow through the strait. Data from the majority of transects in the BeringStrait indicatecurrent flow in a northerly direction,called Pacific Ocean or NorthernSea flow Ratmanov 1937, Leonov 1947!. Counter flow, m 19fI Si/9 19ttJ I&4 t9it9 called the Polar Current, is observedonly in the very 1@'

IH 0 E gg fkf7 I%9 I@9 19N Table 6.1. Average annual volume of water trans- ~~ 19D ported through the Bering Strait. c tgI Years of Transport 'K Author observation krn'lyr 10" km'Isec gg 19' ICQ t9$9 1994 t999 30,354 1.0 co LV. Maximov 1932-1939 CO199 V H. Kudryavtscv 1932-1950 36,000 1.1 H.U. Sverdrup 1934 9,881 0.3 19.$7 IN'9 88 I999 A.K. Leonov 1941 44,814 1.4 G.A. Ba. kakov 1941-1943 ;34,124 1,1 Z,P Fedoiova 1941-1961 29,997 1.0 and Z.S. Yankina 1991 ltt99 %J L.G. Toporkov 1958 22,300 0.7 J..K. Coachman 1967-1970 36,000 1.1 Figure6.1. Temporal i nriatinns af IIte snIt . unof/'ntIAe and K. Aagaard rouse

15441$4$ 1$4$ 1544 4 5451$4$ 154$154$1 $45 1$5$ 15511552 I QM 1$$4I $551 $551$$7 1555 'I QQQ I QQQ I $$I t $52 I 5gg 1$$4I $$$

Figure6.2. Temporal variations of salinityat thetransect Cape Peyek-Cape Prince of Walesfor 1941-J 965 Fedoro ra f968!.

Table6.2. Average monthly salinity ppt! on the transect from Cape Peyek to Cape Prince of Wales.

1 2 3 4 5 6 7 8 9 10 11 12 32. 20 32.07 1941 32.60 33.05 32.91 32.78 31.82 32.28 32. 20 32.06 31,68 81,52 81.18 30.29 1942 32.62 83.61 32.35 32,87 31.01 31.99 32.04 31.58 32.44 29.89 31 59 32.03 1943 34.14 34.45 34.52 84.50 30.19 80.89 32.38 82.82 32.02 32.01 31.37 33.05 1944 32.60 34.06 33,95 33. 38 82.75 30,95 32,33 33.30 31.81 30.77 30.91 32,05 1945 31.42 32.15 32.93 32.87 81.36 31.73 32, 10 32.57 31.68 31.98 29.86 30.39 1946 33. 85 33.03 32.35 34.47 33.76 31. 15 32.44 31.23 31,28 32.12 1947 27.62 32. 12 32,86 31,99 32.91 32,13 31.97 31.52 31.58 30.38 30.56 29.02 25,24 26.24 1948 26.66 32.26 29.38 31.68 33.04 32.48 32.45 31.75 30.60 28.87 80.48 27.62 1949 31.82 31.47 27.67 30.64 28.95 31.92 32.29 32. 17 30.82 31.48 1950 29.43 31.63 32. 13 32 08 81.12 31,0:1 32.62 32.41 31,84 31.52 31.17 27 3 32.22 31.91 1951 31,58 33.23 33.02 32.98 32.52 32. 20 32, 17 32.30 80.31 32.22 31. 18 30.92 1952 31.58 81.55 30.92 30. 51 30.09 32.58 32.66 32. 29 82.50 31.73 31.14 30.38 1953 32.16 81.74 31.05 31.48 81.26 32.50 32,66 32.08 32. 17 31.S6 29.42 30.44 1954 32. 75 33. 36 33,70 32,87 31,12 32.47 32.60 32. 15 31.S8 32.00 29.24 32.23 1955 81.87 33.17 32.98 33.7G 32 65 30,46 32.10 32.09 80.57 27.83 30.04 33.25 1956 31.70 31.92 34,02 33.02 32.20 81.37 32.44 31.66 31.41 31. 84 1957 32.12 31.18 32 30 32.87 32.32 32.05 32.26 32.22 29.92 27.20 30.67 31.32 80.78 32.82 1958 32.34 33.29 33.47 33.36 81.66 82.50 32,05 32.49 32.55 30.53 32.57 32.27 1959 32.62 33 16 33.31 38,26 31.46 32.50 82.03 32.44 32.59 32.67 81.87 32.30 1960 33.38 33.12 33,05 83.56 82.02 32,08 32.13 32 39 32.59 32.57 1961 32.47 31.28 33.65 38.34 28.45 32.41 32.08 82 32 31,47 32.35 31.22 31.67 1962 32.34 32.8S 32.55 32.58 32.70 32.18 32.48 32.06 31. 13 30,46 30,01 29 09 81.20 31.73 1968 30.83 32.93 31.80 30.42 81. 72 31.53 32,35 82.05 82.12 31.16 1964 31.99 32.43 33.23 31,97 32.06 32.23 32.23 32.20 32.15 30.90 29.77 31.45 32.34 32.34 1965 82. 34 82. 74 33.39 83.51 31.67 31.70 32.29 32.27 31.96 31.43 1966 31.80 32.63 32.59 32.67 3i.61 81.85 32.29 32. 12 31,64 31.49 80,73 80.85 Ecologyof tlirt'Bering Sea: A Reviewof RussianLiterature

Doys Table6.3. The coefficient of correlation expressing the inf1uenceof atmosphericcirculation on water circulatiori data from a run- ning five-year average!,

Flow of Pacific Ocean water Atmosphericprocess intothe Arctic Basin O O Eastern forin Simultaneous -0.53+ 0 13 Lagged by one year -0.70+ 0.10 Lagged by tv o years 0,79+ 0.07 Lagged by three years 0.84+ 0.05

Western form Simultaneous 0.27 Lagged by one year 0.04 Lagged by two years 0.35 Lagged by three years 0. 44

Meridional form Simultaneous 0.69 0. 12 Lagged by one year 0.67: 0.11 Lagged by two years 0.67+ 0.11 Lagged by three years 0.74 t 0.11

Basinand the North Pacific,differences driven hy climate,The abovedensity differences produce a meridionaldeclination in the surfacelevel from the southto thc northof about14 cm/1,000 km. Due to theCoriolis force, such a declinationin the deep open oceanproduces a geostrophic current with speeds of about1 ctn/sec,However, in the shallownarrow BeringStrait, the current produced by such a decli- nation v'ould be 40 cm/sec, Thepossible geostrophic origin of the Pacific OceanCurrent and the insignificantinfluence of localwinds were confirmed by the computationsof Arsenev Figurc 5.8-5.10!. Hov ever, one cannot dis- countthe influenceof large-scaleatmospheric circulation on the magnitude of water exchange throughthe Bering Strait, Figure 6.1 illustrates the magnitudeof salt transport through a transectbe- Figure6.3. Integral curoesofannual occurrence frequency tweenCape Prince of Viales and Cape Peyek; Table of theforms Z, MI, M2,and tooter salinity in 6.2and Figure 6.2 show the average annual salini- theBering Strait at thetransect Cape PeyeA- ty onthis transectfor a 25year period Ycdorova CapePrince of Wales!. Sum of occurrencefre- 1968!.It is apparentthat in additionto seasonal quertcvanomal esisdays. Sa! tnity anomalies changes,there are multiyear changes. is ppt Girs 1973/. Researchon the effects of large-scale atmospheric circulationon variability in the salinity in the BeringStrait, region were done by Girs 973 t Study of themultiyear changes in recurrenceofmacropro- cesses W, C, E, Z,%41, M2 i indicatethat theannual recurrenceof these processes substantially changes OceanographicOescfiption fit the Bc'ringSea

Table lL4. Statistical characteristics of the qualita- tive model.

Experiment number g Ql 6 R

3. 5 11.7 14.8 0. 8 5H 0.49 -3 4 11.7 14.8 0.585 0.49 -0.4 9.5 12.0 0.869 0.45

Averagecomputational error. I s I Averageabsolute computational error fi Ivl eonsquare error. R Coefficient ofcorrelation bet vices the factor and the computes value. Expressesthe quality of thecomnputatoo. lf r = I the compoie- tion is good,if s =0 it is bad. Figure 6.4. Leoel oscillatiorts in di fferent ports of the Chukchi Sea; 2 is from obseroatioo data near the shore; 2is from modeling data; 3is from observation data in open sea Proshtrti risky and Frnlori 1988!. in modifying the ability of M2 processes to affect decreasesin salinity. Increases in the salinity curve during 1945-1946were causedby increases in M2. with time, The anomalous periods or epochsin syn- Therei'ore,salinity in the transectbetween Cape optic processesresult from a prolongedtendency of Peyekand CapePrince of Wales,the magnitude of exclusively positive or negative variations in a se- which serves as an indicator of water exchange ries of atmosphericand hydrosphericcharacteris- through the Bering Strait, has clearly expressed tics in the Northern Hemisphere. The influence of long-period variations, caused by changes in atmo- circulation epochs on hydrological features of the sphericcirculation. This conclusionis confirmed by Bering Sea were characterizedby data on Bering data producedlater Shpaikher et al, 1972! compar- Sea salinity as reflected in the transect between ing the types of circulation and the flow of Pacific Cape Peyekand Cape Princeof Wales from 1941 to Ocean water into the Arctic Basin Table 6.3!. 1965 Fedorova 196S!, The work of Proshutinsky and Frolov was of The deviation from the norm in saliruty is illus- great importance to the study of circulation in the trated in Figure 6.3, which also includes integral Bering Strait. They produced a series of model cal- curves of the recurrence of macroprocessesZ, Ml. culations of water circulation in the Bering Strait and M2. The followingconclusions can be derived and the Chukchi Sea. The model was calibrated by from these graphs: salinity in the Bering Strait un- special measurements of sea surface height at sev- dergoessubstantial variationswith time. Long-term eral coastal locations in the Chukchi Sea, Bering periods can be identified during which salinity is Strait, and in the open sea. A number of numerical systeniaticallyhigher or lowerthan the norm. These experiments were conducted to reproduce actual prolongedtendencies correspondin duration and variations in sea level and current and to elucidate time with tendencies in the developinent of atino- the reasons for irregularities in the flow fields. spheric circulation. Kxperinsertfl. Variations in sea level and cur- Decreases in the salinity curve and anomalous rents for the entire observation period were coin- development of M2 processeswere observedfrom puted, basedon wind data, horizontal distribution 1946 through 1953. Insignificant variations in sa- of the vertically averaged water densities, atmo- linity were observedfrom 1954through 1957.In- spheric pressure,and oscillationsin sea lcvclat the creasessin salinity were observedfrom 1958through boundaries of the study region. The result.s of the 1961, which correspondswith increases in the fre- computationsare shown in Figure6.4 and Table 6.4. quencyof Z. Comparisons of the computed currents in the Bering The salinity exceeded the norm in 1942 to 1946. Strait with actual measurements indicate that the. During 1942 through 1944 this occurredagainst a model succeededin simulating only the general backgroundof M2 andZ processes.This contradicts trend in flow with respect to time. Velocities were the conclusion that M2 facilitates decreases in sa- consistently underestimated. The presence of this linity.Apparently, Z processesplay a substantial role consistent error indicates that a tluasi-constant cur- Etology ot theBering Sea: A Reviewot RussiartLiterature

I Bering Strait Region ~ ~ t 5

Figure65. Above' Variations of meanby r.ertical meridional componentof the current speed' in hvBering Strait, and Below: transformation of!he levelsurface tilting; 1 is fromobserva- tinto Figure6.6. Scheme ofintegral circulation of ihe Chuk«l» arrount leveltilting from the PacificOcean to Sea,governed or>ly by thefree surface til ing the Arctic Ocean; 3 i s calculation taking into from southto north 1.5 x 1 >"r 1 rsdirection arcount level tilting 8 x 10 '; 4 is calculated andspeed ofthe calculated current, cm,'se«; 2 seasurface profilealong 168'W;5is prescribed is levelisolines, crn!Proshutinsky ar>dFrolrir seasurface tilti r>galong 168 W Proshutinsky 1988>. and Frolou 1988j. OceanographicDescription of the BeringSea

a 12tvlll so/vN ao/vel loitx l$71s

Figure6.7. Average daily flow through Anadyr Strait l!!QbShpanberg Strait ! Q!, and.Bering Strait ! Q,!. Dtfferencesin flotv i ntoand out of the Chirihov basin ! Q,! throughthese straits. Flour is 10'm'lsec; directionis northwardfor positivevalues, southward for negativevalues, Tiguntsev 1976.! rentruns through the Bering Strait, it is northward, ticular the elevatedcurrent speedsin the eastern andit cannot be accountedfor by only regionalwind half of the strait, were not simulatedd.ue to the low fieM, resolution of the inodel. Experiment2. Thisis a replicationof Experi- The simulationexperiments demonstrated that ment 1, with the inodificationthat water densities inclinations of sea surface from the Pacific to the were assumed to be constant for the entire basin ArcticOcean explain the quasi-steadynorthward duringthe simulation,It turnedout thathorizon- transport of waterin the BeringStrait, It remained tal baroclinicityhad almostno influenceon the sea onlyto elucidatethe influenceof localwinds over surface elevation and water circulation. the Bering and Chukchi Sea basins on water ex- Experiment8. Sincea constantcurrent speed changein the BeringStrait. Winds over the two in the BeringStrait was not obtainedin Experiment basinsproduce large short-period oscillations in flow 1,the hypothesisarose that this quasi-constantflow through the Bering Strait, as well as through the wascaused by an. inclination of the sea surface from straits near St, Lawrence Island Ratmanov 1937, the south to the north, from the Pacific to the Arctic Fedorovaand Yankina 1963, Toporkov 1970t Graphs Ocean.The goal of Experiment 3 wasto selecta sea of the average daily flow through the straits, com- surface inclinationsuch that a repetition of Kxperi- puted froin simultaneousobservations at several inent1 would producesimulated current speeds in points in eachstrait, are shownin Figure 6,7 Ti- the BeringStrait correspondingto actual observa- guntsev 1976!, tions. Simulated oscillations in sea surface height One would expect variations in water flow andcurrent speedswith a seasurface inclination of throughthe threestraits to correspond.Strong north 8 x 10-' are given in Table6.4 and Figures6.4 and winds over the Chukchi Sea markedly decrease 6.5, Coinparedwith Experiment1, the statistical northward flow throughthe Bering Strait and can measures of computational error are considerably even reverse its direction. Changes in flow are ob- lower.Computed current speeds in the BeringStrait servedin Shpanbergand Anadyr straits, However, approximatedobserved speeds. the changesthrough the straits do not exactly cor- Experiment4. Thisexperiment involved mod- respond.Comparison of transport through the e]ing the currentsformed only by inclinations in sea straits near St. Lawrence Island indicate that the level. Current maps wereproduced for both the variations in transport are causedby uneven wind BeringStrait and ChukchiSea. Figure 6.6 illus- fields over the northern Bering Sea. For cxainple, trates the current map produced by a sea surface on 2B-29 August 19?0, when water entered the inclination of 1.3 x 10~. The computed current Bering Strait priinarily through Shpanberg Strait., speedsand transport correspond with actual obser- winds over the Chukchi Peninsula were strongly vations,although details of the circulation, in par- northeasterly,but over Alaska they were easterly. ECO/OgyOfthC 8eri ng Sea: A Rcview Of RciSSIan Literature

V, cm/c V, cm/c -5 1 3 7 'I1 15 19 10 0

500

1500

2500 Figure6. 10. Distri bution ofeffecti re rodiation of sea.surface,kcal icm' a year Batalin 1954!.

Tab]e6.5. Transport of steaterthrough the straits in the Aleutian-Commander archipelago.

Transport Strait millions rn' sec I

Figure6.8. Vertical distribution of meanannual speed of 21.0 water transport from multiyear data fa! Kamchatka Strait to 3,000 m depth through KamchatkaStrait; ! through Vear Kamchatka Strait below 3,000 m depth 2.6 Strait Arsenev 1965!. i%ear Strait -14.4 Amchitka Strait 4.4 Huldir and Arnukta straits -0.7 Veeaurenumbers indicate transport from the Pacific el> ~ ttlS tlS AF ISA tSZi Slf IJlS tt

tiHD depth, m

Figure6.9. Isotachs at the transectthrough the Kam- chatka Strait, a! in summer of 1950, b! in u inter of 1952,calculation relative to 2,000 db Arsenev 19651. OceanographicVedic rip ionof thr 8eringSew

rentcan be tracedto depthsof 200-250m whenav- Aleutian-Commanderstraits eragingmultiyear data sets. However, individual TheBering Sea is connectedto the Pacificby n.u- datasets indicate that it canreach 400-500 m depth, merousstraits through the Aleutian-CommanderThespeeds of the major currents gradually decrease archipel ago. The straits are unique in thatthey are withdepth to a depthof 3,000 m, wherethe direc- quitedeep Figure 1,3, Table l,l!, Therefore,water tion changesback and forth at verylow velocities exchangebetween the BeringSea and Pacific oc- Figure 6.8!. cursnot onlyin thesurface layers, but alsoat great The aboveconclusions are confirmedby instrum- depth,Until nowthere has been insufficient reli- entt observations Natarov 1963!, Transport able instrument data on currentsin the largest of throughthe straitswas coinputed from the cross the straitsthrough the archipelagoto perinit an sectional area and the vertical current structure evaluationof the structureand character of water throughthe straits Figure6.9!. The resultsare exchangein thesestraits. However, the computa- shown in Table 6.5. tionsof geostrophiccurrents Arsenev 1967! are re- An analysisof the distributionof heaton the lis.ble,both in numberand. accuracy. According to surfaceof the Bering Sea Vasyukova 1964, Batalin thegeostrophic calculations, flow occurs through the 1964!indicates that themajor flow of PacificOcean largestfive of the straits: Kamchatka, Near, Buldir, waterinto theBering Sea occurs through the straits Amchitka,and Amutka. Flow is southwardinto the in the westernhalf of the Commander-Aleutianar- Pacificthrough Amutka Pass and northward into chipelago regions ofmaximum heat deficit! and the BeringSea through Amchitka and Buldir Pass- throughthe shallow straits to theeast Figure6.10!. es.Predominant surface currents flow through Near Accordingto thesecalculations, maximum flow into Strait fromthe Pacificto the BeringSea during all thesea occurs in NearStrait, Thetotal inassof v;ster seasonsof the year,but a distinctcounter-current carryingheat into the Bering Sea in theseregions is observedfroin the Beringinto the Pacificin the was estiinatedon the order of 4.76 million rn'!sec. westernhalf Figure5.12!. The current decreases Of this sum, about 3 17 million km'/year enter withdepth, it becomesvery weak at 300m depth, throughNear Strait and about 1.59 million km'/year andit completelydisappears at 500 m depth. throughthe straitsnear the Andrianov Islands. The Currentsthrough KamchatkaStrait areprima- heatresults agree qualitatively with thoseof Ar- rily fromthe BeringSea into the Pacific Figures senev967!. Substantialdifferences in quantita- 5,8-5.10, 5.12!. A weakcounter-current occurs inthe tive estimatesmay be relatedto unaccounted-for easternpart of the strait. It is notalways clearly watertransport at depthsbelow 1,000 m inthe heat- expresseddue to smoothingbyaveraging. The cur- balancecalculations of water exchange. En>log!uf heH~ ring Sea: A Reviewot RussianLifer~tore of the drainagebasin, evaporation, underground 7. FRESHWATERFROM RIVERS flow,etc,! Babkinet al. 1990!.Intra-annual distri- Freshwaterfrom riversplays an insignificantrole butionof river dischargeon thecoast of the Bering in the waterbalance of the BeringSea. Its totalcon- Seais veryuneve~ Babkin et al. 19911 Thernaxi- tribution doesnot exceed2% Leonov1960!. The mumflow in theAnadyr River occurs in, June<42.8'rr! totalfresh water input from both coastal regions and andgradually decreases toward fall 0,7'7 in Sep- islandsis 1,800km'Vyr. Nevertheless, its contribu- tember!.During the period from June to September tions to the hydrological,hydrochemical, and ice about 91,3eAof the total dischargeoccurs Figure regimesfor the entire sea and in separateregions is 7,la!.The total flowduring winter January-Aprill fairly substantial. is about .2-0.3%!. Abouthalf of the river input comesfrom the A differentflow patternoccurs in rivers that Russiancoast Table7.1!, Most of the flow from freezeup Figure7.1bb More than half ofthe total Russianrivers cornea from the AnadyrRiver and a annual flow occursduring snowmelt May-.June', Duringfall the flow quicklydecreases to 8.5 < in numberof smallrivers and streams, most of which September!and essentially ceases in October. The freeze over during winter. Discrepanciesin the estimates of outflowfrom fl owduring May through September is 98.3 i< of the Russianrivers is due to a paucityof information total annual flow. Table7.2!. A portionof thedata on the flowvolume Observationson interannualchanges in river andintra-annual flow distribution is notfrom actu- dischargefrom the Russiancoast indicate a range al measurementsbut basedon analysisof mecha- of valuesbetween 185 and 274 km'/yr Figure7.2!. nisms feedingthe rivers and computationof a This variation is dueprimarily to differencesin pre- correspondingfactor for precipitationover the area cipitationin thecatch basins Grigorkina 1979!.

Table7.1. Area of drainage basins and average annual discharge ofriver water into the Bering Sea. Area of drainage Discharge Year basin km2! knt'/year! River ofbasin Author 52.5 K.P. Voskresenskiy 1962 200 Anadyr River 61.6 T.E. Grigorkina 1979 191 60 S.G. Gorshkov 1980 9291 64. 1 V.l. Babkin et al. 19'91 815 207 Yukon River S.G. Gorsbkov 1980 123 Kuskokwim River S.G. Gorshkov 1980 573 220 Russian coast of K.P. Voskresenskiy 1962 544 222 the Bering Sea T.E. Grigorkina 1979 V.l. Babkin et al. 1991 312

Table7S. Number ofobservation yoints ou river discharge from the Russian coast of the Bering Sea Voskresenskiy 1962!.

Number of Areaof the drainage basin Total br observations < 100 101-500501-1,000 1,001-5,000 5,001-20,000 20.001-50,001 > 50,000 the entire sea

1-5 6-10 11-30 Total OceanographicDescription ol lheBering See

500 40

35 250 30

25 200 20

15 150 10 1940 1950 70

Figure7.2. Interannual oartability of riserrunoff in 0 4 I II 7 ~ %1I111I 1 I 3 4 0 ~ 'I ~ 5II11II ktn'j from the Russiancoast nf the Bering Sea Grigorki no 1979>, Anedyt River f=utfyfreezing rivers

Figure7. l. 1ntra-annualdiStrIbutian Of ri cerrunOff frOm the Russian coast of the Bering Sea Babkin et al. 1991!. Ecologyof theBering Seat A Reviewot RussianLiterature

8. SURFACEHEIGHT Variationsin surfaceheight in the BeringSea are due to the interactionof tides, stormsurges, and atmosphericeffects, and is also influenced toa small degreeby ice conditions, precipitation, evaporation, and freshwater discharge.

Tides Tidesin the BeringSea are very complex, especially in thenorthern Bering Sea, since they are influencedby the interaction of two tidal waves from the Pacificand Arctic oceans. The two wavesmeet betweenthe BeringStrait and St. LawrenceIsland Figure8.1, Leonov 1960!. Due to the small spatial coverageand low magnitude of thearctic tide, rna- FigureB,1. Cotidal lines of semi-diurnaltide 'Lerinoo jor tidalphenomena over the entire Bering Sea are 1960!. drivenpriinarily by Pacific tides through the Aleu- tian straits.Entering the BeringSea through the western-centralregion of theAleutian archipelago, the PacificOcean tidal wavemoves northward at differentspeeds, while simultaneouslyproducing secondarybranches in the easternhalf of the sea, in Bristoland Kuskokwirn bays, and in Karaginand Olyutorskbays in thewest. When passing through AnadyrStrait, the tidal wavedivides into three parts.One portion influences the northernhalf of theGulf of Anadyr,and the second enters Anadyr Strait, whereit undergoesa complexinteraction with the arctic tidal wave.The third portion moves intothe easternshallow region, a portionhits the Americancoast, and a portionenters Shpanberg Strait where it also undergoesa complexinteraction with the arctic wave. Thetypes and amplitudes of tidesare of siinilar complexity Figure 8.2>. I,owest tidal amplitudes in theopen sea are about 0.6-2 m; highest amplitudes FigureB.9, Types artd the largest i alues nrnplitudesi of occurin thebays and gulfs Leonov1960!. The above thetides. 1 isirregularseiiii-diurnal tide. 2 patternis basedinainly on analysis of seasurface is regularsemi-diurnal tide, 3 isirregular heightson the coastand on islands.Observations diurnal tide iLeonno 1960i. of seasurface height in the openocean are few and inaccurate.Therefore, computational estiznates of tideswere attempted Sgibneva and Privalova 1970!. The results are shown in Figure 8.3, pieof a stormsurge in theGulf of Anadyr is shown in Figure 8.4.

Storm surges lnterannualand intra-annualvariations in Stormsurge variations in seasurface height on the seasurface height Russiancoast of the BeringSea are less than tidal variations,Storm surge heights are 130 cm on Rat- Substantial intr a-annual variations in average sea manov,110 crn in ProvideniyaBay, and up to 140 surfaceheight are observed along the Bering Sea cm in theAnadyr Gulf. Greatest, variations in sea coast,as well as on the islandst Figure8.4a-8.Hate surfaceheight due to storinsurges occur during fall However,variations are different in differentre- when the frequencyof storms increases.An exatn- gions.Graphic intra-annual changes in sealevel 40 OcearjographicDescription of thr fkriffgSee

~J rC

Figure8'.4. Development ofa stormsurge cm!in the Gulf of Anadyr during the cyclonepassage on iVo- vember17-20, 1982. a is november 17, 15 h Figurett .'!.Scheme of cotidallines and isoampli fades of 00 min; b is ¹vernber 18, 0,3 h 00 min; c is november 18, 1,5h 00 min; d is ¹t ember 19, the M2 u~avei n the Bering Sea,A. Col

heightoccur in theAleutian-Commander archipel- Long-periodchanges in seasurface height are agoas anuneven sinusoid with a tnaximufnin De- observedat all observationpoints Figure 8,5b-8.8bl, cernber and June and a minimum in April and but characteristicso{'the variations were not deter- August.The maximum average sea level occurs in mined dne to the shortness of the time series at our Decemberand the minimumin August Figure8,5a, disposal,However, the variabilityis probablynon- 8.6a!. The maximumand minimum sea IeveIs in linear, as suggestedby sea surfaceheights at two I'rovidenivaBay occur in Novemberand June, re- adjacentpoints in theAleutian Islands:it increase-d spectively,but duringOctober and April on Rat- {rom 1935-1950 at Dutch Harbor and decreased from manovIs]and Figure 8.7a, 8.8a!. The sea level 1955-1975 at Una l ask a. pattern on RatmanovIsland corresponds closely Long-periodchanges in seasurface height in the withchanges in thetransport of water through the northern BeringSea are directlyrelated to changes BeringStrait. Variations in water transport through in transport through the Bering Strait Vorob'yev the BeringStrait is probablyone of the most impor- and Tiguntsev1976!; increases in transport cause a tant factors in{iuencing sea surfaceheight in the decrease in sea level. The coefficient of correlation northern Bering Sea, between tr ansport and sea height is -0.83. Ecoli>gyof the Bering Sea: A Revievof RussianLiterature

1 950 1 935 1940 1 945 1955 1960 1965 1970 1975

0 1 2 3

Figure8,5. Above: Interannual vanability and Belou>t 0 1 2 3 4 intraannual levelvariationsin DutchHarbor. Figure 8.6.Abave: Interanniini variability andBetosvt intra-annual level variations at Unalaska. 42 OceanographicDescription ot tl>eBering Sea

-10

1950 1955 1980 1985 1970 1975 1 e80 1950 1955 1980 1988 1&70 1975 1980

15 15

15 0 1 2 5 8 5 6 0 1 2 3 e 5 6 7 8 9 10 11 12 Figure8.7. Above: lnterannual variability and Below; F~ure 8.8.Above: Interannual variability and Below; intra-annual level variations in Provideniya. intra-annual level variatione at Ratmanov In- land. fcojogy of the Berr'ngSea; A Reviewof RussianLiteratrtre

ly from the Pacific into the Bering Sea: deeper 9. WATER STRUCTUREAND WATER than 2,500-3,000 in through Kamchatka Strait MASS CHARACTERISTICS and from the surface to the sill depth at about Factorsdetermining the formation of water 2,000 in in Near Strait. structure Water exchangebetween the central Bering Sea Forination of water structure and of individual wa- basin and the Pacific is more liinited due to the ter masses in the Bering Seais determined by com- sinaller sizes of the straits connecting them. plex factors that are tightly linked to the general However, some of the straits have depths of physical-geographicalcharacteristics of the sea. about 500-800 m and one is deeper than 1.000 They include: m. Water exchangethrough the largest of these straits Amchitka with a depth of about 1,100 rn l. The numerous straits of the Aleutian-Cornmand- and Buldir with a depth of about 800 m! is from er archipelago,connecting the BeringSea to the the Pacific into the Bering Sea. Pacific Ocean,influence water circulation in the Bering Seaand directly connectit with the sub- 4. The Bering Sea can be divided into two regions arctic gyre of the North Pacific Burkov 1963!. of alinost equal area: the deep southwestern re- Large amounts of Pacific water enter the Bering gionand the shallownortheastern region. These Sea current system. The major portion of up- depthdifferences produce substantial differenc- per-layer Pacific Oceanwater enters the Bering esin inixingprocesses, especially processes driv- Sea to the east of 170"E Figure 5.12! There- en by winter cooling. The depth of wat,er fore, the upper water massesof the central ba- circulation is limited by bottom depth in the sin mainly in the southern regionsof the Bering shallow region, but such liinitations are absent Sea to the east of Near Strait! are more strong- in the deeperregions where inixing is influenccd ly influencedby Pacificwater than the western by the underlying water massnot subjectedto basin, where Pacific water enters after under- convection. goingsubstantial transformationin the Bering Sea. 5. The exchange of deep and epibenthic waters within the sea is influenced by two major fea- 2. The small size of the Bering Strait, Table 1,2! tures of bottom relief. The first feature is the connectingthe BeringSea with the ArcticOcean, almostcomplete absence of isolatedbasins. The strongly limits water exchangebetween the two depth of severalof the depressionsin the deep seas, The alinost constant northward transport region and onein the shallowsis not muchdif- through the strait puts severelimitation on the ferent from that of the surrounding sea and the role of arctic water in the formation of Bering slopesare very gentle, thus their isolationis very Sea water masses. Due to the shallow depths of limited. Second, the sea is not transected com- the Bering Strait, there is essentially no ex- pletely by any ridge. The ShirshovRidge has a change of deep water between the Bering Sea depth at the crest of about 500-600m, a saddle and the Arctic Ocean, of up to 2,500m depth,and a channel,the Rat- manov, at about 3,500 rn depth. Alt.hough it par- 3. Direct exchangeof deepwater is possible only tially inhibits exchangeof deepwater between with the Pacific Ocean, Water exchange differs the western and central Bering basins, it does between the Pacific and the central and west- not totally exclude it. ern basins of the Bering Sea. The connection between the western basin and the Pacific 6. The great depth and horizontal dimensions of through Kamchatka Strait is not limited to any the Bering Sea greatly influence the processes depth sincethere is no sill acrossthe strait. The involved in forming of the structure of water western basin is also connected to the Pacific masses,In addition, meteorological factors such through Near Strait, which is secondin depth as solar radiation, evaporation, precipitation, but the widest among the straits of the Aleu- and wind, as well as river discharge factors, in- tian-Commander archipelago Table l.l !. Water fluence water inass formation, especially in the flow throughboth straits is probablyconsistent- surface layers. OceanographicDesert ption of theSeri ng .ica

r,'t Water masses pp Watermasses ipithe deep regions of theopen sea a J s r srpt sp Mostof thewater in theBering Sea is in the deep tp regions.The vertical structure has the following features,The entire water column from the Asian con- tinenteastward is clearlydivided into four layers; thesurface, interinedi ate cold, intermediate warm, rppp anddeep layers. This layering is dueprimarily to ip temperaturedifferences andnot salinity; variations insalinity with depth are fairly small and gradual, Ii I as illustratedby curves of thevertical distribution ppp ofsalinity and teinperature Figure 9,1a! and T-S tp ppsp ' n,p n,p «,r pn,p curves Figure 9,1b!. Subarctic features of water tl,pr structureare most clearly expressed in the v estern deepregion of the sea. To the southeast asone ap- proachestheAleutian archipelago. thestratification Figure9. Z. pL Vertical distributi on of temperature i aud graduallydisappears. Thetemperature ofthe core salinity!, b.TS curve of the deep I'vvesternl of thecold intermediate layer increases against a Barents Bea Arsenev 1967!. backgroundofa general increase intemperature and approachestheteinperature ofthe warm interinediate layer. Thesuromer-modified surface water mass A! isthe warmest water mass, occurring toa depthof influenceof freshening factors, Actually, ,hetotal 25-50m Figure9.2a!, It is characterizedbyrela- annualinput of freshwater from continental runoff tivelyconstant temperature -10'! and.salinity andprecipitation is about 0.1% of the total water about33,0 ppt! Figure9.3ab!. The hydrological voluinein thesea Arsenev 1967, Leonov 1960; Table characteristicsat the surface of thislayer are also 9.1!.Such a smallamount of freshwater could not constant.The multiyear teinperature average inthe havea greateffect on the salinityof the opensea opendeep regions ofthe sea varies by about 2-3 Anotherreason for thethicker surface layer is the from7-8' to 10-11'!;it is somewhathigher only in greateramount ofmixing, primarily due to greater EaraginBay. Salinity inthe open ocean isvery uni- waveactivity, Diurnal variations in temperatureat form0 ppt!and is elevatedonly slightly in the the surface cooling at nightand evaporation! pro- centralregions, which is dueto the general cyclonic ducesgreater mixing due to theresulting convec- circulationpattern and the upwelling of higher sa- tion Tiguntsev1976!, The potential inagnitude of linitywater to thesurface, Salinity right next to summerconvective processes in the surfacewater shoredecreases somewhat to32.0 ppt. The decre ase massis reflectedin the verticalwater column sta- in Karaginand Olyutorsk bays is dueto spring ice bility, whichis veryslight and in somecases even negative Table 9.2!. meltand continental runoff. Decreases along the The lowerboundary of the surface water mass Koryakcoast to the south ofCape Navarin are due is definedby the temperaturediscontinuity which to the influenceof the KamchatkaCurrent, trans- produces thegreatest vertical stability Figure 9. p, portingfreshened water from the Gulf of Anadyr. 9.6!,However, the discontinuity layer is weaklyex- Theteinperature at the lower boundary ofthe pressedinthe Bering Sea; temperature gradients surfacevrater mass decreases somewhat to4-6' but andthe thicknessof the layerare notgreat. The changesin salinity are practically undetectable. temperaturediscontinuity layer which could more Thethickness of the surfacewater mass is not accuratelybe called a transitionallayer, serves as constant Figure 9.4a!. It increasesfrom the north- the lowerboundary of'the surface layer and the up- west.to the southeastand by the endof summerit canexceed 50 m. The surface water mass is sub- perboundary of thecold intermediate layer. stantiallythinner in the deep regions near Karagin Processesproducing the coldintermediate lay- Baydue to winter convection andthe distribution er areundoubtedly driven by climate influences dis- ofoceanographic features typical of the entire north- tributedlatitudin.ally, in particular,winter coolirig westernPacific adjacent to easternKamchatka, of the mixedlayer and subsequentwarining of the Thesubstantial thickness of the surfacelayer verysurface portions of themixed layer Dobrovol- in theopen ocean is primarilydue to the weaker skiy and Arsenev1961!. Fcologyot the BeringSea; A Ri viewof kussianlit *r sture

H Car aD tlat SDS

SDD SDD

fSDD

ZSDD

Q h2 cm IZD7 IDiij F4'3 H'Q4 ~D43 1SQL J4I D

IDD

iDDD

LDDD

P'igare9.2. Watermasses A, 8, C, D! of the deepsea region at the i ertieal transect by T-S tndieea' Arsenev7967l. OceanographicOescription of theBering Sea 46

IPPP 1PPP NPD OPPP H,e

2PP

fDPP 2PPP

2PP

1DPP ZPPP dPPP 4'PPP H,H Cg Figure9.3.a. Temperature C!,L salinity ppt!, and c. arbitrary specific volume atthe transect along87'Via August AJ.sertev2967!, Ecologyof the Bering.Sea: A Reviewof RussianLiterattfre

Table 9.1. Freshwater balance in the Bering Sea.

Units Magnitude

Precipitation km'/year 1,300 56

Continental runoff km'/year 400 cm 17

Evaporation km'/year 700 cm 30

Freshwater balance krn"/year 1,000 cm 43

The intermediate Bering Sea water mass the cold interinediate layer, Figure 9,7!, like the surface layer, has fairly uniform characteristics. How- ever,it has a relat,ively deep temperature minimum, averagingabout 150rn depth,The depth and magnitude of the temperature minimum is not uniform in the deepsections of the sea Figure 9.7!. Thedif- ferences are due to differences in mixing processes in several regions,the infiuence of currents, and heat transport by the ocean. The cold intermediate layer is more weakly ex- pressedin the southeasternpart of t,hesea, which is more influenced by Pacific water than other regions,Temperature of the intermediatelayer in the southeastern region can exceed 3.5'. The temperature of the cold core of the intermediate layer within the deep region of the sea decreases in a northwesterly direction to 1.5-2=.The temperature Figure 9,4.Abave: topography of the totoerboundary of of the cold core in the Karagin and the Olyutorsk the surface uni form aver!or thickness of the water mass a mi in summer from mean coldspot is aslow as 1 or colder Ratmanov1937h!. mu tiyear data. Belosvtthickness mi of the Therefore, t.hewestern deep region is characterized water ma's 6 in summer of 1950 Arsenev by a disruption of the normal zonal distribution of 19673. oceanographiccharacteristics. as the mostnorthern part of the west,emregion, the Koryak coast,has higher temperatures than the more southern region around Karagin Bay. The anomalous temperature distribution in the western portions of the Bering Sea are due primarily to unique mixing processes, especially fall-winter convection. The Koryak coast doesnot have large bays cutting deeply into the land inass. Bul. Karagin, Korf, and Olyutorsk bays are subjected to severe cooling from the continent, causing much more intensive convection. Thus the cold water remains for a longer period and greatly influences the adjacent regions of t.he sea. Vote that unique cold conditionsalso occur in bays alongthe coast of East Kamchatka outside the Bering Seaand their effects help maintain subarctic conditions in OceanOgraphicOescription of'rhe Bern>g Sea

Table9.2. Vertical stablbty ofthe mater eoltsntn Ex 10 ! ia the deep regions ofthe Bering Res. 1950o 1951' 1956*' Depth,m August August September August September September October September

495 -111 167 340 10 395 165 3,202 510 2,962 28 2,505

25 0 9,417 1,649 3,010 432 2,604 -65 4,194

1,946 5,058 872 2,742 2,332 692 2,810 3,402 50 171 495 179 726 1,156 701 2,372 432

84 194 234 208 141 274 213 91 100 196 114 129 222 249 277 154 144

150 196 468 273 266 165 276 241 2IH3 200 151 131 186 172 137 205 219 250 135 177 141 355 138 115 139 300 113 91 86 127 87 66

400 41 60 66 86 68

500 50 37 65 69 600 64 54 61 55 53 47

750 55 47 47 38 1,000 45 38 39 37 45 47 1,250 36 21 38 36 28 18 1,500 17 17 25 2,000 12 12

3,000 o Dataof the RV Vityaz, ototiooo 533. 533, 590, 535, 6ls, 959, 965 o" Data of the .Ve~o. otot!oo56 Eco ogyoi tfte HeringSea! A Rev!cwo/ RussianLitorat!!re

fft! IPPPe /sf the surrounding wa.ters,thus influencing the position of the polar front in the westernNorth Pacific, fP The anomalous teinperature distribution in the deepregions of the westernBering Sea are alsore- lated to the transformation of water along its path of flow: the Transverse Current carries relatively warm water from the southern Bering Sea to the Koryak coast,while colder water is carried by the Kamchatka Current to Karagin Bay. The lower boundary of the intermediate Bering Seawater tnass is not as distinct as the upper boundary: it is definedprimarily by salinity, and the tem- peraturechanges marginally and gradually. Salinity distributions in the cold intermediate Depth, m layer arefairly uniform, increasingwith depthfrom P fPP Ps'!E P!P 33.3to 35.5 ppt. Salinity at the lower boundaryof the intermediate layer increases over a relatively short depthinterval to 34.0 ppt, This salinity dis- continuityproduces a secondlayer of maximum stability. However,the stability isan orderof magnitude less than that of the upperdiscontinuity separating the intermediate and surface water layers Figure 9.2, Table 9,2!, Thetopography ofthe lower boundary of thecold intermediate layer follows a certain pattern, It is deepestnear Karagin Bay and in the central basin reaching200-800 m depth!,hut becomesshallower to the southeast at 55'N it is about 150 m depth!, and is completely absent in the straits through the Dept Aleutian archipelago.The thicknessof the Bering Sea intermediate water mass follows a similar pattern: it is 200 in thick or more near the western coast Figure9.5. Curvesof the verticaldistribution of stability but decreasesgradually toward the southeastand rE x1P'! in the deep-searegion. a.in summer is virtually absent near the Aleutian archipelago !August 1959!; b.in the fall L¹vember 1953!; Figure 9.4b!. c. in winter December 1952!; d. in spring The Pacific interinediate water mass or the May 1952!.Dashed line shou.s the component, warm intermediate layer lies beneath the cold in- governedby saltnity; dotted line is by tempera- termediate layer Figure 9.2!. The warm intermedi- ture. ate layer is related to transforined Pacific water. A relatively warin water massenters from the Pacific and cools due to fall-winter convection from above, but the convection reaches only about 150-25G m depth, Waters below 150-200 m also undergosome coohng due to mixing, but the cooling is much less than in the upper layers and causesonly verv slight decreasesin tetnperature. Therefore,a warm intermediate layer is observed below the lower boundary of the convectivelymixed layer and is essentially untouched by the colder oceanic waters. The distribution pattern of the temperature maximum and its depth Figure 9 7! are essentially determined by the same factors, in particular by the connection to the Pacific Oceananrl hy the degreeof transformation of Pacific water in vari'ous regions QceanographicDescription of theBering Sea

3JJ.S JJ.J JJ,J Jt,t JL.JJJ,J 33.$ 34.3 3+.3 JJ.J JJ.J JJ,J Je.J 34.3 3r.S Jz 3 J3.$Jo,tr A,

Figure9.6. TS of the deep,voutheastern partof the sea, a. square 308hz b.314; c. 280; and subarcric region ofthe PacificOcean; d. 411;e 47'19Ã 17557'W seeFig. 5.4! Arseneo1967!.

of the sea. In contrast to the water massesprevi- gion Figure9.8! are exceptionallysmall, The max- ouslydiscussed, the intermediate Pacific water mass imum horizontal differencesin temperature and is characterizedby ranchvertical Figure9.3! and salinity overthe entire deep regionsof the sea horizontal uniformity Figure 9.7b!. The tempera- amountto only about0.1-0.2' and 0,1 ppt, Temper- ture in the warm core of the intermediate layer var- ature belowthe 3,000 m isobathchanges from about iesby only a fewtenths of a degreeover the entire 2.7-3.0' to about 1.5-1,7' at the bottom e.g., it de- deepocean basin, from 3,4 to 3,5 in thenorth and creasesvery little!. The saine also applies to salini- 3,7 to 3.9' in the southeast, Multiyear averages vary ty Figure9.9!, Most of the aboveis presentedin byabout the same amount as the variation in a sin- Table 9 3. glesurvey. Salinity variesby only a fewppt, The horizontaltemperature gradient increases notice- Water massesirt shallowregions and straits ablyonly in the verysouthern regions right next to the straits, where a "pure" subarcticstructure is More complexwater formationconditions occur at replacedby the variable structu.re of the Aleutian the southern boundary of the Bering Sea where it meets the Pacificin the straits through the Aleu- archipel ago. The warm intermediate core is at about 300 m tian archipelago.Near and Kamchatkastraits are depthover most of thecentral region of the sea, but an exception;they are wideand very deep.Condi- it decreasesto the south to about 200-250m depth; tions for water mass formation in these straIts arc to the north and west it increases co about 400 rn similar to thosein the adjacentdeep regions of the Bering Seaand Pacific Ocean. depth or greater, The transition from the warm ls.yerto the deep- Following are some factors directly influencing er layeroccurs quite gradually Figure 9. la!. There- water mass formation and structure in the Aleutian fore the actual boundary between the intermediate archipelagoto the eastof Near Island: Pacific water mass and the deep water must be con- sideredconditional, Accordingto T-S curves Fig- 1. The straits themselves have a strong influence. ure 9.6! and vertical stability, the boundary lies In contrast to the open sea arid ocean, currents between 600-700rn and 900-1,000m. Maximumsta- through thesestraits are quite strong. Strong bilityin this layeris determinedby a barelypercep- flow throughthe straits, andespecially horizon- tible increasein the vertical salinity gradientand tal variability in flow, result in intense water by a very slight changein temperature. mixing, both vertical and lateral. Water mixing The deepwatermass, which makes up the great- is facihtatedby bothnonperiodic currents and est volumeof Bering Seawater Figure 9.2!, is the the elevated speedsof currents through the most uniform. Both differences in depth distribu- straits. tion Figure 9.3i anddifferences from regionto re- Fcology of the Hermg.Sea: A Reviewot RussianLiterature 5!

Figure 9.8. AbovetTemperature 'C!, Beloav:salinity Ippft at the level of 1,000 m Arreneo 1967!. Figure 9.7. Above: Temperature ' .'! and location depth m! of the core of the intermediate layer and Beloan the care of the unarm't ntermediate layer in August. Undulating line shows the hound- ariee of the cold intermediate layer Areenev 1967!. Ocea !ographirDescription ot th» Berir

Table99. Water masses from the deep regions ofthe Bering Sea. Depth of Stability at boundary E x 10" Thermal characteristics lower boun dary Name of water mass 25-50 From 2,000 to Surface suinmermodified! Temperaturefrom 7-1V at thesurface 7,000-10,000 to 4-6' at the lowerboundary, Salinity about 33 ppt 150-250 and From 200 to Minimaltemperature from 0.5-1.0' 600-800 Inter

Temperaturefrom 2,8-3.0' at theupper Sea bottom Deepwater boundaryto 1.55-1,80'at the bottom correspondingtoa salinityof about 34.4-34.7 ppt

2. Substantialand persistent distributional fea- izsr

33 t J3.$ 34tt 3vS JJe NS 34 Jk.S Nit JJS Jkt! Jit,s Jt $ JJO 33,$39, t Je.SJz.$33. JJS 34. t !sS 3$ !

Figure9.10. TS curvesof Aleutian ivater. a. square393b; b. 394c; c. 3656;d. 353a;e. 390a seeFigure 5 4 Areeneo 1967!.

lands to the east of 172-173'E. These alterations caii be illustrated hy T-S diagrams from Aleutian waters. The family of T-S diagrams in Figure 9,10 illustrate the variability of actual water mass formation conditions in the straits and various intensities and depths of mixing. The first T-S curve Figure 9 10a! shows very strong mixing in a shallow strait, the second Figure 9.10b! is from a deep strait, and the remaining three show conditions where mixing is less int,ense in the straits and a short distance froin the straits. The Aleutians are therefore a regionwhere hydrological conditions are anomalous both in salinity and temperature. A negativetemperature anomaly occurs in thc surface layer Figure 9.11a!, Salinity in the surface layer is somewhat lower than in the Bering Sea and the Pacific Ocean, but the differences are not great. Vote that mixing between the surface and underlying layer in the Aleutian straits does not produce a positive salinity anomaly at the surface as it does in straits through the Kurile archipelago. Positive temperature anomalies Figure 9.7, 9.11, 9.12! and negative salinity anomalies 'igure 9.12b. 9.13b! occur in the deeper layers. Therefore, waters around the Aleutians are not transitional between the Bering Sea and Pacific Ocean but are a uiiique Aleutian variant of the subarctic water structure. Water masses in the Gulf of Anadyr and adjacent shallow regions form under special conditions which occur due to the high latitude, shallow water, and continental runoff. Contributing to the l'orma- Figure 9.1I. Teinperature distribution = ,'! in the Hering tion of Anadyr water masses are: ! quite fresh Sea from mean multiyear data Arsenei 1967h OceanographicOescription of theBering Sea

Figure9.12. Temperature distri btstinn 'C! i n theBering Figure9,l3. Salinitydcstri button ppt! in theBering Sea Seafrom meanmultiyear data Arsenev frommean malt yeardata. a. surface.Janu- 1967!, ary-%arch,December isolines with ci rclesJ: k surface,July Arsenevl967!.

waterin the gulf, especiallythe westernregions Figure9.12b>; and ! theformation ofcold arctic wouldoccur if the Gulfof Anadyr were not attached waterin thenorthern and the veryeastern portions to theopen sea, Figure 9.15a, 9,16a!. These curves ofthe gulf and outside the gulf to the west and south- arecharacterized by a relativelyhigh salinity 0 westof St. LawrenceIsland near the Anadyr cold pptat the surface and over 34 ppt at depthsgreater spotaccording to Ratmanov!, The entire Anadyr than100 m!, The high salinities result from ice for- regionischaracterized bya two-layeredwater struc- rnation.Another characteristic of the T-S curves is turewith an. absence ofthe intermediate layer and lowtemperature, about 2 at the surfaceand as low thepresence of an epibentbic cold layer, An inter- as 1,5"at all depthslower than 40 m. Finally, these rnediatecold layer seems to occuronly in thevery easternportion of the Gulf of Anadyr and at itsen- curvesare characterized by very high vertical sa- trance Figure 9. la!, since a slightlywarmer bot- linity gradientsassociated with high continental runoff andpoor mixing conditions. tornlayer is presentin theseregions Figure 9. 14!. Theopen Gulf of Anadyrhas T-Scurves of a SomeT-S curves that aremost characteristic of somewhatdifferent shape Figure 9.15b,9.16b! Anadyrwater give a nioredetailed characterization causedby mixing as well as climatic condit.iona. ofthe water masses and water structure in the Gulf Watermass characteristics are affectedby the deep- of Anadyr Figure 9.15!, TheT-S curves from one of the bays with a sill er regionsof the BeringSea. Two water masses are depthof 20 rn thedepth of the bay is about 150 m I veryclearly distinguishable: surface and. epibenth- illustrate the times of vertical distributionthat ic.They differ from each other by temperature,but Ecologyof theBering Sea: 8 Reviewuf RussianLiterature

Station Number 5St' 5SS N4 Ssv 0 jtt

f00 /20 /40

Stattort Number 0 IO 2P 9P E 4P 90 o. ttP 7P 8 ti 90 /00

Figure9.14. L Temperature,IL Salini ty, in theGulf of Anadyr.

r ttt P

33,P 33,X 34, P 32,3 33,0 PP,P Rt

r tie P

8 LP,P 3P,P 32,0 PP,P 32,P 34,P9, elan

Figure 915. TS curves of the trulfofAnadyr a. for one of theinlets: 6, for open part of the gulf, e. for the easterrrmostpart; d. for coastal regions; e. curtte of transi tional type Arsenet 1967>. OceanographicDescripti o lhc Berittg Sea

-15 -15

-25 -25

-35

-'l2

4 ~ Hl t 'C t C

Figure9 16.T curvesS ofthe tlulf of Anadyr a.for one ofthe inlets; b,for open partof the gulf o. /or the eastern most part;d. for coastal regions; e.curve oftransitional type Arsenev J967!, Ecologyot theBering Sear A Reviewot RussianLiterature salinities are similar. Salinities in the water column are similar to the salinities at the surface ot the deeperregions of the BeringSea about32.5-33.0 ppt.!.These curves essentially form the uppersec- tion of the T-S curves for the deeper regions of the sea,but differ from the latter by the sharpertem- peraturediscontinuity layer beneaththe surface layer.The similarities indicate the origins of the central waters and portions of the easternwaters in the Gulf'ofAnadyr:a currentfrom the deepregions of the Bering Seaentering the Gulf of Anadyr near Cape Navarin, The western portion of the Gulf of Anadyr is characterized by T-S curves having an altnost constant temperaturebut an increasingsalinity with respectto depth Figure 9.15d!,The sharpdiffer- encesin salinity are explainedby dischargefrom Figure9.17. Rear-trottomtemperature 'C.'! rrr summer the AnadyrRiver. The freshwater canbe traced Arserrer! 1967t alongthe westcoast clear to CapeVavarin, with graduallyincreasing salinity at, the surfacedue to mixingwith the watersunderneath, although the t.wolayered system does persist and an intensesa- Seasonaltransformation of water masses linity gradient is characteristicof coastalwaters, As the distance from the coast increases, the water Surface waters in the Bering Sea undergo the great- structure becomesmore similar to that of the cen- est transformations due to climatic factors such as tral Gulf of Anadyr. Transitional T-S curves are a fall-winter cooling, spring-summer heating, convec- combination of both possible variations: the upper tion, and mixing. Intermediatewaters are affrrted layer is characterizedby a horizontal,straight, to a lesserdegree. Thc intermediatePacific water coastal type of curve, the lower tfrorn 20-30 rn masschanges insignificantly during the year and depths!by a straightinclined transition to lower only at the thin layerin direct.contact with i.heover- temperatureand higher salinity.T-S curves of this lying water tnasses;in the summerv ith the Bering typeare not only characteristic ofthe Gulf of Anadyr, 'Sea intermediate water mass, in the winter with but also of the entire west coast, the surface, winter-modifred water mass. Deepwa- The eastern half of the Bering Sea also has a ter massesdo not change noticeably during the year. typicaltwo-layered structure during sutntner. The The most characteristic seasonal water mass T-Scurves and vertical profilesof temperatureand features in the Bering Sea I the elimination of the salinity Figure9.18, 9.19! are very similar in shape cold intermediate layer for exampler are primarily to those of the Gulf of Anadyr. However, the water due to temperature Figure 9.19},since saiinitv is tnassesare a little different. In contrast to the west- conservative and changes very little in the opensea, ern Bering Sea,thc water massesin the east.em even at the surface Figure 9.2a!. Annual changes shallowregions form againsta backgroundof lower in salinity are substantial only in those regionsof salinities Figure 9.18b!,which are distributedover greatestice formation, near the coast, in themouths a much greater area than in the western coastal of large rivers and in the baysIFigure 9.20!. regions.The most interesting feature of the shal- The thermal regime in the Bering Seais char- low BeringSea during summeris the presenceof a acterizedby a fairly distinct temperature change large region of very low temperaturesbeneath a Figure 9,2!,However, seasonal temperature varia- surfacelayer ofwarmer water in the central region tions, although substantial at the surfacei 6-8=in to the south and southwest of St. I.awrence Island the open.sea and 9-12"-in the coastalregions and Figure9.11b, 9.17!, We discuss below the origins of shallov's!, are very quickly reduced at relatively this water mass and why it remainsduring the sum- shallowdepths and by 25-300m depth.easonal mer,since this toucheson questionsrelated to sea- variations are practically absent< Dohrovolskiyand sonal transformed water massesin the Bering Sea. Arsenev 1961!. Average temperature in the»pper Qccanr>graphicDcs<.rip ionof the Bering Sea

5 IS ~ -1 1 3 5 7 -1 1 3 5 1 t'C 0 t C 0 t 'C 0

-10

-20

314

4 5 5 1 5 9 10 3 0 9 4 5 9 0 t C

-30 ->0

-20

Figure9.18, Distribution oftemperature andsalinity ofthe eastern shallow sea.a. square 8d;b. 21b; c.22e; ei. 84, e. 10 fseeFigure 5.4! Arseneo1967!. EculrtgyOi the Bering Sea} A ReyiewOt RuSSian Literature 59

300m of the deep,open regionsof the sea vary by I 6 5 / ' } 6 6 J 0 5 6 7 6 t 5 0 5 6r t only 2' Figure 9.19!. The lower boundary of the upper homogeneous layer,its width andthermohaline features, which varywithin certainlimits duringthe coldperiod of theyear, are determined by the development of w inter convectivemixing in oneor anotherpart of the sea,During maximumcooling, the main surface water mass in the mixed layer, to a depth of about JJS JSJ JJ,SJ>,J JJ,SAtT JJtI JJ,S JIT,J6, +/rg 200rn or deeperin severeyears, cools to an average of l.-2' in the westernand central deepregions of Figure9.19, Vertical distributIon oftemperature solid the sea,and to 2-3' in the southeasternBering J Fig- line} and salinity dashed line} during sea- ure9.9, 9.lla!. This convectivemixing equilibrates sonsin the deepiwestern} Bering Sea. a. thesalinity with respectto depth,leading to slight uinter, b. spring,e. sun>mer,d. autumn increasesin salinity relative to summerby 0.2-0.3 Arsenev l967!. pptin the surface! ayer Figure 9.9, 9. 13, 9.21!. The elevatedsalinity is to a lesserdegree due to icefor- rnation,since it occursonly in a verylimited portion of the deepregions of the opensea tBu!ga!rov C 1963, Krvndin 1964!. tg Much more intensive cooling and ice formation occursin the easternshallows, especially north of St. IV!atthew Island due to the Tnoresevere climate in the region.The entire water columncools to temperat,ureaclose to freezing,Not only are temperatures and salinities much lower in the v estern regionsof the BeringSea and in the easternshelf g8'lF' IZF ZF 5FWX 27W I region,but a muchthicker mixed layer is observed. Month Thisis clearlyvisible in verticaltransects !Figure 9.9!, especiallyin the west where the isolinesare Figure9.20. Averageannual tempera- depressed.The !at,ter is alsoobserved in theBering ture ir> the deep uIeetern} Bering Sea, rt. 0-10 m Seaduring summer,although it, is lessdistinct. layer, b. 0-300 m layer One of the causesfor sinking of water is the cy- ArseneI. l 967!, clonic circulation over the western and central BeringSea basins, circulation causing an upwel!i ng in the central regionsand downvelling at the edges.The strongestdownwe!!ing is observedat the westerncoast and is related to a predominanceof northwestern and western wind drift current, during the entire year tace SeCtiOnT!, leading to COn- vergence.Winter convergenresare particularly strong, since the drift currents during winter are fastestand mostpersistent, During the coldseason the downwellingalong the shelf increasesin intensity due to the thermodynamiceffects of intense coolingalong the westerncoast and over the east.- ern shelf. Inducedmultistepped convection and intra-la yer circulation is important in t.he downwelling. As illustrated in a win.ter stability transect to the southeastof Karagin island Figure 9.22I.the maximum stability right next to shoreat about100 rn depth is fairly high I'about1.000 E x 10'!.Along the continental slopebeneath the zero isoline is a regionof instability occurringbelow',300-400 rn in a OceariographicOescription oi the Bering Sea

Figure9.27. Salinity distributiaii i'ppt! in theBering Sea frorii mean multi impardata. e. 200m, Aug ust; b. 500m, August Arseaev l 967!. Ecofogvuf th»8ering Sea: A Retriesnt Russianiitetaturt 01

horizontal tonguefor 20-30 miles. The water adja- centto this regionalso has a stability closeto zero. Sucha deepregion of instability may be due to two factors:sinking of wateralong the continental margin andslope due to intensesurf'ace cooling and in- ducedconvection resulting from the following. Coolingin autumncauses convection which per- sistssto certain depthsdetermined by t.hemaximum stabilitylayer causedby surfacewaters of reduced salinitv near the coast. Waters directly beneath the depthof maximum stability exper ience cooling f'rom above. Turbulent diffusion produces a positive tern- peraturegradient and a negativevertical salinity gradient,which disrupts the stability,resulting in Figure9.22. Vertical water stability in u interat the convection.Thc deeperconvection is closelylinked transect tu the southeast of Karagin Island to surfaceconvection, although the lower boundary Vityaz, January 7953hDash' d li ne shows of the latter is maintained by the layer of maximum the stability nf >norethan I; ~ 10",arrous stabi 1ity, showfhe probable direction of sinki ng uater. With the start of spring when the upper mixed layerbegins to warm,a coldintermediate layer is formed.Its minimumcore temperature is apparently equalto the lowestsurface water temperatures af the end of winter. The processesdegrading the cold intermediatelayer begin with the formationof that layer. OceanographicDescription o theBering Sea 62

'10. LIGHTAND WATER CI.ARITY Clarityof BeringSea water is differentin coastal andcentral region s, It is directlyrelated to thein- organicsuspended particle load and plankton populations,whose densities decrease with distance fromshore, Water clarity near the shorevaries from 3 to6 rnor less, especially near the mouths of rivers that carryflotsam and plankton. For example, clarity is 4-6m nearshore in the western Bering Sea fromCape Kamchatka toCape Olyutorsk, but is 11- 14rn fartherfrom shore. Clarity is 12-16m in the centralGulf of Anadyrand 2-3 m nearshore. Be- tweenProvideniya Bay and CapeChaplin water clarity decreasesto 7-8m, North of St.Lawrence Island,clarity is 10-14rn in thewest but decreases to9-11 rn or less in theeast due to Yukon River discharge.Highest clarity in the opensea is 16m Le- onov 1960!. Variationsin water colorare causedhy the same factors as variations in clarity: suspendedmatter in the water.Greatest suspended loads occur near the coastand river mouths,and lowest occur in centralregions and in regionsof waterexchange with the Pacific, A map of the relativewater clarity andcolor Figure10.1! indicates the cioserelationship be- tweenoptical qualities of the waterand the distribution of water massesand surfacecirculation Arsenevand Voytov 1968!. The largest gyres, for examplethe large gyre in thedeep Bering Sea iAr- senev1967'i, are fairly closelyassociated with isolines of v:aterclarity andcolor. They also closely Figure10.1. Above: Distribution nf clarityunn Belorvr correlate with boundaries of various water struc- colorof BeringSea vatertn. sunr mer Arsener tureetypes: deep water, shallow water regions, Aleu- and Voytav 1968! tian straits. The influencesof coastalflow can be foflowed easilyin Figure10.1; this effectis insignificanton the scale of the whole ocean. Eiology of the8eri iig Sear A Reviewerot Russian Literature 63

the ice edgeduring winter advancesat a maximal rate. Duringfall andwinter, starting around the endof The depth of convectiongreatly increasesnear September,ice formation occurs in the BeringSea; thecontinental slope FigureIL2!. Therefore,the icemelt usually occurs around 1-15 July. lce can be heatcontent of the water is muchgreater. Thus, in observedin July andAugust in the westernBering Februaryand March the rateof advanceof theice Strait, which is subjectto the PolarCurrent and edgemarkedly decreases, and by March,when it winds from the Chukchi Sea; ice can remain all year reachesthe cont,inental slope, it ceasesto advance. in LavrentiyaBay Leonov1960!. The rnaximurn, Thesouthern edge of ice advancein the BeringSea mimrnum,and average multiyear position of the ice thereforecorresponds to the edge iif the continental edgeis illustrated in Figure 11.1. slope, TheBering Sea can be divided into three regions A majorfactor affecting ice formation in thecen- basedon the originsof the ice:regions of localice tral regionsis water circulation. The major braiich- formation,regions where ice drifts in fromthe Chuk- esof large-scalecurrents in the northeasternhalf chiSea, and regions where ice enters the seaduriiig of the sealead to compactionof the ice; currents in river breakup.River ice is of'secondaryimport. ance the v'est disperseit. The ice is less compactin cy- in the total icebalance of the seaand comprises only cloniceddies and regionsof divergencewhich occur 3-5'yr.Most of the ice cover,about 97%. is formed wheremajor currents divide into secondary branch- locally,During winter up to 13'7iis carriedby winds es:the ice compactsin ant,icycloniceddies and re- and current into the Pacific through Aleutian straits, gionsof convergenceI Leonov 1960!. about l9% is carriedinto the Chukchi Seathrough Dueto the heterogeneousdistribution of factors theBering Strait, and up to 6fi'7imelts in placedur- affectingice, the southernedge of ice coveris far- i ngwinter and sum mer, thest south in Marchi Figure11.3!, but the isolines Usually drift ice is first observedin the western ofice cover density are not even,The most northern BeringStrait. where it is transportedfrom the Chuk- distribution ol'the ice edge occursin the southwest- chi Seaby wind andthe PolarCurrent as early as ern BeringSea, while in the southernpart of the the rniddle or end of September Romanov1993!, oceanice densities greater than 1 arenot, observed. oftenalmost complet,ely blocking Lavrentiya Bay, Ice formation in the northern Bering Sea ends However,this iceis not persistent,and southernor in mid-May;in the southernBering it endsin the westernwinds will clear Lavrentiya Ray and the secondhalf of April. Ice coverbegins to breakup in theriver inouth regionswhere the wateris relatively Bering Strait. I ocal ice formation in the Bering Sea begins in warm,causing thermal and dynamic breakup of the the nort,hwesternregion in the Gulf of Anadyr and shorefastice Leonov 1960!. ln addition, Pacific in Norton Sound, which serve as t,he sea of ice for- Oceancurrents break up icecover in the openocean. rnation. Ice formation in these regions can begin as The area of ice cover in the Bering Sea, its den- earlyas rnid-September,The brackish river mouth sity,and position of the ice edgevaries from year to areasin the northwestern and northeastern regions yearover a broadrange Table11.2t The variation of the sea freeze at the end of October and by early to a greatextent follows thr total averageair tem- November ice can be seen far froin the coast. perature Figure 11.4!.A numberof researchers The start of ice formation and the rate of its Drogavtsev1959. Kats 1960,Kryndin 1964!have growthdepend on the heat,content of the water, relatedthese phenomena t,ovariations in atmospher- Table11.1 presents data on the depth of purelyther- ic circulation. rnal convection in the Bering Sea. These data indi- Changesin icedensity during winter arealso cate the heat content of the water Bulgakov 1965!, quite variable Figure 11.5!.Sharp and frequent Thedepth of thermalconvection in shallowregions variations in ice cover can be observed both during is not great and in a number of casesit, doesnot periodsof icedevelopment and ice melt. Short tc rrn exceed20 m dept,h,as is observedin the Arctic variations in ice cover are due to variations in weath- Ocean, The heat content and its horizontal gradi- er and also due to dynamic factors redi.stributing ent is very small,ice formation is facilitated,and the ice, OceanographicDescription ot'the He ingSea 64

Figurell. l. Positionofthe inc edge in theBerittg 6'ea Bulgakov 1964!. ECt> c>l>rr>tthe l3era>g Sc<<>. 8 RCtRuSS>on l itcr<>tare Tablell.l. Thecritical depth of purely therma! convection ittthe Bering Sea, with and without com- pressibility of sea water. Bottom Convectiondepth, m depth,m Witbout compressibiiityWith compress>hiiity l.atitude 1.o»gitude Date 437 :3,800 52'37'N 177'20'W 13 Jc>or 1933 3,800 422 3,750 52 15'N 176 17'W i 3 June 1933 3,750 491 1.890 52" 15'N 178-28'W 11 August, 1'933 1,890 22 22 60'21'N 171'45< W 9 August 1934 68 21 21 63'25'N 1 12'W 6 August 1934 66 90 54 46'N 166'47'W 22 July 195>9 240 23 23 63'20 V 176'19'W 27 August. 1959 84 286 2.000 58"58 N 178'31'W 31 August 1959 2,000 250 2,000 5o'44 1> 177'24'E 17 September 1959 2, 0 185> 1,080 58' 1.0'N 171'08'E 21 September 1959 1,080 110 110 56 '54'N 171'32'W 30 August 1961 110 409 1,110 54'59'N 167 46'W 12 Septemi>er1961 1,100 183 3,500 59c 35'N 175" 12'E 26 September 1961 3,500

Figure11.2. Disrridutioa of thecritical depth of a purrlvtherrrtal coo- cect>on Bulgakou J9l>'5!. Uceanogrd yhicDescription ot tlie BeringSea 66

8" L I

E Z e

Figure11.4. jfultiyear variations ofai r te

Table 11.2. Total average monthly air temperature and number of days with ice in the Kamchatka region.

Xo. of S year Winter gt,, F e p toudays thousandkm' cv 1931/32 43.6 -55.1 E u 40/41 -31.6 -40. 1 45 di SS Cl -36.9 -53.3 84 C 41! 42

0>, ml/L t d V d d t S d td II ft d i d J v J d t d d r t d dd

sd Sdit i l J rJ ev d dId d Id j v dd 7d t tdd tt Je $d 1d

d'i l duddy dd dt d Jed d ~dd dt!J e J d ~ad io

d t d J N d h' 1 d I IO

Figo re 12.1.Vertical distribution of oxygen i n ml 1! in shallowregions of the BeringSea i n di fferent seasons:a. Bering Strait; b. Chirikoo basin, uest of 16B'00'W;e. Chirikoo basin, east of168'%7'W;d. northenstern GulfofAnadyr; e. southern Gulf of Anadyr: f. Yukon-1Cttskokuimregion; g. CapeOlyutorsk region;h. Pribiluf Jslands region; i. Bristol Bay;g. western Aamchotka Strait; k. eastern Kamchatka Strait Ioanenkoo 1.964!. Fcctlttgyot theHt ring See: A kcvicivui kussianLttetaturc.

6 i d d v 6 6 r 6 6 ir i d J v 6 6 r d 6

!66

Zdd

ddd

I'igure12.8. Vertical distribution of oxygen rnl >'I. h a. at the central basin to the u inter cortvectton depth. I is ui nter; 2 tssprt'ng; 3 is surnrner; 4 is fall: b. in kamchatkaStrait to thetcrii- ter convectionpenetration depth; e, in the uestern basin to the unnter conoectionpen- etrationdepth Ivanenkov1964n

occursi nthe euphoticzone at 20-25m depth,not in the surfaceas during spring.A secondaryrn aximurn in oxygenconcentration occurs at 40-50m depthor at 50-75m depth.This maximum occurs in theden- sitydiscon.tinuit,y and has the same origin as in the shal!ow regions.

Distributionof oxygenby area Widdter.Oxygen conCentration iSCOnstant frotn tOp to bot,tomin the shallowregions during winter since convectionpenetrates to the bottom 8.1-7.5ml,L, 95-93cnesaturation, d.epending on temperature, 1.5- Figure12.2. Vertical distribution ofoxygen trnl /L! in deep 1.0'C1 Dependingon temperature and salinity, sur- uater of the Bering Sea, I is uiinter; 2 is faceoxygen concentrations in. the deepregions of spring;3 is summer:4 is fall !Ivanerikov theBering Sea are 7. 1-7.5 mVL 93-96"» !.Since high- 1964k esttemperatures during winter are observed in the southernand central regions,the highest percent the absoluteoxygen concentration in the euphot,ic saturationin oxygenare observed in theseregions zone,the upper25-50 m, canremain unchanged or Figure 12.4, 12.5!. even decrease somewhat due to higher tempera- Topographyof the isopycnalscorresponding to tures, but the percent saturation increasesto 99- the core of water massesis shownin Figure 12.6- 103%. In those regions into which neritic 12.8.The distribution of oxygenand other dissolved phytoplanktonare advected, oxygen concentration materials relative to these surfacesis exatnined in the samelayer can increase to 8.0-9.4ml/L 03- below. 120/o!. Maximum oxygen concentration occurs in the Oxygenconcentration in the subsurfacewater 0-10 m layer, fromthe upperboundary t,o the lowerduring De- Oxygenconcentration decreases even further in cernberand Januaryvaries from 6.0-4.5 to 2.0-1.0 theupper 25-50 m euphoticzone due to increasesin ml/L.Oxygen concentration in various re gions of the temperaturebut the percentsaturation remains Bering Seain the central coreof this water massat about the same as during spring .6-6.8 m 1/L.100- 2 t.00on the isopycnalsurfaces was 2.2 to 1.3m]II, 103%!,Oxygen concentration is somewhathigher Figure 12.9!.Depth of the 27.00isopycnal varied close to the continental slope ,1-7.4 ml/L, 106- from 200 to 600 m Figure 12.6ai. The averageoxy- 113%!.A slight maximumin oxygenconcentration genconcentration at this isopycnalwas LH ml L: 70 OceanographicOescription of the BeringSr a

Figure l2.4. Percent u. oter saturation ui th oxygenat the sea surface in De- cember 1952- January 1958 It onenhov /964z

the averagedepth of the isopycnal was400 m.Above averageoxygen con.centration and depth of the subsurface water mass core occurred near the continental slope in the central and western basins. This indicates an upwelling of warm, oxygen-poor waters in the central regions of the basins and downwelling of colder, oxygen-rich water near the continentalslopes, which can occur only in the presence of cyclonic gyres. S~rirag. Oxygenconcentration at the surface Figure 12.5. Depth m! of oxygen concentra- andin the 25 m euphoticzone varies spatially from tion in December 1952-January 13,65t 170~x! to 2.0 mUL <25~rr!.The entire sea,with l953. Above: 7 mt/LBelotvt 5 the exception of special areas subject to river dis- mt/L Ivanenhoo 1964t charge, can be divided into two regions based on oxygen saturati on levels of 163%, 7.8-B.O ml/L The 103%isoline roughly divides regions whereneritic phytoplankton predominate from those where oce- River mouth are lower than in the underlying wa- anic species predominate. ters. Regions of maximum oxygen concentrations Summer. As before, the Bering Sea can be di- appearas spots:Kamchatka andBering Strait, Korf- vided into two regions based on percent saturation Karaginregions, Gulf of Anadyr, Bristol Bay,and of oxygen: shallow regions with neritic phytoplank- the continental slopeto the southeastof CapeNa- ton > 103%!and deep regions with oceanic species varin to the PribBof Islands Figure 12.101 These < 103%!, As in spring, regions with neritic phy- spots are regions of elevated primary productionand toplankton are heterogeneousduring summer t Fig- phytoplankton biomass and are the most produc- ure 12.11!. Highest oxygen concentrations in the tive regions in the Bering Sea. upper 10 m t> 7.0 to > 8.0 ml/L, ! 103 to ! 120 t ! The Yukon-Kuskokwim region and the area to occur to the northeast of St. Lawrence Island and the south of Norton Soundare unique with respect in a wide 100-150 mile band from St. Lawrence Is- to oxygen concentration. All surface waters in this landto the Pribilof Islandsand westernBristol Bay, region at the start of spring are oxygen depleted, the Gulf of Anadyr, Ozernoy,and Olyutorsk Hays, averaging20-80~r saturation. but reaching77% at the Bering Strait, and the coastal regions of thc some stations. Oxygen concentrations in the surface Kamchatka Strait. Lowest oxygen concentrations in from the area north of Nunivak Island to the Yukon t,he upper 10 m .5-6.9 ml/L, 93-102/el occur in the Fcc>lo!>yc>tthe' Baric>g Sea. A Reuie~ut RussianLrfarwture

I'igureI2.6. Topographyaf isopyanalsurface cn! I>'igure12.7. Topographyof i sopycnalsurface 'n>. Above:27.00 rniddleof thecore ofsurfc>re Abave: 26.75 >r>addleof the core of thea in- u'ater!;BeIaa>c 27.36' cn>iddle ofthe rare of fer layer of surfnreu ater>;Belatvc 27. 02 interrnectiate wafer! in winter af 1952-I960 tmtdrlleof the corenf sul>surfaceu>ater»'n Ivanenkav l 964!. springof 19r>2 Ioanenkot. !964!. 72 O<:t'.anographnl!ascription <>t lit' Her rjgSea

Figure 12.8. Topographyofisopycnal surface rn! 27.38 0niddle of the vore ofinter

Figure 12,9, Oxygendistribution ml/L< and pH in e'arly u inter. Above:

summer.Above at 20 n. Brlnivi in the rniddle nf he vore of surface rva er at isopyenalsurface 26.70h Solid i nesare oxy- genisolines. dashed lines are pH salines Fi anenko 1964h Figure22.10. Above: Distribution of oxygen ml/L! at seasu r farein spring of 1952.Belou i The degreeof u~atersaturation ivith oxygena seasurfa

Figure 12.12. Ti>pngraphy nf isopvcnal surface ms Figure 12.13, Distributron of oxygen rnl!L! and !>8 in Abave: 26. 70 imiddle of the core of the summer. Above:in the middle nf the rnre ui nter layer of surface >voter!, Beloevt of subsurface rantsr at isopyt nnl surface 27.00 >middle of the core nf subsurface 27.0!; Belorr>tin the middtr of the cnre of u.ater! in summer Ivanenkov 1964!. intermediate water tat isnpycnal surface 27.39! Ivanenkov 1964!.

Yukon-Kuskakwim region and Norton Sound,where Oxygen concentrat,ion in the intermediate wa- much organic matter enters the system with river ter during suznmerchanges between the upper and discharge, and in the western Chirikov Basin. lower boundaries from 2,5-'2,1 to 0.8-1.2 m VI.. The Oxygen concentration in the subsurfacewaters coreof this layer contains the oxygenminimum. 0.3- decreases during summer from 5,0-3,5 to 2,0-1,0 0. 7 rnVI.. Concentrations in the core of the interme- mVL between the upper and the lower boundary. diate water are lowest in the central and southern The maximum depth of the core of subsurface wa- portions of the western basin <0.3 t,o < 0.4 rnUL, ter occurs rrear the northern, northwestern, and Figure 12.14!, where the center of the core is clos- northeastern continental slopes,and the minimum est to the surface < 800 rn!. Oxygen is also low in depth occurs in the central and southern regions of the core of the intermediate layer in the southeast- the western and central basins r Figure 12,12!, The ern portion of the central basin. Oxygen concentra- greatestdepth of the subsurfacewater corresponds tion in the core of the intermediate water is > 0.8 to the greatest oxygenconcentration Figure 12.13!, near the eastern and northern continental slope thus irrdicating downwelling near the edgesof cy- region and in a broad band from St, Matthew Is- clorricgyres, land to the Vear Islands. This slight increase in Ecologyof the Heririg Sea A Reviewot RussianLit rat !re 75

I'i gare . I4. I!istri buti nn nf oxygen m l /I ! and pH i n summer in the middle of the core nf intermediate abater ot i sopycnal iiurface 27.39! Iu anenk on 1964!.

oxygen concentration is apparently the result of sinking of the overlying water mass at the edge of the cyclonic gyre in the convergence zone. Figures 12.15through 12.18 show oxygen distribution during fall. Data on oxygen concentration at 2,500, 3,000, and 3,500 m depth is shown in Table 12.1. The connections between the deep waters of the Bering Sea and Pacific are elucidated by the data in. Table 12.2. As shown in Tables 12,1 and 12.2 and in Figure 12,19, the deep Pacific water is richer in oxygen than the deep water in the Bering Sea. Based on the established tendency for oxygen concentration to decrease along the path of deep currents, one ca» confirm the opinion held by all researchers studying water exchange between the Bering and Pacif- Figure . . Topography of isapycnn! surface mt ic, that deep water enters the Bering Sea froin the Abooe: 26'.7 3 ini dr!le oft tu core of the u an- North Pacific, The deep water can enter t.he Bering ter layer nf surface u uteri; Belotrt 27 08 only through Kamchatka and Near Straits. A tongue middle o/ the core of subsurface ii uteri in of water having elevated oxygen concentration ex- the fnll of 19:i! Ii nnenknc 1964!. tends froin the Pacific into the Bering Sea through Kamchatka Strait Figure 12,19!, which undoubtedly indicates the movement of deep water into the Bering right through the central part of Kainchat- ka Strait. At the same time, oxygen-depleted ivater exits the Bering Sea into the Pacific through the western part of Kamchatka Strait. Judging from oxygen concentration in Near Strait at a depth of' 1,500 m, deep water exits the Bering Sea to the Pacific in the western half of Near Strait but enters the Bering Seathrough the eastern half of i,he strait. Oxygen-rich deep water enters the Bering Sea from OceanographicDt script>or! r!t theHorini, Sea

Figure12.17. Topography vfisopycnal surfa< e rn!27.33' !rniddle of the core of intermedio!a u!ater!

1'igure12.16. Distribut!on of oxygen rnl! L! andpH in the early fall. Above!i n the rn!ddleof the core of he tvi n terlayer of surface u>ater at isopyrnal surface 26.73!; Belnu»~n the middle nf the core of subsurface u ater tai isopycnal surface27.03!. Solid lines are oxygenisoh'net, dashed li~es ore pHisolines !Inanenkov 1964! Figure12,18. Distribution of oxygen ml.! and pWin the early fall in the rniddle of the core of the intermediate v>ater !at isopycnal su>- face27.33!. Solid li nesare oxygenisoli nes, dashed lines are pH isolsnc» Isanenkor 1964!. Err!IOg!rA Review0! Russian ifcrVtu e

Table 12.1. Dissolvedoxygen concentration rnl/L! in the deep water of the Bering Seaat depths of 2,500, 3,000, and 3,600 m.

Depth m! Location 2,500 3,000 3,500

Kamchatka Strait, Vityaz data Stat,ion 524, 17 August 1960, 65'08'N, 164-08'E 2. 14 2. 68 3. 14 Station 525, 18 August 1950, 55'42'N, 164-40'E 2.00 2.53 3. 12 Station 956, 27 Septeniber 19hl, 65'39'N, 164'01'E 1 90 2.43 2.90 Station 959, 30 September 1951, 55 20'N, 165 03'E 2.38 2.88 3 03 Station 1390, 26 May 1952, 55'30'N, 164=06'E 1.8? 2.o3 Station 1391, 26 May 1952, hh 26'N, 164 29'E 2.3 ! 2.92 3,43 Station 1927, 22 December 1952, 55'39'N, 164 11'E 1.99 2.60 3.02

Western basin, Vi yaz Station 1948, 26 December 1952, 67'44'N, 166'55'E 1.46

Southwestern central basin, Vi yaz Station 530, 21 August 1950, 64'44'N. 169'38'E 1.93 2.32 2.86 Station 537, 22 August 1950, 57=25'N, 175'43'E 2.05 2.69 Station 967, 2 October 1951, 55'00'N, 171'01'E l. 68 2.00 Station 1410, 30 May 1952, 54'30'N, 171'09'E 1.90 2.14 2.43

Southeastern central basin, Brou n Bear Station 3, 10 August 1967, 62'29'N, 178 23'E 1.80 2. 16 Station 11, 20 August 1957, 52'41'N, 178'10'K 1.85 2.18 2.44

Northwestern central basin, Vi yaz Station 539, 23 August 1950, 58 39'N, 177'43'E 2. 03 2.16 Station 541, 24 August 1950, 59 42'N, 179'31'E 2. 13 Station 1468, 8 June 1952, 68'22'N. 177'16'E 1.63 1.96 2.23 Station 1552, 20 June 1952, 59'22'N. 178'47'K 1.68 2.05

Table 12.2. Oxygen concentration ml/L! in the deep North Pacific, 30-50 miles south of the Aleutian Islands.

1!epth m I 2,000 2,600 3.000 3,500 4,000

1967 Rroton Rear Expedition Station 10, 17 August, 51 08'N, 174'41'E 1.54 2 18 2.62 2.95 3.22 Station 541, 24 August, 50"-55'N, 177'23'E l. 89 2.42 2.70 3.37 3 I Si,ation 1468, 8 June, 50'22'V, 177'40'E 1.73 2.37 2.94 3.10 3.35 Station 1552, 20 June, 51"02'N, 171 "45'K 1.90 2.33 2.90 3,38 3.39 Orearrograpiric Description ot theBering Sea

the Pacificat depthsof 2,000rn in the rniddleof Near Strait. Flowthrough the Bering Strait also has a sub- stantialinfluence on the spatialand temporal distributionof dissolvedmaterials. The average con.centrationof some dissolved hydrochemical in- dicatorsin the surfaceand epibenthic layers of the BeringStrait during surniner are shown in Table 12. 3,

Phosphorusdistribution Ratioof the species ofphosphorus Theconcentration of inorganicphosphorus in the euphoticzone of bothdeep and shallow regions is lowerthan in the winter layer.The differencesin. the concentrationof inorganicphosphorus between the summerand winter layers are especiallygreat in the shallowregions where productivity in the BeringSea is greatest,These differences apparently disappearduring winter since the upper water co!urnnbecomes a singlehomogeneous layer due to convection,but reappearduring spring with the developmentofphytoplankton blooms in theeuphotic zone,as the phosphorus required by phytoplank- tonis onlypartially regenerated bydissolution and rernineraliza.tionofdead organisms. A largeportion of the organicphosphorus leaves thc euphoticzone as sinkingdetritus and entersthe lower viintert layer;a portionis alsolost when phytoplankton is consumedby zooplankton,Reintroduction of dissolvedphosphorus from the winter layer into the euphoticzone occurs but onlyto a limitedextent dueto the inhibitoryeffects of the intensedensii.y gradientin thepycnocline, The above processes re- su!t in a declineof total phosphorusconcentration in theeuphotic zone during spring and summer in both shallow and deep regions, Inorganicphosphorus concentration is substantiallygreater over the deep water than in shallow regions,in both the euphotic zone and the underly- ingwinter layer during all seasons.This difference occursbecause priinary productionover the deep regionsis severaltiines lower than in theshallow regions.In addition,by the time detritussinks throughthe winter layer in deepregions and enters the subsurfaceand intermediate layers, it is almost completelydecomposed, while decomposition is com- pletedin thebottom sediments in shallowregions. Figure12.19. Distribotiori ofoxygen mi/U. Aborter ot 1.500 m. Dotted line detroter the 1,500m Inorganicphosphorus concentration increases isoboth. Center: at 2.000 m. Dotted line markedlyin intermediatewater relative to surface denotes the 2,000 m i sobath. Betotorot waterdue to the almosttotal absenceof phospho- 2,500m, Dottedtine dertotcsthe 2,500m rus consumptionat thesedepths 00-1, F00m cdis- isoboth Jratierrhov 1964! solvedphosphorus accumulates due to dissolution of organicdetritus. The concentration of organic Ecologyof the Berin/, Sca:A Reviews~of Russian 1 /tablature 79

Table 12.3. Averagevalues and variability of water massparameters in the surface and epibenthic layers of the Bering Sea,

O t e/6! pH Si l pg/h! Surface, Surface, Surface, Month hottom Variability botto ra Varia bi! ity bottom Vari abi1ity

115 lo 100 July 115 20 8.27 0.29 780 210 95 7.98 590 August 115 20 8.28 0.23 850 620 95 8.05 970 September 100 18 8. 16 0,10 530 -250 82 8.06 780 October 100 8.1 1 0. 14 430 210 92 7.97 640

6 t6 66 66 66 6 6 66 66 66 66 se !6rr phosphorus, dissolved and especially particulate, rnq/ms6 ream decreasesby 2-5 times in the subsurface and intermediate layers relative to surface layers.

Verticaldistribution of dissolvedinorganic phosphorusin shallowregions Winter convection in regions shallower than 100- 150 rn reaches bottom by the end of December and January and the concentration of dissolvedinorganic phosphorusbecomes uniform from the surface to the 6 ls 'Ã6 66 66 /66 bottom, difFering from an average value of 66 mg/m' 6 6666 but not more than 6 rng/m'. The concentration of dissolved and particulate organic phosphorus probably also becomesuniform with respectto depth and attains its annual minimum Figurc 12.20k Mineralization of organic phosphorus occurs only during winter, and thus the concentrat.ion of inorganic phosphorus increases, Therefore, the concentration of inorganic phosphorus at the end of winter, before the start of the phytoplankton bloom, is always greater that at the beginning of winter over the entire water column from surface to the Figure J2,20. Vertical distr i but/ on af mineral disso!oed bottom Smetanin 1956 t phosphorus mg/m'j. a. Southern Gulf of During spring, with the initiation of intense Aaadyr; b. /northern Gulf of Anadyr; c, phytoplankton blooms, the concentration of' dis- Pacific Ocean and Bering Sea Ioauenhoc solved inorganic phosphorus in the euphotic zone 1964 t rapidly decreases.but the thickness of the euphotic zone increases from 10 to 25-35 m. At the same time, the concentration of inorganic phosphorus in the winter layer begins to increase Table 12.4I. The concentration in the euphotic zonedoes not always fall to zero but can average 34ri of the average max- irnum concentration Table 12,5t Sometimes it declines t,o 10-20'1 of the maximum. Dissolved inorganic phosphorus does not limit phytoplankion OceanographicUescriptio/I ot fh

Spring1952 Sutatoer196O I all 19/is JJievelccdOmsolvrd Pariiru'.ote DissolvedDissolved Pavo colate D!saolvedDissolved Particulate Tntal inorganic orgenic organi: Wsre r inass Total inorganic organir organic Total inorganic orgsrnc organic

Shallovregions 28/42 16!28 6uphotic rnite 26/34 30/40 /26 20/30 ta-36mt 6/6 Wint.rrIs>rr 104 73'70 16i15.5 E5'146 94 76/8E 12/13 / 35-hottvmi Deep regions 16/26 16/13 90 34/2' 24 26 32/36 Euahotic ron e 64i76 12!13 16'l7 54/67 iu 50roi 12/12 14i14 156 s-i/43 46/3I 43/zn Wmwrlayer 99 79'80 1414 100 74/74 i 56-260m i 14/11 Is,ill ari43 4ti21 63/34 Surfacelayer 126 92rr4 2ll'l6 13'16 132 104/78 I 260-800m i 9/7 185 IIS/I & 43,2:I 54/29 intermediatelayer 129 I I3/89 133 112!84 I600-E,800 mi 102/80 22/18 96!69 49!30 ttt/I I DorpI oyer 126 112/9ll 7/5 126 i > 1,5 00tn >

Table12.S. Average concentration ofdissolved inorganic phosphorus mg/ma> inthe euphotic zone and winterlayer in shallowregions of theBering Sea.

Eall 1961 winter 1962 Spring 1950 Sutnrner 1932-1969 W i0 Leilay 9 i Winter layer Winter layer Winter layer Euphotic 36 rn to mixed to Euphottc 35 m to Euphotic 40 m to zone bottom zunis hnl.toto Regionof the sea lxittorn zone bottom 36 t 16 68 + 4 1 + 5 Kamchatka Strait.tweet half! 62+ 2 202 10 47 2 14 38 >18 74+ 8 34 7 Karagin region 67+ 4 28 t 14 651 5 60 4 5 36K 15 72+ 8 4o+ 6 Olyutorsk Bsy 66 E 2 32 2 16 77 + 12 16+ 10 72 v 10 Gulfof AnadyT tregton influenced 66 2 6 32 l- 20 7527 28 + 20 by TransverseCurrent I 69+ 10 15 4 18 79 + ll 114 6 73 4 lt! Anadyr coldspot 22 2 1S 12 + 10 16 + 10 Yttknn-Kttskckwirnregion 18 2 12 41 21+ 11 76:E 26 BristsylBay 38m 10 36+ 10 Tidallyinfluenced regions 31* 10 I capes,continental slope!

productionsince sufficient concentrations oforgan- values in both the euphoticzone and in the sinter ic phosphorusquickly accuinulate in theeuphotic layer.RegeneratiOn iS alSO important, as deETEOn- zoneand organic phosphorus can be easily assinu- stratedby decreasesin organicphosphorus 1Table latedby phyt41plankton Kabanova 1958!. 12 4!, Duringsummer the concentrationof dissolved inorganicphosphorus inthe euphotic zone contin- VertiCaldistribution of dissoit/edinOrganic uesto declinein thoseregions where blooms con- phosphorusindeep regions tinueand influx of phosphorusfrom deeper regions The vertical distribution of dissolvedinorganic phos- is insufficientto meetdemand and averages about phorusin deepregions of the BeringSea is as ft>l- 30%of the maximum,In thoseregions where pho- lows Figure12,211: lowest concentrations and tosynthesisis curtailed orwhere upwelling is sufTi- substantialseasonal variations occur in the euphoti c cientlystrong, the concentrationsof inorganic zone,there is a sharpdiscontinuity betweenthe dissolvedphosphorus can increase relative to spring euphoticand winter layers, there is a sharpiricreas41 Fat~/hagit>/I/M Ih.ring~ Sea: A KeviiwnLiferaturt

a do ed Sa dd sfsr tdtr d Sd dP dad dd %F td d8 Aft@ ldd g/ma g/ms rn

F>gure12,21. Vertuol distribution of'mineral disco eedphosphor u»I mg/m"6tt, Kamchatka Strait, b. tsestern basis. c. centra/ basin /oanenkoo 19646 in concentration in the winter layer of the surface The greatestchanges in dissolvedinorganic water and in the subsurface water reaching a max- phosphateconcentration occur in theupper 50 m of' imum in the intermediate water, followed by a grad- the euphotic zone.Close to the continental slope. ual decline to the bottom. Such distribution patterns where subst,antial amounts of neritic phytopfank- of dissolvedinorganic phosphorus are characteris- ton are mixed with oceanic species during spring, tic of deep regionsof temperateand high latitude the phosphateconcentrai,ion falls from 60-SOmgtm' seas. to '35mg/m'. With a decreasein the abundanceof Seasonalchanges in the concentrationof dis- ncritic speciesand phosphateregeneration during solvedinorganic phosphorus in deep regions are as summer,the dissolvedinorganic phosphoruscon- follows. Winter convection produces a uniform dis- centration increases in the euphotic zone to 40-50 tribution of phosphorusfrom the surfaceto the low- mgim'. The phosphateconcentration decreases to er boundary of convection. The phosphate 35 mg/m'during f'alldue to a maximumin the abun- concentration in the uniform layer will be higher in danceof oceanicspecies. Seasonal changes in phos- thoseregions where the underlying subsurfacewa- phate concentrationin the euphoticzone in those ter,enriched hy phosphorus,is closerto thesur face. deepregions whereoceanic species rlominate dur- This is observed in the central regions of cyclonic ingthe entire production season are as follows, Phos- gyres. At the edges of cyclonic gyres, where down- phate concentrationgradually decreasesfrom the welling and convectionoccur, the phosphate concen- end of winter to a tninirnum of 40-50 mg!tn" in the tration is somewhat lower. By the end of winter fall, and increases in winter, Seasonal changes in phosphateconcentration reaches60-80 rng/m' in the the concentration of dissolved inorganic phospho- mixed layer near the continental slope and H0-90 rus in the winter layer are 1essthan in the euphotic mg/m' in the central portions of cyclonic gyres. zone. Oceanographicl!escrip[tort ofthe Sert'ng Sea 82

Oistributiunof dissolvedinorganic phosphorusby area Theinorganic phosphorus concentration inall sur- faceregions subject toconvection isalmost uniform in all areasof theBering Sea shallow and deep!, anddepending onthe region, it rangesfrom 58 to 72rng/m' Figure 12,22k The lowest phosphate concentrationsin thesurface waters 5 rng/rn'!occur in thoseregions where the depthof winterconvec- tionis least.Highest phosphate concentrations greaterthan 70 rng/rn'! occur inthose regions where convectionpenetrates to greatdepth. While surfacewaters are enrichedby winter convection,the subsurface waters are impoverished, especiallynear the Asian coast Figure 12,23, above!, dueto intensivevertical displacement and sinking of waterin theconvergence zones, as observed to the northof the Nearislands. The maxirnurn phos- phareconcentration in intermediate waters occurs in upwellingregions, in thecenter of cyclonic gyres, andin divergencezones Figure 12.23, below!. Low- estphosphate concentrations in intermediate waters,as in surface waters, are observed close to the continentalslope in the westernbasin. Thephosphate con.centration in the euphotic zoneat 0.10and 25 m depthduring spring is identical Figure 12,24! and completely corresponds tothe percent,saturation ofdissolved oxygen atthe surface Figure 12.10!. Thephosphate distribution in theeuphotic zone duringsummer issinu! ar to that during spring Fig- ure 12.25!.Lowest phosphate concentrations occur in theproductive regions; theGulf of Anadyr, Olyu- torskBay, the western and eastern portion ofKarn- chatkaStrait, and around the Bering Strait. Themost characteristic features of the horizontal distributionof phosphatein deepwater are as Figure12.22. Distrrbutlon of mineral d sso/cedphos- follows Figure 12.26!. Lowest concentrations occur phorus mg/m~! artd adSea! A Raviervot'Russian Literature

Figure12,24. Distribution of mineraldissolr.ed phos- Figurel2,23. Distribution of mineraldissolved phosphorus mglm'! aud silicon mgl rri'i in phorus mg rn'!and silicon mg/m ! in spring- Above; in the rniddleof the core earlyu'inter. Above: i n themiddle of the r>fthe u:interlayer of surfnieuater 'at coreofsubsurface water nt isopycnol sur- i sopyinal surface 26. 75!; Betouri at 25rn. face27.00!; Below: in themiddle of the Solid lines are phosphorus isolinvs. coreof intermediate uiater at isopycnol dashed li nes are silicon !soli nes surface27.36!. Solid lines are pliospho- rlvanenkoi 1964! rus i solines, dashed lines are sit~con!salines lvanenkov 1!4!. Oceanographic0 scription of thxHenng Sca

FigureI2,26. Distribufxon of mineraldissoleed phosphorus mg/m'! and stlicon mg/ m'! at 2 000m, Solid li nesore phosphorusi soli nes, dashed I ines are silicorr isolines Ivanenkov 1964!.

Siliconconcentrations in the euphoticzone in shallowregions during suxnmer are somewhat higher relativeto springvalues. Some of this increase canbe explained by slower growth of diatoms, sili- conregenex ation, and a greaterinflux of water from theopen. regions of the Bering Sea and from river discharge,in whichthe silicon concentration ishigh- Fituxre 12.25. Distribution of mineraldi ssoluecl phos- er, Siliconconcentration in the winter layer rela- phorus mg/m'! andsilicon mgf ms!in tive to the euphoticzone rapidly increasesto the summer: Above:at IO m; Belotv in the bottom Figure12.271 The increase is dueonly to middle of the coreof surfaceu:ater!at regeneration.The influx of waterfrom the opexxsea isopycnalsurface 26.70!, Sohdlx'nes are cannothave a signifxcanteffect, since silicon con- phosphorusisolines, dotted Iinesare sili- centrationin thewinter layer of the deepregions of coni soli nes Ioanenkoo I964!. the seadoes not exceed800 mg/xn",but silicon concentrationin the winter layerof the shallowregions is 1,000-1,700mg/m'. The minimumconcentration of silicon in the euphoticzone spring,sumxner, fafl! is 300-600 Silicon distribution xng/m';it is 700-800mg/m' for the ent,irewinter- Verticaldistribution of silicon convectionlayer during winter, A distinct Thevertical distribution of siliconis fairlysimple discontinuitylayer with maximumgradient in sili- in bothdeep and shallowregions Figure 12.27> conconcentration isobserved between the euphotic Siliconconcentration in watersof lessthan 100 xn zoneand the winterlayer in the surfacewater dur- depthis alreadyuniform from the surface to the ingthe production season. Fairly rapid increases in bottomby December-January,since convection silicon concentration in the deepregions of the reachesto the bottoxnby that time,Silicon concen- BeringSea occur from 50-70 xn depth to 500-ROOm trationin shallowareas ranges between 600-850 depth.At greaterdepths the rate of siliconincrease xng/xn'.Due to blooxnsof diatoms,which consume slowswith respectto depth. Maximumsilicon con- largeamounts of silicon, its concentrationdecreas- centrationin the BeringSea occursnear the bottom and not at.intermediate depths as is noted for esto xninimuxnvalues in theeuphotic zone during phosphorus.The vertical distribution of siliconixx sprxng. Fcoiogyof the /3rvirrg Sei: A Revieivof Russiarr i.i eratirrc IdddJRU dÃ4 iOZi ddlr ddda %SF P rdWZdpa JNd dslÃ Jdad pal' tNN d AV ddd radd rrrdd ldda Zddaedda Sc mg/ms m rd ld

dd dp dd ra dd dd /dd I ld aa /Nd wa rdddAdd Zddd , mg/ fd zd dd Vd dd dd

fpp rrp rgd

Figure1227.trvrticrrl distribu ofsi!icon ion rrig/mr! inthe slra!lou. anddeep searegions. N.southern GulfofAnadyr, 6.northern Gulfof Anadyr o.cen basin,ral d.rcestern basin.I Isu inter;2 issprrng; 3 issummer; 4rs foll /IoanenhnoI &64!.

Asin winter,silicon distribution in thesubsur- theBering Sea differs from that ot the Pacific, where faceand intermediate water is uniformat 600-900 thedepth of maximumsilicon concentration is at and900-1,100 mg/m' respectively. Lowest silico~ 1,500-2,000 m, concentrationsduring surniner occur in theAnadyr Silicondistribution by area coldspot and in theeastern shallow regions i Figure Silicondistribution in the surfaceand subsurface 12.25,above I.The euphotic zone in the southern and watersat the beginningof winteris fairly uniform, centralportions of the western basin is enrichedin without.clear r egions of elevatedor depressedsilicon silicon[800-1,200 mg/in' !: theseare regionswiih miniinal primary production. concentration Figure 12.22, 12.23!. Its concentration Dependingonits depth, silicon concentration in in the surfacewaters is 650-850mg/m', concentra- thewinter layer varies f'rom 800-900 to 2,000-2,200 tionsin the subsurfaceand intermediatewater are 1,200-1,600and 1,650-2,050 mg/m' respectively. mg/m" Figure 12.25, below!, The close to thesur- Silicon distribution during spring reflects re- facethe coreof the winter layer,the greaterthe gionsof varying silicon consumption byphytoplank- mixingwith the overlying water and the lower the ton, Almost all of the northern shallow regions, silicon concentration in the winter layer. includinga largeportion of theGulf of Anadyr.the East-westdriffcrences in siliconconcentration coastalregions between Cape Navarin anrl Kam- declinein the subsurfaceand intermediatewater, chatkaStrait

5 a 4 q «z-aqra yr ssraai 5'Irma

Figure12.29. Loca ioraofuater masses of the Ber ng Seaat the trarrsectrVear Strait-Anodyr Strait. su m mer of 1950, R V Vi fyas, surface vote mass: a is summerlayer, 6 is iirirrter layer; 2. subsurfacu uater mass;8. intermediate uater mass;4. deepuater mass.

ofthe BeringSea are under the influenceol Pacific Oceanwater just southof the Aleutians.

CiassificatiortOf water massesusing hydrologyand hydrochemistry Theclassification of water masses,suggested hy Arsenevt1961, 1967! and which we examinedin Section9, isbased only on therrnohaline characteristics.However, a numberof' dissolved substances, Figure1'2.28. Distri bra ionof mineral dissolved phos- in particularoxygen and silicon, can be importsiit phorus mg m'zand silicon mg m'!in indicatorsof watermasses t,oobrovolskiy 1961; Ru- summer.Above; iu the middle of the core sanov1972, 19741.%ater mass classificatior using crfsubsurface uater at iaopyraalsurface hydrochemicaldata was suggested. by Ivanenkov 27.00>;Belotv: in the nsiddleuf the core I,'19643.The author distinguishes the followingfour of i ate mediateieater at isopycna1sur- waterinasses in the BeringSea: t 1t surfaceBering face26;39t Solid linus are phosphorusiso- Seawater, heterogeneous during winter hut consist. li nes. dotted lines are silicon iso nes ingof twolayers during summer, the summerand I< a nonkoo 1 964o minterlayers; ! subsurfacewater; t'3! interinedi- atewater; t4! deepNorth Pacific water. The boundariesbetween these water masses were defined by chatkaStrait is lowerthan duringsummer, an in- thelayers of maximumstability and the rnaximurn dicationnof the i~tensityof photosynthesis in these verticalgradients of temperature, salinity, oxyg ii, and silicon, regions. Lowestsilicon conceratration in the deep water Themajor difference between this classification below'3,000 ntgfnia! occurs near the continental andthat ofArsenev consists of the separationof the slopein thecentral and western basins; highestcon- surfacewater into twolayers, the suinrner and win- centrationsoccur in thesouthern and eastern por- ter Figure12.29't, The distinction.is basedon dif- tionsof the centralbasin over4,000 ntgi raajand in ferencesin oxygenconcentration in theselayers. The thecentral regions of the western basin over 3,500 thermohahneand hydrochemical characterist.ics o f mg m'!.Sdicon concentratio~ at2,0t m depthsouth the water massesfor the deepand shallow regions of theAleutian islands is 2,500-6,0ttng rn',indi- of the BeringSea are presentedin Table 12.6 and cat,ingthat the entire southern and eastern portions 12,7. Ecologyof the Bering Sea. 8 Reviewof RussianLiterature Table12.6. Boundaries andcharacteristics ofwater masses inthe deep regions ofthe Bering Seaduring vari ous seasons. P Si VO-V Temperature Sa'linity O., pH mg/m' tmg/mi! Img/m'! 'C! ppt! ml/L!

!, Rurface water mass January! 1.0to25 33.2-33.3 7 5-7.8 8.03-810 60-80 i00-900 05-1.5 Lpper boundary 0 in 34,4-34.5 6.0-4.5 8.0-7.9o 75-85 900-1,100 0 1 J.owerboundary 150-200m closei.o 1.7 to 2.5 the continental slope 300-350 m! Spring May-.luiie! Upper t summeri layer: -0 3 to4.5 32,5-33.210.5-7.5 8 55-8.25 lo-40 200-400 0.5-1,5i Upper boundary 0 m -0,9to 2,5 33.1-33.28.5-8.15 8,30-8.1540-70 400-600 0,5-2.5 Lower boundary 20-50 m Winter layer: lower boundary 150-200m closeto 1.8 to2. 8 33. 45-33.555.0-4. 5 7. 95-7.90 80-90 600-1,100 0 1 the continental slope 250-300 m! The minimal temperature in tbe core of the winter layer during summer .July-/!iugust!was 0.2" to 2.6 C. Summer layer: 10.5to 6.5 32.8-332 7.2-6.9 b.30-820 35-65 500-1,0000.5-1.5 upper boundary 0 m 6.5to 3.5 JJ 1-33.3 7.8-70 8.20-8.10 60-80 r50-1.2501.0-4.5 lower boundary 25-50 m Winter layer: 33.5-33.8 5.0-3.5 7.95-7.80 80-95 !.000-1,500< 0.1 lower boundary 150-200m 50- 2,5 to 3,7 300 m close to thc continental slope and 100-150 m in the cyclonic gyre! The minimal temperature in the core of the winter layer during fall ! October! is from 0.5- to 3 5'C. Summer layer: 10.0to 7.0 32.9-33.2 6.8-6.5 8 25-8.20 30-45 00-800 1.5-.5 upper boundary 0 m 6.0to 3.0 33.1-33.3 7.5-6.8 8 20-8.10 50-60 1,000-1,5002.5-9.5 lower boundary 35-60 m Winter layer' lower boundary 0-200 m 50- 2.5to 3.5 33.;i-33.8 5.0-3.5 7,90-7.80 70-85 2,000-2,500< O.l JOOm close to the continental slope! The minimal temperature in the core iif the wint,cr layer was from 0.8' to 35 C. OCeanOgraphic:DesCripti/!n uf hcB/'ri/!g c e~ Table12.6. continued. 3Boundaries andcharacteristics ofwater niasses inthe deep regions ofthe Bering Sea during various seasons.

Temperature Sa1in.ity 0,, P 8! NO-N C! ppt! ml/L! pH tng/m' ! mg/mI,'mgjm'!

2. North Pacific subsurfacewater inass, winter and spring 33.95-34.052.2-1.3 7.73-7.68 80-95 1,200-1,500 260-350m core00-500 m closeto 3.60to 3.35 the continental slope near Olyutorsk Bayand 500-700 rn in Kamchatka Strait! 34.0-34.22.0-1.0 7.70-7.6390-100 1,250-1,750 360-460m lowerboundary 00- 3.4to 3.2 600 m closeto the continental slope nearOlyutorsk Bay and700-800 rn in Kamchat.ka Stra! t! Sominer and fall 260-300m core00-450 m closeto '3.65to 3.46 33.95-34.052.2-1.3 7.82-7.6885-110 1,500-3,000 the cont.>nental slope 1 340-34.2 2.0-1.0 7.70-7.83 90-1101,500-'3,OGO 360-450rn lower boundary00- 3.4to 3.2 600 m closeto the continental slope! S. North Pacific intermediate water mass, fall and winter 34.30-3435 0.2-0.7 7.65-7.6395-105 1,500-3.000 600-?60m core 800-900 m closeto 3.1to 2.9 the cont!nental slope! 1,000-1,500m lower boundary 2.8to 2.3 34.40-34.56 0.8-12 7. 65-7.80 90-1052,000-:3,000 Spring and surnrner 34.35-34.400.3-0.7 7.63-7,65 100-1201,500-2,000 700-900ni core 900-1,000m closeto 3.2to 2 8 the cont,mental slope/ 34.42-34.560.8-1.2 7.6'3-7.75100-115 1,500-2000 1,0001,500 cn lower boundary 2 7lo 2.2

4. Pacific Ocean deep mater mass 90-125 1,500-3,000 2.30 to 2.15 34 48-34.65 0,8-1.2 7.68-7.75 Depth 1.500m 85-120 1,750-3,000 1.95 to 1.80 34.57-34.69 1.3-1.6 7.76-7.80 2,000 m 80-110 2,000-3,30O 1,75 to 1.70 34.60-34.69 1.5-2.4 7,80-7.83 2,500 rn 80-106 2,500-3,5GO 1.60 to 1.55 34. 64-34 73 2.0-2.9 7.83-7.85 3,000 m fCO/O o>y !te f3nr 'ngSe, 8: RevieWOf RuSSi, I In Cr,r t>re Table12.7. Boundaries andcharacteristics ofsurface water masses inshallow regions ofthe Bering Sea during various seasons. P Si NON 0,, Temperature Salinity pH mg,>m' ! 'C! I ppt,! nt

1. Regionto the north of 63"N, Spring June-firsthalf of July! A. West of 168"W 7.5-13.6 8 30-8.60 25-60 500-1.000 Upper summ 1.5 to + 1.7 32. 5-33.4

Summer July-September! 500-1,000 29. 5-32. 5 7.0-12. 8< 8.16 860 20-60 Summer layer 10-20 m 3 to 6 5 8-7.3 8.05-8.14 50-70 500-1,500 Winter layer 10-20m to bottom 0 to +1.5 32. 0-33. 0 B. East of 168'W. Spring June-first half of July! 5.5>-9. 8 8. 05-8. 25 25-40 200-250 Upper< summer!layer 10-20m -1 to4 30.0-32.5 4.0-6.0 7.90-8,00 46-50 300-700 Winter layer -20 m to bottom 1.6 to 0.5 32.5-32 Summer July-September 8 to11 29.0-;31.86.4-6.7 8.10-8.15 5-25 200-500 Summer layer 10-20 m 2 to6 31.5-32.0 3.5-5.5 7.90-8.0545-50 300-750 Winter layer 10-20 m to bottom 2. Southerncoastal region of the Ciulfof Anadyr from the mouth of the Anadyr River to Cape Navarin, Summer July-September! 8.45-8. 25> 10-25> 200-500 2.0-9.5 1.0 to 14.5 26 0-31.0 10.5-7.0 Summer layer 10-25 m 500-1,000 1.0-0.5 31.0-3 3.0 6 0-5.0 8.20-7. 90 30-75 Winter layer 10-25 m to bottom +3.2 to 1.3 3. Yukon-Kuskokwim region to the east of 168 W between 5 and 64"N! Spring June! 1.0t 14 5 12.4-32.4 8.0-1.8 nodata 2-:30 50-1,400 Summer Layer 10 m 3.2to 1.3 312-32.4 4.6-1.9 nod ta 20-,0 50-1.400 Winter layer 10 m Io bottom SummerI July-September! 5 7 to 11 5 297-31,7 6.95,5 n<>data 5-15 150-550 Summer layer 10 m 3!.A-32.0 6.7-5.6 no-1.7 32.6-33.6 8.9-6.0 . 15-7.90 r>0-90 500-700 0.5-1.5 Winter layer 35 m to bottom Summar July to September 3,6to 8.0 31.0-33,08.2-6,5 8 30-815 5-30 150-400 0,5-6.5 Summer !eyer 0-30 m 1.2to 2 4 32.0-333 10.0-4 0 8.24-7,0 50-90 400-1,2001 0-4.5 Winter layer 30 m to bottom Fall october 1 2.5to 5.5 31.-33.2 7.6-8.7 8.30-820 12-40 400-00 0.1-36 Summer layer 0-35 m 1.5to 2.5 33.3-33.88.1-4.9 8.20-7.85 40-80 800-2,5000.5-2.5 Winter layer 30 m to bottom Oceanographic.Descripti oin the BeringSea 90 Table12,7. cmntinnedJ Boundaries andcharacteristics ofsurface water masses inshallow regions of the Bering Sea during various seasons.

P S j VO-."4 Temperature Salinity 0, 'C! ppt! ml/L! pH mg/m' tmg/nr'! mg/rn'!

5. Western coastal zone from CapeNavarin to KamchatltaStrait! at depth to 200 m, Winter January! -1.5to 1.6 32.7-32.8 7.9-7.R R,lo-8.08 62-65 750-850 1.5-1.5 0 rn to bottom Spring May-June! 100-200 P. 1-1.0 Summer 0-25 m 0,0 to 4.5 81.5-32,7 11.5-8.2 8.60-8.20 12-30 200-850 1.0-2 8 Winter layer 25 rn to bottom -1.8 tc 0.0 32.7-33.4 8.9-2.8 8.30-7.59 40-130 Summer July-September! 7.5-6.5 8.20-8.05 20-60 400-750 1.5-3/7 Summer layer 0-40 m 3.0 to 8.5 28.5-33.0 7,4-5.2 8.10-7.90 60-85i 700-1,200 1.5-35 Winter layer 40 m-bottom 1.2 t ! 3.0 33. 1-33. 3

6. Eastern shallow region east of line between St. Mattbevr Is]and and Pribilof islands-Unimak Pass Summer layer 0-15 rn 6,2t.o 9.2 31.9-32.5 7.5-7,2 8.25-8.15 30-5iD 100-300 Winter layer 15 m-bottom 1,5to 3.5 32.5-32.6 7.5-6.8 8.20-8.00 50-65 250-550 Summer July-September! 3.0to 10.2 31.2-32.3 7.8-7,3 8.20-8.05 20-70 250-1,0000.1-6.5 Summer layer 0-20 m Winter layer 20 rn-bot.tom 1.9to 'A.p 32.2-33.4 7.3-6.0 8.10-7.90 40-100 500-1,0000.5-8.0

7. Continental slope < 2,OOOm, Winter Jarnuary! Mixed layer of surface water 33.1-33,2 7.5-7.2 8.11-8.09 65-66 750-800 0.2-0.7 Upper boundary 0 m 0.7 to 1.4 33.2-33.3 7.2-7.0 8,07-8.02 88-75 800-9fi0 0.2-t .8 I,ower boundary 300-420 m 1.5 to 1.7 Spring May-June 1 Upper t summerI layer: 32.6-33.3 9.6-7.7 8.4?-8.15 10-30 100-300 0.1-2.0 Upper boundary 0 m 1.4 to 4.5 33.1-33.35 8.6-7.2 8.38-8.08 30-60 200-500 0.5-4.0 lower lrnundary 35-50 m 0.7 to 3.2 Winter layer: 1.8co 2.8 3345-33,55 7.5-4.5 8.10-7.90 60-85 600-800 0.1-1., lower boundary 300-450 m Minimal temp, in coreof winter layer is +1.Dt<> 3.0=C, Summer July-Sep t 7.2-7.0 8.30-8 10 25-op 250-600 0.5-3.0 Summer layer 0 rn 6.5 to 10.0 3.25-33.0 7.4-6.5 8.05-8-00 60-65 700-850 0.5-7.0 lower boundary 50-80 rn 3.0 to 4.0 33.1-33.2

Winter layer: 3.2to 3.3 33.5-33.6 ',0-4,0 7.80-7.70 65-85 1,400-1,6000.1-I0.5 lower boundary 250-300 m Minimal temp. in corenf winter layer is ~1.7' -to 3.5'C, 1"all Octn 33.0-331 7.2-7.1 8.25-8.15 20-30 700-900 1 5-2.5 Summer layer: 0 m 5.3 to 7.0 33 1-A3.3 7.0-6,9 8,15-8.05 50-60 1,000-1,500?1.5-3 5 lower boundary 50-60 m 4.0 to 5.0

Winter layer: 33.5-33.5 5.5-4.5 7.95-7. 85 60-75 2 500-2900v lower boundary 250-300 m Mtnirnurn temp. of core of vnnter layer i: +1.7 to 3.5-C Ecologyot tlie BeringSea: A Reiiewot Rus>iant iteratLire 91

Part 2:1-12,U.S, National TechnicalInforma- REFERENCES tion Service, TT 67-51024, Antonov,V.S. 1958. The role of continental discharge in thecurrent regime of theArctic Ocean, Probl. Belyakov,L.N., and V,P. Rusanov. 19 i 1.The distn- Severa 1, Izd, Akad, Nauk SSSR, Moscow. bution of Pacific Ocean water in the Arctic Ba- sin accordingto nutrient data. Prob!.Arktiki i Arsenev,V.S. 1965. Water circulation in the Bering Antarktiki 38:112-115. Sea.Okeanologicheskiye Issled. 13, Moscow. Bogdanov,K.T. 1961. Water exchange between the Arsenev,V.S. 1967. Currents and water massesin BeringSea and PacificOcean through Near the BeringSea. Nauka Press, Moscow. English Strait. Tr. Inst. Okeanol.Akad. Nauk SSSR38. translationby S. Pearson, 1968, U.S. Dept. Corn- Rorisov,L.A. 1975,Changes in averagesea level inerce, NMFS, Seattle, 147 pp. height.in theeast. Siberian, Chukchi and Bering Arsenev,V.Sand A.O. Shchebinin.1963. Research seas, Okeanologiya 15' 6 t on current.s in Aleutian waters and the Bering Sea, Okeanologicheskiye Issl. 8, Moscow. Bulgakov,N.P. 1963. The effect of compressibilityof seawater on thermo-convection,Vopr. Geografii Arsenev,V.S., and V,I. Voytov.1968. Relative clarity 62. andcolor of BeringSea water, Okeanologiya 81 Bulgakov,N.P, 1964. Ice distribution in the Bering Atlas of the Global Water Balance.1974. Supple- Sea, Okeanologiya 4i 5 I:831-841. ment to the monographGlobal Water Balance and Water Resources of the Earth. Gidrome- Bulgakov,N.P. 1965. The winter limits of icein the far eastern seas OkeanologicheskiyeIssled. teoi zdat. Moscow-Leningrad. 13:66-76, Nauka Press, Moscow. Babkin,V.land T.E. Grigorkina. 1991,Water resources of the Far East: Their development and Burkov,V,A. 1958. The hydrology of the Coininander- applicationin agriculture.Tr. GGI352:28-44. Kamchatkaregion of the PaciHcOcean iiuring spring.Tr. Inst.Okea»ol. Akad. Nauk SSSK 27. Babkin,V.I., G.A. Plitkin, andT.E, Grigorkina. 1991. Interannual variation in discharge from Za- Burkov,V.A., and Y'u.V.Pavlova, 1963. Geostrophic baykalrivers in the Far East.'I'r. GGI 352:45- circulation at the surface of the iNorth Pacific du.ringsummer. Okeanologicheskiye Isslerl. 9, 51. Izd. Akacl. Nauk SSSR, Moscov;. Babkin et al. 1990. Methods for calculation of annual disrhaige and its intra-annualdistribution Burmistrova,V,D. 1956. Sciisonal changes in baric in the absenceof hydrological data, Tr. CEGI and wind fields over t,he Bering Sea. MGY I!41os- cow. State Universit.yl. 338:13-35.

Babkin et al. 1991. Current water resources of the Coachman, L.K., K. Aagaard, and P.B.Tripp. 1975. USSR. Tr. GGI 352:3-21. Bering Strait: The regionalphysical oceanography.Univ. Washington Press, Sr.attle, 1i2 pp. Batalin,A,M, 1959.lieut, balancein the far eastern Russian translation, 1979, The Bering Strait. seas, Izv. Akad. Nauk SSSR,Ser. Geogr, 7. Gi drometeoizdat200 pp. Batalin,A.M. 1960. Attempts at the computationof Davidovich,R.L. 1963.Hydrochemical features of heat balancein the BeringSea. Komissii Akad, the southern and southeastern Bering Sea Tr. Nauk SSSR 7, Moscow. Vses. Yauchno-lssled. Inst. Morsk. Rybn. Khoz. Okeanogr. iVNIROi 48, Moscow Batalin,A.M. 1964.Water exchange between the BeringSea and Pacific Ocean. Tr. VNIRO 49:7- Davydov.I.V., and F F.I.ipetskiy, 1970. The hydrol- 16.Fnglish translation, 1968, in; Sovietfisher- ogyof the Karaginand O]yutorsk-Navarinrorn- ies investigationsin the northeasternPacific, mercial fisheries regions. Izv. Tikhookean. OceariographicDescription of the Heriiig Sea 97 Dunayev,A,L., and V.K. Pavlov. 1991, Some results Nauchno-lssled.Inst. Rybn. Khoz. Okeanogr, of the arcticexpedition on the RV Akaderiiik TINROj 73, Shokal'skiy.Tr. ArkticheskiiAntarkticheskii Dobrovolskiy,A D,1949a. A mapof surface currents Nauchno-Issled. Inst. 425:101-106, in the North PacificOcean. Tr. Inst. Okeanol. Fedorova,Z.P, 1968. Transfer of saltsthrough the Akad. Nauk SSSR 3, Beringstrait to the Chukchi Sea. Okeanologiya Dobrovolskiy,A,D. 1949b.The position of the zero 7 1 !:49-54. surfacefor dynainiccornput.ation in theNorth Fedorova.,Z.P., and Z.S. Yankina, 1963. Inflow of Pacilic.Tr. Inst,Okeanol. Akad. Nauk SSSR 4, Pacificwater through the Beringstrait to thc. Dobrovolskiy,A,D. 1961a,Determination of water Chukchi Sea. Okeanologiya 3!. masses.Okeanologiya 1 I!. Fedosov,M.V,, and R.L, Davidovich, 1963. Some fea- Dobrovolskiy,A.D. 1961b. Water masses in thewest- turesof thehydrochemical regime of the Bering ernPacific Ocean. Tr. Komissii po rybokhozyay- Sea, Tr. VNIRO 48, Moscow. stvennymissledovaniyarn zap. chasti Tikhogo okeanal Proceedingsof the FisheriesResearch Gerinan,VKh., and A, Levikov.1988. Probability Commissionfor the WesternPacific]. Pishche- analysisand tnodeling of variationsin sealevel. Gidrometeoizdat, Leningrad, 232 pp. promizdat, Moscow. Gershanovich,D.E., andV.V. Natarov. 1992. The Dobrovolskiy,A.D., and VS. Arsenev, 1959. Currents in the BeringSea. Probl. Severa 3:3-9. English BeringSea; A collectionof articles.Vol. 8. translation,National Resource Council Cana- Girs,A,A, 1973.Multiannual variations in atmo- da, Ottav a. sphericcirculation and long-terin tendenci esfor Dobrovolskiy,A,D., and VS. Arsenev. 1961. Hydro- changein hydro-meteorologicalconditions in the logicalfeatures of the BeringSea, Tr, Inst. BeringSea region. Probl, Arktiki i Antarktiki Okeanol.Akad. Nauk SSSR38. 42. Gorshkov,S.G. 1980a, Atlas ofthe oceans.Informa- Dobrovolskiy,A.D., and B.S. Zalogin. 1982, Seas of tion tables.Publication of the DefenseMinis- theUSSR. Moscow University, Moscow, 192 pp. t.ry. Dobrovolskiy,A.D., A.S. Ionin, and G,B. Udintsev, Gorshkov,S,G, 1980b. Atlas of the oceans.The Pa- 1959.The history of researchin theBering Sea. cificOcean. Publication of the DefenseMinis- Tr, Inst, Okeanol.Akad. NaukSSSR 29, try. Doronin,Yu.P. 1986. Regionaloceanography, Grigorkina,T.E. 1979. Water resources of'far east- Gidrometeoizdat,Leningrad, 304 pp, ern rivers and their variability with time. Tr, Drogaytsev,D.A. 1954, Construction ofwind fields GGI 260:74-82. overthe ocean. Tr. Inst. Okeanol.Akad. Nauk Gudkovich,Z.M, 1961. The nature of Pacificcurrent SSSR 9. inthe Bering Strait and the reasons for the sea- Drogaytsev,D.A.1955 Computation oftangential sonal differencesin its intensity. I!. windstress curl over the sea, Meteorol. Gidrol. 5. Gurikova,Z.FT.T. Vinokurova, and V. Natarov. 1964,Wind circulation scheme and currents in Drogaytsev,D.A. 1956. Construction ofgeostrophic the Bering Sea during August, 1959-1960 windfields over the sea,Meteorol, Gidrol. 2. VNIRO 49, English translation, 1968,in; Sovi- Drogaytsev,D.A. 1959. Long-term ineteorological et fisheries investigationsin the northeastern predictionsbased on computation oftempera- Paciftc,Part 2:48-77,U,S. National Technical ture oscillations.Gidrometeoizdat, Leningrad. Information Service,TT 67-51204, Ecologvot tfie Hc ring Sea: A R l aerature

Zooplanktonofthe Bering Sea: A Reviewof Russian-LanguageLiterature InstituteK.O. CoyleofMarine Science, Schoolof Fisheries andOcean Sciences, Unir.ersity ofAlaska Fairbanks Fai rbanks, Alaska

V.G.Afarine ChavturBiology Institute, Russian Academy ofSciences ofthe Far East Vladi vostok, Russia

A.l. Pinchuk ZoologicalInstitute, Russian Academy ofSciences St. Petersburg, Russia

searchquestion. To address the above concerns, we ABSTRACT havecompiled much of the literat.ure on zooplank- Themajor Russian-language literature addressing t

A.I.Piitchtdt etttreotly iestudying stthe School of't isheriee andOcean Sciences, L ttiversity tjfhlaska Fatrbattits Zooplanktonor the0cririg Sea 98 collectedlater 929! by the expeditionon the ice- planktology.In addition, a numberoflarge biblio- breakerF. Lr'tke. Unfortunately, plankton materia! graphicpublications have appeared i Romanov 1959, fromthese cruises was never processed. Early in Fotapov1965, Mileykovskiy 1970, Chavtur 1965!, the 1930s,samples were collected froni the western makingit easier to! ocate the available information. andnorthern Bering Sea, the Bering Strait, bays Most of the previousresearch on BeringSea alongthe Chukchi Peninsula and t,he Gulf of Anadyr' zooplanktonhasdealt with species and community bythe Pacific Expeditions ofthe Governrnr.nt Hy- composition,andspatial, vertical and seasonal dis- drographicInstitute and the Pacific Institute of tributionrelative to watermasses and current pat- Fisherieson the trawlers Dalrrerrostok 932! and terns.Such information is usefulin the preparation Jtrasnoarrneyers933!. Duringthese expeditions, of ongoingand future research projects to avoid planktonwas routinely collected from depths of200- duplicationandto target new efforts inregions and 500m andt.wo samples were taken to depthsof seasonsso that the maximumamount of informa- greaterthan 1,000 rn, The results from some ofthe tion canbe obtainedwith availablefunds. Modern sampleswere published byStepanova 937i; only ac9b,19631 onthe vesselsTnvmyr and 1roygach 910-1914k From 1949to the present.,the Pacifi fecriogycrfthe Bering Sedi .4 Review otRussian l r'teralure mass,and potential plankton-fish interactions. Bio- Vladivostoklhas undertaken studies of the food massvalues reported here are in formalin-preserved stocksof corninercialfishes from the surfaceto depthsof 100-200rn, rarely to 500-1,000m.Morc wct weightunless otherwise noted, than4,000 zooplankton samples were collected duringthe above period, about 1,500 ofwhich were tak- TAXONOMICCLARII-ICATION enin spring May-June l, more than 1,900 in summer July-September|,morethan 200 in fall October-'I'henames applied to someof the common zooplank- November!and about 400 in winter November-tontaxa in thisreport may be different in someof Apri/!,Numerous research vessels, exploratory thepublications cited due to differencesin publica- fishingvessels, and coininercial vessels were used tiondates and differences between east, and west in for this research.The most intensive research was theapplication ofgeneric and specific designations. undertakenbythe Bering Sea Commercial Research Thefollowing explanations should clarify any name cont'u sion. Expedition,1958-1964, sponsored byTINRO and the EVhenzooplankton research was begun in the All UnionInstitute of Fisheriesand Oceanography BeringSea, the only Calanus species recognized for in Moscow VNIRO!. The results of the aboveexpe- Arctic-borealwaters was C. finmarchicus.Since ditionswere published in a conipendiumon Soviet then,C. fi rrmarchicushas been divided into tv o new fisheriesresearch in the northeasternPacific Ocean species:C.p aria isand C. rrrarshal!ae. Most Rus- r Moiseev 1970!. sianliterature identifies Calanus in the BeringSea Duringthe 1960sresearchers at TINRO again asC. glacialis because C.marshallae was described initiatedplankton research in thewestern Bering as distinct from C. glacialis only recently Frost Sea.The results from theseexpeditions were pu.b- 1974!,and the differencesbetween the two species lishedin a seriesof papers Volkov 1988. Volkov and arenot always distinct. There is undoubtedlya great Efimkin 1990,Efimkin and Radchenko1991, and othersl. Unfortunately,more than half of themate- dealof overlap in therange of the two species in the rial collectedduring these expeditions was discard- BeringSea and there may be considerable hybrid- ed;the remainder isstor ed at DVO RAN. All reports ization.The tivo species name.s sornetiines are used interchangeablyin the literature. on TINROcruises are archivedat TINRO Vladi- Recent.ly,thc genus Calanus was divided into vostok!. In additionto Russiaand t,heLrnited States, Xeocalanusand Culanus tBradford and Jillett 1974i .Japaneseresearchers have devoted special efforts andthe speciesCaiarrus plurrrchrus and Calcrnus to theBering Sea, especially to fisheriesi'esearch. cristatuswere assigned to Ãeocalarrus. Russian tax- The Oshr>roMaru was particularlyactive in the onornistsdo not generally recognize the distinction 1950s-1970s.primarily during summer. A nuinher andcontinue to referto the abovetv o specie. of publicationshave resulted Karohji 1958, 1959; Calanus.Thus, X. cristntu»and X. plur»cirrusare Minoda1958; Kawamura 1961; Koseki 1962; Kuri- identicalto C, cristalusand C.plume hrus in Rus- oka 1962;Murioka 1962; Namaoka 1970; Nemoto sianliterature. Russian researchers refer to a sniall 1933,1962; lVIarumo 1956; Kawarada 1957; Kawara- raceof C.plunirhru,s which may be identical to a da andOhwada 1957; Yabuguchi 1957; Iizuka and newspecies, lV. flerrringeri, recently described from Tamura1958; Kusajima 1959; Yamaoto 1959; Nish- the North PactftciMiller 1986cX, plume-hrusand io 1961;Varnanat.a 1961; Kawarnura 1963; Ohwada ,'v'.fleming eri aremorphologically nearly identical andAsaoka 1963; Ohwada and Kon 1963; Yarnaza- andhave essentiallybeen lumped together in most ki 1963;Okori 1965; Katsumura 1966; Kotori 1969. of thc literature. 1972,1976; Taniguchi 1969, 1976; Fukuchi 1970; Pseudocala»usspecies in theRussian literature Marioka1970; Minoda 1971; Yamade 1971; Ikeda havecommonly been assigned to P.elo»garus and 1972;Karohji 1972; lVlotoda 19r 2, 197',3:Taguchi P,mi rrutus. The differences between the speciesin 1972;Motoda and Minoda 1974; Shim ura 1975;Sai- thisgenus are extrerncly minor and species distiric- noand Hattori 1977; Ikeda and Motoda 1978; Ornori tionswere long considered uncertain. Recent literature in. t,hetrVest has oftenreferred to speciesiii 1965 t Thisreport summarizes mainly the Russian lit- thisgenus as Pseudocalanus spp. Frost i 1969rde- erature. Much of the English Japaneseliterature scribedseveral new species of Prseucfcrcalonrrsand hasbeen suminarized in two compendiums Hood redefinedolder species designations using biochem- andCalder 1961, Hood and Kelley 1974 t The fol- icalevidence and very minor morphological distinc- lowingchapters summarize information on the tax- tions.The specific de ignationsused for Pserrdrr- onomy,community composition, horizontal and calonusin thc Russianliterature do not necessarily verticaldistribut,ion, abunclance and wet v, eight bio- conformto the desigriationsof Frost r 1989'. Zooplanli

Recent Russian literature has referred to Sag- Table 1. Numbering system for silk mill cloth itta elegansas Parasagitta elegans, and Centropag- Kiselev 1969! esmcmurrichi in the Russianliterature is usually Mesh designatedCeritropages abdorniiialis in the West, 14esh No No. pores Old New per cm-' s ize i min ! While these and other taxonomic difficulties or un- 7 certaint.ies are not itnportant in most fisheries re- 0000 I 49 1 364 search,detailed studies of the structure and 000 9 81. 1.024 dynamicsof planktoniccommunities for biogeo- 00 11.5 132 0.752 graphicresearch and pollution impact will proba- 225 0.569 bly requirea carefulanalysis of the systemat,icsof 15 01 19 361 0.417 notonly the inajorgroups, but othergroups as well. 0.336 There aremany keys for identificationof Bering 21,5 441 Seazooplankton. Unfortunately, not all groupsare 23 529 0.333 includedin keysand someof the keys do not meet. 24.5 580 0.318 the demandsof current research.Some Brodskiy 246 26 37 676 0.282 1950,for example!contain short descriptions and 29 841 0.239 poorillustrations which are often insufficientto 32 1034 0.224 make a positiveidentification, Others are not use- 34 1156 0.203 ful askeys, since the species diagnoses do not always 9 38 1444 0.168 use taxonomicallyvalid characters Vinogradovet 10 43 1849 0. 158 al. 1982!.Some of the charactersare so dificult to 11 46 2116 0.145 assessthat theyare useless in field keys Kasatki- 2300 0. 112 na 1982!.Due to the paucity of inforination it con- 12 13 51 2601 0.112 tains,the publicationA FieldGuide to thePlankton 0.099 972! is useful only f'or identification of the most 14 55 3025 0.094 morphologicallydistinct species. 15 59 3581 Methodological note: Russian planktologists 16 62 3730 0,086 usuallyreport the mesh size of theirnets as a inesh 17 64 4225 0.081 number.Since this systemmay not be familiar to 18 66 4356 0.079 westernresearchers, a briefsummary from Kiseiev 19 67 4489 0.077 969>is presentedhere for the benefitofthose who 20 68 4624 0.076 mayseek out the original literature. For small nets, 25 77 5929 0.064 the inaterial is referredto as inill cloth andthe lit- eraturemay report the meshsize using old or new mill cloth numbering systems Table 1 showsthe old and new nunibering systems,along with the cor- Table 2. Numbering system for coarse respondingmesh size in inm. The newsystem is mesh. Corresponding silk mill most commonlyencountered in the literature as it cloth numbers are given in pa- givesthe numberof threadsor poresper 10 rnm of rentheses from Kiselev 1969!. netting. In addition to inill cloth, coarsenets may havetheir ownnumbering system, The coarse mesh 14, 16, 18 000l numberingsystem and corresponding sizes for the 20, 22, 24 00! old mill cloth numbering systemare presentedin 26, 28, 30, 82 0! Table2 sothe numberingsystems can berelated to Oi eachother. Most Russianplankton programs in the 34, 36, 38 BeringSea from 1949to 1982used a standardgear 40, 42, 44 ! type,usually reported as a 37cm dianieterJuday 46, 48, 50, 52 ! net with Xo. 38 .168 mm! mesh Volkovand Chu- 54, 56 ! chukalo 1985!.The data in this compendiumwas 58 60 > collectedwith this standardgear type unlessother- 62, 64 <5i wise stated. Lubny-Gertsyk!1961!reported using 66, 68 i ichthyoplanktoiigear with No.150 silk netting.This 70, 72 ! is probablya misprintsince the standardichthy- oplanktongear uses No. 15or 0.569inm mesh. Ecologyot lie 8eritig.'iea:A Revieiir> RussiariLiter~tore

FigureI. Faunisticgroups ofeoop1ankron in theRaring Sea for summer 6ased on samp1es andiiterarore data throughI952. I issouthern Bering Sea rr< conic group, 2 isnorthern Bering Sea oceanic group, 3 isirene emneritic group, Vis eastern neritu group modi fied from Vinngradoo 19566!.

SPECIESCOMPOSI'TION Based on faunistic analysis of calanoid copep- Accordingto Kun 975h the planktonicfauna of ods,Brodskiy 955, 1957!and Rrodskiy et. al. ~ 1983I the BeringSea includes about 300 species; the fol- identified four major faunistic groupsin the upper lowinggroups are mostabundant: Copepoda, Coe- pelagiczone of the Bering Sea: southern Bering Sea lenterata,and Amphipoda. The above taxa makeup oceanic, northern Bering Sea oceanic, western ner- 37%,17'7o, and 12'7rof the total abundancerespec- itic, and easternneritic Figure1, Table3c Fach tively.The species composition of the epipelagicre- grouphas its primaryand ~condary species, defin- gion-200 rn!has received the most attention. Little ing the faunisticfeat.urea of the group.The disti~- research has been done on the deep fauna, especial- bution and locations of the major aggregatesof the!e ly on organismsof all majorsystematic groups liv- speciesare relatedto hydrographicand seasonal ing below1,000 rn with the possibleexception of conditions,and changesin speciescomposition in- the copepods!,Nevertheless, the informationavail- dicatechanges in physicaland temporal conditions. ableon the deepwaterplanktonic fauna doesgive a The.copepod faunistic groups and their distrihutioii rough representationof the structure and charac- as definedby Brodskiyalso hold for otheranimal ter of vertical distribution. groups Vinogradov 1956ai, although the exact Zory yart feinr ~ffh< Herirfoo Sea

Table3. Speciescomposition offaunistic groups ofpelagic calsnoid copepods inthe Bering Sea

Frequency Percent of tota1 Frequency Percent oftotai at the pop ui ation at the popu1 at,ion stat>one Species density stations Species density Western neritic group Southern Bering Sea oceanic group 100 Pseudacalanus e ongafws 69.5 ]00 Pseudocalanu s elongatu.s 35.0 Centropagesabdorni nalis 11.5 Ca-lo nu.s pl umchrus 8.6 75 Evcalanus dungii Eucalanus burigit 8.16 Acarti a longi remi» 9.1 Calan u s cri sta f us 1.56 50 Afetridia pacift'ca 2.96 75 Metridta paci fica 45.6 Calanus glacialis 50 Scoleci thri eel a mi nor <1 Calanus plumchrus <1 25 Acartra longtremis <1 Acartta tvmida <1 Aficroca anus py gmaeus 4 Pseudocalanus sp. Gaefanus simp ex 25 Ca anus crfstatus Pareuchnetajaponica 1 2.58 Pleuromamma.vcufullata 1 F urytemora ftfeferi Euryfemora herdmani 1.64 Candacia columbiae 1 Sco ecith rf ce a mi nrrr Uaidtus uarfabilis 1 Acartia clausi <1 Heterohabdus fanneri 1 100 Torfartus discavdatur Po n uchaeta japonica 100 Vorthern Bering Sea oceanic group 100 Pseurlocalanuselongatus 66.6 <'alanvs glar ialis 3.07 Eastern n critic group Pseudocalanus elongatus 61.6 hfefridia yarifica 24.2 100 Acarfia longiremis 24. 1 Errrolanus bung i 1.35 75 1.96 Galan vs plum chrun <1 Calanvs glacialis Tortanus dtscaudatus 2.63 Ca anus cri status Epilabtdoceraamphifri tes 1 Microcalan us pygmaeus 4.45 50 Cenfropagesabdomi nalis 2.75 Acartia longirernis 1.93 cl Scr>lect'thricella m'tnor Eurytemora herdmani Arartfa claust 4,84 Pseadnralanun sp. 25 <1 Centrr~pages ah domi na f's <1 Eucalanvs bungi t Acarfr'cl r' aust' <1 Met rtdta pari fica 100 Calanus plumchrus Calanus cri status Sco et r thrice a minor fficrocalanus pygmaeus < 1 100 4'rrte,Accocdrntt tnTI YRt! date, danstty inall nr the Srnnps isdominated byOrafrnrro atmrfra,pscrrtfnnrfa avenccupie~ secondpiner Fcolog>of the Hering Sea: A RevieivorRussi,in Literature 10.3

St. LawrenceIsland, the northern BeringSea group boundariesbetween groups can vary somewhat from mixeswith oceanicand neritic species.Some spe- yearto year Vinogradov1956b, Volkov and Chu- ciescharacteristic of the northernBering Sea group chukalo 1985!. Thesouthern Bering Sea oceanic or "openocean" canbe carried into Norton Sound. the Gulf of Anadyr, groupoccupies thesurface layer to 200 m depthover and southto CapeLopatka alongwith the cold all deepregions of the BeringSea. Its faunistic epibenthicwater layer. compositionis nearly identical to that of thesur- The neritic group,conditionally divided into facelayer of the northwesternPacific. This group westernand easternsubcategories, occupies coast- characteristicallyconsists of large concentrations of al water and alsothe broadshallow shelf of the themajor open ocean species in the far-easternseas: western,eastern, and northern Bering Sea. The dis- Calanuscristatus, Calanus plumchrus, Fucalanus t,ributionof the neriticgroup changes markedly by bungiiand less abundant bathypelagic species: Ra- season,reaching its greatestrange in summerand cooitzanusantarcticus, Scolecithricellami nor, pract,icallydisappearing in winter.Although Parathemistojaponica, Oncaeaborealis, Primno Stepanova937l listedseveral species character- macropa,Vbmopteris spp. and others. The first. three isticof the easterngroup but absentfrom the v est- calanoidslisted abovemake up the dominantzoo- ern,all of'those species were later identified from planktonbiomass and are major food items for theAsian coast Ushakov 1947,Vinogradov 1956b!. planktivorousfishes in the BeringSea. Therefore,the speciescomposition of both coasts The oceanicgroup is carriednorthward in a appearsto beidentical. Differences between the broadband along with BeringSca slope waters into easternand westerngroups involve the relative theGulf of Anadyr,through the AnadyrStrait and densitiesof warmand cold-waterspecies and the into the ChirikovBasin, where it mixeswith the disappearanceofwarm-water species from the Asian northernBering Sea and neriticgroups, Some oce- coastat moresouthern latitudes than on the Amer- ican coast. anicspecies are carried clear through the Bering Theneritic group,inhabiting shallow brackish Strait and into the Chukchi Sea, Theoceanic group is mostclearly expressed in regions,is characterizedbydense concentrations of the southwesternBering Sea,along the Aleutian Podonleuckarti, Centropages abdominalr's and, in Island archipelagoto the CominanderIslands, someregions, Acartia clausi, which is sometimes wherecold intermediatewater is overlainby a seenin denseconcentrations in brackishor pract,i- warmersurface layer. Warm-water species such as callyfresh waters of estuaries. Barnacle nauplii and bivalvelarvae, Acartia longiremis and Eurytemora Calanuspaci ficus are carried as far north as60"N herdmani,occur in somewhatmore open, saline con- with this warm surface layer. Speciescommon to ditions Echinoderrnlarvae predominate in coastal the North Pacificbut rare in the Bering Sea Sagit- waterswith little or no freshwaterinfluence. De- ta lyra,Phrotuma sedentaria, Paraphroiuma cras- pendingon the species composition, polychaete lar- sipesetc. t canbe carried into t.he Bering Sea with vaecan sometimes occur at highdensities in coastal thedeeper layers flowing northward through the watersduring fall, but are alsosometimes ubiqui- Aleutian Island passes, Thenorthern Bering Sea group occurs over the toussduri ng spring. shelfin the northernBering Sea. It is characterized An especiallyrich developmentof the neritic bya partialor totalabsence of'the major open ocean communityoccurs in thebroad shallov; regions of species,in particularCalanus cristatas, Calanus theeastern Bering Sea; the neriticcomplex ranges plumchrus,Prirnno macropa and other warm-wa- northwardthrough the BeringStrait andinto the ter taxa, Coastalspecies are also usually absent. ChukchiSea Virketis 1952,Vinogradov 1956b. Dominantspecies in the northernBering Sea group Pavshtiks1984, Pinchuk 1993!.Iiowever, due to includeCalanus glacialis and Pnrathemistolihet- coldertemperatures north of St.Lawrence Island, lula, which are seenas far north as 8o=N. the areaoccupied by the warni-waterspecies con- The northern Bering Sea group in its purest siderablynarrows, This colder northern region. the formwas observed only towardthe mouthof the 'hirikov Basin,conl.ains more cryophilic species, Gulf of Anadyrin 1950-1953 Vinogradov 1956bh characteristicof bothcoasts. The oceanic. northern, However,judging from the resultsof otherexpedi- andneritic groups inix in theCbirikov Basin, The tions Johnson1953!, t,his group usually encompass- westernBering Sea neritic groupoccurs south of esthe entireregion between St. Lawrenceand St. St. LawrenceIsland in a relativelynarrov band MatthewIsland, and appears to beassociated with alongthe coast; it widensonly in theGulf'i! f Anadyr watershaving temperatures ar'ound O'C andsome- andOlyutorsk Bay. The freshest regions are occu- what lower salinities than oceanicwaters. North of piedby the brackish-waterconiplex, consisting iif Zorrpf,>nkurrrrr/ the BeringScu f04 andC, mcmurrichi,F-. herdmani, Cladoceru, and Limnocalanus grimalclii, Heterocope sp., Bosmi na echinoderm larva e disappear. sp.,Acartiaclausi and so on. This complex has been Seasonalchanges in the vertical distribution of describedfrom the Anadyr estuary Vinogradov zooplanktonarecaused primarily by changes inthe 1956b!,but it undoubtedlyalso occurs in otheres- hydrologicalregime inthe upper 200 m andare vir- tuaries.lf sweptout to sea,these species quickly tuallyabsent from the deeper layers. During win- die.For example, dense aggregates of deadL. grim- ter in theoceanic regions of the BeringSea, intense aldii wereobserved in surfacewaters of elevated coolingofthe upper 200 m and the near absence of salinityat themouth of theAnadyr estuary Vino- phytoplankton push the major mass of' zooplankton gradov 1956b!. belowthe layerof winterconvection. Zooplankton Transitionalzones with a mixtureof speciesoc- biomassis thereforevery low in the epipelagiclay- curat boundariesbetv'een species groups, thus in- er it doesnot exceed 50 mg/m', and it is distributed dicatingmixing of variouswater masses. Such 'I transitionalregions are commonly observed inthe relativelyevenly, Biomass below 200 rn increases to 200 mg/m' or more. BeringSea Stepanova 1937, Vinogradov 1956b, Dueto the warmingof the surfacewater and Pinchuk 1993!. phytoplanktonblooms in the upper 100 m, the zooplanktonmigrate from the warmer intermediate lay- V ERTKAL AND SEA SON AL er to feedand reproducein the epipelagiclayer, DISTRIBUTlON wheretheir biomass between 10 and 100 m depth canreach 1,500-2,000 rng/in' Figure2!. The biomass Fourbiological seasons can be distinguished in the of thelargest species, Calanus cristatus, C. plum- developmentof plankton:winter, spring, summer, chrus,and Fucalanus frurrgii, can reach 90%%ur ormore andfall, Theymarkedly differ from analogous seaof thetotal planktonic biomass. The ascent of the sonsin thepolar basin and Atlantic as follows: some largecopepods ends at the beginning of.July, when of theinajor copepod species reproduce in the win- theupper 0-25 m containnumerous copepod eggs ter,copepods undergo rapid growth in thespring andnauplii. The above species are advected north- andmolt to laterstages, and spring is theannua 1 v.ard over the westernshelf and into the shallower maxiinumin zooplanktonbiomass. As in the Atlan- regionsofthe northern Bering Sea along with the tic,there is a delayin t,heonset of biologicalsea- Anadyrwaters. Fucalanus bungir produces the sons from south to north, Winterextends from the endof Octoberto the greatestbiomass in thewestern shallow regions endof Mayin thewestern Bering Sea and until duringspring. The total zooplankton biomass in the April-Mayinthe eastern Bering Sea. Reproduction upper100 m is usually somewhat over 500 mg/m' andpopulation maxima ofCalanus cristat us and the However,near Olyutorsk Bay and Cape Navarin it largeform of C. plu.mchrus occur during winter. isbelow 200-300 mg/rn' Vinogradov 1956b t Unusu- Springruns fi omthe end of May to the end of June ally highbiomass of Calanusplumchrus i>,'3,000 andearly July. With the beginning of spring,phy- rng/m'!has been recorded northwest of thePribilof toplanktonblooms occur, Metridia paci fica and Eu- islands Meshcheryukova 1970a!. calanuslrurrgii reproduce, and polychaete and Biomassin the shallowregions of the ivest.em barnaclelarvae appear in the plankton.Summer BeringSea is low during spring, 200-300 mg/m'. Con- beginsat theend of June-July and continues until centrationsof E. bungiiand C. plumchrusare low the endof Octoberin the southand until thebegin- andthe biomassis composedprimarily of eggs,nau.- ningof Septemberin thenorth. During summer, plii,meroplankton, andsmall juvenile stages of cope- reproductionand annual abundance maxima occur podsand euphausiids, Biomass in theAnadyr cold forthe small race of Calanus plumchrus, for Oi tho- spotis evenlower < 100mg/m'! and is composedof' na rirnilrs, and for Parasagii aelegans. Also in the northernspecies group, primarily C.glaciulis. summerCarr tropages mcmurrichi, Eurvtemora herd- alongwith Parathemisto libellula andParasugi ita mani,and Podorr leuc/rar occur i in thecoastal re- elegaas Vinogradov 1956b!. Similar values 00-500 gionsand maximum abundances ofechinoderm and mg/m',rarely higher! have been reported for the bivalvelarvae are observed. Fall runs from the be- shalloweastern Bering Sea, where the dominant ginningof' September till the end of October in the copepodsare Calanus glacialis and Pseurlocalanus north and from Octoberthrough November in the mirrutus Meshcheryakova1970a, Kun 1975!. south.The annual abundance maxima of Metridia The neritic zooplankton group during spring pacificaand Pseudocaiarr usrnrnutus occur during consistsprimarily of rneroplankton polychaetes. fal].Phytoplunkton blooms cease at theend of fall barnacles,echinoderrns, bivalves!, with lov num- Lcologyof fhcBc irrl,'bea; 3 IZcrle>v !f k'us!rr rLifer itutc

4 Vjkaeck~i

Biomassetistridult'on rng!'m't along ageneralizedtransect northrr arrl through F'igure 2. theBering Sea rturcng spring. A istotal biomass, 8 rs di omass ofEueatanus bungri,C isbiomass ofCalanus plumchrus, D is bionrass ofCulanus cristatus from Vinogradoc1956hz

bersof coastalcopepod species. Total biomass does thelayer Calanusplurnchrus, C. cristutusr; type 2, not exceed50 rng/m' Mednikov 1957hBut because throughthe layer iVetridiapacifiica, Plcuromum- ofintense reproduction, certain species can achieve ma scutulnto!; and type,'3.below the layer. highbiomass during late spring:Podnn leuckerrti In the shallowernorthern shelf region the cold 00 mg/m"I,Centrnprrges mcrnurrichi 95 kg/m'h intermediatelayer becomes the cold eprbenthrc lay- andFurytetrrora herdrnani 7 mg/m"b er;ternperat,ures areeven lower in theAnadyr cold Thelarger copepods, K bungii, C.cristatus and spot.The colder waters are inhabited by speciesof C.plumchrus, gradually descend to deeperlayers the northerngroup, especially Colanus glacialis, in June-July.Distinct stratificationoccurs in Au- whosebiomass is greater in t,heepibenthic layer gustor a litt.leearlier, and the vertical distribution than in the overlyingwarmer water. A rapid cool- ofzooplankton acquires its typicalsummer charac- ingof surface waters in thefall leads to declinesin ter.The biomass maximum, averaging 470 mg/rn', zooplanktonabundance, especially in the colderre- occursin the relatively warm 8-10'! upper layer to gdonsnear the coast. The descent of Crrlarrusplum- depthsof 20-30 m, below which is thothermocline. chrus and C. cristatursf'ollov ing the spring bloori! Deeper,in the colderintermediate layer, a remnant leadsto increasesin the relativeabundance of Eu- from winter cooling,the biomasssharply decreases calanusbungii, Prrrtrtlrerrristo japonica. Pnrusagi f- to 100mg/m', and below 200 rn, in the v'armerin- ta elegans,and others. Seasonal changes in the termediatelayer, it again increases.During surn- verticalplankton distribution in thedeep Bering Sea rnerthree types of diurnal vertical migration occur aredue mainly to changesin thedepth distribution relativeto the coldintermediate layer: type 1,above of themajor copepod species i C. cri status, C. p um- Zooplanktonnf theHerrng Sea 106 from10,4% 9. 6 x10' tons! to 15.7%,49 x 10'tons t chrus,E. bungii!.The major populations of neritic ofthe total estimated Bering Sea stocks respective- speciesarelimited to the warmer freshened coastal ly betweenApril and October. Relative biomass in surfacewaters abovethe thermocline. During winterin the southwesterndeepwater thedeepwater regions ofthe Bering Sea decreased regionzooplankton biomass in theepipelagic zone duringthe above period from 78.8"r< 7.26 x 10tons t is low dueto seasonalmigration of the largecope- to 56,8%.42 x 10'tonal Shuntovet al. 1993b!, podspecies to deepdepths; it doesnot exceed 50mg/m' and consists primarily of eurythermal spe- PLANKTON DISTRIBUTION IN THE ciessuch as Oithona si mi li s andParasagitta elegans. SOUTHEASTERNBERING SEA Closerto the coastthe biomassis somewhathigher Therewere no data sufficient to produceany rnean- upto 100rng/m' near Karagin Island!, This ten- ingfuldistribution pattern of zooplankton in the dencyis especiallypronounced in the northern re- southeasternBering Sea before t,he TIVE RO-PIN RO gions,where the northernBering Sea group, expeditionsof 1958-1965. Based on samples from Calanrrsglacialis for example,has a widerdistri- theabove expeditions Figure 3 kmajor distribution butiorrin winter than in other seasonsand pene- andseasonal patterns of zooplanktonin the south- tratesclear to theoceanic waters of the BeringSea, easternBering Sea were outlined by Meshcheryak- However,the shallow shelf region is characterizedova964, 1970a,1970b!, Oceanic species, in mainlyby low biomass < 50 rng/m '! and the domi- particularEucalarrus burrgii, dominated over the nantspecies are Pseurtocalanus minutus, Oithona shelfbreak. Surface species Pseurlocalanus minu- similis, and Calartusglacialis. iVerit.ic species are tusand Calunus glacialis dominated in t.he shallow nearlyabsent during winter data available only for centralshelf region where. salinities v.ere someyv hat the westernregion; Vinogradov 1956b!, 'Theamplitude of diurnal vertical migrations of reduced,and neritic species Centropages nrcmurri- themajor species in theBering Sea usually do not chi andAcartia longiremis were dominant in the brackish coastal zone. exceed50 m, rarely 100 m. Therefore, diurnal verti- Substant,ialinterannual differences in bio~ass calmigrations in theupper 50 m haveonly a sec- werenot observed in the shelfbreak region; howe v- ondaryeffect on the species compositiori. They do er,interannual variability was observed over the notaffect the majorspecies or thecommunity type. shelf.Oceanic species occurred much farther onto Thesmall amplitude of the diurnalvertical migra- the shelfin warmyears whe.n the winter remnant tion is due mainlyto the cold intermediatelayer wateroccupied a smallerarea, temperatures were withrapirl changes in hydrological indices..tfetrtd- warmer,and thc 32 ppt isohalinepenetrated far- ia pacificaundergors the greatest vertical migra- theronto the shelf iVeshcheryakova19"r0b; Figure tion,followed by Parutlrernrstojaponica, Calanus 41 In addition,much denser concentrations of Cala- cristatus,Parasagittu elegarrs. and Oncaeuborea- lis. Minormigrations are noted for Calunusplum- nusglacialrs and Pseudocalanus rninutus were ob- chrusand Pseudocalanus rninutus and vertical servedin warmeryears, especially to the north of migrationshave not been noted in Orthorrasimr lis. thePribilof Islands and near Lrnimak Island. Warrn- Latercopepodid stages undergo greater migrations er conditionsalso seernerl to befavorable for pl ank- tivorous fishes. thando younger stages. Dense concentrations of Examination of material froin cross-shelf phytoplanktoncanaffect species difTerently. ..eris- transectsrevealed thatPseurlocalanus minutus and tutusavoid dense phytoplankton concentration, M. Calanus glacialis v erealways predominant during pacifrcaare indifferent tothem. and species such springand summer in theshallov regions of the asO. borealis, 0, similis,P, rninutus, and Parasag- southeasternBering Sea Meshcheryakova1970a i. itta elegansoccur at higherconcentrations in phy- Summerpopulation maxima of P. minutusand C. toplankton layers. glacialisnorthwest oft.he Pribilof Islands were rle- Two-thirdsof the annualzooplankton biomass layedby approximatelyone month relative to the in theupper 200 m of'the Bering Sea occurs over BristolBay populations. Regions of minimumplank- thedeep basin of the western regio~, the renrainder ton densitieswere always observed in the central occurringon the shelf zone r Shuntovetal. 1993b!. shallowshelf region Figures 5 and6!. Densit.iesand Theamount of zooplanktonin the shelf zone rela- exactpositions of the populationsand trarisition tive to the entireepipelagic zone increases as tern- peraturesincrease. Inthe upper shelf; and the lower zonescould vary somewhatseasonally; however, shelf-continentalslope, zooplankton stocks increase populationswere always elevated on the eastern and from10,8'r I 10'tons! to 27.5'4t 2.62x 10'tonal and westernsid,es of the Bering Seashelf. Some increas- 10r Ecologyofthe Bering Sea. A ReviewofRussian Literature

Figure4, Theeuitern boundary of Calanusplumehrus distributionand thepos tionof the subalpine tn Apri/ 1960and 1962.1 oi C. plutnrhrus bounrlory in 1960,2 i si n 19tl2;3 tsi soholi ne in 1960,4 ts iu 1962>from 34esheheryuki>ua 1970hz

esin thezooplankton biomass over the shallow shelf regionswere observed in August average values 100 ntg/nt'!. Zooplankt.onbiomass maxima vvere observed overthe slopein June,but movedshorev ard in Augustand September tFigure 7: Kun 1975 t The Junernaxirnutn ove:r the slopeand deepwater was dominatedbyseveral species. incontrast to the shal- lover regionswhere Pseutioralanus pretlominated. Calanusplume hrua was predominant over the shelf' brcakduring spring, while Eucufanus builii and Metridio panficu predominated in the summer and fall iMeshcheryakova1970b t Highestzooplankton F'figure9. Stationdistribution during Tf.'VRO plankton densitieswere observed between the Pribilof islands surveys,1958-196rj. Aboret 1 =-jrawfer and St. Matthew, island. Zhemrhug,end af June 1958;2 = Trauler During winter-spring February-April: zoo- Pervenets,end of Juneand ear yAugust 1959: planktonbiomass over the shelf break averaged 70- 3 = Trawler Peroenetgearly Septetnberf959: % rng/m".Early ropepodid stages of' C. frfuntchrus 4 = Trawler Ogon, September1959 fj'rom predominated.Biological spri~g in the southeast- A&sheheryakoua1964o Belaso: 1 =end ofltfay ern BeringSea begins in April andreache its ze- 1964;2 =June 1964; 3 =end of August 1964; nith in 5Iay-June.Average zooplankton biomass 4 = September1964 fromMesheheryukoea increasedas spring progressed but variedfrom year 1970a t toyear from 100 rnghm' to > 200mg.'tn'. Thephytoplankton data reported by Meshchery- akova f1964, 1970a,1970bi vvascollected in zoo- planktonnets. Therefore, the taxareported con- Zottpl,~nkton<~tthe Rc rj tgSoa

7ooplanktonbiomass mg ms> in thesouth- eas emBering Seo. Abovet At heend of2une 1968.Betotv: In earlyAug ust 1959.1, > 500, 2. 500-200,3, 200-100,4'. < 100 from kfesheheryakuva196'4n Figure6.Zoop!onkton btornass g/m-'!inThe0-10 n~ layer or 0 to fhebutton uf >fhe southeastern BeringSea.. Above: In earlyJune I964.Be- lorutIn late August J'9h4.1. > 100,2 50.10 !. ,3. 10-50, 4. 5 10, 5. 1-5, 6. <,5 ifroni 5 eeAeheryalzooa 1970a/. fcokrgyof theBering Sea: A Revieivot kirssianLiterature

ZOOPLANKTON DISTRIBUTION IN THE WESTE RN B ERI NG SEA Expeditionsof theInstitute of Oceanography I Vladi- vostok!operated in the v'esternBering Seaduring 1950-1953.Data were collected on the distribution, life cycles,and vertical migrationsof the majorzoo- planktonspecies, Kajor distributionpatterns and seasonal variations were outlined by Vinogradov 95bb!. Although somewinter data werecollected. material was insufficient to provide a winter distribu- tionmap; nearshore sampling was not possible due ta ice. Generally,plankton densitiesin the surface waters of the western Bering Sea were low and few specieswere present. In the absenceof largecope- podsin the upper 100m, the greatestbiomass was due to Oithonn similis up to 25 mg/m"! and Sagitta eligans I 10-50mg/m'!. The greatest concentration of S. elegans,excluding the northernsha]low region, was observed in western Kamchatka Strait at stations with unusually low temperatures. Biomass in the upper 100rn changerllittle from station to station, rlid not exceed50 mg/m"in the central region,and reached 100 mg/m' near Karagin Island. Due to aggregatesof Ãetridi a pncifico and Sngitta elegans,bioinass was markedly higher in the shallow region to the northeast of CapeNavarin <470 mg/m'!, Zooplanktonbiomass in the oceanicregions of the westernBering Sea was very high in May-June Figure7. Planktonbiomass distribution mg/m'r in the 1952,due to vertical migration of the large cope- eastern Bering 1eo iAugust-October 1968 rs podsor their developmentalstages to surfacelay- froin materiatcollected by Chuchukalo;early ers. The averagebiomass in the upper 100m v as June 1964 is from Meehcheryakooo1970!. 500-1,000rng/rn' over inuch of the region Figure 8, above!. Biomass to the east of Karagin Island and at individual st.ationsin other regions was over 1,000 sistedprimarily of largediatoins and dinollagellates. mgirn', sometimesexceeding 2,000 mg/m~. In con- Since it is no longer considered valid to attempt trast, biomass in the Gulf of Anadyr was usually phytoplankt,onstock assessments using net-caught under,'>0 mgim'. More than half of the biomass at samples,the data are not of muchuse in interpret- most stations consisted of Eucalonus frungii, with ing current researchor in planning new studies. highest values to the southeastof Karagin ]ala»d Detailedstudies of phytoplanktonand zooplankton IFigureb, below!.Ca/antes plumrhrus tended to have cornrnunities in the southeast Beriiig Sea were car- higher biomassthan E. bungii in the northwestern ried out in the late 1970s and early 1980s by regionof the study area Figure 9t Lowestbiomass PROBES and related projects Alexander and Nie- of both of the abovespecies occurred in the north- bauer 1981;Niebauer and Alexander1985; Schan- ern shallov region in stagnant areasto the cmouth delmeier and Alexander 1981; Sambrotto 1986; of CapeNavarin, and southeastof CapeOlyutorsk Cooney1981; Iverson et al. 1979a,1979b; Cooney planktr>r>r>fthe Bering Sea

Fig»re8. Zooptonkto»biomass mg/ni'! in theupper Figure 9. Zooptr>nktonbin»u>ss rn>g/m "> in the «pper 100mofthe south«'extern Ber>ngSeain June 100»>of the enutI>urestern Bering Seo. Above: 1952.Abor.e> total zooplankton.Belolv> Ca/or>uspl>>mehrus in June l952. Beta>»>tr>- Fum V>nogradou 1956bh tal zooplar>kton>n August-September /95 > fromV> nogrr>doc 1956b!. ofAnadyn; v,here nauplii, copepodid stages I and II, andadults were most abundant., Other species of due both to the descentof the larger copepodsto the oceaniccomplex were present. at lowdensities overwinteringdepths and predation.The richest anddid not substantially influence the overall bio- areasoccurred in westernKamchatka Strait and rnass.Members of thenorthern Bering Sea species nearCape OlyutOrak; the pOOreatregiOnS were in complexwere not abundant in the western Bering the stagnantarea south of Capesavarin. in the Spa during spring. Thcgeneral distribution of zooplankton biomass northernand northwestern Gulf of Anadyr,and in in theupper 100 m inAugust-September wassimi- regionsoccupied bythe northern Bering Sea group. lar tothat for spring, although the values were low- Theaverage zooplankton biomass in the centralre- er byabout half i Figure 9!. Reduced biomass was gionof the study area was 326,6 mg/m', Ecologyot theHering Sear A Reviewo RussianLiterature

Table4. Abundanceand densitynf Afeocalauurrp/umchrus in the northernand western Bering Sea,1956-1952 from Heinrich 1957!.

June Aug-Sep Sep-Oct Nov

Abundance No./rn'! 3,600 Western region 0-200 m 2 1,000 3,400 5,200 9,400 6,800 Western region, 0-500 rn 23,000 4,800 orthern shallows t55 m depth!, 0-bottom 1,800 500 200

Density t No./m"! 30 Western retdon, 0-200 rn 127 Northern shallows, 5 m depths, 0-bottom 20 3

Anespecially rich neritic fauna developed in the washigher in fall thanin summer,primarily due to coastalregions during fall andthe oceanicspecies increasesin the densityof Eucalanusbungii, whose complexwas pushed farther offshore due to substan- biomassreached 500-1,000 mg/m" in the upper 50 rn. tial fresheningof coastal wat,ers.The nerit.ic spe- Highesttotal zooplanktonbiomass. 1,000-1,500 ciescomplex occupied regions of OlyutorskBay, the mg/m',occurred in the northeasternsection of the Koryakcoast, and the entire northern portion of the Gulf of Anadyr near Ugolnoi Bay,where denseag- Gulfof Anadyr Figure11, Podon leuckrJrti was ob- gregatesof F. bungiiwere observed. As in summer. servedat concentrationsof 200-300specimens/m' the northern Bering Sea speciesgroup had loivest in the northern Gulf of Anadyr and attained densi- biomassin fall; biomassdid not exceed100 mg/m', tiesof 6,000specimens/m' in the upper10 m atsome althoughCalrirrus glacralis could reach average den- stations. The biomassof Centropagesmcinurrichi sities of 400 specimens/m' in some regions. wasas high as 50 mg/ms in shallowregions and b ays Meroplanktondensity in the northernportion in the northern Gulf of Anadyr and in the coast.al ofthestudy area was substantially lower in thefall regionbetween Cape Navarin and Cape Olyut.orsk. than summer.Polychaete larvae were practically- Acartia clrrrrsi occupied a similar range, was con- absent,barnacle nauplii occurred at densit.ies of 10- fined to surface waters, and its biomass reached 100speci mens/rn' not morethan 40-50 miles from 112,5mg/m' in theAnadyr estuary and 221.5 mg/m" the beach,and echinodermand bivalve larvaewere in RudderBay. Echinoderm and polychaetelarvae scatteredirs distribution and where present,their occupieda narrowregion along the coast in the Gulf densities were very low. However,rneroplankton of Anadyrand OlyutorskBay. Bivalve larvae and densitresin the southern portion of the study re- barnaclenauplii also occupieda narrow region in gionwere much higher, especially in OlyutorskBay OlyutorskBay but, attained densities of 30,000and andnear CapeArika, wheredense aggregates of 5,000-7,000specimens/m' respectively, near Cape barnaclenauplii and echinodermand bivalve larvae were observed. Begimiing in fall, cooling tern- Navarin. InsuAicient material was collected between the peraturesbegan to kill off the neritic speciesgroup. end of Septemberand end of October1951 to pro- P. letrr&arri disappearedfrom the plankton in the videa generaldistribution pattern for zooplankton Gulf ot'Anadyrand Centropages rrrcmurrichi densi- in fall; however, the. available data suggest a pat- ties did not exceed»0-60specimens/m-'. However, P. tern quite similar to that of summer.The richest leuckorti, C, mcrnurrichi, and quadric nordmrrnni regionremained the westernhalf of Kamchat-ka continuedto bepresent iri thesouthern range of the Strait. where biomass in the upper 100 m was 5S0- study area. 770 mglrn'. Lowest biomassocr urrcd in the stag- Heinrich t 1957!examined pat.terns of reproduc- nantcentral part of the studyarea, where values as tion anddevelopment of the majorcopepod species low as 60-90mg/m' were recorded.Generally. the in t.he western and nort.hem Bering Sea. Thc data biomass over the entire southern deep region was for ¹ocrrlorrusplurrrchrus, Fucrrlanus burrgii, and somewhat lower than in summer, due primarily to Metridicrpacifica are presentedin Table~4-6 and t'urtherdecreases in Colanusplurnchrusand Cala- summarizedin Tables7-8..V. pluur chrus abundance. nus cristorus in the upper 100 m, Zooplankton bio- is great.esf,in Juneand declinesin later monthsa mass in the shallow regions of the Gulf of Anadyr the aninials descendto overwintering depths. Nau- Zuop!anktof! >f the BeringSc.a

Table5. Abundanceand density of Eucolanne bnngii in thewestern Bering Sea, 1956-1952 from Heinrich 1967!.

June Aug-Sep Sep-Oct Nov

Abundance Nn.!'m'! We stern region 0 Vauplii, 0-200 m 98,600 6,500 1,100 65 Copepodids, 0-200 m 10,400 4,500 1,200 5,900 Copepodids,0-500 m 19,000 6,500 4,000

Northern region Nauplii, 0-bottom 5 m! 29,0GG 400 290 Copepodids,0-bottom 5 tn! 400 490 6,000

Denrity No./tn ! Western region 0 Naupl ii. 0-200 m 596 45 0.3 Copepodids, 0-200 rn 63 29

Northern region Nauplii, 0-bottom 5 m! 446 5 Copepodids, G-bottom5 m! 6 112

Table6. Abundanceand density of Metridia paci!fllca in the western Bering Sea, 1950- 1852 from Heinrich 1857k

June Aug-Sep Sep-Oct Nov

Abundance No.fm'! Westernregion, 0-200m tnight stations! 5,600 29,200 30 500 5,300 Northern region, 0-bottom 5 m ! 5,300 17,200 14,00G

Density No.fm ' ~ 179 21 Western reg!on, 0-200 m 32 146 Northern rey'on, 0-bottom 5 mi 62 320 26D

pliar stagesof Z. bungiiare high in June,indicat,- in theupper 200 m. I'lankton samples were collected ing a laterreproductive cycle than that ofX. plum- to 500m duringAugust-September and abundance chrus. Note the high populationsof M pacifico in in the upper500 m wasonly 682 specimens,'m', 350 Augustand. September. The presence of thesetaxa specimens/m'-'in the upper200 m, equivalentto 2 in the northern region is a reAectionof transport specimensfm'.However. duringthis pertod C. cristn- onto the shelf by the Anadyr current tuswere distributed to > 4,000m depth.lt i; there- Since CoIonus cfistatus seasonallyoccurs at forenot possibleto determinewhether decreases in greatdepth where few samples were collected, esti- densitywere due to mortalityor migrationbegun mates of seasonal changes in abundance were not in June to ovcrwintering depthf Vinogradov1956b !. possible.However. during June C, crisfutus attained C. cristntusabundance in the upper200 m in Sep- abundances of 2,095specimenslm'-' in the upper200 ternber-Octoberwas 170 specimens/m'.220 speci- m 3 specimensim'!.Judging from two stations mens/m' rn late December about 1 specimen.'rn'!. wheresamples were taken to 500m depth,abun- Mostof thepopulation in f'alland winter was below dancein theupper 500 rn wasabout 1.5 times t.hat 200 m depth. Ecolotl!Ul tile I3eririg Sea;8 Rtvietv iit Riissi,iriLiterature l l.3

Table 7. Zooplankton biomass gtme! in the west- Table 9. Annual copepod production in the ern Bering Sea, 1950-1952 from Heinrich Bering Sea g/m'! tfrom Heinrich 1956a!. 1957h Western region Vorthern region June Aug-!iep Hep-Oct Nov Calanus in arshallai Western retdon Neocalartua plum Chrus 22 1Veacalanus cristatus 11.3 7.5 1.3 2.5 'veaca la au s c ri st a tus 26.5 hl. plumchrus 20 5 1.3 Euralanus bungii 51 1.6 Eucalanus bungii 57.5 7.5 7.5 2 r> liifendi a paCifica 16 33 llfetridia pactfica 0.3 2.9 4 0.6 Total 115.5 10.1 Total 115 40 40

Northern region Calanus m arshallae 0.5 5 375 Calanus glacialis was seen in substantial nurn- llletridi n pari fi ca 1 1.75 2.5 bers only in the northern shallow region. Abundance %cocalan us plum ch rus 2.15 1 038 from June to August dropped from 3,900 to 2'100 Total 10 16.3 27.5 specimens/msin the entire water columnfrom surfaceto bottom averagedepth of 55 m !,but remained substantially unchanged in September-October ,600 specimens'm'LThe abovevalues correspond Table 8. Densities Norm'! of copepod nauplii and to 57, 34, and 47 specimenstm' respectively. copepodid stages in various regimes of Heinrich 956a! estimated copepod production the western Bering Sea, 1950-1952 from from data on changes in copepod weight hy stage, Heinrich 1990!. growt.hrates, sum of the maximumbiomass accumulated during the year, and biomass lossesdue to Layer Shelf Transitional Oceanic mortality at early copepodid stages Table 9!. I~w E. bungii isummer! productionrates onthe shelfwere at, tributed to food limitation, since reproduction of C. gloria!i s and M, 0-50 152.4 1143 291 Va upi i i parifina correspondto periods of maximum phy- 50-100 4.1 120.5 23.7 toplankt.on biomass. 1 100-200 31. 3 Size distribution data were collected on Sagitta .:opspod id s 0-50 0,7 14.6 8.3 elegaris during several seasons iHeinrich 1956bi. 50-100 1. 8 1.6 Individuals of 15-20 mm length predominate in 100-200 5.1 235.4 June, individuals of 17-22 inm length vvere predorn- inant in the southern part of the study area at the Adults 0-50 1.5 0.9 end of June, and 30-34 mm indi~dduals with eggs 50-1 0 ! 05 4.2 were observed at 200-500 rn depth, along with low 100-200 65 numbers of individuals of < 10 mm length, Size composition had decreased by the end of August and ~V.plumChrus Summeri early Septemberand the population consistedof Copepodids 0-50 34. 3 132.4 juveniles of the next.generation. Juveniles of 3-7 mm 50 100 9.8 4.7 982.13 length predominated in thc northern region in De- 100-200 1.4 0.2 cember-January, indicat,ing t,hat reproduction had recently occurred. Specimens of 10-18 rnrn length M plumchrus i fall! predorninatetl in t.he southern portion of the study Copepodids 0-50 0.9 18.4 9.4 area where growth r ates were undoubtedly higher. 50-100 0.9 2. 4 0.9 Average abundance in the upper 200 rn increased 100-200 0,5 0.1 froin June to September from 200 to 2,500 specimens/m'-', Abundance exceeded 14,000 specimens/m-' in the northern region but was only 500 speci- rnenstin-' in the south. Size frequency analysis on Eukrohnia hanmta did not reveal significant trends, spawning did not occur between June and January. Zoopianktorro the 8«ri»g be@

FigureI I. Boundarybetuieen neriti« I!,transrtrona/ II, and oceanic III! regimes in Karagin Bav. BerrngSea. Dotsindicate statiorsloca!lans from Voikoo I988!. Figure10. Zooplankton biomass in KorfKaragin Bay .'g/nr-'iin the upperI00 rnor fromsurface to bottom.J. < I g; 2. I- t0 g; 3. l0-20g; 4. 20-50 g; 5. > 50g fromLu bhv- Ger tsyk 1961!. surfacesalinities t24,8 ppt!. Bivalve, polyrhaete, and echinodermlarvae and barnacle nauplii occurred in the centerof the bay at salinii,iesof 32 ppt. The mos: widespreadof the oceanicspecies was K. bungir, PLANKTON DISTRIBUTIDN which reacheddensities of 7 g/m' even in Korf Bay IN KORF-KARACINBAY where salinities were 26.8 ppt. IV, aria/rr tus v as seen Planktonsamples were collected with a 30cm di- onlyoccasionally in the shallow regions and A, plurrr- ameter.569 rnmmesh! ichthyoplankton net from chrusand M. paci/ica were ubiquitous but not a bun- the bottomto the surfaceor from 100rn to the sur- dant.All copepodswere in their laterdevelopmental facein Korf-KaraginBay during August-September stages;eggs and nauplii wererare, perhapsa re- 1956 Lubny-Gertsik1961!, The coarsermesh ex- IIection of the meshsize of the sampling gear.The cludedphytoplankton and microzooplanktonfrom boundarybetween the neritic and oceanicspecies thecatch. CoHections were made during August-Sep- groupsduring summer appeared to be at about.the tember1956, at the heightof summerwith surface 100 rn isobath.Thus, most,of Korf-Karagin was a temperaturesof 10-13'C,Maximum zooplankton neritic domain Safronova 1991!. biomassof 100-160g/m' wererecorded off Cape TINRO undertook a plankton survey of Korf- Govena Figure 10 !, whereaggregates ofthe ocean- KaraginBay in September1983 using a luday nwas screensof 1.2-1.3mm, 0.5-0.57mm, and 0.11 rrrrrr observednear the beach, where abundant hut small mesh.The region was dividedinto three zones.ner- neritictaxa occurred: CentroImgea m

Table10. Densityand biomassof major taxa in the neritic N!, transitional T!, and oceanicEO! zoo- planktoneommnnities ofKaragin Bay, September 1988 from Volkov 1988!.

Dens il, v No, rn ' 1 Biomass mg m 'E 0

Aglantlra rligitalv 3,5 5 16 10.5 15.0 48.0 I.imacina hei eisa 134 95 0.7 0.9 0.7 Clione lrrnaci na 11 128 5 1.1 12.3 0.5 Podon leuckarlr' 338 6 1.3 6.1. 0.1 0.1 b'oadne nordma nni 17 2.5 0.3 0.1 4.2 Calanus crrstatvs 0.3 Cala n uspl u nichrus 4.1 25 50 10.2 62.5 2 1 0 2 Calanus glacia rs 0.3 0.4 0.5 0.2 51 2 Eucalanua bungii 3 ri 41 3.8 18,8 PseudOralrint S m nutus 1,180 490 275 82.6 19.2 111.3 Itfetri dia pac firn 19 214 1.0 9.9 Acartia longiremis 1,725 236 29 69.0 9.4 1.2 Centropagesabdomi»ali s 23 46 2 1.2 0,1 Eurytemora par i fica 15 0.6 0.5 0.1 Orthonrr simr.lis 3,496 1,728 2,127 35.0 17,3 21.3 2 0 Para the!ni stoj apon! r a 0.2 2 0.2 Thysnnoessar aschii 2 20 15 5.0 50.0 37.5 35!.2 83.6 Sagitta elegans 10 16 22. 0 0.4 Oikapleura sp. 257 9 18 .r! tE 2.0

Larvae 0.7 Cirripedia 185 36 36 3.7 0.7 Bivalvia 906 459 285i 6.3 3.2 2.0 1.6 Polychaet.a 122 61 16 12.2 6.1 Echinodermata 495 166 16 0,5 0.2 U.02 0.3 P,1 Co pe pod nauplii 1,238 282 102 1.2

Total biomass 274 229

Table11. Percentcomposition by biomassof thedominant zooplankton specie.s in KaraginBay, Septetn- ber l983 t from Volkov 1988!.

Neritic zone Transit.ional zonr. Oceanir zone Taxa Biomass Taxa Biomass Taxa Bl o r a ss

Pseud< cala nun min u tus 30.7 'I'hysanoessa rasch i 22 0 .Hetrrdi a pac fica 24.8 Acartia longi remis 25.6 Sagitta elegans 15.5 Sagitta elegans 18.7 Oithona simrlis 13.0 Pseudoralanus rninutus 15 1 Calo»vs plum hrus 14.0 Sagitta elegans 8.2 Fuca la n us bu n g i 8.3 hvcalanus bung Larval Polychaeta 4.5 0 'thona s n ilia 7.6 Agio» th a d rale 10.7 Aglantha digitale 3.9 Agin n tha d gr ta Ir 6.6 Thysnnrn ssa raschi 6,4 Larval Bivalvia 2.3 Clione lin!acina 54 O thona similis 4.8 Podon Ieuckarti 2.2 Ccrlanvs plumciirus 4.5 Pseudocalanv s !rl no I vs 43 Calanus plumchrus 1.9 Metridia paci fi ca alnnvs r status 09 Thysanoessa raschii 1.9 Acartia longiremis 4.1 Para ther!!isto Japnnt< a 0.4 Total 94.2 93.5 98 4 Z'onplarik onot the 8cringSea Table12. Density Nodni'! bysize fraction inthe neritic N!, transitional T!,and oceanic ! zones of KaraginBay, September 1983 from Volkov 1$88!. Small Medium Large N T 0 T 0 N 'r 0 12 Agtantha d

Larvae 60 12 27 10 0.8 Cirripedia 130 Bivalvia 870 570 160 50 5 6 11 0.07 Polychaeta 110 160 10 30 20 0.4 Echinodermata 300 840 187 63 41 1.4 Tol.al larvae 1,410 236 226 25 119 Totalabunt!ance 8,555 3,716 2,630 531

markeddecline in herring stocksoccurred at the end Phytoplanktoncaught with the zooplankton indi- of the 1960sand commercial fishing was cornplete- catedthat a fallblooin was occurring in theshallow ly suspendedfor fiveyears in the 1970sbut stocks coastal regions. Zooplanktondens ity in allthree zones was dom- did not recover.During the same period pollock inatedby Pseudocalanus, Acartia longiremis, and stocksincreased. Therefore, TINRO researchersini- Oithnnasirriilis; however, the bioinass in theocean- tiated a studyof the distributionand seasonaldy- ic zonewas dominated by lessabundant but larger namicsof zooplankton in Olyutorsk Bay< Belousova taxa: Calan vs pl u mcht us, Zucala nus bungii, 1975;Shaginyan 1982!, Samples were collected with Metridiapacifica, Thysanoessa raschii, and Sagitta a 37 cm diameterJuday nct, No. 61 gauzei0.091 elegans Table 10!, Therefore, the threezones out- mm!,at standarddepths of 0-10,10-25, 25-50, 50- linedabove could also be separated by sizefraction, 100, and 100-200 in. Thesmall andmedium-size fractions made up al- The most abundant copepodsduring spriiig- most90% of thebiomass in theneritic zone, but only summerand winter wereFucalanus bvrigii, Cuia- 30%-and 45 ic of the biomass in theoceamc and tran- nusplumchrus, Oithona similis, and Pseudocalavvs sitionalzones respectively Table ll, 12,13!. The elongatus.The abundance ofechinoderm! arvae and largefraction, more than 300 mg/m' or about70% euphausiidnauplii increased in mid-May and earh- of the total biomass,predominated in the oceanic Juneto 20%,16.4% of t,hetotal zooplanktonabun dance.Copepod nauplii madeup 76-80%of the to- zone. OlyutorskBay is a majorforaging region for the t,al abundance.Copepods comprised. 80-95% o f thc Korf-Karaginherring stocks Belousoval975!. A total biomassduring spring-summerbut onlv 670< ECOlagyOttltf' BI rirlgSea; A RevietvOt /t'Itaatart Lileratiiro

Table13 Summaryof regionalcharacteristics and zooplanktonbiomass indices in Karagin g 9ytf Bay,September 1983 fromVolkov 1988!.

Zone N T 0 Total Averagedepth I mI 32 44 88 9//t/P

Area km'! 8,900 9,200 12,200 30,300 Phytop!ankton l 37 roof/ biomass 76,5 92 453.6 622.1 Zooplankton JIII919 biomass total!

Biomass fraction Small 28.3/37* 26.7/29 59/13 114 Medium 37.5/49 15.7/17 81.6/18 134,8 Large 10.7 '14 49.6/54 313/69 373. 3 * 'Ihleft nf the slash:biomass, tit nusands of ttine:to right tif th.ettlatth: Month proportionhy %. VI V II VIII IX X X I

No./m3 in the fall dueto increasesin the bioinassof Sagitta 9~ andeuphausiids. The average zooplankton biomass in the upper 100m in OlyutorskRay during the JSSIP 1950swas 500 to 1,000mg/m'; biomass farther south wasmore than 1,000mg/m', with valuesup to 2,000 mg/rn' Vinogradov1956b!. The maximum zooplankton biomassin the upper 100m during the 1970s did not exceed560 mg/rn".Substantial declinesin the biomassof F..bungii and C. plumchrushad occurred maximuin values of'305 and 130 mg/m" respectively!.Substantial declines were also recorded for P, elongatusand O. similis during winter maximumbiomass of 50 mg/ms!.Thus, a majorcause of declinesin herring growth rateslnay have been food Month V III IX x limitation Relousova 1975!. VI VII The concentrationof zooplanktonprey of larval btgure 72. Seasonalpopulation dynainics of Above: herringin theKorf-Karagin region during June over OI't bonasi milt s and BefOfstPseuduuul an us a 13-yearperiod from 1968to 1980was found to be elongatusin OlyutorshBury. June-September quitesensitive to waterteinperatures in May Mak- and Ãtn'ember 197 /. l. Total densify, 2. nau- simenkov1982a, 1982b!, Prey for larval herring in plit. 3.copepodids, 4. adults'from Shot in@on Korf-KaraginBay include bivalve larvae, naupliar 1982/. andearly copepodid stages of Oithortaand Pseudo- calattus,barnacle nauplii, PorIpon, and tintinnids. Elevatedsurface temperature of as little as about I' ' producedas much as a five-foldincrease in zoo- planktondensities in lateJune 00 to 25,000spec- imens/m'!,with an r for the resulting logarithmic regressionsas high as 0.97,However, no distinct lOng-terintrendS in telnperatureOr biornasS were observedfor the 12-yearperiod. In addition, data before 1975 were adjusted using an undisclosed method for estimating catch efliciency. Zooplankfonor the geringSea

The populationdynamics and age-classstruc- chi Sea. Springer et, al. 1989,mesh size = 0.202- ture of Oithonasimilis andPseudocalanus elonga- 0.303!.A studyof zooplanktondistribution on both tus wereexamined for fall of 1976 Shaginyan1982!. sidesof the borderwas undertaken in 1991as part O.simili s occursyear-round in OlyutorskBay Hein- of a Russian-Americanexpedition Pinchuk 1993, rich 1961!and is a major fooditem for larval and meshsize = 0.332!.Both of the latter studiesfound juvenilepollock Matyunina 1972!, as well as pred- similar distribution of zooplankton relative to ma- atorycopepods and chaetognaths Brodskiy 1948, jor watermass types in the northernBering Sea Shuvalov1964, Kozhevnikov 1975, Fedotova 1975!. and Bering Strait, 0, similis populationsranged from about1,300 in Two zoogeographicregions were identified, Juneto 13,000specimens/m' in September Shag- basedon zooplanktonspecies composition; eastern inyan 1982!,a patternsiinilar to that observedby andcentral-western. Hydrographic analysis indicat- Heinrichi 1961!.Using an equation relating the gen- ed that Alaskacoastal waters occurredin the east- erationtime to temperature G = 1251'~", 0 is the ern sectionand a mixture of Bering Seaand Anadyr generationtime, t is thetemperature in 'C Menik- watersoccurred in the central and westernsection, ova1962!, approxiinately 100 days are required to where the denserAnadyr waters commonlyoccur producea singlegeneration of O.similis at a mean beneath a surfacelayer of lower-density Alaska temperatureof 2.4'C,common in the surfacewa- coastalwaters, Plankton biomass in the surf'acelay- tersof OlyutorskBay in May.O. si rni lis populations er of Alaskacoastal waters was 1,5 tinies higher than. producea singleabundance peak in late August- biomassin the surfacelayer of Bering-Anadyrv.a- ters Tab!e14!. iVo differences were observed in zoo- early September Figure 12k Pseudocalanuselongatus is a majorfood of pol- plankton density and biomassbetween the lock;its frequencyof'occurrence in pollockdiets is thermoclineand surfaceand bottom and surfacein about 75'7.and it makes up 53'7rby weight Matyun- Alaska coastalwaters, while in other regionsmaxi- ina 1972!.Pseudocalanus density during the sum- rnumdensity and biomass occurred belov' the ther- inerof 1976in OlyutorskBay was fairly stable, with mocline Tables 14, 15!. a rangeof 132-7,655specimens/m", the maximum The domin.antspecies by biomassin Alaska occurredin September Figure 12! in thenearshore waterswere Calanus glaciaiis and cuphausiidlar- regionand the minimumin t,heopen ocean region. vae,Xeocalanus cristatus, ¹ocolanus plumrhrus, Cohortanalysis indicated two reproductivepeaks, andSagitta elegans dominated in BeringSea v ater in earlyJuly and the endof August-earlySeptem- andX. plumchruswas dominant in Anadyrv stere. ber. The interval betveen reproductivepeaks was Physicalconcentration of zooplanktonby currents 45-50 days,suggesting that P. elongotusmay pro- led to highestzooplankton densities near the Di- duce3-4 generations froin May to!November, in con- omede Islands Average density and bioniass were trastto O.simi lis whichproduced 2 generations, O. 3,899+ 1,321specimens/m' and 571 z 50 mg m~; simi lie populationsconsisted mainly of copepodidsthe maximumvalues were 6,473 specimens/m' and f about,5IKc !, v ith nauplii andadults comprising 27'7~ 630 mg/m'. and23'rc respectively. P.elongatus populations con- sistedprimarily of naupliilabout 65%!. However, GENERAI PATTERNSOF the lowdensities reported f' or 0, sirnilis nauplii inay be relatedto meshsize, since the nauplii of O.si rni- ZOOPLANKTON DISTRIBUTION li s are considerably smaller than those of Based on data sets like those outlined above, at- Pse udocal anus. temptsto assessplankton stocks and stockdistri- bution overthe entire Bering Seawere undertaken ZOOPLANKTONDISTRIBUTION IN THE more than once Markina and Khen 1990!. Foi. example,Kun 975! pooleddata on the quantitative BERINC STRAIT distribution of inesoplanktonfrom l.wosurveys, tak- Until recently,research on zooplankton in the Bering en in different regionsof the sea during different Strait waslimited mainly to speciescomposition in years.Since there has not yet beena singlecorn- an attemptto identifyindicator species of various pletesurvey of the entireBering Sea, attempts at water ma.sacsto determine the influence of the assessinghorizontal distributions of epipelagiczoo- BeringSca on Chukchi Sea fauna Stepanova1937, planktonare basedon a compositeof data taken Virketis1952 t Zooplanktonsamples were analyzed over many years. ona seriesof transects taken in 1985and 1986 from The compositeapproach v as also adopted the Alaska coast up to the conventionline, in the Volkov and Chuchukalo 985'l to obtain a general Chirikov Basin, BeringStrait, and southernChug- patternof planktondistributions based on TINR ! Fcologyof theHertng 'iea: A Reviewol Rosin/anliterature

Table14. Dominantzooplankton species by percent contribution to totalbio- massin Bering-Anadyrwater BAW!and Alaska coastal water ACW! massesin the Bering Strait region,July 1991 meshsize = 0.333mm, from Pinchuk 1993!.

Bottom to surface Thermocline to surface BAW ACW SAW ACW

Calartus plumchrus 45 5 10,H 1 1 Calaaus rristatus 12 1 42.4 Cala a us ntarsh al lac 1 54 1 7.2 Parasagitta e!egans 12 17.5 7.6 1 Cirripedia larvae 9.6 9.5 21.4 Euphausiacea larvae 1 5.5 1 20.8 4.6 Pseudoca!anidae 4.4 4 1 8'ucalanus httngei 4.6 1 4,7 1 1 Metridia pari fica 3.7 1 14 3 Majidae zoea 1.7 1 Paguridae zoca 1.2 1 8.4 1 52.3+ 11.5 mg/m' 86.4 + 7.0 59.1+ H.O l9+ 2.9

Table15. Dominantzooplankton species by densityin Bering-Anadyrwater BAW!and Alaska coastal water

13ottom to surface Thermocline to sur ace ACW AW ACW

.irripedia l arvae 74 46 80 14,4 24.8 Ca la nu s marsha l la e 1 34 1 4 Pseudacalanidae 13.5 6 3.6 28.2 Kuphausiacea 1 5 2.8 Ca anus plurrt chrus 6.7 1 1 1 Metridta pari fica 23 1 1 1 Oikopleura sp. 1 15 Polychaeta larvae 1 1 1 Aglarttha digitale 1 1 1 2.5 480+73.2 No./m' 689+169 6011304 328+132

collectionstaken from 1949to 1982. During the elude O. similis 900 specimens/rn'>, P. minuius aboveperiod about 2,800 samples were collected dur- 00!, Microcalanuspygmoeus 90!, Metridia paci- ingseveral seasons as outlined in the introduction. ftca0!, andLimacina helicina specimens/rn"i. Their conclusionscan be summarizedas follows: Most of the biomass consists of crustaceans. mainly duringwinter the averagebiomass reaches about euphausiids,although Cnidaria i Agiontha di gi talc t 100mg/m', Over the shelfonly 14species achieve chaetognaths,and meroplankton can also be abun- anaverage density greater than 10specimens/m', dant.During winter the zooplanktonmigrate down with Oit/torta similis and Psettdocalanus minutus to the epibenthiclayer overthe shelf and to 300- havingwinter populations of over 100 specimens/m', 500 m over the continental slope and open basin. Winterzooplankton densities over the deepbasin Zooplanktondevelopment during spring varies aremuch greater than overthe shelf, averaging substantiallyin differentregions of the BeringSea, about1.200 specimens/tn'. Most abundant taza in- due to differences in climate, depth, and hydrogra- Zoriplan/ on «/ theBering Sea UO phy,The spring phytoplankton bloom corresponds with themaxirnurn reproduction of Calanusglacial- is,P. min utus, Thysarroessa irrermis, T.longi pcs, and Parathernistopacifica. Seston biomass varies over a widerange during the diatombloom 00-3,500 mg/rn'!when average biomass attains its annual 0 maxirnurn,100 mg/m'1Mesoplankton biomass can exceed100 rng/m' in thesouthern Bering Sea where upwelling near the Aleutian archipelago affects production;however, plankton densities in this region aregenerally low, with biomass reaching only 0.2- 0.5 mg/m', Thegreatest phytoplankton andzooplankton biomassoccurs off the easternBering Sea shelf ,000-2,000rng/m'!, and in theGulf of Anadyr, Norton.Sound, and BeringStrait, wherebiomass oftenexceeds 2,000 kg/m' andcan reach 3,000-3,200 rng/m'.There is a narrowerband of high biomass alongthe narrowerwestern shelf ,000-2,000 60 mg/rn'!,with maxirnurn values inKaragin and Kam- chatkabays ,000-3,100 mg/m'!, The remaining deepwaterregion has a relatively even distribution of biomass 00-1,000 mg/m'!. Thegeneral pattern of biomassdistribution duringbiological summer July-September! is similar to thatduring spring, although the valuesare somewhatlower about400 mg/rn'!. Mimrnum bio- 1BS~aA 37S mass,100-200 mg/m', is observedin the southern regions,intermediate values occur over the deep Figure13. Above: phytoplvnkton, Betoiziz zooplankton. basin00-500 rng/m'!,and higher values over the Multi-yearaverage of biomassirng/m'! in, the shelf00-1,000 mg/m't Highestsummer biomass BeringSea. T. l00, Z. 100-500,X 500-C,OOO. wasmeasured in the Gulfof Anadyr,000-1,400 4, ! 1,000 /from Markina ond Khen E99G'!. mg/m'!.Meroplankton densities are especially high duringAugust and September, when secondary bloomsoccur over the shelf.Bivalve and gastropod larvae can reachdensities of 1,500-3,000speci- mens/rn';polychaete and echinoderm larval densi- specificregions was inferred Mileykovskiy et al. tiesof severalhundred per cubic meter have been 1977,Vinogradov and Shushkina1985, Zernova observed Meshcheryakova 1964!. 1985, Moiseev 1989!. The biomass over the upper 100 m in some ar- Another assessmentof phytoplankton and zoo- easof thedeep basin remains quite high in fall 00- planktondistribution was attempted by Iviarkina 400mg/rn", October-early November!, while biomass andKhen990!, whopooled all of the accumulated is substantiallylower over the shelf00-200 mg/m'!. hydrobiologicalinformation, primarily from the pre- Thetotal plankton biomass in theBering Sea dur- vious25 years,and averaged the dataon biornas; ing springis 2,5x 10"tons, 10" tons during summer, fromnet-caught phytoplankton and zoopian.kton for and2,5 x 10 tonsduring winter Volkovand Chu- the entire Bering Sca, excluding any data taken chukalo1985!. Unfortunately, Volkov and Chuchu- outsidethe productionseason of April-November. kalo985! didnot separate sea.sonal phytoplankton The distribution schemeis basedon data collected andzooplankt,on biomass assessments, although it with 37 em diameterJuday nets .168 mm mesh i is wellknown that thephytoplankton and zooplank- fished in the upper 100rn. Standard techniquesfor tonproduction seasons differ markedly byregion averagingthe data were applied Markiria and Markina and Khen 1990!,A very roughidea of Chernyavskiy1984, 1985!. The a.bovetechnique planktonbiomass byseason was attained from sev- pr'oducedseparate distributions for phytoplankton eral one-timesurveys done in the far-easternseas and zooplanktonfor the entireBering Sea Figure duringthe 1950s and 1960s, and information for 13!.Estimates were higher than earlier calculation- F

Table16. Phytoplanktonstocks and biomass in the Bering Sea fromNlarkina and Khen 1990!.

Area Net estirnale Probable total 10' km-' 10' t rng/m' g/mr Region

Over the shelf 240 to 200 rn 1,061.2 810 Over regiorrs of depth 13.2 115 to 200-1,000 m 112. 8 4.4 390 102 3 90 over 1,000 m 1,141.4 34. 1 300 540 373.5 160 Entire sea 2,315.4 124.5 1:SSR zone 970 81 290 t,o 200 m 277.0 2.72.0 6 215 200-1,000 m 28.0 710 40.5 105 over 1,000 rn 395.0 13.5 340 127.5 180 Entire zone 700.0 42.5 610 U.S. zone 175.8 22 > to 200 rn 784.0 58.6 750 12.6 150 200-1,000 rn 85.0 4.2 490 100 over 1,000 m 542.0 18.2 335 243.0 175 Entire zone 1,411.0 81.0 570 3.0 15 Internat.ional zone over 1,000 m! 204.4 1.0 50

both in the coastalregions and olTthe shelf, Plank- !.onbiomass in excessof 500 rng/m" were estimated for the easternBering Sea shelf break. Marki naand Khen990! emphasizedthat their plankton dist.ri- hutionpat.terns generally conform with the locations of cyclonicand anticycloniceddies and other current patterns in the Bering Sea Figure 14!. The authors determined the total stocks of phytoplanktonand zooplankton for various regions separately Tables 16 and 17!. The estimates were made 5S' using averagebiomass in onedegree quadrants Vfoiseev 1969!. These results produced maximum net-caughtphytoplankton and zooplankton biomass estimates ot'970 and 1,500 mg/m' in the shelf waters of the Soviet economic zone, with an average for the entire Bering Seaof 540 and 795 mg/rn' re- I igare 14. Major currentsin rhe Bering Seaduring spectivelyand total estimatedstocks of 1.245x 10' the warm period average of mu ti-year and 1,838 x 10' tons, The nannoplankton cornpo- data!. I. Isobaths nr/, 2. Currenr direcnon nentof the phytoplanktonand the micro-and mac- frorrr Marhr'na and Khen 1990!. rozooplanktoncomponents were not taken by the catchgear and thereforeare not includedin the aboveest,imates. Phytoplankton biomass estimates were therefore multiplied by three. the ratio of net- caught.phytoplankton biomass to biomassestimates fromhydrographic bottles for Peterthe GreatBay, Seaof Japanl Konova92ova1980!. Total phytoplankton biomassfor the entire Bering Seawas therefore estimated at 3.735 x 10e tons Table 17t The ratio Znoplvnktonot' the BeringSea 122

Table17. Zooplanktonstocks and biomass in the of micro-and macrozooplankton to total zooplank- BeringSea fromMarkina and Khen ton Sorokinand Fedotov 1976, Konovalova and Ro- 1990!. gachenko1974, Konovalova 1980, Fedotova 1975, Pushnikovet al. 1979,Pogodin ct al. 1982,Afan- Net estimates Probable total as'yev1981, Ponornareva 1957, and others! was es- 10' t mg/m' 10' t g/rn' tiinatedto beat leastthree. Multi plying net-caught Region stockestimates by three, the total zooplankton Over the shelf stocksin the upper100 m forthe entireBering Sea to 200 in 105.8 996 317.4 300 wascomputed tobe 5,514 x 10'tons Table 17!. Since Over retrions of depth correctionfactors for the inicroplanktonand nan- to 200-1,000 rn 14.9 1,300 44.7 400 noplanktonare based on data froin the Sea of Ja- over 1,000 rn 63.1 55 189.3 165 pan,which markedly differs from the Bering Sea 551.4 238 bothhydrographically and biologically, and rnac- Entire sea 183.8 795 roplanktoncorrections are based on en phausiid data USSR zone only Ponomareva 957!, the Bering Sea plankton to 200 m 41.1 1,500 123.3 450 11.1 270 stockscomputed by Markinaand Khcn 990! are 200-1,000 m 3.7 900 probablyonly first orderestimates. over 1,000 m 28.9 750 86. 7 225 Basedon the abovebiomass estimates, Marki- 221.1 320 Entire zone 73.7 1,050 na andKhen 990! coinputedpotential production US zone rates asfollows: The daily P/B production/biotnass! to 200m 59.4 755 178.2 230 ratiosin the far easternseas varies from 0.5 to 3 200-1,000 m 8.8 930 26.4 280 but is usuallyabout 1 Sorokinand Fedotov1976, over 1,000 m 16.6 500 79.8 150 Konova]'ova1980!, Based on 50 years of data, Marki- Entire zone 94.8 670 284.4 200 naand Khen 990! estimatedthe length of the pro- In ternati oriel zone 15.3 630 45.9 190 ductionseason in the BeringSea to rangebetween

Table18. Phytoplankton andzooplankton wetweight production inthe Bering Sea from Markina arid Khen 1990!.

Phytoplanktont 10't! Zooplankton 0'l Net Pt obable total Region Net Probable total

!ver t.he shelf 317. 4 952.2 to 200 m 12.9 38.7 44.7 134. 1 200-1,000 m 0.7 2.1 189.3 567 9 over 1,000 m 5.4 16. 2 57.0 551.4 1,654.2 Entire sea 19.0 USSR zone 12.0 123.3 369.9 to 200 m 4.0 11.1 33.3 200-1,000 m 0.3 0.9 86,7 260.1 over 1,000 m 2.2 6.6 !9.5 221.1 663.3 Entire zone E S. zone 26.4 178,2 534.6 to 200 m 26.4 7'9.2 200-1.000 m 0.6 1.8 79.8 239. 4 over 1,0OOm 2.9 8.7 36.9 284.4 833.2 Entire zone 12.3 459 137. 7 In ternati ona! zorie 0.2 0.6 123 Ecolrigyof theBering Sear A iscviewot krtssirn Literature

mgtrn g1 so 3900

20DII

%00ti

SS 2s ls RNIN 3s ts 7s 6s fov

Figure16. Biomass of largefraction zooplankton >3.5 mm! and densitiesof planktir orousfish in the Figure 15. Boundariesof the major plankton ronimuni- westernBer'rng Sea. 1 is plankti corvusfish tiesand homogeneousregi ons: 1. Plankton sta- densi ty t km"-i, 2 is biomass'mg / m'Jof large tions.2. Boundariesof plankton communities, <>oplanktonfrarti onexcluding ehaetogna the 3. iVeritic or coastal V!, shelf lSJ and open euphausiids,amphipods, copepods!, 3is chae- neaterrOW!. 4, 1,000m isobath. 11V= north- tognathbiomass!rnglm'> from Volkoi arid ern.Gulf of Anadyr,2X = u,'esternCJulf of Anadyr,3X = O yutorsk-savarincoastal re- I;'fimkin 1990k gion, 4lsr = Olyutorskcoastal re@i on, 5X =- Korf Bay,6X = Karagin Bay,7iti = CopeSreuchiy, 1S = St. LawrenceIs.-Bering Strait, 2S = eri- closedregion of the Gvlf ofAnady r, 3S = north- intosubregions based on geography, veater massr s, easternGul f of Anadyr,4S = southu estern Gulf andRow patterns i Figure15!. The following data ofAnadyr, 5S = Otyutorsk-Ãararin shelf, 6S v,:eretabulated for eachregion: phytoplankton bio- = OlyutorskShelf, 7S = Korf Krrragtnshelf, 8S = CommanderIsland shelf, 1OW=- operr mass,zooplankton bioniass by sizefraction, total uratercentral region,2OW = roesternbasrn zooplanktonbiomass, t,otal biomass f'or varioustax- fromVolkov and Efimkin 1990k onorniccategories, and the biomassof the largezoo- planktonfraction relative to the densitiesof planktivorousfish Tables19, 20, Figure 16!. The authorscompared the biomasscontribution of' the 90 and 180days, depending on the location.They three size fractions of zooplanktonin the various thencomputed the average annual production from regionsto the biomassof planktivorousfish. The biomassestimates and the length of the production cont,ributionof the small zooplanktonsize fr'action season Table 16k Due to the large numberof as- i»creasedfrom the openocean r10ci< I to the shelf' surnptionsrequired for boththe biomassand pro- 2' i, with the greatest,fraction occurring in the duction estimates,the results may only be useful ncritic zoneI 86'.i! wherebiomass was greatest< 496 forrough comparisons between production and bio- kg/nr'!.The percentage contribution of the large mass estimates in the Bering and other far-eastern fractionincreased from a minimumof 49 r in nerit- seas Shuntov et al, 1990!. ic waters to 88'1 in oceanic waters, but the greatest total biomassoccurred on the shelf i 1,356mgirn'. ZOOPLANKTON AS FORAGEFOR r6cyc!.The highest predation from fish apparently occurredin the shelf communityto the southof the PELAGIC FISHES cold-waterregion in the Gulf ofAnadyn. v herefish Volkovand Efirnkin 990! examinedthe estimated densitieswere 22-35 tonsrkm'-', and lowestin north- daily ration of planktivorousfish and cpipelagic ernregions of highest zooplankton biomass i exclud- planktonstocks in the wesi,emBering Sea from ing chaet,ognathsi,where fish densitieswere < 2 CapeOzernoi to the Bering Strait meshsize = 0.168 tons/km-',The authors therefore postulated that mm!.'1'hey divided the region into neritic, shelf, and densities of the large size zooplankton v'ere regu- openocean zones. Each zone was further diiided lated by predation. Zooplanktono/ th» BeringSea

Table19. Bioinassofvarying size fractions ofplankton inthe western Bering Sea fall 1986; mg/m'! from Volkov and Efimkin 1990!.

Total of three Phytopl ankton Zooplankton biomass zooplankton fract ion s Region~ Depth, m biomass Sin all Medium l.arge

Coastal-n critic communities 193 1,226 1,747 }V 40 310 328 1,421 2,130 2N 63 590 335 374 1,253 2,035 3N 74 30 573 209 349 404 1,44 i 4N 63 433 693 517 13,577 5N 60 273 639 201 172 197 859 6N 60 180 490 71 171 419 7N 82 0 177 668 1,37o Average 211 496 211

Shelf communities 572 2,049 2,977 18 41 454 356 453 3,952 4,802 28 66 0 397 1,215 1,576 SS 77 4 139 222 195 1,023 1,336 4S 121 14 118 ~3 1,018 ],331 5S 55-1,000 80 240 94 699 1,123 6S 50-2,000 456 330 143 803 1,058 7S 97-3,000 4 112 30 452 542 8S > 3,000 14 60 205 1,356 1,765 Average 138 204 Open water communities 90 49 893 1,032 1OW > 2,000 497 639 2OW > 2,000 74 68 693 834 Average 83 58 ' see Figureis.

Note that the role of chaetognathsin the epipe- postulatedthat stocksof foragezooplaiikton less lagiczone is high in the fall in oceanic,shelf, and than 100 tons/km' are insufficient for dense-fish neritic communities.The authorsconcluded that the concentrations.Decreases in the biomassof large abovefactor is evidenceof substantialremoval of zooplanktonbelow 200 mg/in" forces the largepol- otherzooplankton by fishpredation, Chaetognaths lock schoolsto moveon. Theauthors concludedthat are not a majorfood for fish and therefore,their pelagicfishes in OlyutorskHay and KaraginHav abundanceand biomass do not correlatewith fish were food limited. densitiesand they are apparently regulated by their In comput,ingzooplankton bioinas, the above authors Efirnkinand Radchenko 1991, Volkov and own food base. Concurrentlywith t.heabove work, additional Efiinkin 1990! applied catch coefficient,s t.o correct studiesw ereunder way in thesame regions, depths their stock estimates as measured by a Juday net iindseason to examinethe foodbase and. distribu- with 0.1 ms mouth opening. Biomass estimates tion of epipelagicfish Efimkinand Radchenko were obtained by multiplying the data by catch 991!. Data wereaveraged over 12 biostatistical coefficients as follows: small size fraction = 1.5, regionsand the biomass and corresponding concen- medium size fraci.ion = 2,0. euphausiids and chae- tration of zooplanktonand pelagicfish werecom- tognathsto 10mm length = 3, 10-20inm lengt,h= pared,as well as data on the diets and daily ration 5, larger than 20 mm length = 10, hyperiids to 5 of the fish. Thetotal zooplanktonstocks in theup- min length = 1..5,5-10 min length = '3,larger than per200 m wasS.71 x 10'tons, fish biomass was 7.B 20 mm length = 5, copepods= 2 Volkov and Efimkin x 10' tons,with pollockcomprising 89.9', It was 1990k The accuracy of these coefficients is un- Ecologyof thr Brririf, Sea: i! RsianLiterature

Table20 Compositionofthe large zooplankton fraction in varioius regions of the western Bering Sea fall 1986,mg/m't from Volkovand Efimkin 1990!.

Region' Euphausiids Amphipods Copepods Chaetognaths Others

Coastal-neri tie communities 17 1V 63 1 879 266 6 2N 790 18 412 195 3N 51 515 202 463 229 4N 1 6 37 35 20 5N 95 21 87 294 2o 6N 9 43 113 7 2 28 7N 1 15 125 21 Average 93 125 183 246

Shelf communities 1S 823 350 713 160 3 14 2S 1,852 122 1,327 907 3S 21 97 758 337 4S 239 5 472 304 3 20 5S 5 74 159 76 ! 68 272 26 74 312 16 13 7S 227 19 254 290 6 8S 141 23 58 224 Average 494 88 4'17 348 9

Open v ater communities 1OW 107 38 163 554 31 21 2OW 63 23 144 246 27 Average 91 29 157 389 sse Figure ls.

known,as they are basedmore on assumptionthan for all three cornniuxut.ies as a whole i up to 1.2 x 10' tons! and for each individually .0 x 10' tons, coast- empirical data. A suxnxnaryof the mu!tidisciplinary research al;3.0x 10 tons.shelf; 9.26x10' tonsoceanict Thus. doneby TINROin primarily the westernBering Sea two-thirds of the total zooplankton stocks occur in during the last ten yearswas writt,en by Shuntovet the openocean region between 0 and 200 m dept.h. al, 993bt. The book contains a wealth of informa- If stocks deeper than 200 m are included, the open tion on zooplanktonfood fields, conditions affecting BeringSea is clearly predominantin terms of zoo- the food stocks and stock size pp. 231-277, tables plankton st,ocks. 36, 37, 39, 45, figures 108-110, 113-117k The au- However, most of the currently exploited fish thors present stock estixnatesfor the meso-and stocksforage in the upper 200 m The continental macrozooplanktonbiomass by individual groupsand slopein the Navarin-Karaginregion, with charac- phytoplanktonstocks in the coastal,shc! f, and oce- reristically elevat.edconcentrations of food organ- anic communities in the epipelagic zone of the east- isms, v,as shown to be one of the xnost important ern and western Bering Sea during individual foragingregions in the westernBering Sra tShunt- seasons,Seasonal dynaxnics of t.otalzooplankton bio- ov et al. 1993a, 1993b!. Even though zooplankton rnassare elucidated for the western Bering Sea.The stocks are sometimes Iow in the Navarin-Karagin data upon which the conclusionsare basedconsist region.fish do not disperseor abandonthis feeding not only of averagesfor the entire Bering Sea,but region.apparentlv due to thc consisteiit advection alsoof averagesfor severalyears. Highest zooplank- of zooplanktoninto thc area froin surroundingwa- ton stocks for the epipclagic zone of the vvestern ters. Stable f'rontal ysterns along the continental BeringSea occurred during the summer-fallperiod slopeapparently also contribute to thc aggregation Zooplarrktonot the BeringSea 126 of zooplankton.In additionto allochthonouszoo- ISHTARproject examined the effect of nutrient-rich plankton,high phytoplankton production along the Anadyrwaters on carbon and nutrient cycling, zoo- slopeproduces favorable conditions for growthof planktondistribution, and the distribution of benth- endemiczooplankton populations. In contrast.to the ic communitiesin the northernBering Seaand sloperegions, the openocean and shelf regions, southernChukchi Sea Hansellet al. 1989,1993; wherewater massboundaries are lesspronounced, Coachmanand Hansell 1993;Walsh et al. 1988: arenot asstable in zooplanktonabundance and bio- Springeret al. 1989!,Hydroacoustic data have re- massand fish schoolstend to bc muchmore motfle, vealedthe importance of tidal advectionan.d tidally the onlyexception being the frontal system near the generatedfronts in the small-scaledistribution, southernboundary of the Anadyr coldspot. density,and composition of food fields for seabirds andfish I Coyleand Cooney 1993, C oyleet al. 1992!. !n addition to small-scale processes, recent re- CONCI USIONS search has also been examining processesoperat- Interannualdifferences in planktonabundance and ing over decadesand oceanbasins producing its quantitativedistribution must influence nekton, long-termoscillations in fisheries populations. The especiaflythose as abundant as pollock, Neverthe- effect,sof El Niiro SouthernOscillation on fisheries less,simple comparisons of nektonand plankton populationsfrom South America to the westcoast stocksdo not reveal an immediatepattern. Not a of North Americahave beendocumented Enfield singleinstance of a large-scale.consistently posi- 1989,Mysak 1986, Miller 1985,Pear'cy et al. 1985t tive relationshipbetween nutrients, plankton, and The effectsof climate oscillationswith periodsof fish stocks was identified from any of the numerous severaldecades on phytoplankton, zooplankton, and TINROexpeditions Shuntov et al, 1993b!.The lack fisheriesstocks in the North Atlantic have also r e- of correlationbetween large-scale zooplankton and ceivedconsiderable attention surnrnarizedin Mann fish stock estimatesis not surprising. Basin-wide and Lazier 1991!. Long-term trends in ice cover, stockestimates ignore the smallscale patterns of surfacetemperature and fish stocksin the Bering horizontal and vert,ical zooplanktondistribution Seamay be influenced by oscillationin the average actuallyencountered by foragingfish. Zooplankton positionof theAleutia~ Low Niebauer1988 t The often concentratein narrowpycnocl ines and frontal apparentdecline in zooplanktonstocks in Korf-Kara- regions,Any interannual differences in thelocation gin Bavbetiveen the 1950sand 1970s may have re- andintensity of suchphysical features may mark- sultedfrom long-term climate oac illation s. Averaging edlyalter the actual food fields encountered byfish of'multiannualdata to obtainbasin-wide stock esti- but be undetectedby basin-widestock estimates. rnatesmay actually mask the important signals af- Recentand ongoingresearch in fisheriesocean- fectingfisheries populations. ographyhas emphasized the overwhelminginflu- Recentdevelopments in satelliteimaging, acous- enceof mortality of early life stageson later tic technology,optics, moored sensors, and towed recruitment.Processes affecting such mortality of- arrayspromise to greatlyexpand the rangeof tenl- tenhave little relationshipto eventson a basin-wide poral and spatial scales over which data may be col- scale.Future researchon the influenceof zooplank- lected and analyzed, offering much greater ton densitieson fish stocksmust take carefulmea- possibilitiesfor locatingand irlentifying those pro- sure of the temporal and spatial scales of the cessesmost, responsible for influencing populations processesactually limiting the targetspecies. As in the sea.The hypotheses guiding future research TINRO researchhas demonstrated,casual assess- mustincorporate the entirerange of newtechnolo- rnentsof zooplanktonand fish st.ockshave for the giesin an effortto identifyprocesses of the appro- mostpart failedto identifythe key events affecting priate temporala»d spatialscales to answerthe questionsbeing addressed. It is only this waythat conirnercial fish populations, Recent efforts in the Bering Sea by U.S. re- sufficientlyaccurate models can be generatedto searchcrs haveemphasized the importanceof fronts, providethe levelof understandingand prerhct,ive watermass distribution, and other physical features potentialrequired to manageglobal fisheriesre- on nutrient and carboncycling in the BeringSea. sources.Future cooperative research efforts betw een ThePROBES project examined the influence of fron- American and Russian institutes must combine both tal structureover the southeastBering Sea shelf on technologicaland theoreticalexpertise to address primaryproduction, zooplankton distribution. riitro- the environmentaland fisheries challenges created gencycling, and carbon cycling to bothbenthic and bythe ever groudng demand on Bering Sea resources planktonicecosystems Cont, Shelf Res. 1986!, The by the international community. Icotogyof thr Reririp; Seen A lceviewr!l Rtrssisnli teratcrre

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Afanasyev,N. N, 1981,Macropla.nkton as a foodbase Chavtur, V.G., and E.I, Shornikov. 1974. Planktonic for pelagicfish in the OkhotskSea. Izv. Tik- ostracods of the Bering Sea. Zool. Zh. 53k285- hookean. Nauchno-Isslcd. Inst. Rybn. Khoz. 288. In Russian.! Okeanogr. I TINRO! 105;56-60. In Russian.i Coachman, L.K., and D,A. Hansell edsi. 1993. Alexander, Vand H.J, Niebauer. 1981. Oceanogra- ISHTAR. Inner shelf transfer and recycling in phy of the easternBering seaice edge in spring. the Bering an.dChukchi Seas.Cont. ShelfRes. Limnol. Oceanogr. 26:1111-1125. 13/6!:473-704.

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Stepanova,VS. 1937,Biological indicators of cur- Vinogradov,M.F,, A.F. Volkov, and T.N. Semenova. rents in the northern Bering and southern 1982.Hyperiid amphipods Amphipoda, Hyperi- Chukchi Seas.Issled. Morei SSSR25:175-216. idae! of the v'orld's oceans.Opredeliteli po I'aune SSSR[Keys to thefauna ofthe USSR!. Izd. Zool. In Russian.! In-tom. Akad. Nauk SSSR 132, 493 pp. In Rus- Taguchi,S, 1972.Mathematical analysis of prima- sian.! ry productionin the BeringSea in suinrner.In: A.Y.Takenouti et al. eds,h Biologicaloceanog- Virketis,M,A. 1952. Zooplankton in theChukchi Sea raphyof the northernNorth Pacific Ocean Mo- and BeringStrait. In: Krayniy severo-vostok todacommemorative volume!. Idemitsu-shoten, SSSRlThe far iiortheastof the USSRl. Izv.Akad. Nauk SSSR,pp. 323-335. In Russian.! Tokyo, pp, 253-262. Taniguchi,A. 1969.Regional variat,ions of surface Volkov,A.F. 1988,The horizontalstructure of the primaryproduction in theBering Sea in sum- plankton communityin Karagin Bay.Biol. mer and vertical stability of ivater affectingthe Morya 4:19-24. In Russian. ! production.Bull. Fac.Fish, HokkaidoUniv. Volkov,A.F., and V.I. Chuchukalo.1985. The com- 20!: 169-179, positionand distribution of inesopl ankton in the Taniguchi,AS. Kazutoshi,A, Koyama,and M. Bering Sea from investigationsby TINRO, Fukuchi, 1976,Phytoplankton corumunities in 1949-!982i.Izv. Tikhookean.Nauchno-lssled. the BeringSea and adjacent seas. 1. Communi- Inst, Rybn.Khoz. Okeanogr. TIVRO! lit:120- ties in early warming seasonin southernareas, 124. In Russian. l J. Oceanogr.Soc. Jpn. 32!;99-106. Volkov,A.F., and A.Ya. Efirnkin. 1990. The planki.on Ushakov,P.V, 1947. Works of the KamchatkaMa- coinmunity and food haseof fish in the epipe- rine Station of the State Hydrological Institute. lagic zoneof the BeringSea during fall. Izv. Tr. Gos.Okeanograf. Inst. I3!, In Russian.! Tikhookean,Nauchno-Issled. Inst. Rybn.Khoz. Okeanogr.

SpeciesComposition andDistribution ofSquids in the WesternBering Sea

Ye.I.Sobolevsicy MariireBiology Institute, Russian Academy ofSciences ofthe Far East Vladivostok, Russia

INTRODUCTION and500-1,000 m. Squidbiomass was computed as Squidcatches in theBering Sea are minor compared outlined in Radchenko l1992!. to the large-scaleharvest of Theragrackalcogram- ma,Gadus murhua, salmon, and other commercial RESULTS fishes,probably because the biology of manycepha- lopodspecies ofthe Bering Sea is poorlyknown. We Schoolsof squidwere most common in the western havevery little reliableinformation on species corn- BeringSea in deepv atersof the CommanderBa- position,dynamics, and distribution, Most studies sin, ShirshofRidge, and the mesopelagiczone near focuson specificbiological questions of individual the shelf break from Cape Olyutorsk to CapeNa- squidspecies, in particularon Berryteuthismagis- varin, Squidwere consistently taken in thesere- ter Fedorets1986, Kuznetsova and Fedorets 1987, gions,which characteidstically contained the highest Okutani 1988!.or report generalinformation about speciesdiversity of squid Figures1-2!. Fourtee~ to speciescomposition, depth dist.ribution strata, and sixteensquid species, predominantly members of the evolutionot cephalopods Zuev and Nesis 1971; Nesis familyGonat,idae, were take~ in catchesfrom the 1982,1985!, Squid are importantin the diets of westernBering Sea Didenko1991, Radchenko whalesand seals Okutani andNemato 1964, Panina 1992 i. 1970,Berzin 1971, Sobolevsky 1983, Laevastu and Thespecies composition ot'squids in trawlcat.ch- Larkins 1981!and many speciesof fish Ito 1964, esis shownin Table1. In addition to th< 15 species Radchenko1992, Soholevsky et al. 1994!.They are taken during winter I TableIh Didenko I199l i re- thus a fairly substantialcomponent of the pelagic corded ari additional two speciesin the pelagic zone ccosysternsof the BeringSea Shuntov et al, 1993t of the westernBering Sea: C~onatupsismokko and Chirute u thisca lyx, Both speciesare characterized by a low biomass. MAEERIAIS AND METHODS Analysisof squidcatches has revealed a regu- Thepresent paper summarizes previous publica- lar distributional pati em. Berryteuthis magister tions on speciescomposition and distribution of occurspredominantly on the continentalshelf and cephalopodsin the BeringSea. Informat,ion is also in epibenthiclayers over the shelfbreak i FigureI !. presentedon the resultsof researchcruises to the Juvenile and subadultB. rnagisterwere generally westernBering Sea by TINRO, cruises participated caughtin thepelagic zone at depthsof 0-500m. One in byniembers of the MarineBiology Institute. Far- of the most abundantspecies. Crnrratupsis borealis, EastDivision of the RussianScience Academy. Basic wasfound in all regions.but the largestcatches were informationon species composition and distribution in deepwaters of the CommanderBasin and off- is takenfrom catchdata coHectedin 1987and 1991- shore waters of t,he Koryak shelf Figure 2I. espe- 1992iluring TINROcruises in v hichthe author ciallyyin winter ~December-January!. Both of the dominant species,B. rnugisterand partici pated. Squidwere taken in 108/528rope trawls w.ith G. borealis,were consistently present in the epipe- small-mesh liners. Hour-long trawls were done at lagiczone during the night,but highestcatches of 3-5 knots at various depths:0-200 m, 200-500m, bothspecies were taken from the mesope!agic zone Spc~ivsComposition an<7 Distribution ol lVestern 8 Sod Squ

Catch rate kg/hour! April-June 1990

Serryfeuthis Younggonatid squid magister <3 0 3-to 0 io-so Q 50-toOQ >00C, >30

B. magisfer areasof concentration, fall t 990 Adults Juveniles

Figurel, Catch deasof

Catch rate kg!hour! April June 1990

Gonatopsi s Gonatus spp. boreahs < 0.5 0 0.5 1 0 . 3-5 .

Gonatopsis borealis areaS of canCentratlan, fall 1990 r r r r

Figure 2. Catch distribution kgi hour trau led! of Qonatopsis borealis and Gonaius spp. ni depthsof200-500m and500- 1,000 ra in the south oestern Bering Sea in April-June 1990, andareasofroneentra- bon of Gonatopsis borealis in fall 1990. Adapted from Radrhenko 1992.3 738 Spttins Compositionand Distributionof westernBering Sea Squids

Table 1. Species composition aud occurrence of squids in trawl catches in the western Bering Sea, December 1881Qanuary 1882.

%:caught in n i trawls at depths of 0-200 m 200-500 m 500-1,000 m All dc ths Species n = 39! n = 36! n = 6i n = 81! tierryteuihi s niagi ster 25.6 63.8 16.7 42.0 Cronatopsi s borealis 64.1 86,1 66.7 74. I Gonatopsi s ottutani 5.1 33.3 8,6 Gonotopsis octopertatus 00 2.7 0.0 1.2 Gonatus tinro 15.4 83,3 100.0 519 Gonatus hamtschaticus 28.2 77.7 66.7 53.1 C~onatus pyros 2.5 16.6 16.7 9.9 Gonat us 6erryi 12.8 13.8 0.0 12.3 Gonatus onyx 5. l 5.5 33.3 7.4 Cionatus madottai 0,0 2.8 0.0 1.5 Gonatus sp. 0.0 8.3 0.0 3.7 Belonella borealis 0.0 44.4 100.0 272 Belonella phyllura 0.0 2.7 0.0 1.2 Gatiteuthts phyllura 0.0 50.0 18.5 llforofeuthi s rohusta 0.0 5.5 16.7 3.7 SOurse.S A Sharuiskkcru!ie Of SCienufir Ri SaarCh Ship PrnfeiSOr XaeVeuei in 199nlsa2

The deepwater species Belonella boreali s and B. magister was substantially lower. Gonatus tinro and phyllttra occur fnainly at meso- and bathypelagic G. kamtschaticus were among the other specieswith depths Nesis 1985', and were not caught in the biomass greater than 10% Table 2!. epi pe1agic zone. In the winter B. magister catches were slighl,lv Berryteuthis rrtagister juveniles were caught higher over the continental slope and in deep re- mainly during the summer in the shallows of the gions. In fall and early winter B. magister juveniles Gulf of Anadyr, where they were probably carried .5-5.5 cm long! were consistently caught in the by the Navarin current Radchenko 1992!. Commander Basin area. Adulte were taken less fre- Berryteuthi.s magister, Gonatopsis borealis, Go- quently in this region. natus tinro, and G. ltamtschaticus occur in the win- By and large, the general species distribution ter rn.ost.oft,en in upper shell'and open waters of the of squid in the western Bering Sea in late f'all and mesopelagic zone Table I!, T!uring summer and early winter was the same, with the rnaj or stocks aut,umn these species are found fairly regularly in concentrated in the mesopelagic zone over deep the central and v estern regions of the Bering Sea water and near the continentalslope, Such a distri- and over the shelf break to 500 rn depth. In spring bution of squid is consistent wit,h their ecological and early summer April-June!, B, magister is evolution. It is hypothesized that evolutionarily ad- caught most often at depths of 0-200 and 200-500 vancedspecies of squidinhabit the continental shelf m, and seldom occurs at 500-1,000 m depth. and surface waters Nesis 1985!, where their prey Juvenile Gonatidae were caught fairly consis- is abundant, Thc shelf and slope are biologically tently in all depths, but catcheswere greater at 500- highly productive, with high concentrations of plank- 1.000 m depth. ton, benthic organisms, and a high biomass of benth- In fall the catches were slightly different. The ic and pelagic fish Moiseev 1952, 1969; Shuntov et most abundant species,B. magister, was practical- al. 1993; Borets 1995!, ly absentfrom catchesin the epipelagiczone -200 Squid stocks in the western Bering Sea have mk Analysis of trawl catch dynamics at various received tittle study. Stock data Table 2! are baserl depths showedthat in fall and winter Gonatopsis on collections from a scattered station grid which borealisgenerally predominatedin surfacewaters did not cover the entire region and which was sain- and at 200-500 in depth, while the biofnass of B. pled during different seasons, Therefore, squid Eco!oglctf the Bering Sea: A Reviewof RuSSianLiterature 739

Table2. Squidbiomass thousands oftons! in the pelagic zone of the western Bering Sea in different seasons.

Biomass at trawl depths ol' Work period 0-200 m 200-500 m 500-1,000 m

May-July 1989 21.4 148.3 422. 1 April- June 1990 101.7 310.0 890. 1 October-November 1990 75.1 519.5 389.9 Including: Berrytertthis magisier 0.7 42. 8 0.0 Gonaropsis borealis 63.7 145.8 126.7 Belon ella borealis 0,0 6.6 131.3 December1991-January 1992" 61.2 66,6 Including: Berryreutht's magister 0.8 12.0 0.7 Gonaropsi s boreali s 57.5 24.0 10. 2 Gona us kant tschaircus 1.2 12.4 15.3 Gonarus tinro 0.3 16.4 20.0 Belonella borealis 0.0 8.8 70.6 Sources:Didenko 1991; Rsdthenko 1992, unpubl data from cruue nf ScientiticResearch StupPrOfeSSOr K~zei i acr in 1991-1992, Nutnhersfor squid biomass in 1991-1992 sre underestimates because the data for those yearSde net inCludeSu regteneOf I.he Western senna See.

stocks undoubtedly are higher than indicated. estimates from different seasons and years. Al- TINRO specialistsrecently estimated Bering Sea thoughthe estimatesdiffer significantly,the total squidstocks at 4 million tons Shuntovet al, 1993I. biomassof squidis substant,ialand is probablynot The estimate of 2.3 million tons l,Radchenko 1992 l lessthan 4 million tons for the Bering Sea.Although is probablycloser to the actual stocksin the west- squidbiomass is lowerthan fish biomass, v hich was ern and central Bering Sea. 50-60 m i llion tons in the 1980s Shuntov et al. 1993!, they have a fairly important ro]e in the ecosystem of the Bering Sea. DISCUSSION Juvenile squids are important in the diets of Fourteento sixteenspecies of squid commonlyoc- manycommercial fish species,particularly sockeye cur in the western Bering SeaiDidenko 1991,Rad- salmon Oncorhynchusnerlra l f Chuchukalo1994a l. chenko 1992!, but on]y a few species are dominant Theyare frequently consurncd by pink O.gorbu- by biomass,Adult specimensof oneof the dominant schal, sockeye,and churn O. keia l salmon during species,Berryteuthis magisrer,have been caught their anadromous migrations through deepregions mainly on thc continental slopeand the ou.tershelf of the Bering Sea Volkov 1994,Soholevsky et al. Okutani and Nemoto 1964, Fedorets 1986l. Cro- 1'994!.Juvenile squids primarily I3errvteuthis mag- natopsisborealis, Gonatus rinro, G. karntscharicus, ister and Gonatopsis borealis,i can comprise 40.8- and Belonella borerdiswere predominant in biomass 51.6'ycof the total weight of the food bolus in the during different seasons.Although fairly common stomachs of chinook salmon lO. lshawytscha l taken in the catches, the rest. of thc specieshave low bio- in fall and winter Chuchukalo et al. 1994bl. In Oc- mass and cannot be considered major species;thus, toberjuvenile squids make up 52r< of the rationof they have a minor role in the ecosyst,emsof the immature churn salmon in the Commander Basin Bering Sea. f Sobolevskyet al. 1994!. Squids and their young are As mentioned above, different researchers pro- important foodsfor marine mammals and birds. ducedsignificantly different estimatesof squidbio- Large numbersof seals,whales, and dolphinsfeed rnassin the western Bering Sea I edorets 1986, on squids Sobolevsky1983, I.aevastu and Larkins Didenko l991; Shevtsov 1991; Radchenko 1992, 1981l. The annualconsumption of' squids by toothed 1994!. The differences are especially marked for cetaceans,including spr rm whale f Physerermacro- Species<.oirrposi ionand Oj~tnbution afWee errBcvirrg Sea,Squi Ck 140 resourcesof the PacificOceanl. Tikhookean. cephalus!,killer whale Orcinus orca!, bottlenose Nauchno-Issled.Inst. Rybn. Khoz. Okeanogr. whales Berardi us borealis!, and dolphins, is at least TINRO!,Vladivostok, pp. 90-92. In Russian.! 0.1-0.15million tons Sobolevskyand Mathisen 1996 If. t.heannual consumption of squidsby pin- Fedorets,Yu,A. 1986. The biology and squid resourc- nipedsis added,the figureincreases by 0,2-0.25 esof Berryteuthis magister Gonatidae! near the million tons Sobolevsky1983!. Laevastu and I ar- CommanderIslands. In: Resursyi perspektivy kins981! estimatedthe yearly consumptionof squidsin theBering Sea by all whaleand seal spe- ispofzovaniya kal'marov Mirovogo okeana. Vses. ciesat 1.369million tons,The above figure .369 Nauchno-Issled.Inst, Morsk.Rybn. Khoz. Okean- million tons!must be an overestimate,because the ogr. VNIRO!, Moscow, pp. 57-66. In Russian.! computationwas based on the assumptionthat Ito,8, 1964. Food and feeding habits of pelagic salm- spermwhale stocks in theBering Sea were at 20,000, on genusOrrcorhynchus! in their oceaniclife. andthere have never been 20,000 sperm whales in Bull.Hokkaido Reg. Fish. Res. Lab. 29:85-97. the BeringSea. Despite large difTerencesamong publishedestimates ofsquid consumptio~, thefig- ures,although not absolutelyaccurate, do give a Kuznetsova,N.A., and Yu.A. Fedorets. 1987, On the generalpicture of the importance ofsquids in the foodof theCommander squid, Berrvteuthis nrag- foodchains. Preliminary estimates by Radchenko ister.Biol. Morya Vladivostok.! 1;71-73. In Rus- 992! suggestt,hat nearly 6,6 million tons of squid sian.! are consumedin the BeringSea annually. Never- Laevastu,Tand H,A,Larkins. 1981, Marine fish- theless,squid stocks in theBering Sea are sufficient eriesecosystem: Its quantitative evaluation and to allowa targetedsquid fishery in thenear future. management.Fishing News Books, Farnham, England,162 pp. Russiantranslation, 1987, REFERjNCES Agropromizdat,Moscow, 166 p. Berzin,A.A, 1971. Kashalot [The sperm whale]. Pishch,Prom., Moscow, 368 pp. In Russian.! Moiseev,PA. 1952.Some specific characters of distribution of dernersaland near-bottomfish in thefar easternseas. Izv. Tikhookean, Nauchno- Borets,I..A. 1995. Donnyye ikhtiotseny Rossiyskogo shel'fadal'nevostochnykh morey: sostav, struk- Issled.Inst, Rybn.Khoz, Okeanogr. TIVROI tura, elementyfunktsionirovaniya i promyslo- 37:129-137. In Russian,! voyeznacheniye lAssessment. ofground fish on the Russianshelf in the far easternseas: Com- Moiseev,P.A. 1969. Biologicheskiye resursy iVIiro- position,structure, the function ofelements and vogookeana [Biologica! resources of theworld commercialimportancej. Doctoral thesis, Vladi- oceans],Pishch. PromMoscow, 339 pp. In vostok, 48 pp. In Russian.i Russian.! Chuchukalo,V.IA,F, Volkov,A,Ya, Yefimkin, and Nesis,K.N. 1982. Kratkiy opredelitel' golovonogikh N,A. Kuznetsova.1994a. Food and daily ration mollyuskovMirovogo okeana lShort key to ceph- of sockeye Oncorhynchus nerka duringsurn- alopodsof theworld's oceansl. Legkaya i pish- rner, Izv, Tikhookean,Nauchno-Issled. Inst. ch. Prom.,Moscow, 355 pp. In Russian.! Rybn.Khoz, Okeanogr. TINRO! 116:122-127. Nesis,K.N. 1985.Okeanicheskiye golovonogiye In Russian.! rnollyuski; rasprostraneniye,zhiznennyye Chuchukalo,V.IA.F. Volkov,A.Ya. Yefimkin, and formy,evolyutsiya [Oceanic cephalopods, their A.I.Blagoderov. 1994b. The distribution and diet distribution,life cyclesand evolution]. Nauka, ofking salmon Oncorhynchus tschorciytscha ! in Moscow,287 pp, In Russian.! the northwestern Pacific. Izv, Tikhookean. Okutani,T. 1988. Evidence of spawning Berryteuthis Nauchno-Issled.Inst, Rybn. Khoz.Okca,nogr. nragisterin thenortheastern Pacific Cephalopo- TINRO! 116:137-141. In Russian! da,Gonatidae!. Bull. OceanRes. Inst. Univ.To- Didenko,VD. 1991. The biological resources ofsquid kyo 26!;193-200. in the westernpart of the BeringSea during thefall of 1990.In: Ratsional'noyeispol'zovaniye Okutani,T., and T. Nemoto. 1964. Squids as the food bioresursovTikhogo okeana [Rational use of the of spermwhales in the BeringSea and Gulf of fcolng~i'c>t the Bering .'iea: 4 Reviewo RussianLiferature

Alaska.Sci. Rep. Whales Res. Inst. Tokyo18:111- the tar eastern seas]. Tikhookean. Nauchno- 122. Issled. Inst. Rybn. Khoz. Okeanogr. TINRO!, Vladivostok, 426 pp. In Russian.! Panina,G.K. 1970.The foodof fur sealsin the neigh- borhood of the Commander Islands. Izv, Sobolevsky,Ye.I, 1983.The importanceof marine Tikhookean. Nauchno-Issled. Inst. Rybn. Khoz. mammals in food r.hains. Izv. Tikhookean. Okeanogr. lTINRO! 70:38-43. In Russian,! Nauchno-Isslcd. Inst. Ryhn. Khoz. Okeanogr. TINRO! 107:120-132. In Russian,! Radchenko, V.I. 1992. The role of squid in the pe- lagicecosystein of the BeringSea. Okeanologiya Sobolevsky,Ye, I., and O.A. Mathiscn. 1996.Distri- 32!:1093-1101, In Russian.! bution, abundance,and trophic relationships of Bering Sea cetaceans. This volume. I Radchenko,V,I. 1994.Sostav, struktura i dinamika nektonnykhsoobshchestv epipclagi ali Beringo- Sobolevsky,Ye. I, V.I. Radchenko,and A.V.Startsev. va morya lComposition,structure, and dynam- 1994. Distribution and food of churn salmon, ics of nektonic corninu.nities in the epipelagic Oncorhyrichuskenya, in fall and winter in the zoneof the BeringSea]. Candidate thesis, Vladi- western Bering Seaand the Pacific waters of vostok, 24 pp. In Russian.! Kamchatka.Vopr. Ikht,iol. 34:35-40.

Shuntov,V.P., A,F. Volkov, O,S. Teinnykh, and Ye.P, Zuev,G.V., and K.N. Nesis.1991, Kal'mary biologiya Dulepova.1993. Mintay v ekosistemakhdal'ne- i prornysel! Squid biology and fishery!]. Pishch. vostochnykhmorey l Pollockin the ecosysteinof Prom., Moscow,360 pp. In Russian. i Ecr>lrigynt the BerirrgSea: A Reviewu RussrdrrLiterature 7 4.3

Long-TermFluctuations inthe Ichthyofauna of the WesternBering Sea

N.l. Naumenko KamchatkaResearch Institute of Fisheriesand Oceanography KamchatXIKO! Petropavforxsk-Kamchatski,Russia

ABSTRACT Balykin 1981; Kachina and Savicheva 1987; Thiswork presentsthc resultsof trawl surveysdone Sokolovskiyand Glebova 198.'r; Fadeev 1986a, 1988; in the westernBering Seafrom 1958to 1993,and Zolotov et al. 1988; Balykin 1990;Naumenko 1990; examines structural changes in the ichthyofauna Shuntov 1991a; Shuntov et al. 1993! The list of overthe 36-yearperiod. Four periods with different publicationson groundfishesof the westernBering ichthyofaunalcommunity structures were distin- Sea is much shorter and half deal with feeding and guished,This paper outlines the causesof t,heob- trophic relationships of fishes Tokranov 1986a, served fluctuations in fish stocks. Causes include 1989;Tokranov and Tolstyak 1989;Tokranov and cornrnercialfishing and environmentalconditions. Vinnikov 1991a!. The remainder address biology and Thebiomass of planktivorousfishes varied relative populationdynamics Tokranov 1986b, 1988; Borets to variation in food supply. The total fish biomass 1989;Tolstyak 1990; Tokranov and Vinnikov 1991bt increased in years when water masses were warm In the last few years a aeries of separate arti- and decreased in colder years. clesand compendiadealing with different functional aspects of ichthyofaunal communities have appeared,a portion of which deal with the Bering INTRODUCTION Sea ecosystem Kachina 1979; Sobolevsky1983; Thecontemporary state of ecosystemresearch in t.he Fadeev 1986b; Shuntov 1987, 1991b; Shuntov et al. western Bering Sea is adequate.The number of 1988, 1993; Markina and Khcn 1990; Naumenko et publicationsdealing with climaticvariability and al, 1990; Shuntov and Dulepova 1991!. oceanographicconditions in the westernPacific, in- This work uses the results of trawl surveys done cluding the Bering Sea,may not be great but they over many years in Karagin and Olyutorsk bays to summarize a broad series of extensive observations docurocnt changes in the structure of the ichthyo- Karpova 1963;Davydov 1975,1984, 1986,1989; faunal community and establish the reasons for the Khen 19911 Seasonal and annual changes in thc changes. structure of the zooplanktoncommunity are also fairly well studied Volkov and Chuchukalo1985, MATERIALS AND METHODS Bulatov 1986,Safronov 1987,Volkov 1988!.The food base,diet, and feedinginteractions of larval fishes Regularichl.hvological research started in t,hewest- in Karagin Bayhave beenstudied for a numberof ern Bering Sea with the establishment of cornmer- years Maksimenkov1982a, l 982b,1984 t cial fishing in the late 1930s.Initial studies were Most of the work has addressed the biology and done primarily from coastal stations. Observations stock size of the two most abundant commercial fish- from oceangoingvessels became the main sourceof es in the western Bering Sea: herring Clupea pal- ichthyological information in the late 1950s. lasi! and walleye pollock Theragra chakogratrrma!. Trawl surveys were done in Karagin and Olyu- Thereare nearly100 such publications but mostdeal torsk bays every year in the late fall and early v-in- with specificbiological studies on individual species ter from 19;>8through 1993, except for 1984, 1991, and only 13 of thosecan be consideredsignificant and 1992. The survey grid consisted of 100 si.ations Serobaba 1977, Kachina 1981, 1986; Kachina and during the first 3 yearsand 6o stations thereafter Long-TermFIuctustionsin thekhthyof~una ofthe tVe stern Bering Sea

58'N

16 Figure1. Standardtrau~l stations inthe sample grid.

8. Othertlatfishes Acanthopset ta nadesh nyt, FigureI!.A total of 2,839 trawls were done during Qlyptocephatus.stelleri,Hippoglossoities ro- thefall-winter study season, In addition to the stan- bustus,Lepidopsetta bilineata. Lin!enda dardfall and winter observations, supplemental aSpera,Limanda prnboScidea, Ptatiehthyk surveyswere done once every 3-4 years in spring ste/lotus,Pleuroneetes quadri tubercula tus! andsumtner. A total of 10 spring 05 trawls!and 9 9. Sculpins Cottidae, Blepsiidae, Psychro- summersurveys 76 trawls!were done, A half-hourtrawl was done at eachstation ur- lutidae! 10. Poachcrk Agonidae! inga benthictrawl with a 10-mm mesh cod-end lin- 1l. Others Rajidae, Stichaeidae, Zoarcidae, Cy- er whichretained fishes of all ageclasses starting clopteridae,Liparidae, Hexagrarnmidae, with 0+. Surfaceand bottom water temperatures Ammodytidae,others! weremeasured after each trawl. In addition,0-age pollock, herring, capelin, Pacific Standardroethodh were used to sortall fishin cod,saffron cod, and Greenland halibut i Reinbnrd- eachcatch into ll categories: tiushippoglossoides! werecounted separately in 1. Walleyepollock Theragra chalcogramma! every catch. 2. Herring ClupeapaQasi ! Sincethe typesof vessels and size and construc- 3. Capelin Mo1lotuk socialis! tionof thetrawl s ehange d periodically, all dataw ere 4. Smelt Osmerusmordax! normalizedto a standardtrawl fishing550 m of 5, Pacificcod 'odus maerocephalus! water. 6. Saffroncod E/eginus gracilis! Eachbay was divided into threebathymetric 7. Halibuts Atheresteseuermanni, Hippoglos- zones:under 50 rn, 50-100 m, and over 100 rn. I lance sus stenolepis,Reinhardtius hippoglos- the entireresearched area was divided into kix un- soi des! Ecologyot the Bern!gye,i: 8 Re!:iceof Rusxt~»Literature equalareas h aving similar speciescomposition. The Table 1, Bathyrrretric characteristics of Karagin catchper standardtrawl effortin weight

RESULTSOF THE TRAWL SURVEYS Spatialandbathymetric distribution offishes Aftercomparative analysis ofthe distribution offish- esin Karagin and Olyutorsk bays, it. becameclear thatin all seasonstwo groups of fishescan be dis- Figure2. Generalizedcurrent syeteras tinguished,which are conditionally referred to as in Karag>'ri Ray during coastaland deepwater Figure 3!. Safi'roncod and iuarm and ioId years.See smeltare typical of thecoastal community; Pacific Figure 7 for geographic cod,halibuts, and to a lesserdegree pollock com- a am.es. rAdupted from thedeepwater complex. Poachcrs are associ- Daoydoo1972, u:itti addi- atedprise mainly e with the deepwater group, and flatfishes tions. > withthe coastal group. Mature herring spend rn ost of theirlives with the deepwatergroup; however. theyoccur in depthsless than 100 m inspring dui- ing th e spawningspa in migration and the initial stages of theforaging inigration and thus occur with the coastalcomplex. The distribution of capelinis unique:: there ere is noconsistent distributional patt.em. betweencapelin catches and those of anyother tish or group in any season. ECOIOgyOrttt t Berirt~Sea: A ReuietvOl RuSStart I.iterature Table2. Trawlcatch in thousands oftons! of principal commercial fishes inthe western Bering Sea. Karaginand Olyut,orsk bays WesternHaring Sea* Species 1958-19671968-1977 1978-1987 1988-1993 1958-1967 1968-1977 162.8 Pollock 5.8 86.3 143.3 9.5 131.1 t 0.4 Herring 131. 1 4.5 16.5 3.8 28.8 Pacific cod 16.8 21.5 3.4 5.2 Saffron cod 3 9 2.7 6.8 8.1 5.o Flatfishes 2.3 4.3 6.2 7,5 Pink salmon 9.6 11. 7 17.5 Churn salmon 0 5 0.4 4.8 Datarrnni Fedeesi lSSsbi.

Walleye pollock Halibuts Spring Pacificcod Sculpins Poachers Pacific herring Flatfishes Saffron cod Smelt Capekn Ftaffishes Sculpins Sum Capelin Smelt Saffron cod Pacific cod Halibuts Poachers Walleye pollock Pacific herring Walleye pollock Paciiic cod Halibuts Fall-Winter Pacihc hemng Poachers Sculpins Saffron cod Flatfishes Smelt Capelin 5 1 0.01 Pacific cod Halibuts Walleye pollock Pacific hernng All seasons Poachers Sculpins Smelt Saffron cod Flaffishes Capeiin 5 1 0.01 -Q.5-0.4 -0.3 -02 -0-1 0 0 1 0-2 0.3 0.4 0.5 0 6 0.7 Q.ft0 9 1.0 Correl ation coefficient

Figure3. Clusteranalvsis of jish distribution tn Karachiri nnd Olvut<>reit bavs. Dashed ucrtical lines rcpreseritpro6abr/it t tei elec Long-TermF uctrrations inthe fchthyotauna otthe 'IVestr rnBering Sea Table3. Distribution ofbioxnase offishes in the western Bering Seaby survey fishing areas anddepths andcatch per standardsurvey trawl.

Saffron Flat- Pacific cod fishes HalibutsSculpins Voachers Others Area PollockHerring Capelin Smelt cod

Biomassby fishing area 9 I 15.8 30.r 64.9 60.6 13.4 40.0 I 8.3 24.7 61.2 55.9 16.5 16.0 16.0 7.9 23.5 8.4 37.2 16.6 16.9 16.5 11 11.0 5,1 14. i 17.2 1.5 7.5 20.6 16.3 III 29.3 14.1 14.2 2.9 23.8 12.8 5.7 11.8 '3.4 2.0 10.8 8.9 4.6 IV 3.6 3.9 7,5 7.9 11.0 53 57 11.1 11.1 V 20.0 17.6 5.8 0.4 11,4 26.1 10.9 42.1 14.2 2.9 1.6 20.9 2.5 5.1 VI 27.8 34.6 0.2 1.2 5.6 10,0 1.7 3.7 All areas 42.4 23.7 1.0 07 98

Bathymetricdistribution of biomass t~r! 26.2 45.7 27.6 34.0 57.9 27.3 73.8 65.2 < 50m 11.9 28.6 68.7 15.8 34. 5 22.2 22.2 27. 1 27. '1 50-100m 31.0 22.7 14.2 37,6 28.0 46.7 27.2 56,6 3 i.5 ! 100 m 57.1 48.7 17.1 4.5 44.7 4.0 12.6

Averagecatch per standardtrawl lkgl 0.76 4.08 19.7 35.2 6.11 13.1 Total 149.1 83.3 3.46 2.45 34.6 natefrom traal aureeyr inrruxragin antiOlyatorek baya,19SS-1993 excluding i9S4,199i, and 1999 I

Thereare four statisticallysignificant correla- bathymetricdistribution offishes in KaraginBay tionsin fish distributionduring both winter and areless extreme: catches near the shelfbreak area spring.Pollock, halibuts, Pacific cod, and sculpins III! areonly 2-5 times greater than catches in shallow waters area Il. co-occurin thespring, as well as herring and flat- A moredetailed presentation of catchst,atistics fishes.There is also a strongcorrelation in the catch bydepth in thewestern Bering Sea during fall and distributionof pollock,Pacific cod, halibuts, herring, winter is givenin Table5. andpoachers during winter. There are only two sig- Springis a periodof ini,enseforaging for fishes nificantcorrelations in the distributionof fishes ofthe arcticboreal and boreal f'aunistic complexes, duringsummer, in Julythrough September: flat- whichinclude most of the westernBering Sea spe- fishesand sculpins are correlated, and Pacific cod cies.Pacific cod, halibuts, and some other flatfishes and halibuts. graduallymove from the deep areas not covered by For9 months,October through June, the most, surveysto thecontinental shelf, Therefore, Pacific productivefishing area in the study region is the codcatches are 1.2 times greater on the shelfin sinn- shelfbreak zone near Olyutorsk Bay areaVI; see merthan in otherseasons, the catchesof flatfishes FigureI!, wherea substantialpart of the pollock, are 1.6-1.7times greater, and catchesof halibuts herring,Pacific cod, and halibut stocks are concen- arealmost twice as high. Capelin, saffron cod, and trated Table3!. Thetotal catch of all thefishes per smeltconcentrate in coastalareas, in shallowla- standardtrawl in thatarea is about 780 kg in spring goons.coves, and sometimes in estuaries, and are andalmost 1,200 kg in winter Table4!. Catches thereforeinaccessible to trawls on the standardsta- nearthe shelfbreak off KaraginBay {area III! are tiongrid. Thus, surnrner catches of thesespecies are somewhatless: 405 and R84 kg for spring and win- 1.7-4times below winter catches.The remainir,g ter,respectively. Catches decrease with decreasing species,pollock, herring, flatfishes, and sculpins, are distancefrom shore and are minimal in thecoastal spreadover the entire area of the bays. Differences zoneof OlyutorskBay I areaIVI, wherethe average v intercatch is only76 kg per trawl,and barely in bathymetricdistribution of the catchesbecome reaches20 kg pertrawl in spring;half of thecatch lessapparent in summerthan in winter or spring. consistsofjuvenile pollock. Therefore, during spring especiallyinOlyutorsk Bay. Therefore, the catch per andwinter there is anorder of magnitudediffer- standard trawl effort in summer is maximum. encein the bathymetricdistribution areas IV-%! 466kg, asopposed to 345kg in winter and 295kg of fish catchesin OlyutorskBay. Differences in in spring. ECOIOgyOfth< Bering 5edi A RevietvOt RucSian Literature

Table4. Averagecatch Igg! of fishes per staadard survey trawl by area and season. Parirtc SaffrOn Flat- Totalin Area PollockHerring CapeltnSrnelt cod cod fishesHa!ibuta Sculpina Poachcrs Others the area

Spring April-June 1 41 6 0.5 6.7 0.34 3.1 199 li 3 95.2 1.2 2.1 36.3 ai.3 1.6 11.6 0. 10 3.4 194 Il 37.3 57.2 50.4 1.9 32.7 10.9 19 4 6.2 29.6 0. 75 89 405 I 2030 lrs 3 1.9 2 4 112.3 5.6 1.5 0.4 3.5 0 0.2 20 TV 9.6 0.3 0.9 0 2 3 1.6 19 9 8.4 30.5 3.2 557 V 382 6 41.1 0.5 0.1 61.J 9.0 lb 4 24.0 i6.9 9, rt 783 VT 414.6 189.4 0.2 0.4 100.5 3. 4 29.9 4.44 13.0 0.82 4. 14 295 Mean 110.3 74.7 2 76 1.16 34.9 19.2

Summer July-Septemberi 769 37 170 0 36 2.0 281 I 68.7 66.3 36 1 3 25 2 16 4 41.2 6.6 11.2 0.36 9. 1 292 11 174 0 4.5 1.6 2.4 27 3 13 5 407 178 141 0.47 7.2 968 III 670.4 143.1 2.4 0 71.0 0. 5 24.1 20.2 7.4 1.50 0.4 414 139.0 81. 2 3.7 08 90.8 45.4 175 63 66 0,71 2.3 966 V 536 9 348.2 45.1 2.4 92 136 63 1.90 4.3 591 VI 461 5 48.0 45 2 09 0.67 3.9:3 466 Mean 242.8 90 5 235 108 409 143 484 861 125

Fall-Winter Ortober-March! 0. 22 38 151 I 29.8 10.3 6.2 6. 3 11.9 39.9 38.3 1.6 13.1 20.1 6.6 11.2 0 si 3,1 205 II 76.6 lfts 2. 2 8.8 33.0 25.9 18 8 12.2 22.1 1.74 58 884 III 5i9.3 158.6 8.7 0.3 73.0 3.3 0.93 29 76 IV 11.1 11.6 2.5 0.6 13.2 4.0 17.5 1.9 9 5 22.1 6.1 11.2 0.81 5. 3 220 V 839 468 4.5 0.1 21.6 17.7 23.1 12.0 18 1 2. 51 4 3 1,195 Vl 527.7 523 1 2.2 0.8 72.5 9.1 5,10 13.6 0. 77 4.00 345 Mea» 14'3.9 82 6 4.73 4.36 33.2 24 6 27.7 notafrom trawl surveys taKarogio and < liyutorskbays, 1956-1993 i exvlutriog 1984.1991, and 1992

Long-termchanges in abundance and Duringfall andwinter whenthe annualstock structureof ichthyofauna assessmentswere made, the catcheswere somewhat Fish biomass in the western Bering Sea is dorninat- different.,but onthe wholethey were similar to the edby pelagicspecies. Groundfishes are less abun- annual average 1Tables3, 6!. dant due to the limited area of the shelf, The pelagic The abundance and composition of fish stocks ichthyofaunaincludes pollock, herring, capelin, and in the western Bering Sca changedsubstantially smelt, All others are benthic. overthe yearsof the study1Table 6!. Herringdorn- Over36 years, the averagecatch of pelagicfish- inatedthe catchesduring the first. 7 years.An aver- esper standard trav.1 has been 238 kg 7,7'yrof the ageof 1,746herring or 291kg total weightwerc total catchof all speciesand groups!; the ground- takenper trawl on the shelfin 1958-1964.Herring fish average is 113 kg 2.3~r l. comprised77'ii oi't.he total pelagicfish biomassand The dominant fish speciesin Karagin and Ol- 611.9"iof the total biomass. In addit.ion to herring, yutorsk bays are pollock and herring. They corn- smeltcatches were also maximum during this period prisedup to 42.4~/

Karagin Bay 334.6 596 ! 501.9 18,6 84.3 123.4 Pollock 0.1 13. 8 190. 7 19fi. 2 233.4 24.0 10.5 16.1 17.5 Herring 1.8 0.6 0 2.0 24.6 9.7 2.2 7.4 2.4 tlapelin 38.1 !0',3.9 121. 3 12.2 22,3 43.7 28,8 Pacific cod 0.4 0 12. 1 10.4 19 0.8 28.3 44. 5 39.7 SatTron cod 18.4 20.5 11.0 20.4 19. 7 26.2 Flatfishes 26.9 39.6

Olyutorsk 13ay 13.0 99.6 2:39.3 6442,'331. 3 202. 5 Pollock 7.6 67.0 1,296.1 596.9 93.8 105.7 0 1,9 11.8 26.6 Herring 5.3 5.6 2.1 1.0 0 2.0 2.5 3.7 Capel in 12. 1 ,'31.2 71.8 93.6 68.6 56. 2 Pacific cod 1.0 13.2 12.4 12.0 19.0 14.0 1.5 19 Saffron cod 3. 7 4,1 12.5 31.8 25.7 18.2 12.6 35.9 Flatfishes 2,9 17.6

Table6. Average number andsveight offishes caught perstandard trawlby period ofyears, 1958-1893. PollockHernng Capelin Sruelt Pacificcod Saffroncod Flat-fishesHalibuts Sculpins Poachers Others Total Years in nuinber of fish Averagecatch per standard trawl 15 2 86r 25 65 147 7.5 31 1958-1964 365 1,746 317 145 3 I 2.246 17 83 152 2,2 21 1965-1974 623 618 663 44 23 2,355 36 242 54 2.8 10 1975-1987 1,278 372 297 23 18 4.290 79 548 134 1.7 41 1988-1993 630 1,877 843 24 11 23 2,728 35 204 115i Mesri for 792 965 504 53 36 years ni weight kgi Average catch per standardtrav, I 0.41 5.:1 47&.7 27.0 10 0 32 9 5.8 19.3 72.0 291.4 2.9 11.7 1958-1964 3.4 10.4 0,95 4 1213 6 70.7 46.'l 7.7 3 1! 15.3 11.7 39.7 1965-1974 3.9 6.4 1.01 3.5 349.9 2 1 1.9 28.7 25.8 13.6 1975-1987 238.5 24.5 0.37 3.'1 394 7 80.0 60.2 32.3 9.7 27. 7 198H-1993 145.3 24.8 7.6 3.4 4.7 4.4 33.2 24.6 27.7 5.1 13.6 0.77 4 0 344 6 Stean for 143 9 82.6 36 years Ecologyof theBeriiig Sea: A Reviewof Russianliterature speciesby bioinass were flatfishes, herring, and pol- stocks Naumenko et al. 1990!. This can he con- lock.Catches of pollock,Pacific cod, ha!ibuts, and firined by comparisonof multiannual changesin the total catch in this period were lowest, but cape- biomass of western Bering Sea pollock and herring !in and flatfish landings were rnaxirnum. with catchdynamics during the trawl surveys.The Pollockbegan to dominatethe catchesin 1975 information in Figure 4 conclusively demonstrates anddominated during the following13 years. It was that the surveydata conform with long-termtrends the absolute dominant in both abundance and bio- in the biomassof both species.The correlation fac- inass. The average pollock catch in 1975-1987was tors characterizingthese relationships are high and 238kg per trawl, or 68.2~icof the total catchof all significant:for pollock.r =0.927, t = 11.9> t,, wit.h fishes.The stocksof herring, capelin, and smelt, n = 22; and for herring, r = 0.601, t = 6.85 > t... alongwith benthicspecies such as halibutsand with n = 32. sculpins,were very depressed, Catches during this However, best results are obtained if 5 years of periodwere under the historic maxiinum by 12times standard trawl data are smoothed and displaced for herring, 6 timesfor smelt, 4 timesfor sculpins, back or laggedby l year, In that casethc correla- and 3 times for halibuts, tion coefficients increase to 0.928 and 0.646, respec- In recentyears there has beena slight,recovery tively. ofthe ichthyofauiia. Although pollock retained their Therefore, the results of the trawling surveys, dominancein biomass,they neverexceeded half of after transformation, adequately reflect long-terin the total catch in 1988-1.993.The portion of cape!in changesin the biomassof the twodominant pelagic and smelt in the catches substantially increased. speciesin the westernBering Sea, pollock and her- Capelinwere particularly abundantin the late ring.The above may also be valid for two otherpe- 1980s,and approachedtheir peak abundancesin lagicspecies: capelin and smelt.In any case,the the late 1960s and early 1970s. Strong year classes useof the surveydata for comparingthe numerical of herring occurredin the westernBering Sea in dynamicsof'afl four pelagic species seems entirely 1987, 1988, and 1993, resulting in rapid increases appropriate. in abundance.Although herring biomass has not as As mentioned before,t.he pelagic fish conimunity yet increasedas much, it wi!I probablycontinue to in Karaginand Olyutorsk bays has been quite vari- grow for several inore years. ableduring the study period.The overall situation On the whole, the past 6 years 988-1993! can has been determined by the pollock stocks. The bio- be considereda period of groundfish dominance. massof the other three species has been lower, as Maximumcatches per standardtrawl surveyeffort confirinedby correlationanalysis Table 7i. Cape- wereattained f'or Pacific cod 80 kg!, saffron cod0.2 lin areprobably at the bottom of the hierarchybe- kg!,halibuts 9,7kg!, and scu!pins7.7 kg!. Flat- causetheir abundancesharply increases in the bays fish catches were a! so above the long-term average. for only a short time, when herring and pollock Thus,four periodscan be clearlydistinguished stocks are minimal. These interactions in the corn- in the ichthyofaunal community of the ivestern rnunity suggestthe presenceof food competi ,ion BeringSea; herring 958-1964i, transitions! 965- amongplanktivorous fishes, an opinionshared by 1974!,pollock 975-1987 i, andgroundfishes or another researchers Kachina 1979, Shuntov et al. other traiisitional period, starting in 1988 and 1988, Berets 1989!. continuing at present, In addition to the general teridenciesoutlined above,the directionof herring andsmelt stockfluc- tuations is the saine; however, this probably reflects DISCUSSION the usual relationship betweena predator smelti The trawl survey data permit us to comps.rethe and its prey larval, post-larval. 0-classherring!. catchper standardsurvey effort in Karaginand Smelt consumea fair!y large amount of'juvenile Olyutorsk bays over the last 36 years. They also herringin KaraginBay during suinmer,consider- permit us to assesshow the results reflect actual ably more than juvenile pollock Karpcnko 1982a, changesin the fish community.[n addition.it is in- 1982bk teresting to comparechanges in stock size of the There is much less information on groundfish- majorfish specieswith climaticand oceanological es;however, judgi ngfrom trawl surveyresults, they processes. alsoundergo long-term changes. In the first 15years The results of the trawl surveys are considered I 1958-1972k flatfishes dominated benthic com- an accurate reflection of actual changes in popula- munitybiomass, averaging about 45'.< of the total tion structure and speciescomposition of pelagic catch of all dernersalfishes. Saffron codbecame dom- Long-TermF ttctuations in tht !chthynbttn,]ot thelk'estetn Bering Sea

400

300

200 160 1 DXto

1960 1970 1980 NO0 K O C CI 2.0 400 I Q. O 300 O

1.0

0,5

1970 1990 Figure4, Changesinstock abundance andeotekes perstandard suroey trau l ofpollockond herringin the western Bering Sea. En>logyot the HeringSea: 8 Revieivot Russiantitr- rature 153

Table 7. Results of the correlation analysis of removed, quickly led to a collapsein the population. stock abundance for pelagic fishes in the By the endof the decadespawning stocks were only western Bering Sea correlation coeffi- 2% of the optimal number for effective reproduction cients!. Kachina 1981k Pollock in those years and in the 1970s did not experience any fishing pressure, and Pollock fishirig pressurematched the stocksize only in the Species Herring Capelin Smelt & herring 19&OsiBalykin and Maksimenko 1990, Shuntov et al. 1993l. Smelt and capelin were never exploited Pollock - 0.704 ' 0.589' 0.663' 0.4G1 at a commercial level. Herring t1.164 0.646* 0.195 Capelin,haidng the shortestlife cycle,were suit- 0.808' C apelin 0. F25 ed to occupy the niche vacated by herring, but were '1m elt 0,140 quick!y forcedout by the better-adaptedpollock. 'r,nrri laliiiiisilrnificaiii! P S 0OL! Flatfishes in the benthic community are analo- gousto herring in the pelagiccommunity. Accord- ing to trawl surveys.their stocksin the late 1960s and early 1970s were very limited, but the commer- inant in 1977-1980 fi1%! and cod have dominated cial fishery continued to grow. Cods, on the other since 1981 1% 1 However, as compared to pelagic hand, were intensively fished in the western Bering fishes, variations in the groundfish community were Sea only in the late 1970s. lessabrupt, with lower amplitudechanges in abun- Nevertheless, some aspects of ecosystem func- dance of individual species, tion in the western Bering Sea cannot be explained Fourgroups of fishescan be distinguished, based by the anthropogeniceffect alone, in particular, the on catch per standard trawl Figure 5k sharp decline in the biomassof both pelagic and benthic fishes, observedduring the transitional pe- 1. Capelin and flatfishes,whose stocks were high- riod in the late 1960s and early 1970s.There is no est at the start of the second and end of the third satisfactory explanationof why for 8 years, from ichthyofaunaldevelopmental periods and low- 1963 through 1970, the number of herring progeny est.at the end of the secondperiod and begin- was less than that of the spawning adults and why ning and middle of the third period. a similar situation has occurred in pollock popu]a- tions over the last few vears. Finally, reasons for 2. Smelt, sculpins, and halibuts, whose stocks in- synchronousdeclines in stocksof both exploited and creased during the first period and end of' the nonexploitedgroundfishes during the secondperi- third period,and decreasedin the secondperiod od and increases at the end of the third and fourth andbeginning and middle of the third period. periods remain unexplained. Causes for those stock changes are probably 3. Gadids pollock, saffron cod,and Pacific cod!, related to changing environmental conditions as whose stocks have been gradually increasing. characterized by one of the more universal environment,al indices water temperature. The four ich- 4. Herring and poachers,whose stock fluctuations thyofaunal periodsdetermined above for Karagin were not related to each other' or to the abun- and olyutorsk bays can be characterized by bottom dance of the other groups. water temperatures in fall and surface temperatures in spring and summer.The first periodwas rnoder- The next step in this research is determination ately v"arm, the.second abnormally cold, and the of the causes of the changes, A number of hypothe- third abnormally warm Table 8 t The fourth, which ses are currently under consideration, but the actu- appearsto be transitional, is still under way.There al causes of such extensive variations in the fish are not yet sufficient.da a to classifythe fourth pe- communityof' Karagin and Olyutorsk bays proba- riod, but surface temperatures during the first 6 bly involve unevenfishing pressureon individual yearsl 1988-1993!remained warm while the bottom componentsof the communityand environmental vvater cooled somewhat. factors. Undoubtedly, a combination of those two Fluctuations of the zooplankton biomass v ere factors led to the observed structural changesin the closely correlated with fluctuations in water tem- ichthyofauna. perature;biomass was highest during the abnormal- The intensification of the herring fishery in the ly warm pollockperiod and lowest in the abnormally 1960s, when 30-65'7cof the spawning stock were cold transitional period i Table Sl, However, the ra- l ong-TerrrtFluctuations in the Ichthyofaun~ ot the Westent Bering, See

Capelin Flaffishes Pacific herring Smelt Sculpins Halibuts Poachers Walleye pollock Saffron eccl Pacific cocf I I 5 1 001 -0.3 -0.2 -0.t 0 0.1 0 2 0.3 0.4 0.5 0i6 0.7 0.8 0.9 1 0 Correlation coefficient h'igure5. Clusterrelationships offishes for catch per standard traul data. in the u esternBering Sea. Dashed vertical line~ represent probability levels.

O 0

1955 1960 1965 1970 1975 1980 1990 Year Figure6. Long-termvariation.«n minimum. uiater temperaturein thecold intermediate layerby the southeast coast ofKamchatka data smoothed for5-year peri odsi. Redrau:n from Davydov 1989.J Ecologyoi the Bering Sea:i~ Reviriv of RussianLiterature 755

'fable 8. Characteristics of average environmental conditions of the western Bering Sea.

Total Season 1958- 1965- 1975- 1988- period of or depth 1964 1971 1987 1993 observations

Anomalous water temperature on the surface

Anonialous water tern perat.ure.near bottom in November r 'C! Karagin Bay < 50 m +0.02 -0.39 +0.32 -0. 18 1958-1990 50-100 m -0. '! 5 -0.31 +0.48 0.68 1958-1990 > 100 m 0,15 0.36 +0.28 +0.38 1958-1990 Olyutorsk Bay < 50 ni +0.04 -0.11 +0.01 +0. 22 1958-1990 50-100 m +0.09 0.26 +0.18 0. 13 1958-1990 > 100 m +0,06 0.47 + 0.37 -0.16 19 iH-1990 Anomalous zooplarik on J>iomassin Olyutorsk Bay in, June mg/m'! +107 -306 +111 1952-1986

tio of the average zooplankton bio nasa in Olyutorsk to the water temperature. The abundance of benth- Bay to the average catch of planktivorous fish per ic fishes lagged behind v ater temperature changes ur it of effort, an index of the relative food supply. and the magnitude of the lag was greater for fishes was almost unchanged during the study period ,3 with longer life cycles. nig m "kg ' during the first period and 2.5 mg m 'kg ' during the second and third periods!, Long-term fluctuations in the mini muin ternper- CONCLUSION ature of the cold intermediate layer near the south- Standard trawl surveys were conducted in Karagin eastern coast of Kamchatka Davydov 1989! are also and Olyutorsk bays for 36 years between 1958 and important to this discussion. Most interesting are the 1993. The catches consisted primarily of pelagic fish- sudden reversals in warini ng and cooling trends which es. Catches of benthic fishes were louver due to the exactly correspond to changes in the ichthyofauna in limited area of the continental shelf. The st,ructure the western Bering Sea Figure 6!. Davydov 989! of'the fish community was highly variable during predicted that the warming event which began in 1982 the study and could be divided into four distinct and reached its zenith in 1986-1987 would last until periods: 1958-1964, when herring dominated: 1965- 1990-1991, and be followed by a cooling period. This 1974. a trani itional period when no single species prediction corresponds exactly to community changes was dominant and stocks were uns ,able; 1975-1987, in the western Bering Sea ichthyofauna. when pollock dominated in both abundance and bio- Warm years also produced favorable reproduc- mass; and 1988 to thr present, characterized hy a tive responses among the groundfish commuiii .y. At gradual decline in pollock and an increase in ground- any rate, the survey catches of Pacific cod, halibuts, fishes. 1'he changes in t,he fish coinmunity v"ere due other Aatf!shes, and sculpins varied proportionally to fishing pressure and environmentalchanges, Iong-Term !.luctuao'ons inthe Ichthyofauit a of!he 1+'estern Bering Sea 156 Davydov,I.V, 1989,Characteristics of development REFERENCES of atmosphericcirculation in the northernPa- Balykin,PA. 1990.Biologiya i sostoyamiye zapas- cific Oceanand their role in deterrninglong-term ov mintaya zapadnoychasti Beringovainorya changesin the abundanceof certainfishes. In; [Biologyand composition of pollockstock in the R.J.Beamish and G.A.McFarlane eds.!, Effects westernBering Seal. Avtoreferat dissertatsii na of oceanvariability on recruitment.and evalua- soiskaniyeuchenoy stepeni kandidata biolog- tion of parainetersused in stockassessment icheskikh nauk fCandidate thesis], Petropav- inodels,Can, Spec,Publ. Fish. Aquat. 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Maksimenkov, V.V. 1984. Feeding relationships of Shuntov, V.P., A.F. Volkov, and A.Ya. Efiinkin, 1988. the larvae of several fish species in Korf Bay, Composition and current condition of the pelagic Vopr. Ikhtiol. 24!:972-978. fish communities in t.he yvestern Bering Sea. Biol. Morya 2:56-65, Markina, N.P,, and G.V. Khen. 1990. Major fuilc- t,ional elements of the pelagic community of the Shuntov, V,PA.F. Volkov, O.S. Temnykh, and Ye.P. Bering Sea. In: VP. Shuntov ed,h Rezul'taty Dulepova. 1993. Mintay v ekosistemakh ekosistemnykh issledovaniy biologicheskikh dal'nevi>stochnykh morey [Pollock in the ecosvs- resursov dal'nevostochnykh morey [Results of tems of the far eastern seas]. Tikhookean. ecosystem investigations of biol ogical resources Nauchno-Issled. Inst. Ryhn. Khoz. Okeanogr. in the far eastern seas], Izv. Tikhookean. Vauch- iTINROI, Vladivostok, 426 pp. no-Issled. Inst. Rybn. Khoz. Okeanogr.t TINRO! 111:79-93. Sobolevsky,Ye.I. 1983. Role of marine mainrnals in the food chain of the Bering Sea. Izv. Nauinenko, N.I. 1990, Reasons for the long-term Tikhookean. Nauchno-Issled. Inst. Ryhn. Khoz. collapse of Korf-Karagin herring stocks. Biolog- Okeanogr. TINRO! 107:120-132. icheskiye rcsursy shel'fovykh i okrainnykh rnorey [Bioiogica] resources of the shelf and Sokolovskiy, A.S., and S.Yu. Glebova. 1985. I.ong- marginal seas]. Nauka, Moscow, pp. 139-148. term fluctuations in pollock abundance in the Long-TermF iuctua in ions heIchthyofduna of hetVc~tern Haring Sea 158 namikichislennosti promyslovykh ryb Kam- BeringSea, Izv. Tikhookean. Nauchno-lssled. chatskogoshel'fa [Research onthe biology and Inst.Rybn, Khoz. Okeanogr. T!NRO! 110:3S- populationdynamics ofcommercial fishes on the 42. Kamchatkashelf!. No. 1, part II, KoTINRO, Petropavlovsk-Kamchatski,pp.36-54. Tokranov,A.M, 1986a. Diet of the eastern Kamchat- ka cod.In: Treskovyyedal'nevostochnykh rno- Tokranov,A.M., and A,V, Vinnikov. 199lb. Dietary rey[Gadids ofthe far eastern seas]. Tikhookean. featuresof thePacific cod and its placein the Nauchno-Issled.Inst. Rybn,Khoz. Okeanogr. foodweb of the coastalwaters of Kamchatka. TINRO!, Vladivostok,pp. 102-111. Vopr.Ikhtiol. 31!:253-266, 'Ibkranov,A.M. 1986b. Sculpins and Irish lords. In: Tolstyak,A.F. 1990. Effects ofsome environmental Biologicheskiyeresursy Tikhogo okeana [Biolog- factorson the stock abundance of Kamchatka ical resourcesof the PacificOcean}. Nauka, saffron cod. In: Biologicheskiye resursy Moscow,pp. 319-32S, shel'fovykhi okrainnykh rnorey lBiological re- sourcesoi'the shelf and marginal seas I.Nauka, Tokranov,A.M, 1988. Species composition and biomassof sculpinsin Kamchatkawaters. Byull, Moscow,pp. 148-154. MoskovskogoObshchestva Ispytateley Prirody Volkov,A.F. 19SS. Horizontal structure of the plank- MOIP!, Otd. Biol. 93!:61-69. toncommunity in KaraginBay, Biol. Morya 4:19- Tokranov,A.M. 1989,Diet of theyellowfin sole in 24. the southwesternBering Sea. Vopr. Ikhtiol. Volkov,A.F,, and V.I. Chuchukalo, 1985. Structure 29 k I 003-1009. anddistribution of rnesoplankton in the Bering Sea based on research by TINRO, 1949-82!. Izv. Tokranov,A.M., and A.F. Tolstyak. 1990. The food Tikhookean,Nauchno-Issled. Inst. Rybn.Khoz. nicheof thefar eastern saffron cod in Kamchat- Okeanogr. TINRO! 110:119-124. kawaters. Izv. Tikhookean. Nsuchno-Issled. Inst. Rybn.Khoz. Okeanogr. TINRO! 11I:114-122. Zolotov,O.G., PA, Balykin, and N.P. Antonov, 1988. Relationshipbetween reproductive stocks and Tokranov,A.Mand A.V. Vinnikov. 1991a. Repro- progenyofpollock in watersaround Kamchat- ductive.features of the codin thecoastal waters of Kamchatka.In: Issledovaniyabiologii i di- ka, Rybn. Khoz,S;43-45. 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,respectively 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. nannochir.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

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

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 Sea: A Rcviervof RussianLiterature

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 distribution 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.Vand 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 mesopelagic 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,Jand 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.land 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 distribution 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 estimate the average fecundity and weight of the fish. The number of feinales was estimated by dividing 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 usually 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 undertaken 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 reproductive 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 15 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 little 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 erig Sea:A RC'VieWOtRt5!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 1619581 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 269291 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 remained 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 patterns 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,Vand E.I. Yelkin. 1977.Some biological factors regulating the Okhotsk Sea herring fishery. Rybn. Khoz. 4:14-17.

Walker, R.Vand 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 Tyurin962! 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 anomalies in pollockyear-class strength in the easternand westernBering Sea is the same.which is a resultof the common cliinatic and oceanographic regime. Wespestad991! 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"~rdecrease. Given a high number of spav-ners, arate trends caused by interactions within a more favorable or unfavorable temperature condi- DynamicsandAbondani eot Western Bering.Sea I Valfeye Pt>liock ! Table3. Abundanceandbioraass ofexploited western Bering Sea pollock, 1970-1990. Total Commercialstock Spawningstock Number Biomassin Number Biomassin Numbe r B iornassin inbillions millions oftons inbillions millions oftons inbi!lions millions oftons Year 0.34 0.129 0.075 2.48 0.56 1. 13 1970 0.204 0. 123 0. 78 0.98 0. 38 1971 3.35 0.153 0. 83 0.39 0.257 1972 3. 14 0.81 0,58 0.335 0.203 3.69 0.98 1.39 1973 0.421 0.271 l 2'3 1.64 G.68 1974 4.S6 0.300 2.H5 0.95 0.462 1975 6. 86 1.60 1.07 0.493 0.296 7.96 1.87 3. 18 1976 0.731 0.447 1.98 3.38 1.34 1977 7.12 0.651 5,06 1.70 0. 990 1978 7. 18 2.20 2.36 1.074 0. 749 B.53 2. 47 7,99 1979 1.015 0. 702 3.18 7.45 2. 16 1980 13. 15 0.593 4.48 1.71 0. 93H 1981 14.27 3.37 2.75 1, 192 0.738 11.75 3.29 8.92 1982 1.477 0. 971 3.92 5.76 2.26 1983 9.99 0.956 3. 83 2.01 1. 416 1984 10.83 3.11 2,31 1.155 0.791 9. 24 2.45 7.09 1985 1,100 0.669 2.53 3. 27 1.64 1986 10,05 0.753 4. 97 1.67 1.311 1987 10.87 2.43 1.65 1.269 0. 75,> 9.68 2.32 4.72 1988 1.263 0.756 2.1] 4,34 1.60 1989 8.15 0.'717 3.81 1.47 1.232 1990 6. 77 1.87

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

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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 ecosystems 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 walleyepollock 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 Kamchatka949!, 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 subzone1.02.1! 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 department of Kainchatka Kamchatrybprom KRP!. In 1991-1993the surveys and collection of the biostatistical data were done on small- and medium-sized boatsequipped with Danishseines. The study area included the continental shelf and the upper continentalslope 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 materials 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 Polutov937! 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'!. Moiseev954! 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 seev953!, 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 5i 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. rnain 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 ichthyoplankton 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 Bulatov986>. 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 Musienko970!, "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

C dt 20 at L + <0 «0

20 20

Age Figure2b.Age eninpoeition ofcod incatches takenu ith different fishing deuieeein thenorthwestern.Bering Sea Anadyr-iVavarin region! in 1984-1998.

I'acrfic Cod of Iht WesternBc ring Sea

989

c 20 c O

50 c2 <0 CL

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 equation 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 Gordeeva952, 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 mysids5-74% 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 invertebrates;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 fishery,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 16,4'7sianLiteratur<

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 naturalmortality, 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 individuals.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

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 t Russian Literature 20

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.102:97-101. of the Pacificcod Gadrrs morh ua marrorrphaius 1'acidic :ocl oi fhe tVecternBering 5eo

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. 2,34!: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 Tikhonov969! 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 Sea: rt Reviewot RussianLderatttre F07

to the shallow parts of the bays. In those years several 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 processes.Such processes of upwelling insure the aeration of the bottom levels, and also the rising of the abyssal waters, rich with biogenic eletnents, to the surface,forming zonesof high biologicalproductivity, High concent,rationsof commercialfishes are usually associatedwith suchzones. As a rule,there is a steeptemperature gradient in theseregions. There- fore, the large concentrationsof flounder that occurred 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 regionof 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 1VIikulich954! 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

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 condition 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. Nikolotova979!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 yellowp- 'l978 80 82 84 86 88 90 92 tion of certain groups of organisms explains the con- Year ditionindex for differen years of the research period. The "valley in the graph of the Fulton condi- Figure 9. Fulton condi ion index foryellou~fin solea age tion index that occurred in 1986 Figure 9i proba- 8+ in Li ke 8/rai t and Korf Bay i n 1978-1992. bly reflects an improvementin the food supply for yellowfin sole due to decreasedstock density. In 19H6,the annual flounder catch in this region increased by almost 100% compared to the previous year, which must have affectedthe food supplyfor the fish. The last circumstance also influenced t,he growth of yellowfin sole.The differencesare less obvious for maturing 5-year-oldfish, whichis a resultof their coastal distribution, but for mature fish that live farther from shore, they are more distinct Figure 10!. As shown by the long-term research data on the sizes of the 9-year-n]d yellov

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 tem982!, 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 consumedby 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 development 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 Petrov925!, 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 Chugunova959!, Pravdin966!, atures,we used temperature estimations from sur- andBryuzgin969!. 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 separate 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 Q u 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

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 significantly 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 downstream 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 included polychaetes, mysids, garnmarids, euphausiids, 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, gammarids, and polychaetes 'Table 10!. The differences were significant at the 0.1% probability level, The basic food of Arctic smelt in the open waters of Karagin Bay was young fishes, mainly sand Ecr>k>gyr>/ thr RcrrngSea> / RfRt>asi,>r> liters i>re 275

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 feeding, 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

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.

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

o 30 ce cr 20

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 significantly. 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. Mater. reachlengths of 6,1-8.3cm t Karpenko1982b!. po faune PriobskogoSevera i e ispol'zovaniye The consumptionof young pink salmonby H. I Studieson the northern Ob fauna and its ex- olidus occurred only in 1978 in the est,uariesof the ploitation] 1:58-73. In Russian.t Makarovka and,Dranka rivers Karpenko 1982a!. The maximum number of fish eaten by one smelt Amstislavskiy,A.Z., and I.N. Brusynina.1963. Ma- was6. In those estuaries, pond smelt consumedmore terialss on the food of the Asian smelt in the Gulf juvenile pink salmonthan did Arctic smelt in the of Ob. Tr. Salekhard. st. Ural. frl. Akad. Nauk estuary of t,he Belaya-KichigaRiver Table 19t SSSR 3:123-128. In Russian.! Due to the lov feedingactivity of smeltsduring the pre-spawning,spawning, and early post-spawn- Belousova,S.P. 1975. Food and trophic relationships ing periods,as wellas periodicfluctuations in their of the pond smelt Hypomesusotidus Pallasin abundance, the loss of young salmon due to smelt.s Lake Az abach ie. I zv, Tik ho ok can. N auchno- canbe significant.only in somecases. For example, Issled. Inst,. Rybn. Khoz. Okeanogr. TINRO> Dobryninaet al. 988! reportedhigh consumption 98:148-155. tin Russian,! ofyoung salmon hy predatorswhen the salmonstay in the estuarybecause of high spring tides at night Bryuzgin,V.L. 1969.Metody izucheniya rosta ryb and in the morning that reduce outflow of water in po cheshuye,kostyam i otolitam [Methodsof the "throat" of the estuary and the lower reachesof studying fish growth by scales, bones, and the river. Churikov 975! reportedconsuinption of otoliths]. Naukova dumka, Kiev, 188 pp. In 7.7-51.6%ofyoung pink salmonand 11.1%ofyoung Russian,! churnsalmon by Arctic smeltfeeding in NyyskiyBay shallowsalty reservoirwith a large area!.Large Chugunova,N,I. 1959.Rukovodstvo po izucheniyu concentrations of young salmon usually occur in vozrasta i rosta ryb [Manual on studies of the estuary zonesand coastalwaters due to high tem- ageand growth of fishl. Akad.Nauk SSSR,Mos- peraturesand salinity, which leads to high consurnp- cow, 164 pp. g'iea, A Reviewot RussianLiterature 233

Churikov, A.A., and V.I. Karpenko, 1987. Hew data Ivanova, Ye.I. 1955.Essay on the far-eastern smelts. on silver smelt, Hypomesusjapon.icus Brevoort!, Tr, Inst. Okcanol. Akad. Nauk SSSR, pp. 35-41. distribution in USSR waters. Vopr. Ikhtiol, In Russian. i 27k157-159. In Russian.] Karpenko, V.I. 1982a.The amount.of young salmon Dobrynina,M.V,, S.A. Gorshkov,and N.M, Kinas. consumedby predatory fishes.Rybn. Khoz. 4:41- 1988.Effect of the density of pink salmon Onco- 42. In Russian.! rbynch us gorb use ha fry migrating downstream Karpenko,V.I. 1982b.Food of predatoryfishes and on consuinption by predat,ory fishes in the Utka their effect on young salmon in coastal waters River Kamchatka!. Vopr. Ikhtiol. 28!:971-977. of the Bering Sea. In: Sb. Tikhookean. Vauch- In Russian.! no-Issled.Inst. Rybn.Khoz. Okeanogr. lT!NRO collection], pp. 104-113. In Russian.! Dudnik, Yu,I., and G,F. Shchukina. 1990. Spawn- ing of Arctic sinelt, Osmerusmordant dentex, in Karpenko, V,I. 1982c. Role of predatory fishes in rivers of northwestern Sakhalin. Vopr. Ikhtiol. regulating the abundanceof easternKamchat- 30 l!:151-154. In Russian.! ka salmon. Tezisy Vtoroy Vsesoyuznoy konferentsii po morskoy biologii [Abstracts of the Fresh, K.L., and S.L. Schroder.1987. Influence of Second Soviet Union Conference on Marine Bi- the abundance, size, and yolk reserves of juve- ology! 3:18-19. In Russian.! nile chum salmon Oricorhytichus Acta! on predation by freshwater fishes in small coastal Karpenko,V.I. 1983a.Size and weightcomposition streains, Can. J. Fish. Aquat. Sci. 44!:236-243. of some fishes in the coastal waters of Karagin Bay.In: Tezisydokladov Vtoroy regional'noy Gritsenko, O.F. 1990, Prokhodnyye ryby ostrova konferentsii molodykh uchenykh i spetsialistov Sakhalin sistematika, ekologiya, proinysel > Dal'negoVostoka [Abstracts of papers of the lAnadromous fishes of Sakhalin Island: Systern- SecondRegional Conferenceof Young Scientists atics, ecology,fisheriesl. Avtoref, dokt. diss, [Doc- and Specialistsof the Far East],p. 37. ln Rus- toral thesisl, Moscow,42 pp. In Russian.! sian. !

Gritsenko, O.F., and A,A, Churikov, 1983. Classifi- Karpenko,V.l. 1983bBiologiya molodi tikhookean- cation of' silver smelts of the genus Hypnmesus skikh lososeyv pribrezhnykhvodakh Kamchatki Salmoniformes, Osmeridae I of the Asian Pacif- [Biology of juvenile Pacific salmon in the coast; ic coast. Zool. Zh. 62k553-563. In Russian,! al waters of Karnchat.kaJ. Avtoref. kand. diss. [Candidate thesisJ, Vladivostok, 22 pp. ln Rus- Gritsenko,O,F,, and A.A. Churikov.1984. Reproduc- sian.! tive ecology of silver smelt, Hypomesus riippoti- Karpenko,V.I, 1991.Role of carly marine life in ensis McAllister, on southern Sakhalin. In: forming Pacific salmon production. In: Proceed- Biologiya prokhodnykh ryb Dal'negoVostoka ings of the Syinposium on Biological Interactions i Biologyof anadromousfishes of the Far East], of Enhanced and Wild Salmonids, Nanaiino, p. Nzd-vo DVGU [Far Eastern State Universityl, 29-30. Vladivostok, pp. 74-78. In Russian.! Karpenko,V.I. 1992.Pacific salmoninvestigations Gritsenko, O.F.,A.A. Churikov,and S.S. Rodiouova. in the marine period of life. In: Proceedingsof 1984a.Ecology of silver sinelt, Hypomesusoli- the International Workshop on Future Salmon dus Pallas! Osmeridae!,in reservoirs of Sakha- Research in the North Pacific Ocean, Shiinizu, lin Island. Vopr. Ikhtiol, 24!;517-579, In pp. 67-70. Russian. ! Karpenko,V.I. 1994a.Forming peculiarities of salrn- Gritsenko,O.F., A.A. Churikov,and S.S. Rodionova. on productionin northeast Kamchatka.Salm- 1984b. Reproductive ecology of Arctic smelt, on Rcport, Series 37:285-301. Osmeruseperlari us dentex Steindachner, in Sa- khalin rivers. Vopr, Ikhtiol. 24k407-416. i In Karpenko, V.I. 1994b.Methods of estimating the Russian.! mortality rate of Kamchatkapink salmonin the 734 Biolog>'of Smeltirt theKorf Karagin Coastal Area ot theSouthivestern Bering Sea

early marine period, Izv. Tikhookean, Nauchno- Naumenko, N.l., P.A. Balykin, E.A, Naurnenko, and Issled. Inst. Rybn. Khoz, Okeanogr, TINRO! E.R.Shaginyan. 1990. I ong-termchanges in the 116:152-162. In Russian.! pelagicichthyococnosis of the western Bering Sea. Izv. Tikhookean. Nauchno-Issled. Inst. Klyukanov,VA. 1969,Morphological basis of sys- Ryhn. Khoz. Okeanogr. TINRO! 1]1:49-57. In ternatics of the genus Osmerus. Zool. Zh. Russian.! 48!:99-109. In Russian,! Petrov, VV. 1925. Materials on the classification of Klyukanov,V,A. 1970.Morphological basis of sys- the Russian smelts, Izv. Otdela Prikladnoy Ikhti- ternatics of silver smelts, Hypomesus Os- ologii i Nauchno-prornyslovykhIssledovaniy meridae!. Zool. Zh. 490!;1534-1542, In 3!:87-108. In Russian,! Russian.! Pirozhnikov,P.L. 1950.Data on the biology oi'the Klyukanov, VA. 1975. Classification and relation- Asian smelt, Doki. Akad. Nauk SSSR 74!;1037- ships of smeltsof the generaOsmerus and Hy- 1040. In Russian.! pomesus and their distribution, 7ooh Zh. 54!:590-596, In Russian,! Podushko,Yu.X. 1970a. Biological characteristics of Asian smelt, Osmerus eperlonus dentex Stein- Kokhrnenko,L.V. 1964,Trophic relations of'young dachner, in the lower reaches of the Amur Riv- Pacific salmon with nonanadromous and er.Izv. Tikhookean. Nauchno-Issled, Inst. Rybn. anadromous fishes in the lower tributaries of Khoz. Okeanogr.

Mesyatsev, I.IS,G. Zusser, Yu.V. Martinsen, and Shershnev,A.P. 1971. Biologiya rnolodi kety Otrco- A,N. Reznik. 1935, Fish abundance and fisher- rhvnchus keta Walbaum! v pribrezhnykhvoda- ies intensity in the northern Caspian Sea. Rybn. kh yugo-vostochnoy chasti Tatarskogo proliva Khoz. 3:5-19. i ln Russian.! [Biology of young salmon, Otrcorhytrchtzsketo Eco ogynf the BeringSea: A Revieivof Rusii,>nLiters ure

Walbaum!, in coastal waters of southeastern Tatar Strait.]. Avtoref. kand. diss. [Candidate thesisj, Vladivostok, 20 pp. In Russian.!

Shershnev,A.P. 1975, Biology of young chum salmon in coastal waters of southeastern Tatar Strait. Tr. Vses, Nauchno-Issled. Inst. Morsk, Rybn. Khoz. Okeanogr. VNIRO! 106:58-66. In Rus- sian.!

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Zadorina,L.G. 1980.Some questions of the population dynamics of silver smelt, Hypomesuspre- ti usus, in Peter the Great Bay, Izv, Tikhookean, Nauchno-Issled. Inst. Rybn. Khoz, Okeanogr. TINRO! 104:105-108. In Russian.! Ecologyol the Beritig SeatA Revieivo Russiart Literature

Distribution,Biological Condition, and Abundanceof Capelin Mallotusvillosus socialis!in the BeringSea

E.A. Nat!menko Kamchatka Research Institute of' Fisheries and Oceanography KarnchatXIRO! Petropaulovsk-Karnchatski, Russia

ABSTRACT 1926, Taranets 1937!. The Pacific capelin is now con- This paper summarizes the results of more than 30 sidered a subspecies, Ma!lotus vi llosus soeialis. The years of research on capelin Mallotus villosus so- geographic distribution of capelin in the Bering Sea cialis! in the Bering Sea, Distribution, biological and adjacent waters was described by Andriyashev condition, and changes in abundance are briefly 939!, Some fraginented data on the biology of described, Capelin inhabit the continental shelf and Bering Sea capelin were included in papers by shaHow waters around islands in the Bering Sea. Rumyantsev 946!, Barsukov 958!, and Musien- The largest concentrations occur in the Gulf of ko 963, 1970!. The results of research on capclin Anadyr and around St. Matthew Island and the in the Bering Sea and adjacent waters for the last Pribilof Islands in the fall. The distribution of cape- 20 years have been i~eluded in Pahlke 985! and lin in the Gulf of Anadyr depends mainly on the Naumenko 986a, 1986b, 1990!. properties of t,he water masses. The goal of this paper is to summarize long-term Bering Sea capeliii reach a maximum length of data on distribution, some biological features, and 18 cm, and maximum age of 5+ years, The size coin- abundance of capelin inhabiting the continental position of the stock varies by year, season, depth, shelf of the Bering Sea. and region. Young and mature fish usually live separately. Capelin grow year-round, more in the fall than in the spring. They mature at i,heage of 2 years. MATERIALS AND METHODS In the Gulf ofAnadyr, there are immature fish of all This paper is based on data gathered diiring trawl sizes and age groups. surveys in Karagin and olyutorsk bays, off the 01- Probably as many as five populations of capelin yutorsk-Navarin coast, in the Gulf of Anadyr, and inhabit the Bering Sea, The Anadyr and western in the eastern Bering Sea. The western portion of Bering Sea capelin stocks are subject to substantial the Bering Sea has been studied most thoroughly: annual changes,During the last 20 years,the biomass in 36 years of research, there have been 52 surveys of these stocks has varied in different directions. 33 in the fall, 10 in the spring, and 9 in the suinmer. Capelin in the Gulf of Anadyr have been studied I NTROD U CTION since 1969.There have been 17 trawl surveys, mostly in the fall. For 7 years 970-1976!, trawl sur- The first mention of capel in off the Kamchatka coast veys were conducted on the eastern Bering Sea shelf, was made by Krasheninnikov 949! in the mid- usually in November or December. eighteenthcentury. In the nineteenth century, the At each survey station a bottom trawl with a naturalist S.V. Pallas used the name Salmo social ts small-ineshed 0 inm'-! net inserted in the cod-end for capelin of the North Pacific Jangaard 1974!. In was dragged for 30 minutes. The catches were sort- this century, several publications have focused on ed by species, The numbers of individuals of each the classification and distribution of capelin in Rus- species, including capelin, were counted, and their sia's far-eastern seas Soldatov 1923, Knipovich w eight det.ermined. 238 Distribution,Hiologica! Condition, anil Abundann ot Capehnin th

I'igurel. Oenemtdiagrain of eupetin. distribution in theBering Sea.

Biologicalanalysis samples were taken accord- REsULrs ing to the frequencyof the fish, in an attempt to Distribution cover the maximum number of regions. The weight of capelinwas taken mostly from the large catches, In the Bering Sea,cape!in are distributed every- of 500 kg and more. where within the boundaries of the continental sheI f Agewas determinedfrom otolithstaken from and shallow water around islands Figure 1!. They freshly caught capelin, using the methodof are seldomfound at depths below 400 m. In the Prokhorov 965 !. Most of the otoliths collectedwere westernpart of the sea, capelin are distributed wi th- useful for determination of age and annual incre- in the 50- to 60-mile coastal zone. In the eastern ments in length. Bering Seathey live as far as 800-350miles away Growth rate was estimated from rneasurernents from shore,since the shelf is broaderin 0henorth- of capelinlength at, different ages and by the rnodi- ern and eastern parts of the Bering Sea. fied relationshipbetween year ring radius andsize Capelinare distributedevenly over the entire of fish Gjosaeterand Monstad1977!. shelf in spring. In the western part of the Bering The abundance of western Bering Sea and Sea.in April andMay, they are foundwhere bottom Anadyrpopulations of capelinwas calculated from depthsare 90-125 m andbottom water temperatures the trawl survey data using the methodof Aksyuti- are 1.5to 1.0' .; Table 1!. By the end of'May,they na ! 1968!.Vear-class abundance was determined by graduallymove toward shore and concentratein the agecomposition of researchcatches, calculated areas with bottom. depths of 50-90 rn Figure 2!. riatural mortality rates, and data on abundanceof Spawningstarts in KaraginBay in ear'lyto mi d- capelinin everyparticular year. These methods have June and lasts about 1 week.Capelin spawn at about beendescribed in detail in previous works Naumen- the sametime in Olyutorsk Bay, hut,the length of ko 1986a,1990; Yaurnenko and Davydov 1987; Nau- time they spendclose to shorehas decreasedto 3 or menko et al. 1990!, 4 days in receiit years. Lr ofogy of th» f3cring Searrt Rev etvof Rtcss anLiterature

Tablet. Distributionof trawl catchesof capelinin Karagisinnd Olyutorsk bays by depthand demersal water temperature average data as a percentage of maximum catch!.

Aprd May October November Aprd May October November Depth Drags Catch Drags Catch Drags Catch Temperature Drags Catch Drags Catch Drags 1 etch ml i Ni r'4 1 iNi i'5! cY« i 4i i'-Ci Ni I "»i tNi I'3! iNi 10-20 0 28 11 4 -2.0 to 1 5 139 49 13 ii 20-30 2 56 30 12 3 1.5to -1.0 100 100 16 15 30-40 6 9 65 49 24 10 1 0 to-o. 69 9 81 14 24 40-50 4 34 54 43 19 31 0.5 to 0.0 73 12 3 29 100 50-60 ll 21 57 22 29 0 0 to 0 5 25 22 25 16 60-70 12 1 2? 100 20 100 0. 5 t,o1.0 23 46 24 14 70-60 16 12 29 61 16 17 1.0 i.o 1.5 24 2 21 60-90 22 10 20 2 20 100 1.5 t.o2 0 36 91 33 90-100 25 loo 16 11 12 2.0 to 2.5 73 7 5i 100-110 40 92 96 20 19 7 2.0 to 3.0 65 13 14 110-120 32 4 7 15 2 3.0 to 3.5 50 10 6 0 120-130 20 I 0 3.5 to 4.0 28 1 4.0 to 4.o 15 19 4 5 ro 5.0 2o 1 5.0 to 5.5 101 0 1

Migration of capelin to shore in the Gulf of During the spawning migration, capelin in all Anadyr takes place in late June. Right before that areasof theBering Sea stay in small,mobile groups, time, they usually concentrate in the cent,ral part of OftenSCattered Over a large territOry. In Juile or July the gulf. By the end of June, significant concentra- they form pre-spawningconcentrations at depths tions of pre-spawning capelin are located at the en- of 10-15 rn, When spawning is intensive, the areas trances to Ilgolnaya, Gavriila, and Egvekinot bays, where capelin approach the shore are easily recog- The first post-spawning individuals, mostly f'emales, nized because of the large number of fish-eating were caught in the southeastern Gulf of Anadyr: in birds. 1978 on 4 Ju]y; in 1983 on 10 June; and in 1994 on All Bering Sea stocks of capelin have the same 24 July 994 was probably an abnormally cold year, bathymetric location on the spawning grounds. Re- since water temperature in the gulf was 2'C below production takes place on sandy or small-pebble average!. Migration of capelin to the coast contin- bottoinsalong t,he shore from the water'sedge to a ues throughout July. In late July there is still a sub- depth of 4 rn. During periods of maximum stock stantial number of pre-spawningfish in Bering Strait abundancethe spawningground may bc enlarged, andthe easternGulf of Anadyr.Thus, the spav'ning becausesome fish spawn in deeperregion, to 8- nugration and spawning itself last longer in the Gulf 10 ni. In Karagin and Olutorsk bays, the Gull of ofAnadyr than in the western Bering Sea. Anadyr, and around the Commander Islands, In the eastern Bering Sea in spring of 1969-1978 spav'ning does not start. until the water near shore capelin were taken at depths of 20-90 m, with bot- has v'armed to 4.C. Iritensive spawning usually tom water teinperature from 1.7 to +1.5-C Table takes place when the water temperature is 5-9 C. 2j. Thelargest.concentrations of capelininApril and In the Russian c.conomiczone, the peak of spawn- May were recorded by the Pribilof'Islands. Accord- ing norinally coincides with the period of'maxintuni ing to Vahlke 985!, capelin spawn in the eastern tides. parts of the Bering Sea from May Togiak Bayl un- After spawning, the fish move away f'rom shore til late July tVorton Sound!. anddistrihut.e t.hemselves over the gulf territory, and Around the Commander Islands,the spawning in the Olyutorsk-savarin region they reinain iii peak f'or capelin usually occurs in the first days of shallow water out to the 50-m isobath. Individuals June. not takirig part in spawning stay offshore in the Distribvtion,Ba>logical Condition, «nd Abvnttance ot Cape Jrn in theBerin~~ Sea 240

Figure2. Regionswherepre-epaivrung andepauning capelin arefound inthe cuvetern Bertng Sea, A.Commander Islands;R Karaginand Olyatorsk days; C. Gulfof Anadyn

bays.In theeastern Bering Sea, such fish inhabit term researchhas revealed a closeconnection be- the seawardregion of the shelf Pahlke1985!, tween distribution in October and Novemberand The distribution of capelinin late fall andearly water inass characteristics.The Navarin Current winter hasbeen studied most thoroughly because most penetratesthe Gulf of Anadyrfrom the abyssal of the trawl surveyswere done during this period. southwesternpart of the sea,This current possess- In the westernBering Seathere are sinall cori- es relativelyhigh water temperature;2'C accord- centrationsof ca.pelinin LitkeStrait, northernKara- ingto Arsenev967!, or up to 3.5'Caccording to gin Bay,and eastern Olyutorsk Bay. During this Khen989! Figure9!. The countercurrentis cre- time,most fish stayat depthsof 30-90m wherethe atedby coldwater coming out of the Anadyrestu- watertemperature is from 1.7to 1 VC TableI!, ary and Krest Bay. Majorconcentrations of capclinon the eastern Dependingon the intensivenessand location of BeringSea shelf in late fall andearly winter are eachof these currents, capelin redistribute them- locatedclose to St. Matthewand the PribilofIslands selvesin the Gulf ofAnadyr accordingto the follow- at depthsof 60-100m wherethe water temperature ingfour patterns: ! concentrationsin the northern is 1.8 to 2.0=C Table 2, Figures 3-8!. part of the gulf; ! concentrationsin the eastern Table3 providesdata on di stribution of capelin and northwesternparts; ! concentrationsin the in catchesin the Gulf ofAnadyr in fall by depthand southeasternand southwesternparts; and ! even temperatureof the bottomwater layer. The long- distribution overthe gulf, with no concentrations. Eco ogvof fre Heri !g5ev: A Revietvof Russ ,!nLi esture

Table 2. Distribution of trawl catches of capelin in the eastern Bering Sea by depth and delnersa} water temperature average data as a percentage of maximum catch!.

Depth m!

0-10 10-20 20-30 11 73 76 6 1.0 to -0.5 38 98 39 64 30-40 7 0 72 2 0.5 to 0,0 28 67 45 47 40-50 ll 68 82 19 0,0 to 0,5 22 100 53 29 50-60 24 21 60 13 0.5 ,o 1.0 18 52 61 20 -70 95 100 1].2 100 1.0 to 1.5 16 26 88 11 70-80 67 46 91 45 1.5 to 2.0 17 9 100 100 80-90 26 34 54 48 2.0 to 2.5 24 2 84 ll 90-100 14 0 40 29 2.5 to 3.0 15 7 81 0 100-125 69 0 48 4 3.0 to 3.5 15 24 40 15 125-150 207 0 45 1 3.5 to 4.0 19 30 51 6 150-300 8 103 0 4.0 to 4,5 169 3 I 4.5 to 5.0 0 5.0 to 5.5 16 2 5.5 to 6.0 7 14 6.0 to 6.5 6 1

Table 3. Distribution of trawl catchesof capelin in the Gulf of Anadyr by depth and demeraal water temperature average data as a percentage of maximum catch!.

October November October November Depth Drags Ca .ch Drags Catch Temperature Drags Catch Drags Catch m! N! %! N! 'C! N! %! IN! «7

10-20 I 0 2,0 to -1.5 2 0 20-30 10 9 1.5 t.o 1.0 17 0 30-40 15 7 1 1.0 to 0.5 33 2 40-50 26 33 59 024 -0 5 to 0.0 26 100 100 5>0-60 14 7 0.0 to O.;> 16 5 60-70 23 12 11 5 0.5 to 1.0 31 10 70-80 45 44 14 100 1.0 to 1.5 38 5 13 80-90 100 13 1.5 to 2 0 37 8 90-100 25 8 2I 2 2.0 to 2.5 19 42 18 100-110 12 6 10 2.5 to 3.0 9 110-120 3 0 3.0 to 3.5 2 2 3.5 to 4.0 2 1 4.0 to 4.5 4 1 242 Distribution,Biotogical Condition, and Abundance nfC~pelin in the Bering Sea

Figure3. Dtstributianoftrau 1 catchesofcapetini n theCiulfofAnadyr andeastern Bering Seaduring standard su/ veys,October-hr'avember 1971. fcology ut the Herir>gSea: A Reviewot RUssiatrLitaratura 2'$.3

Figure 4 Dtstribution of tratol catches of eapetin in the Gulf of Anadyr and eastern t3ering Sea dart»g standard surveys, October-¹uernber 1972. Distr''bution,Hioinyica Condition, andAbundance otC aptiini nthe Bering Sea

F'rgure5. Distribution oftratol catches ofcapelin inthe C~ulf ofAnadyr andeastern Bering Sea duringstandard suroeys, October-Wavember 1978. Ecologyof the BeringSt.'a:,4 Ret,iew vf RussianLi tera Ure

Figure 6. Distribution of trau'l catches of capelin >'nthe Gulf of Anadyr and eastern Bering Sea during standard suroeys, October- Vouember 1974. Distribution,Biologic:al C"ondition, antiAbundant e of C.,ape!in in the Raring Sr'

I'igure 7. Distributionoftrawl catches ofeapeti n in the Gulf af Anadyr and eastern Bering Seaduring standard suraeys, October-november 1975. tcolog< of tht Hi'.ringSea: A Reviewof RussianLiterature

Figure 8. Distribution oftrau l catchesofcapeltn in the CulfofAnadyr and eastern Bering Seo during =tandard nurvey.~,October-november 1976. 248 Distribution,Biological Condition, ~nd Abundant e i!f Capelin in theBering Sev

The first distribution pattern occurs in years when the direction of'the current from the open sea into the Gulf of Anadyris closeto average,and cold watersare carriedout of the estuaryand Krest Bay. The Navarin Current absorbs part of this water, whichhelps create dynainically active zones, The largerpart of the capelinstock is concentratedin the peripheryof thesezones in the Gulf of Anadyr, Theyfeed at depthsof 40-85m wherethe temperature is below zero.This situation was observedin 1970 and 1975. In 1982, 1985, 1986, and 1993there was a pow- erful inflow of the warm marine waters of the Na- varin Current, which was distributed over the bottomlevel, isotherm2'C, and reachedthe north- easternboundaries on the gulf. The borderline of the coldSt. Lawrencespot, normally locatedbetween St, Lawrenceand St, Matthew islands, movedto- ward the Gulf of Anadyr,causing cold water masses to occupyits southeasternpart. In this case,more polarizedfrontal zones were created. A significant portionof the capel in stockfollowed the second type of distribution pattern; i.e., concentrationsin the peripheryof the cold spot, in thezone of highertern- peraturegradients, at depthsof 80-90 m wherethe bottom water temperature is slightly below zero 0.1 to -0,5"C!, With such distribution of the currents,capelin concentrations are situatedin the northwesternpart of the gulf. Bythe endof feeding,Anadyr capelin inhabiting the coldspot area graduallymigrate to the St.Lawrence St. Matthew area and mix with another stock there Nauinenko 1986a!. The clearestexamples of the third type of distribution occurred in 1969 and 1983,when inflow of warm seawater was insignificant. Almost the entire gulf was occupiedby relatively uniform water masses. Cold currents from Krest Hay and the Anadyrestuary were directed into the southeastern and southwestern parts of the gulf. Capelin concentrated at the borderline of the cold currents and the weak Navarin Current. The fourth type of distribution pattern is commonfor years when capelin abundance is low. There are no concentrations at all in such years. Figure9. Diagramofcurrents and rlistri bution ofcape- li n in the Civlf ofAnadyr during October-1Vo- cemberin average,relatively warm, and Biologicalcondition relatirely coldyears .'1.warm savarin Cur- rent; 2. <+Idcurrents, 3. frontal zones;4. cape- Capelinin fiveage groups, from 1+to 5+years, are lin concentrations; 5. cold spot , caughtin bottomand rnidwater trawls with a small- meshedlining in the cod-endcatch. If nothingis inserted,capelin occur rarely in the catches,and the fev' incidental catches consist of larger fish, 3+ to 5+years of age.During trawl surveysin fall, fish fcolof,t of the Hen'ogSea: A Reviewof RussianIi esture 249

Table 4. Size of capelin in different geographic regions. 30 Maximum Average Region length cm1 length cm! Source 10 Ne wfoundlan d 210 16.5 Ku 6 rin 1975 20 Bsrent~ Sea 19.5 16.4 Luke 1975 10 Japan Sea 21.O 17.0 Rutnyantaev1946 Okhotsk Sea 1S.S 13.6 Shilin 1970 20 17.6 13.8 The aut.hor Bering Sea ~o 10 Chukchi Sea 15.5 12.7 The author Iiritiah 12.7 11.5 llart & McHugh o 20 Columbia 1944 ~ 10 0 ~ 10 E 0 ~ 10 that are 0+ years old recruit to the catch, One of the characteristics of the age composition of capelin 10 stocks is the dominance of one year class, which most 50 often is age 3+. Thus, Bering Seacapelin have a short life cycle, 30 never exceeding 6 years. The cycle is the same for the majority of populations of the Atlantic and Pa- 10 cific subspecies Prokhorov 1965, Vyelikanov 1986, Vilhalmsson 1994!. 4 6 8 10 12 14 16 18 20 Bering Sea capelin grow to 18 cm in length, but Length cm! the modal group in the research catches consisted of individuals 12-14 cm long. In this quality, Bering Figrtrc ltt Size compoarttortof capelin tn Kar agin and Seacapelin are in an intermediate position: the At- Olyatnrak baysin fall by depth, lantic subspecies and capelin of the Okhotsk and Japan seas have a greater maximum length, while Chukchi Sea and British Columbia capelin are smaller Table 4!. peaks, However, this doesnot incan that on the part The size composition of Bering Sea capelin is of the shelf with bottom depths of 30-60 m, finger- quite variable; it changesby year, region, season, lings and large capelin mix. Trawl catchesvAth fin- and depth. In the Gulf of Anadyr, during short trawl gerlings and older age groups about,equal in number drags, there were often cases when at one station are extremely rare. the catch almost entirely consisted of large <14-15 The size compositionof the capelin stock changes crn! males, and at the one next to it, of small 111-12 with t he season, In summer July and August!, pre- crn! ferns.le capelin. spawrung, spawning, and post-spawning concentra- The young and mature fish remain separate. tions occurin the Gulf ofAnadyr, During this period, This is most evident in the western part of the Bering 3-year-olds are the majority and, to some extent, so Sea,where the bathymetric range is broaderthan in are the 2-year-oldsand 4-vear-olds. In September, the other regions and is more fully observed. At the size range increasesbecause recruits join the depthsof 20-30 m in October and November,only mature fish stock, and so do some of the largest fish fingerlings 3.5-7.5 cm long are caught Figure 10!. that havenot taken part in the current year'sspawn- As depthincreases, significant changesin sizecom- ing. In October, capclin size composition is quite position occur:the proportionof smallfish gradually diverse;the proportionof youngfish, which feedin decreases fingerlings disappearcompletely starting shallow water, increases rapidly. As a result, the at the 60 m depth!,and the proportionof larger fish average length of capelin in the samples declines increases, At the boundaries of the bathymetric gra- from 13-14 cm to 11,5 cm. In November, ice cover dients,the size compositioncurves have one peak, above depths less than 50 rn has formed, and this whereasin the middle layers they each have two part of the gulf becorncs inaccessiblefor trawling. A 250 Oistribtttion. Biological Condition, and Abundancer>t Cfpelfn in the Bering5ea

Gulfof ing up in the samples, and the size composition Anarly r St. Lawrence- curves became mul tipeaked, St Maffhew The long-term dynamics of the average size and ~ ' P ribrlofs weight of the two most thoroughly studied capelin populations, Anadyr and western Bering, are rep- 40 resented in Figure 12. 30 Regional differences in the size composition of capelin stocks are also obvious, In some years they are more distinct, than in others see Figure 11!. 10 Growth of capelin in the early stages of ontogenesis has been studied without specifying genders 30 of the fish, while for older ages the research is done separately for males and females. 20 Capelin larvae caught in Karagin Bay had a 10 e ~Q well-preservedfat droplet and fin folds. Their length varied from 4.5 to 6.7 mrn. The age of su.ch larvae, ~o 30 accordingto the experiment,aldata, must be 1-8days 20 Savicheva 19821 Body weight of the larvae varied Q. E 10 from 0.28 to 0.34 rng. The length of larvae without 0 the yolk sac was somewhat greater, 5.1-8.0 mm. O 40 According to Musienko 1 1970!,capelin 1arvae caught in the eastern part of the Bering Seain August were 4,8-16.0 mm in length. 20 Juveniles were caught with the Isaac-Kidd rnid- 10 water trawl in northern Karagin Bay 1-1.5 months a'fter hatching. Their length varied from 17 to 29 mm, and the modal group was 23 mrn, By the time they are 4 months old, juvenile capelin in the Bering Seagrow to 35-38 mm long. Such a significant difference between the values has to do, 107 89 1011'f21314 1515 l7 1819 probably, with the feeding conditions of'the fish at Length crn! the beginning of t,heir life cycles, considering that some of the larvae are carried out of the bays and Figure ll. Size composition of capelin in the Bering Sea lagoons, and some stay within them. The average in faH by veor and region. length of the fingerlings in November of 1978-1990, in spite of the differences in size range, stayed the same: 60-62 cm. Bering Sea capelin grow year-round, gaining more length in the fall than in the spring Table 5l. significant part of the young fish, especially the During the first year of life, capelin grow to about smallest individuals, become inaccessible; and the 7-8 cm, In the age groups from 3 to 5 years, the anaverage length increases to 13.3 cm and remains at nual gain in length is decreasedto 0.5-],5 cm. Gen- the level common for feeding capelin of this region. der differences in length are quite evident, While The size composition of feeding capelin stocks during the first year males and females grow at the in the fall apparently varies among years. In all the same rate, in age categories 2 and 3 years thc lin- compared regions, these changes have a rpecific ear gain for males is greater than that for females. character. In 1971-1973,the most numerous group The difference in length between fish of different consisted of fish 12-15 cm long. The size range was sexes increases to 1-1.5 crn by the time they are 3-5 not very large. The proportion of small fish was no years old

of the Herirtr,Seat A Reviewc>t Russia >Literature 2.51
14 O
'3 o C ro 20 12 18 cs Q 16 11 cn 14 c 12 10 8 err ro
gs qo q~ qw 1'3qi' g6qs q1 qt' 19 's 0 t~ g ii3 a oP e> t6 so 1 y5 g%so
Yea r
Figurel2. Langterm variation rn average wright . Karaginarid Olyutursk bays; 2. Gulfaf Anadyr i and lengrh. Karagirrand 0/yutarskbays; 4. Gulf of Anadyr!of eapelr'nin theu:esrern Bering Seo.
in either pre-spawning concentrations or on the Table5. Growthof the 1976year class of capelin spawninggrounds; i.e fish of the last agegroup in the Gulf of Anadyr. +! do not last until the next reproductionseason, or very few of them do.Therefore, we could suppose Age Length Increment in Number of that a certainpart of the capelinstock, even if they years! Season cm i 1ength crni observations live until the rnaxirnum age, never participate in 0+ fall re p roducti on. 4.8 4.H 100 Capclin inhabiting the waters around the spring H,l 3.3 173 Pribilof Islands have the fastest, maturation rate: 1+ i'all 10.2 2.1 135 they becoinecompletely mature at,the ageof 4 years 2 spring 1 l.2 1.0 135 Table 7!. 2+ fall 12.8 13 135 Thc reproduci,ivesystem develops earlier in fernales:out of 100fishes that weremature at 2 years of age,87 were females.That is why they dominate in the spawningstock amongyounger fish. At the age of 4, t,hesex ratio is closeto 1;1. In older age groupsthere are moremale capelin,a result of the higher mortality of early-maturingfemales. BeringSea capelin vary significantlyby year in the size at which they becomesexually mature. In some years 977 and 1983!, 80% of the Gulf of Anadyrfish ruatured as soon as they reached a length of 13.5 cm males! or 11,5 cm females!. In other years, maturation was slower, In 1975 a.nd 1978 SO'ic of the capelin matured only when they reached a length of about 16 cm males! or 14 cm females 1. 252 Distrihotior!,Biological Condition, and Abundance of Capeiinin the BeringSea
Table 6. Average length of capelin by age group in different regions of the Bering Sea.
Length tcm! at age years! Region Sex 1+ 2+ 3+ 4+ 5+ N
Gulf of Anadyr male 7.6 11. 1 13.2 14.7 15.9 1,126 female 7,3 10.6 12.6 14.0 15.3 600 Karagin Bay male 7.9 11,1 13.1 14.3 15.4 980 female 7.7 10.5 12.4 13.7 14.8 782 Olyutorsk Bay male 7.6 11.0 13.0 14.5 15.3 713 female 7.5 10.5 12.3 13,6 14,9 602 Pribi 1 ofIs. male 8.2 11.5 13.5 15.0 16.5 395 female 8.0 11.1 12.7 14.2 16.0 333 Commander Is, male 8.0 11.7 14. 1 15.1 113 female 7.9 11.2 13.2 14.1 104 St, Lawrence- male 7.8 11. 1 13.3 14.7 16.3 320 St. Matthew Is. female 7.6 10.7 127 13.9 15.3 374
Table 7. Average raatisrationrate of capeHnby age group in different regions of the Bering Sea.
% of mature fish at age years! Region Sex 1+ 2+ 3+ 4+ 5+
Gulf of Anadyr male 3.4 40.3 89.6 92.5 96.8 female 33.3 64.1 66.5 82.8 93,3 Karagin & male 10.7 50. 5 82. 9 97.8 100. 0 Olyutorsk bays female 39.1 69.6 90.5 96.6 100.0 Pribilof I a, male 15.0 83,5 96.7 100.0 100.0 female 70.6 82,7 92,2 100.0 100.0 St. Lawrence- male 6.1 53.2 66,7 88.9 1DO.O St. Matthew Is. female 44.3 75.7 76.3 80.7 100.0
DISCUSSION The ovaries and testes of Bering Sea capelin, as in other waters, are asymmetrical: both males and Bering Sea capelin live in diverse environments, females have a better developedleft gonad.The eggs which allows one to assume that there are several in both ovaries develop simultaneously, so they are populations.In the northern regions,conditions are always at the same maturity stage. No significant severeand closeto an arctic type. The Gulf of Anadyr differences in egg size have been found, is covered with ice for the larger part of the year, The range.of fecundity of individual Bering Sea from late October u~til June. The southeastern part capelin is substantial, from 6,000 to 24,700 eggs of the Bering Sea, on the other hand, is under the Table 8!. The average fecundity of Gulf of Anadyr influence of warm water masses of Pacific origin, so females is 10,200 eggs: Karagin Ray, 14,500; ,om- it has a milder climate and thermal regime Karpo- mander Islands re non, 12,800;and Pribilof Islands, va 1963, Arsenev 1967!, Feeding conditions are also 14.400. diA'erent. In the eastern part of the sea,capelin feed The natural mortality rate of capelin at I+ to 5+ on the broad shelf and move 300 and more miles yearsof agein the Gulf of Anadyr is 51%;and in the away from the shore, while in the west they stay western Bering Sea is 54%. In the spawning stock within ernbaymentsall ol their lives becauseof the the mortality rate is 63% and 70%, respectively, narrowness of the shelf. &co!ogyof the Bering Sea:A Revievvof RussianLiterature 253
Table 8. Fecundity of capelin in different geographic regions.
Number of eggs Number of thousands! gravid females Region Range Mean in sample Source
Bering Sea: Gulf of Anadyi 6.0-15.3 10.2 52 The author Karagin Bay 7.5-24.7 14.5 76 The author Commander 1s. 7,3-18.3 12.8 79 The author Pribilof Is, 9.0-24.4 14.4 47 The author
Okhotsk Sea. Western 3.2-20,2 9.1 115 Shilin 1970 Eastern 5.0-38.2 16.5 146 Savicheva 1975
Japan Sea 15.0-56.5 26.3 21 Rumyantsev 1946
Newfoundland 16.6-61.5 33.9 103 Winters 1966
Barents Sea 5.3-46.3 17.6 816 Galkin & Kovalev 1975
Capelin differ in a nuinber of biological features Anadyr, St. Lawrence-St. Matthew, and Pribilof. size and age composition, stomach f'ullness, fecun- The last three areas have the highest abundance. dity, rates of linear and weight growth and maturi- The available materials made it possible to ex- ty! between regions.The total biomass of Anadyr amine the abundance dynamics of two capelin pop- capelin is approximately 5 times greater than that ulations: Anadyr and western Bering Sea. of the Karagin and Olyutorsk bay stocks taken to- The Anadyr capelin stock was most abundant gether. Yearswhen strong year classesoccur do not in the inid-1970s. At that time, the biomass of fish correspond; the natural mortality rate of capelin in at age I+ and older exceeded 1 million metric tons the western part of the sea is higher than in the Figure 13!. The lowest abundance of the stock was Gulf of Anadyr; the difference in long-term abun- registered in 1988, at 14,000 tons. Generally, this dance fluctuations is significant Naumenko 1986a!. population undergoes sharp annual Auctuations in Average length and weight by year difTer greatly bioinass. For instance, in 3 years, 1972-1975, the between the Anadyr and western Bering Sea stocks Anadyr capelin biomass increased 30 times, and for see Figure 12!, the entire period 970-1988, 1993, 1994! it has in- Capelin inhabiting the southern Bering Sea creased 100 times. Fluctuations in abundance of sin- close to the Pribilof and Commander islands have a gle year classes are also large. The nuinber of faster growth rate than that of the northern stock 2-year-old fish of the 1974 year classwas estiinated differences measured by t-test, are highly signifi- at 94 billion, yet. the 1975 year classwas only 1 bil- cant and vary from 4.5 to 14.6, P > 0.999!. In addi- lion Figure 14!. tion, Pribilof capelin reach sexual inaturity on the ln the year-class abundance dynamics of Anadyr average a year earlier than in other regions, and capelin there have been two distinct periods: 1968- their fecundity is higher. The differences in fecun- 1974 and 1975-1985. In the first period, newborn dity and inaturity rate between the Pribilof group recruitinent was large: 35-94 billion fish at the age and aII the others, after comparison by t-test, ap- of 2, or on the average for those 7 years about 52 pear to be very significant; 19.9-27.6, P > 0.999, and billion. All year classes of the secondperiod were 6.6-10.7, P > 0.999, respectively. More than 80% of weak, and even the inost abundant, 1980, did not fernale capelin caught in fall and winter close to the reach the abundance of the poorest year class of the Pribilof Islands are mature at 10 cm in length, while first period. in other parts of the Bering Sea only half of them Abundance of the western Bering Sea stock fluc- are mature at 10-13.5 cm in length, tuated from 208,000 tons in 1969 to 22,000 tons in Thus, there are at least five populations of cape- 1973, and biomass has averaged 90,000 tons. Twice, lin in the Bering Sea: western Bering, Coinmander, in the late 1960s and late 1980s, short-term increas- 25-f Distribution,Biofogies! Condition, arid Aburrrfanre of Cipelinnr the Beririg 5es
90 1.3 8O G uli or Aoadyr oi 70 II W. Bering sea 60 X ll e 50 o 09 II II g 40 I I /it ' 0 v i I C! C 0.7 I X
0.1
1965 1970 1975 1980 1985 1990 1995 1965 1970 1975 1980 1985 1990 Year Year
Figure l3. Biomassofcapelin in the Gulf of Anadyrrrnd Figure 14. Abundanceofcupelin byyear classin the Gulf ir extern Bering Sea. of Anadyr and u esiern Bering Sea.
es occurred in capelin abundance in Karagin and trations of capelin stay near frontal zoneswhere the Olyutorskbays, when capelinbiomass exceeded water temperature at the bottom is 1,8 to +2.5'C. 150,0GGtons. A smaller increase,up to 10G,GGGtons, Major concentrationsoccur in October-December for this populationoccurred in 1977. near St. Matthew and the Pribilof Islands, and the Higher abundancein the westernBering Sea northern, southwestern, and southeastern Gulf of stock occurredin series of'2-4 yearsin the late 1960s, Anadyr. mid-1970s, and late 1980s. Capelin are short-lived fish; they grow to 18 cm In comparing the abundanceof two capelin pop- in length and 5+ years old. In the catches, the dorn- ulations, we could note some similarities, as well as inating group is 4-year-olds that are 12-14 cm long, significant differences.The year-classstrength of They grow year-round. The gain in length during capelinin bothregions is subjectto significant an- the first year of life is 7-8 cm; in older age groups nualchanges, but the differencein year-classabun- the gain decreasesto 0.5-3 cm. Femalesmature a dance in the Gulf of Anadyr is almost an order of year earlier than males,In the spawningstock, fe- magnitude higher than in Karagin and Olyutorsk males dominate among the younger fish. At the age bays.The years of strong newyear classesdo not of' 4 the sex ratio is close to 1:1; in the older age corrcspond either. Beginning in 1972,the biomass groups,males prevail. The averageindividual fe- fluctuation tendencies of the Anadyr and western cundity of Anadyr capelin is 10,200 eggs; western Bering Sea stocks have been opposite.The overall Bering, 14,500; Commander, 12,800; and Pribilof, abundance level is also different: in the Gulf of 14,400, Anadyr it is 5 times greater. Abundance of capelin in the Gulf of Anadyr is approximately 5 times greater than in Karagin and Olyutorsk bays. In the 1970s, 1980s, and early CONCLUSIONS 1990s,the Anadyr capelinstock biomass varied from Cape/in are distributed in large groupsover the 1,460 to 14,000 tons. and the western Bering stock entire continental shelf of the Bering Sea out to the biomass from 208 to 22,GGG tons, For the last 20 200-rn isobath. They also inhabit narrow shallows years, variations in abundance of these populations near the islands. In the wester n Bering Sea, spawn- have been in opposite directions. ingtakes placein baysand lagoons in June through There probably arc at least five independent July, when the water temperatureis 4-9'C, mostly capelinpopulations in the BeringSea, three of which derring the maximum tides. During feeding, concen- inhabit the Russian economic zone. fcology of the Hering5ea: A Reviewot RussianLiterature 255
REFERENCES Knipovich, I,M. 1926. Opredelitel' ryb morey Bar- entseva, Belogo, i Karskogo [Manual on fishes Aksyutina, Z.M. 1968. Basis of mathematical esti- of the Barents, White, and Kara seas]. Tr. mations of data from biological and fisheries Nauchno-Issled. Inst. po Izucheniyu Severa research. Pishcheprornizdat, Moscow, 288 pp. < In 27:182 pp, In Russian.! Russian.! Kudrin, B.D. 1975.Nastavleniye po poisku i promys- Andriyashev, A,P. 1939. Ocherk zoogeografii i lu rnoyvy Severo-Zapadnoi Atlantiki [Manual on proiskhozhdeniye fauny ryb Beringova rnorya i locating and harvesting capelin in the northwest sopredel'nykh vod [Outline of the zoogeography Atlantic]. Sevryba, Murrnansk, 86 pp. In Rus- and origins of the fishes of the Bering Sea and sian. ! adjacent waters]. Izd. Leningr. Gos. Univ., Len- ingrad, 187 pp. In Russian.! Luka, G.I. 1975. Nastavleniye po poisku i promyslu rnoyvy Barentseva rnorya lManual on locating Arsenev, V.S. 1967. Techeniya i vodnye massy Ber- and harvesting capelin in the Barents Sea], ingova rnorya [Currents and water masses of the Sevryba, Murmansk, l05 pp. {In Russian.! Bering Sea]. Izd. Nauka, Moscow, 135 pp. En- glish t.ranslation, 1968, U,S, Dept. Commerce, Musienko, L,N, 1963.Ichthyoplankton of the Bering NMFS, Seattle, 147 pp. Sea in the collections of the VNIRO-TINRO Bering Sea expedition of 1958-1959. Tr. Vses. Barsukov, VV. 1958, Fishes of Providence Bay and Nauchno-Isa]ed. Inst. Morsk. Rybn, Khoz. adjacent waters of the Chukotski Peninsula, Tr, Okeanogr VNIRO! 48:239-270. English trans- Zoo!. Inst. Akad. Nauk SSSR 25:21-28. In Rus- lation, 1968, pp. 251-286 in: Soviet fisheries in- sian.! vestigations in the northeastern Pacific, Part I, II S. National Technical Information Service, TT Galkin, A.S., and S.M. Kovalev. 1975. Fecundity of 67-51203. capelin, Mallotus viHosus villosus Mullerl, in the Barents Sea.Vopr. Ikhtiol. 15!:646-650. In Musienko, L.N. 1970. Reproduction and develop- Russian. 1 ment of the Bering Sea fisher. Gidrobiologiya Kiev! 15!:25-27. t in Russian. ! Gjesaeter, J,, and T, Monstad, 1977. Growth of Bar- ents Sea capelin of the year classes 1967-1970, Naurnenko, E.A. 1986a. Biologiya, sostoyaniye za- J. Cons. Int. Explor. Mer 37:1-15. pasov i perspektivy promysla moyvy Bcringova morya [Biology, stock abundance, and harvest Hart, J.L., and,I.L. McHugh. 1944, The smelts of prospectives of the Bering Sea capelin]. Avtoref British Columbia. Bull. Fish. Res. Board Can. diss. kand. biol. [Candidate t,hesis in biology]. 64, 27 pp. Tikhookean. Nauchno-Issled. Inst. Rybn. Khoz. Okeanogr. TINRO!, Vladivostok, 22 pp. { In Jangaard, P,M. 1974. The capelin Mallotus villo- Russian. ! sus!. Bull. Fish. Res. Board Can. 186, 68 pp. Naurnenko, E.A. 1986b. Estimation of'the commer- Karpova, A.A. 1963. Basic features of the Bering Sea cial stock and recruitment of the Anadyr cape- climate. In: Soviet fisheries research in the lin. In; Dinarnika chislennosti promyslovykh northwestern Pacific. Tr. Vses. Nauchno-Issled. zhivotnykh Dal'nevostochnykh morey [Popula- Inst, Morsk, Rybn. Khoz, Okeanogr. VNIRO! 48 tion dynamics of the commercial marine animals {Izv. Tikhookean. Nauchno-Issled, Inst. Rybn. of the far-eastern seas]. Tikhookean, Vauchno- Khoz. Okeanogr. {TINRO! 50!:97-110. In Rus- Issled. Inst. Rybn. Khoz. Okeanogr. TINRO!, sian.! Vladivostok, pp. 93-99. {In Russian.!
Khen, G.V. 1989, Oceanographic conditions and Naumenko, E.A. 1990. Biological characteristics of Bering Sea biological productivity. In: Proceedings the northwestern Bering Sea cape]in. In: Bio- of the International Symposium on the Biology logicheskie resursy shel'fovykb i okrainnykh and Management of Walleye PoRock.Univ. Alas- rnorey Sovetskogo Soyuza lBiological resources ka Sea Grant Report 89-01, Fairbanks, pp. 79-89. of the shelf and ext.ernal seas of the Soviet 256 Distribution,Biological Condition, and Abundanceof Capelinin tlie Bcririg5ea
Union!. Nauka, Moscow, pp, 155-162. In Rus- Okeanogr, TINRO!, Vladivostok, 6:70-75, In sian.! Russian,! Savicheva,E.A, 1982,Ernbryonal developinent of the Naurnenko,E.A., and V.G.Davydov. 198'7, Estima- far-eastern capelin,Mrillotus villnstrs socialis tion of the abundanceof the eastern Okhotsk Pall.! Osrneridae!,in the easternOkhotsk Sea. and Anadyr capelin.In: Biologicheskiyeresursy karnchatskogoshel'fa, ikh ratsional'noyeispol- Vopr,Ikhtiol, 22!:253-258. In Russian.! zovaniyei okhrana [Biologicalresources of the Shilin,Yu.A. 1970, Some biological features of cape- Kamchatkashelf, their rational exploitation and lin, Mallotus villosas sociolis Pall.!, in the preservation].KoTINRO, Petropavlovsk-Kam- northern Okhotsk Sea. Izv. Tikhookean.Nauch- chatski, pp. 91-93. In Russian.! no-Issled,Inst. Rybn.Khoz, Okeanogr. TINRO! 71:231-235. In Russian,! Naumenko,N.IPA, Balykin,E,A. Naumenko, and E.R. Shaginyan.1990. Long-terin variations in Soldatov,V.K. 1923, Materialy po ikhtiofaune the pelagic ichthyocoenosisof the western Karkogo i vostochnoy chasti Barentseva morey BeringSea. Izv. Tikhookean. Nauchno-lssled. [Materials on the ichthyofauna of the Kara and Inst.Rybn, Khoz. Okeanogr. TINRO! 111:49- eastern Barents seas],Tr. Plov. Morsk. Nauchn. 57. In Russian,! Inst79 pp. In Russian.! Pahlke,K.A. 1985,Life historyand distribution of Taranets, A.Ya, 1937. Kratkiy oprcdelitel' ryb capelin Mallotus villosus! in Alaskanwaters. sovetskogoDal'nego Vostoka i prilegayushchikh M.S. thesis, Univ. Alaska, Juneau, 76 pp, vod [Short key to the fishes of the SovietFar East and adjacent waters]. Izv. Tikhookean. Prokhorov,V.S, 1965.Ecology of the BarentsSea Nauchno-Issled. Inst. Rybn, Khoz. Okeanogr. capelinand the prospect for commercialuse of TINRO! 11, 200 pp, In Russian.! the stock, Tr. Polyarn,Nauchno-Issled. Inst. Morsk. Rybn. Khoz,Okeanogr. PINRO! 19:3- Velikanov,A Ya. 1986,Pacific capelin. In: Biolog- 63. In Russian.! icheskiyc resursy Tikhogo okeana [Biological resources of the Pacific Ocean]. Nauka, Moscow, Ruinyantsev,A.I. 1946.The Japan Sea capelin. Izv. pp. 135-146. In Russian,! Tikhookean.Nauchno-Issled. Inst. Rybn..Khoz. Okeanogr. TINRO! 22:35-74, In Russian.! Vilhalmsson, H. 1994. The Icelandic capelin stock Rit Fiskideildar 13!, 281 pp. Savicheva,E.A. 1975, Fecundityof the eastern OkhotskSea capelin.In; Issledovaniyapo bi- Winters,J.H, 1966,Contributions to the life hist- ologiiryb i proinyslovoyokeanografii [Research ory of the cape]in,l fnllotus villosus, in New- in fish biology and applied oceanography]. foundland waters. Bull. Fish. Res, Board Can. Tikhookean.Nauchno-Isa!ed. Inst. Rybn, Khoz, 879. 56 pp. Ecologyot the8ering Sea: A Rrview of RussianLiterature v$7
DevelopmentandDistribution ofthe Young of NorthernSmoothtongue Leuroglossus schmidti! in the NorthwestPacific Ocean and Western BeringSea Ye.l.Sobolevsky arid T.G. Sokolovskaya MarineBiology Institute, Russian Academy of Sciencesof theFar East' Viadi uostok, Russia
INTRODuCT1ON Pacific Kashkina 1970, Nusienko 1970, Okiyama Thispaper reports survey data from the northwest 1988,Masaki Miya 1994>.Reproduction and possi- Pacific Ocean and western Bering Sea on the eggr blemigration routes ol'the juveniles are still poorly andyoung of a speciesof bathylagidfish, the north- re searched. ern smoothtongue Leuroglossus schmidti !, Fishes of the family Bathylagidaeare someof the most MATER1ALSAND METHODS abundantrnesopelagic fishes of the Pacific Ocean. In the Okhotsk Sea they contribute up to 86%of Ichthyoplanktonwere collected during TIVRO ex- the mesopelagicichthyofauna, in both numberand peditionsusing a conicalegg net IKS-80!with an biomass,and in the Bering Sea they accountfor openingdiameter of 80cm hauled vertically through 12-13% Pearcy et al. 1979,Balanov and Il'inskiy the top 200m ofthe water.Eggs, larval. and juve- 1991kAlthough bathylagids are widelydistribut- nile stagesv;ere also collected by other fishing gear: ed andknown to play an important part in the bio- planktonnet Jedi BSD!,bongo net, and multi.-depth logicalproductivity of the North Pacific,they are. trawl. still not fully researched, The most well-known A total of 107survey stations were set up in the bathylagid speciesare thosefrom the easternPa- Pacific Oceanoff Kamchatka and in the western and cific Ocean Chapman 1943; Cohen 1956; Ahlstrom central Bering Sea,Collections in October-Decern- 1969b,1972; Pearcy et al, 1979;Peden 1981; Dunn her 199Gprovided 70 ichthyoplanktonsainples. In 1983;Mason and Phillips 1985!,Bathylagids of the 1991the surveyswere in June-Augustand Novem- northwest Pacific, where domesticsurveys of ber-Deceinber. Therefore, we had three seasons of d.eepwaterfishes were held in recentyears, are less data: summer, fall, and winter. Eggs, larvae, and well known Rasa and Kashkina 1967;Borodulina juveniles of L. schnridti werefound at 33 stations. 1968,1969; Fedorov 1973; Parin andFedorov 1981; From 40 sampleswe obtained88 eggs,26 lar- Parin 1988!. vae, and 9 juvenilesof I.. schmidti. The catch loca- Someof the important problemsin studies of tions for thesespecimens are shownin Tables1 and rnesopelagicfishes, including the Bathylagidae,re- 2. Consideringthe lack of publishedinformation on late to their spatial distribution and reproduction. the ontogenyof L. schmidtiin the ivesternBering There is some knowledge in the national literature Sea and northwest Pacific and disagreement among on distribution and relative stock sizesofbathylagid descriptions Ahlstrom 1965, 1969; Dunn 1983 i from fishes, but the early stages of ontogenesisarc hard- specimensoutside these waters, it is appropriateto ly known.Some works only mention the larvaeand describethe early stagesofL. schtnidtidevelopment juveniles caught in someareas of the northwest basedon the recentlycollected material. 258 Developmentand Distribrjtion ot the Youngof fvorthernSmoothtotigtje iti the West«rn8ering Sea
Table 1. Catch locations and number of eggs of Ieurogtossus schmidii in the Pacific Ocean and Bering Sea off east Karn- chatlra; sarnp!ing horizon 0-200 m.
Number Date Location Gear of eggs
Bering Sea 05 Nov 1990 54" 00'N 170'00'E 23:30 IKS-80 3 05 Nov 1990 55'00'N 171-00'E 12:45 BSD 6
Pacific Ocean 13 Nov 1991 48'40'N 160'18'E 18:40 BSD 15 Nov 1991 48'42'N 162'23'E 23:35 rKS-80 25 1 18 Nov 1991 49'55'N 165'04'E 04:04 IKS-80 18 Nov 1991 50 '34'N 164'00'E 16:10 IKS-80 10 19 Nov 1991 50'29'N 166'23'E 23:45 1 KS-80 11 19 Nov 1991 50'29'N 166"23'E 23:45 BSD 106 20 Nov 1991 51'05'N 167'29'E 15:55 BSD 20 Nov 1991 51'05'N 167'29'E 15:55 IKS-80 24 Nov 1991 51'48'N 166"33'E 02:30 IKS-80 1643 1 24 Nov 1991 52'24'N 167'52'E 12..05 1KS-80 04 Dec 1991 56'10'N 170"47'E 22:30 HSD 06 Dec 1991 53 44'N 167"58'E 14:55 BSD 07 Dec 1991 53'51'N 165'30'E 14:15 BSD 52 3 11 Dec 1991 51'55'N 164'10'E 05:30 BSD
SURVEYRESULTS short,hardly visible stalks. The lower jaw protrudes slightly forward beyond the upperjaw. Developmentof Leuroglossusschmidti In our collections the smallest larvae ranged The eggsof L. schmidtr'.are spherical and are larger from 10.8 to 13.2 mm, so the description and draw- than eggs of other bathylagid fishes. The diameter ings start with those sizes. Larvae 10 mrn or more of the 80 mature eggswe collected ranged from 1,68 in length have large, oval-shaped eyes which have to 2.0 mm and averaged1,84-1.90 rom, which is al- pigment and, seenfrom above,jut out from the head. most the same as the size determined by American There is pigment on the operculum, and dark spots ichthyologists for L. schmidti eggsfrom the north- on the ventral and caudal parts of the body. One east Pacific: 1,65-1.90 mm. The egg yolks are large, spotis at about40% of the lengthof the larva be- averaging 1.5 mm in diameter.There are several tween myorneres11 and 15! and the other is at 65'7c fat droplets,which is a characteristicof Letrroglos- of the length. The notochordis somewhatrounded srrsspecies. In each eggat stages I and II of devel- and pointed upwardtoward the end of the body. opmentthe dropletsnumber 5 or 6 and 7 or 8, Dorsal, anal, and other fins are seen as wrinkles on respectively. By the time of formation and develop- the body Figure IB!. ment of the embryo stages III and IV!, the small Larvae in the size range 16-25 rnm change their fat droplets coalesceinto one big droplet Figure I!. external form significantly and are different not only Other bathylagids do not have this feature. in pigmentation,but also in body proportions.At The embryo of L schmidti is relatively large this stage of development the notochord noticeably before hatching, and occupies all the surface of the straightens. The eyes grow dark and narrower, and yolk.It has large, non-pigmentcdeyes, and clearly set themselves at an angle to the entire body of the visible myomeres. The embryo has characteristic larva. The dark spots start transforming into star- pigmentation, which the hatched larva keeps, likeemel anophoresdistributed along the sides of the I~uroglossus schmidti larvae are slender and larva, The anus is pigmented with three rnelano- have a long intestine which occupies up to 75% of phoresand one melanophoreis present.dorsolater- their length. They have large, almost round eyeson ally near the tail. The lower jaw starts to pr'otrude Eco f hr r ring Sea:A Reviewof RussianLi erature
Table 2. Catch locations, number,and size of lwuroglossrrascfrmidti larvae and juveniles collected in the Pacific Ocean and Bering Sea off east Kanichatka; sarnp!ing horizon 0-200 m except as noted.
Larvae andluveni]es Date Locat,ioo Time Gear Vuraber Length i mm 1 Stage
Bering Sea 16 Oct 1990 61'38'N 177'25'E 23:05 BSD 1 33.0 ! tlv. 22 Oct 1990 59=0G'V 179000'F. 23:20 BSD 1 32 0 3tlv, 23 Oct 1990 59 57 175 56'E 01.00 bongo 1 33.0 juv. 28 Oct 1990 58'00'N 173 45'F. 02: 15 I KS-80 1 270 1 sr. 29 Oct 1990 58'00'N 178'ppcg 18:20 IKS-80 1 25. 5 lar, 31 Oct 19.10 57'00'N 179"00'E 07;15 IKS-80 1 20.8 lar. 01 Nov 1990 56'00'V 177'57'E 00:40 trawl* 1 32.0 juv. 05 Nov 1990 56'GO'N 172'00'E 05 00 BSD 2 29.0, 30.0 lar. 05 Nov 1990 56'54'N 171'07'E 18:00 trawl' 1 28.0 lar. 05 Nov 1990 54'00'N 170 00'E 32 30 BSD 1 31. 0 1 av. 17 Nov 1990 56'04'N 169"56'E 00:40 trawl 6 2 1.0-26.0 1 sr.
Pacific Ocean 04 J1111991 53 15'N 168'01'E 05.55 IKS-80 18.1 lar. 04 Jul 1991 54'00'N 166 00'E 14:14 IKS-80 14.9 lar. 04 Jul 1991 54'45'N 165'lb'E 22:35 1KS-80 13.2, 18.7, 20.8 1 sr. 05 lul 1991 55'30'N 162'08'E 00:40 IKS-80 31.0, 32.0, 33.G 3uv. 07 Jul 1991 52'50'N 165'16'E 18:02 IKS-80 16.7, 21.0 lar. 08 Jul 1991 51'1 O'N 164=50'E 06:15 I KS-80 15.2 lar. 23 Jul 1991 48'08'V 155=35'F. 18:27 IKS-80 27.8 lar. 25 Jul 1991 49'00'N 153'14'E 01:GG I KS-80 30.0, 31.0 lar. 15 Nov 1991 48'42'N 162' 23'E 32:35 IKS-80 10.8 lar. sampl!nghonzoo 200-soo m.
beyondthe upper jaw. Rays form in the pectoral and morphologicalchanges which can be summarized caudal fins, Dorsal, anal, and adipose fins are still as follows: ! the eye stalks disappear and the size in the form of wrinkles Figure ICt and shapeof the eyeschange; l the fins form in Larvae exceeding 25 mm in length have two sequence;and ! t.ransformationends as the pelvic dark spots on the caudal peduncle, four melano- and adiposefins form alongwith all t,heother char- phores on the side, and intensively pigmented guts. acteristics of a mature fish. A spotappears on the operculum.opposite the base of the pectoralfin. The pectoraland caudal fin rays Recurrenceand distributionof eggs, continue forming. The dorsal, anal, and adipose fin larvae,antj juveniles wrinkles are lifted. The body proportions keep changing Figure 1D!. Over the period June-December,the eggsand lar- Larvae longer than about 80 rnrn have practi- vae of L. schmidti were f'ound relatively often in the cally completedtransformation. The dorsal and anal ichthyoplankton: 4,5-68.4~rin samplesfrom the fin rayshave developed,and the pelvicfins andad- 1'acific Ocean off southern Kamchatka. and 0.8- ipose fin have appeared. There is darkening over 21.1% in Bering Sea samples. the jaws and operculum. Figure IE!. Zggs of L. schmidfi were distributed cast of At 32-33 mm in length transformation is com- Kamchatka over a largearea of the northwestPa- plete and the juvenile fisheshave acquiredall the cific and southwestern Bering Sea over bottom characteristics of mature individuals Figure 1F h depths of 500-5,400 m Figure 2h The eggs were The descript,ion given above shows that during found in the catches of both!KS-80 and the largr ontogenesis I., schmidti larvae undergo extensive Jedi plankton net BSD! during hauling in the sur- 260 Develop>mentandDistribution ofthe 'Young oftv<>rthern Smoothtrinoue in ti'ic 11'estc'rn Gnrinp Sea
10,8 mm
0
31 mrn
41 mrn
Figurel. Externalmar phology of northernsmoothtongue, Leurogtossus sehmcdti, rlurin deoelopmentiA, em6ryo; B-E, lari ae; F j uoenile. Lcofogyot the RenngSea: 8 Review nf RussianLiterantre 7b!
65
60
55
50
45 'N 160- 170 E 160 170 W 150
Ftt>ure2. Spatial distribution of eggs,larvae. andjut eniles of northern smoothtonpue,Ieurat,loseusschmnlti, in the Beruig Sea and northern Worth Pacific Ocean. Data teest of about 180=are from tlris stuely,and existof about IHO' f om Dunn 71983!. Data onjuveniles tcere not revtetceel b0 Dunn <1988>, henceare no!i ricluited in this figure.
face 200 m Table 1!. Egg diarncter varied from 1.68 5-6 eggs. They were practically absent where bot- to 2.0 mm. The eggs were in stages from cleavage t.o tom depths v'ere Jess than 500 m. embryo. ihiater temperature v hen eggs were found Most 8.9'! of t,he observed eggs were in the ranged from 2.8 to 8,9'C, cleavage stages I and II! of development; only 6.8cr In the Bering Sea eggs were tound in the ich- had a developed embryo. thyoplankton from time to time, mainly on the Pa- cific borderline of the continental slope of the Aleutian Islands Figure 2!, Eggs were observed D lSC USSIDN there in both Vovember and December. It was previously shown Sobolevsky and Boko- The highest number of L schtnidti eggs were lovskaya 1998! that the spawning period of Leuro- found in the fall-winter period in the Pacific oA Karn- glosstts schtnidti in the Pacific On.an off Kamchatka chatka above bottom depths from 4,300 to 5.400 rn begins in fall to winter. This is confirxned by the between latitudes 49-51-N and lortgitudes 165- catches of L.. schmidri larvae and juveniles in sizes 168'E! Table 1!. There, the catches ranged from 11 from 10.8 mm to',U.O mm in November through duly to 20 eggs per 15 minutes of haul at a temperature over the entire territory of our survey! Table 2 i.Eggs of 3.9 O at the 200-m depth. Toward the coast the and sinall larvae of L. schrni dti were found over a number of eggs in the ichthyoplankton decreased to large area of the western Bering Fea and north' est 262 Orvr!opmcnt arrd' Distribution ot the 'Youngof VorthemSoN>othtongue in the Vt'r'skrn BeringSea
Pacific by the east coast of Kamchatka. The devel- Sea. We even found some L schniidti spawners in oping larvae distributed themselves over an even October and November. wider area and occupied not only the eastern Karn- The biological condition of L. schmidti from field chatka shelf, but also the deepwater region of the observations and the times of finding their eggs, Bering Sea. More often arid in relatively large quan- larvae, and juveniles in the northwest Pacific indi- tities 8.9% of the total ichthyoplankton catch! the cate the length of the spawning period. Spawning larvae caught were in the size range 18.0-28,0mrn. begins here, just as off the American Pacific coast, Larvae in the size range 10.S-25.0mm were found in late fall to early winter, and ends in the spring. by the eastern Kamchatka coast,closer to the shelf, In the summer there were no eggs in the ichthy- as were the eggs. These larvae probably caine from oplankton, but there were some larvae of small siz- the fish that spawned in the spring-summer period. es 3-18 mrn I and some juveniles up t o 33 mm. The Juveniles of L schmi Cti were noted mostly in frequency of observations of larvae is not great, the Bering Sea, in the deepwater areas, which we which is probably a i'esult of their vertical distribu- believe was a result of the dynamic regime of the tion. The presenceof both multi-size larvae and ju- currents and their directions. In the Pacific oA'Kam- veniles of L, schmidti in the samples indicates the chatkathey were found much more infrequently and extended nature of spawning. A long spawning pe- mostly on the border of the Bering Sea. According riod is also a normal characteristic for I, schmidti to Ahlstrom 965, 1969al and Dunn 98.'3!, there in the northeast Pacific. The timing of the spawn- are very few L schmidti larvae and juveniles in the ing period in the northwest Pacific, from October northeast Pacific. We think such insignificant num- through April, is also the same as Dunn 983! ile- bers of them in the ichthyoplankton can be explained scribed for the northeast Pacific. by the ecological features of rnesopelagicfishes. Ac- The spatial distribution of eggs, larvae, and cording to Parin 988!, they perform ontogenetic young fishes of L. schmidti is influenced by the force nugrations. Eggs and larvae develop close to the and direction of currents that dominate in the ex- surface,moving down into deeperwater as they con- arnined region, We noticed that the current carries tinue to develop. Consequently,juveniles are less larvae from southeast to northwest. The distribu- likely to be caught in the top 200 m than at depths tion of young L. schmidti in the deepwater central of 200-500 m. A similar pattern of surface distribu- part of the Bering Seaalso depends on the direction tion of eggs was observedin the area of the Califor- of currents and their branches and most of the time nia Current. Ahlstrom 1965!. At the same time in concentrations were due to the surface turbulence the Bering Sea, by Kodiak Island, Masonand Phil- of the water masses. lips t1985! observed a significant number of L. schmirjti eggs at depths below 200 m. The distribu- REFERENCES tion patterns of eggs, larvae, and juveniles of L schmidti in the different areasof research probably Ahlstrom, E.H. 1965. Kinds and abundance of tish- have specificqual ities that are governedby currents, es in the California Current regiori based on egg depth of thermocl inc, and other factors. In the north- and larval surveys. Calif, Coop. Oceanic Fish. east Pacific, L. schmidti eggs have been found in Invest. Rep, 10:31-52. the area of latitudes 47-51 N, and their larvae have beencaught to the north of 54'N, mainly in the area Ahlstrom, E.H. 1969a. Mesopelagic and bathypelag- of latitudes 56-59 N where they comprise up to 5,0% ic fishes in the California Current region. Calif. of the ichthyoplankton Dunn 1983i. The authors Coop. Oceanic Fish, Invest. Rep. 13:39-44. point out that the surface geostrophical currents flowed from south to north. We most often found Ahlstrom, E,H, 1969b. Reniarkable movements of the larvae at the steep drop-offs. Eggs of I,. schmid- oil globules in eggs of bathylagid smelts duririg ti were most numerous in the eastern Pacific in the embryonic development, J, Mar, Biol, Assoc, In- fa]l Dunn 1983>, They were found there in the sum- dia 11:206-217, mer and winter also, but in smaller numbers. Lar- vae were found in the ichthyoplankton year-round, Ahlstrorn, E.H. 1972. Dist,ributional at,las of fish but there were no signi.ficant seasonaldifferences. larvae in the Calilorma Current region: Six com- Our research indicates that L. schmrdti spawns inon mesopelagic fishes Vincigverrr'a lucetia. in the Pacific Ocean off Kamchatka at latitudes 49- Triphoturus mcxicrinu s, Stenobrachius leucops- 54'N. This is thc rosin spawning area in Kamchat- arus, Leuroglossusstit6ius, Bathylagus u:esethi, ka waters, with fewer fish spawning in the Bering and Bathylagus ochotensis, 1955 through 1960. fcoiogv ot the OenngSr,i: A Revieivoi Russianti teraturr '6!
Calif. Coop. Oceanic Fish. Invest. Atlas 17, Mason, J.C., and A.C. Phillips. 1985.Bioiotg of the 306 pp. bathylagic fish Leuroglossus schnudti in the Strait of Georgia, British Columbia, Canada. Borodulina, O.D. 1968,Taxonomy and distribution Can. J. Fish. Aquat. Sci. 42:1144-1153. of the genus Leuroglossus Bathylagidae, Pi- sces!. Prob!, Ichthyol. Engl. transl. Vopr. Ikhti- Musienko, L.N. 1970, Reproduction and develop- ol.! 8!:1-10. ment of the Bering Sea fishes. Sovetskiye ry- bokhozyaystvennyye issledovaniya severo- Borodulina, O.D. 1969. Osteology of Leuroglossus vostochnoy chasti Tikhogo okeana l Soviet stilbius schmidti Rasa,Bathylagidae. Prob!. Ich- fisheries investigations in the northeast Pacific thyol. ,Engl. transl. Vopr. Ikhtiol.! 9:309-320. Oceanl. Part V. Tr, Vses, Nauchno-Issled. Inst. Morsk. Rybn. Khoz. Okeanogr. VNIRO! 70, Izv. Chapman, W.M. 1943. The osteology and relation- Tikhookean, Nauchno-Issled. Inst. Rybn. Khoz. ships of the bathypelagic fishes of the genus Okeanogr. TINRO> 72:166-224. In Russian.! Bathylagus Gunther with notes on the systein- atic position of t~ uroglossus stilbius Gilbert and Okiyarna, M. 1988. Family Bathylagidae. An atlas Therobromus callorhinus Lucas. J. Wash. Acad. of the early stage fishes of Japan, Tokai Univ. Sci, 33!:147-160. Press,Tokyo, 1154 pp.
Cohen, D.i%I.1956. The synonymy and distribution Parin, N.V. 1988. Fishes of the open ocean. Science, of Leuroglossus sti lbi us Gilbert, a North Pacific Moscow, 273 pp. bathypelagic fish. Stanford Ichthyol. Bull. 7:19- 23. Parin, N.V., and V. V. Fedorov.1981, Comparing the pelagic deep-water ichthyofauna of the north- Dunn, J.R. 1983, Development and distribution of western and northeastern areas of the Pacific Ocean. In: Biologiya bol'shikh glubin Tikhogo the young of northern smoothtongue,Leuroglo- okeana I Biologyof the great depthr of the Pacif- ssus schmi dti Bathylagidae!, in the northeast ic Ocean]. D~TS [Far-Eastern Branch] Akad. Pacific, with commentson the systeinatics of the Nauk SSSR, Vladivostok, pp. 72-78. fin Rus- genus Leuroglossus Gilbert. US. Natl. Mar, sian.! Fish. Serv. Fish. Hull. 81!:23-40. Pearcy, W.J., T. Nemot,o, and M. Okiyama. 1979. I edorov,V.V. 1973. Ichthyofauna of the continental Mesopclagic fishes of the Bering Sea and adja- slope of t.he Bering Sea and some aspects of its cent northern North Pacific Ocean.J. Oceanogr, source and development, Izv, Tikhookean. Soc.Jpn. 235-4!:127-135. Nauchno-Issled. Inst. Rybn. Khoz. Okeanogr. TINRO! 87:3-41. In Russian.! Peden, A.E, 1981, Recognition of' Leuroglossus schmidti and L, stilbiua as distinct, species in Kashkina, A,A. 1970. Summer ichthyoplankton in the North Pacific Ocean. Can. J. Zool. the Bering Sea. In: Sovetskiye rybokhozyay- 592!:2396-2398. rtvennyyc issledovaniya sevcro-vostochnoy chasti Tikhogo okeana [Soviet fisheries investi- Rasa,T.S., and A.A. Kashkina. 1967. Batilyagi Pi- gations in the nori.heast Pacific Ocean], Part V. sces, Bathylagidae! severnoy chast.i Tikhogo Tr. Vses. Nauchno-Issled. Inst. Morsk, Rybn, okeana IBathyfagid fishes i Pisces, Bat,hylagidae Khoz. Okeanogr. VNIRO! 70, Izv. Tikhookean. of the North Pacific Oceanj, Tr, Inst, Okeanol. Nauchno-Issled. Inst. Rybn. Khoz. Okeanogr. Akad. Nauk SSSR 84:159-208. In Russian.! TINRO! 72:225-245, In Russian.! Sobolevsky,Ye.i., and T,G.Sokolovskaya, 1993.New Masaki, M. 1994. Seasonal occurrence of deep-sea information on smoothtongue, Leuroglossus bathylagid fishes in Sagarni Bay.central Japan, schmidt< Bathylagidae!. biology in the north- with notes on their reproduction. Jpn. J. Ich- western Pacific, Vopr. Ikhtiol. 33' 6!:780-784, In thyo1. 40 4!:433-440, Russian. ! Eculory Sea: 8 Review«f Russi,znLiterature
Distribution,Abundance, and Trophic Relationshipsof Bering Sea Cetaceans
Ye.hSobolevsky marine Biology hzstirute, Russiaiz Academy of Sciences of the Far East Vedi oostok, Russia
Ole A. Mathisert Juneau Center, Sckoo of Fisheries and Ocean Sciences, Uniuersify of Alaska Fairbanks Juneau, Alaska
I N TROD U CTION MATERIAL.S AND METHODS Whales were targeted for intensive harvest in the This paper is based on riurnerous publicat.ions on North Pacific in the nineteenth century and most of Bering Sea cetaceans Townsend 1935; Vadivasov t,he twentieth ceiitury. The rapacious whaling com- 1946: Sleptsov 1955, 1961; Tomilin 1957; Arsenev pletely undermined the baleen and sperm whale 1961; Berzin and Rovnin 1966; Rice and Wolman stocks in the 1960s and 1970s Berzin and Yab! okov 1971: Blokhin 1990>. The published data allow us 1978, Zernskiy et al. 19791 The top of the Bering to estimate the abundance of whales and their bio- Sea food pyramid, comprising the cetaceans. was rnass before the beginning of large-sca/e whaling in destroyed or severely reduced. The sudden decrease the Bering Sea fthe mid-runeteenth cent,ury!. We in the number of whales in the Bering Sea caused estimated current abundance from the most recent changes in trophic relationships that, had existed works
170'W 60'W
5'N
55
55'
Figure1. Distributjonofthe most common species ofwholes in the Bering Sea Blohhin 1990, Vlodimiroo 7998, arLdour own obsess:otiose!. merousspecies of baleenwhales have been the bow- year.This wastaken into considerationwhen cal- headand gray whale Kschrichtius rob tstus!,and of culatingthe annualfood requirement Tables 1 and toothedwhales, the white whale and killer whale 2!. In the nineteenth and twentieth centuries the Orcinus orca!. Balaenopteridwhales are not very bowhead stock has been exploited intensively. Ac- numerousin the BeringSea, and the bluewhale Bal- cordingto the specialists'calculations, the Bering- aenopteram ttscultts!and sei whale B. borealis!are Chukchi stock consisted of 15,000-30,000 whales not found there at all Vladimirov 1993! Figure 1!, beforemass whaling began Bockstoceand Botkin 19SO!.In the I ate nineteenth century the stock was at theedge of decimation, and in theearly twentieth Bowhead Balaerra mysticetus! centurythere waspractically no bowheadharvest Bowheadsprefer to live closeto ice. In the spring becausethey wereso rare along the northwestern theyare observed in BeringStrait, on their migra- coast of Alaska. The stock started recovering slowly tion north along the coast of Alaska to Arnundsen after prohibitionof whaling, By the endof the 1970s Bayin the BeaufortSea. In the secondhalf of the the populationwas about 3,000 Berzin1981!, and summermost of the v"halesmigrate to WrangelIs- in the 19ROswas estimated at 7,00G-S,OOO Zeh et land in the Chukchi Sea Bogoslovskayaet al, 1984, al. 19RR!. Vladimirov 1993!,When dense ice fields fortn, the At presentthe status of bowheadpopulations is whalesmigrate along the Chukotsk coast to thewin- not clear.An opinionhas beenexpressed that there tering groundsin the BeringSea. We believe that are severalpopulations in the Bering and Chukchi bowheadsstay in the Bering Sea7-S months everv sea.s. Col the BeringSea: 3 Kcviett Of RuSchrrtLtferdture
Table 1. Number thousands! and biomass thousands of tons! of cetaceans in the Bering Sea before large-scalewhaling postWorld%sr ll!, and daily and annual amountsof foodconsumed thousands of tons!.
Annual food con sumpt.ion Daily food Plankton Species Number Biomass consumption Fish Capha 1opods and other Tots!
Bowhead 15-30 750-1,500 30.I60 6,900-13h800 6,900-13,800 Right whale 0.5-lv 22-44 0.9-1.8 190-390 190-380 Fin whale 6-8 210-280 8.3-1I I 500-700 1,000-1,300 1,500-2,000 hIinke whale 4-6 2D-30 0.8-1.2 90-140 50-70 140-210 Blue v:hale 0 05-0.1 3-6 0.1-0.2 20-40 20-40 Sei whale O.I-D.2 3-8 0. 12-0.24 8-16 1-2 13-26 22-44 Iturnpback whale 2.5-3 70-86 2.8-3.4 250-310 250-300 500-610 Gray whale 15-30 230-460 9-18 1 0-20 1,610-3,220 1,620-3,240 Sperm whale 1.8-2.5 45-63 1.9-2.5 20-30 410i570 430-800 Ktl 1erwhale 3-5 12-20 0 8-1.4 80-130 60-120 70-130 210-380 White whale 8-10 2-2.5 0.14-0.17 40-50 40-50 Oceandolphins 15-20 0.3-0.4 60-90 10 70-100 Tot.al 71-116 1.370-2,500 55-100 1,060-1,490 480-700 10,100-19,270 11.640-21,450 Sources:Scammon 187 1 Townsend1935, Vsdivasov f948, Tomilin 195r. Riceand Woliaan 1971, Iveshin et al. 1972.Zemskiv et al. 19is. Soholevsky1983a, Vtadtmirov 1993. " Otherestimates give s valueol shool.10O
Table 2. Current number thousands! and biomass thottsands of tons! of cetaceans in the Bering Sea, and daily and annual amounts of food consumed thousands of tons!.
Annual food consttmption Daily food Plankton Species Number Biomass consumption Fish Cephalopods and other Total
Bowhead 7-8 350-400 14-16 3,220-3,680 3,220-3.680 Rtght whale 0.2-0.5 9.8-22 0 35-0.9 70-190 70-180 Fin whale 0 5-1 17.5-35 0.7-1.4 40-72 86-17R 12ti-250 Minke whale 1.0-1.5 5-7.5 0 2-0.3 20-30 15-22 35-o2 Humpback whale 0.3-0.4 8 4-1 1.2 0.3-0.4 19-25 35 47 Gray whale 18-19 27,5-290 10.7-11. 3 0.5-1 1.925-?,033 1.926-'? . 034 Sperm whale 0.1-0.2 2 5-5 0.1-0 2 1-2 22-44 23-46 Ktller whale 3-5 12-?0 08-14 80-1,'10 60-120 70-130 210-380 White whale 8-10 2-2.5 0,14-0, l7 40-50 4 0-50 Oceandolphins 15-20 4-5 0 3-0.4 80-90 10 70-100 Total 53-66 685-800 29-32 260-4DO 92-174 5.420-6,?RO 5.770-6.850 Sources:Soholevsl'y 1983a, Zeh et al. 1988,nlokhin 1999.tt'Iadtmtrov 1993. 768 DiStrihu irin,Aiiundanre, and Tniiiitic Re!a iOr>SOf Bering SeaCetaceanS
Rightwhale Eubaiaenagfaciaiis! Nlinkewhale Salaenopteraacutorostrata! Right whales were a common species in the North The tninke whale is the smallest of all the Balaenop- Pacific before intensive whaling started. Their num- tcridae. In the Bering Sea they occur mostly scat- ber in the North Pacil~c had reached 10,000 Berzin tered, but distributed over a large area. In the 1940s and Yablokov 1978!. Before the beginning of inten- whalers sometimes observed theni by Cape Navar- sive whaling these whales were seen co the north of in, in the Gulf ofAnadyr, and in Beririg Strait Vadi- St. Matthew Islaiid and in Bering Strait Townsend vasov 1946!. In those years they were not considered 1935k They were regulars around the Cornrnander of commercial value, as the large whales sper m, and Aleutian islands. In the mid-twentieth century fin. and huinpback were being exploited in the significant concentrations of right whales v erenot- North Pacific. The absence of recorded information ed in the southeastern Bering Sea Omura 1958 t on minke whales in the area makes it difIicult to In the 1960s these whales were distributed nort.h to estimate their original stock size, We estimate 4,000- latitude 59" N. The current right whale stock size is 6,000 in the Bering Sea Table I! from t,he original estimated a.t 200-500 Vladiinirov 1993 t number of 34,000-36,000 minke whales in the northwest Pacific Vladimirov 1993!, We estiinate the current Bering Sea stock size at 1,000-1,500 Table Finwhale Baiaenopteraphysalis! 2!. Numbers may be significantly lower in years Fin whales are common in the Bering Sea. In the when fewer whales arrive due to food shortage in 1930s and 1940s they werc observed near the Com- the foraging areas. inander Islands and in Olyutorsk Bay and the Gulf ofAnadyr, Between 1932 and 1942 the average num- Bluewhale 8alaenopteramuscuius! ber of fin whales seen in the Coinmander Islands area was 384, and in the northern Bering Sea Gulf Blue whales are not observed in the Bering Sea at of Anadyr and Bering Strait! was 497 whales Vadi- present, Vladimirov 993I expressed the opinion vasov 1946!. These data indicate that the original that they have never been there, The proof for that, fin whale stock numbered 6,000-8,000 Table I!. could be the whalers' catches which indicate that In the 1930s groups of fin whales arrived in t,he the northern limit of the blue whale range is the spring in May!. They were most often observed in Aleutian and Coinmander islands. Blue whales were Olyutorsk Bay in June-October,and in the Gulf of recorded as not observed in the Bering Sea as early Anadyr in August-September, They were seen in the as the 1940s Vadivasov 1946!. In the 1950s to 1970s Chukchi Sea in May through Septeinber. Those ar- Japanesewhalers rarely observed the whales to the eas were regular feeding areas of the fin whales south of the Cominander and Aleutian islands, and during the summer and fall, The numbers of tin did not report, them at all in thc Bering Hca Nasu whales in the Bering Sea remained high in the 1974!. At the same tiine there are reports of sight- 1930s, which allowed an increase in the harvest. ing blue whales to the north of t.heAleutian Islands Zenkovich 1938!. In the 1950s and 1960s Japanese and in t.he central part of the Bering Sea Sleptsov whalers observed fin whales in June-Septeinber by 1961!. We believe that before large-scale whaling the Commander Islands and along the Aleutian began, blue whales did enter thc Bering Sea during Ridge. In June-August, fin whales were seenin the the feeding period, but their stock size was not large centra! part of the Bering Sea and in Olyutorsk Hay. 0-100; Tabte I!. Significant nuinbers of fin whales stayed around Cape Vavarin in those years Nasu 1974I, The fin Seiwhale Balaenopteraborealis! whale stock was overcxploited in the following years and stayed at low numbers for a long tiine. Since Sei whales also have not been seen in the Bering the late 1970s fin whales have been seen again in Sea lately Vladimirov 1993 i. Migration of sei whales the Gulf ofAnadyr, the Cape Navarin area, and Bris- into the Bering Sea in the 1930s t.o 1950s was not,ed tol Bay. The available data indicate that fin whales by some researchers Neinoto 1957, Tomilin 1957, are very slowly increasing in number, but it will take Nasu 1974!. The whales were seen in the central them a long titne to completely recover.We estimate area of the sea, and there are reports of harvesting current abundance in the Bering Sea at 500-1,000 them to the north of the Aleutian Islands Sleptsov individuals Table 2t 1961!, It is dif%cult to assess the accuracy of that Eeoc>gyot' the BenngSea»t RfRussian Li tersiu00 sperm whales. In the 1950s sperm seen in the Chukchi and Bering seas. The current whales were observed to the north of the Aleutian size of the Bering-Chukchi humpback whale popu- Islands and iri the cent,ral Bering Sea. In those years lation is estimated at 300-400 Table 2!. they were actively exploited in the different area~ of the North Pacific Berzin and Yablokov 1978 t As a result, the stock was greatly reduced, The current C raywhale Eschrichtiusrobusfus! abundance of sperm whales in the Bering Sea is Gray whales are the most numerous of t,he Bering estimated at 100-200 Table 2t Their northern lim- Sea large whales. The Chukchi-California popula- it runs from Cape Navarin southeast.to the Pribilof tion has about 21,000 individuals Breiwick et al. Islands and to Bristol Bay %adirnirov 1993 t 1989l, Gray whales enter the Bering and Chukchi seas in the early sumnier to feed, and stay there for Killer whale Orcinus orca! 6-7 months. In the early 1940s gray whales were often seen Killer whales ar e seer>ail year in some areas of the in the area of Cape Navarin and in t.heChukchi Sea. Bering Sea. In summer and fall they occur in prac- In 1942-1944, 300 gray whales were seen and 40 tically the entire sea. In some years there are large caught by CapeNavarin, 123were seenand 6 caught aggregations of the animals, usually during the in the Gulf of Anadyr, and 1.074 were seen and 55 migrations. In fall 1974 we observed a large con- caught in Bering Strait Vadivasov 1946!. Accord- centrat.ion of killer whales in the Commander Is- ing to Vadivasov the average number of gray ivhales lands area. The animals were moving in straight seen each year during the period 1932-l942 in lines in groups of 3, 5, or 7 individuals. Killer whales Bering Strait and the Gulf of Anadyr was 466 were observed from the research vessel Ucherti i for whales. a distance ofmore than 4-5 miles, and for about half The number of gray whales in the rnid-nine- an honr they were crossing the boat's course ithc teenth century has been est,imatedat 15,000-30,000 speedwas 10 knots t Concentrations ofkiller whales IScarnmon 1874, Ohsumi 1976!. In the period of were also observed near the Pribilof Islands i Berzin unregulated whaling gray whale stocks were seri- and Vladimirov 1988!. Distrihuuori,Abundanrr, anrl Troplrk Re!a ionaor BeringSca Cetaceans
This speciesof toothed cetaceanwas not an ob- fin whale stomachs Zcnkovich 1937! showed that ject of harvest and its abundanceprobably did not the first item on their menu was plankton organ- undergo any great changes. isrns 2,5~if ! and the second was fish i 21.4~re.!. Among fishes, whales prefer herring Clupea pallasi !, Arctic cod Boreogadus sairla!, and saffron cod Elegirrus White whale Oe!phinapterusIeucas! gracilis!. The stomachsof somewhales contained '6'hite whales are one of t,he most common spe- 600 herring. Stomachs of fin whales north of the cies of toothed cetaceans.They are we!l adapted to Aleutian Islands contained Atka niackerel Hexrr- linldngin the northern Bering Sea,Gulf of Anadyr, grammos sp.! and Pacific cod i Gadusmarrocephalusi and Chukotsk waters. The summer range limit of Nemoto 1957!. In the Bering and Okhotsk seas, the white whales lies to the north of Cape Navarin. In fin whale diet includes squids, herring, saffron cod, the springthere are oftengatherings of the animals smelt Osmerusmordax!, capelin Mallotus villosus!, in the northeastern part of the Gulf of Anadyr, in pollock Theragraeh alcograrr nna !,Arct.ic cod, Pacific the openleads in the iceby Sircniki, and in Mechig- cod, Atka mackerel, chum salmon Oncorhyrrchus menskiy Bay. There are reports of white whales keta !, and other fish species.The coinmon speciesof wintering in the icefields of the ChukchiSea Klein- fish pollock, smelt,herring are important in the enberg et al. 1964!. diets of blue, sei, and minke whales Sleptsov 1955!. White whales were not exploited on a large scale Thus, fish is an important, item in the diet of in the Bering Sea, and their removal was limited to balaenopterids. We took this into consideration the needs of the local inhabitants Arsenev 1939!. while calculating the annual food needs for the Bal- The arctic white whale stock in the early 1980s was aenopteridae Tables 1 and 2!. estimated at 25,000-30,000 Burns 1984!, In the The diet of the gray whale is well rcsearched. Bering Sea,the number of white whalesis saidto Its food items are diverse Zimushko and Lenskaya be 10,000 Vladimirov 1993!. 1970! and include about 150 speciesof benthic and nektobenthic organisms Blokhin 1990!. Species found most often in the whales' stomachs were Pon- Other species toporieafemorata and Ampelisca macrocephala. In In someyears in the Bering Sea other toothed ceta- some cases there were Arctic cod. ceanswere reported such as Baird's beaked whale Plankton and fish play an important role in Berardius fiairdii!, Cuvier'sbeaked whale Ziph- humpback whale nutrition. Earlier, in the Bering and. ius cavi rostris!, Dali porpoise Phocoenoidesdalli !, Chukchi seas their stomachs contained herring,Arc- and other dolphins Sleptsov 1955, 1961; Tomilin tic cod,saffron cod,and sinelt, and in someyears the 1957; Lowry et al. 1988! share of fish was 25-55% Zenkovich 1937!. Slcptsov The abundance of small cetaceans in the Bering f1955! found cephalopods,pollock, Atka mackerel, Sea is unknown. For our calculations we used the churn salmon, pink salmon Oncorhynchus gorbus- earlier published materials Sobolevsky 1983a!. cha!, and Pacific cod in humpback w'hale stomachs. Cephalopodsand fish have long been known to be the major food of toothed whales and dolphins DlrT Tomilin 1957!. An analysis of 184 sperm whale The basic food for right whales, including bowhead stomachs showed that squids and octopuses made and Pacific right. whale, comprises planktonic eu- up 72% of the volume,fish and cephalopods20%, phausiidsand Calanoida IEuphausia pacijica, Cala- and 8% of the stomach volume was empt.y Zenkov- nusplumchrus, C, cristatus,C. finmarchicus!. These ich 1937!. Cod and skates were the most frequently are abundant in the Bering Sea Omura 1958!.Right found fishes. According to Berzin 959!, fish make whales feed mostly in the surface layers. As plank- up 5-10 1g!ut tb» Hering5e i: 8 Revieivot RussianLiterature 277
BIOMASSAND NUTRITIC!NAL The current abundance of whales is a lot lower. 57-75~ir of' the estimated abundance before the be- REQUIREMENTS ginning of commercial exploitation iTable 2!. The The available information on abundance and diet decrease came about first of all due to the decrease allow some preliminary calculations of the daily and in the number of bowheads to 7,000-8.000, down annual food requirements for the exarnincd species from 15,000-30,000, and decreases in the numbers of cetaceans in the Bering Sea Tables 1 and 2!. Such of Balaenopteridaelespecially fin whales!,hump- calculations have been performed before Sobolevsky back whales, and sperm whales. Small t,oot.hed 1983a!, but gray whales and bowheads have in- whales and dolphins kept their original abundance creased in abundance in the last 13 years, so we becausefew were targeted for harvest. made the appropriate changes, The number of Because the number of large whales declined whales and dolphins before the beginning of intcn- by 50-709<,the biomass and the daily requirement sivc whaling was supposedly 71,000-116,000, of of foodalso dropped. As a result,the annual require- which 42-52r!c were bowheads and gray whales. ment of food is now 32-49'r. of the original. The Among the Balaenopteridae in those years the fin whales consume half the amount of plankton now, and minke whales had the highest numbers, while 20-254 less of cephalopods, and only 25;c of the t,he abundance of the blue and sci whales was very former consumption of fish, This happened mostly low. The total number of balaenopterids was less becaure of the decrease in the number of right than the number of bowheads.Ainong the toothed whales, Balaenopteridae, and humpback and sperm whales, the white and killer whales were most nu- whales. Bowheads have kept the leading position merous. The abundance of the largest species of the in foodrequirement, 4-56% !, andso have the gray toothed whales, the sperm whales, at that time was whales 0-33'ir !. The role of other whales in the greater than t.hat,of the Pacific right whale, the blue yearly balance is not so significant, even though they whale, and sei whale all taken together, but it was are the main consumers of fish and cephalopods, still 8-12 times less than the abundance of the bowheads and gray whales. DISCUSSION Follovring are percentages of cetaceans in the Bering Sea before large-scale exploitat.ion: The contemporary abundance of many species of whales has. not reached the original level calculat- Right whales 22-27 ' ed by specialists Bockstoce and Botkin 1980, Zeh Bal aen opt,e rid ae 12-14cii et al. 1988!. At present, some Bering Sea whale Gray and humpback whales 24-28'k stocks are iiicreasing. Over the last 15 years the Too thed cetaceans 32-39% number of bowheadshas increasedsignificantly i Zeh S perin whales 2. 1-2.5c~ et al. 1988!, and the range and abundance of gray Right whales mainly bowheads! made up more whales arc increasing Brei wick et al. 1989, Blokhin than half 6-62"~< ! of the total biomass of all t.he 19901 However, along with the positive events there Bering Sea whales, Other important species were are some negative ones. Most of the Balaenopteridae the gray and fin whales, The toothed whales con- have not been restored to their original abunrlance, tributed only 3,6-4.6'7< to the total biomass. A simi- and the blue and sei whales are not seen in the lar relationship existed in the dist,ribution of daily Bering Sea at all anymore. The existing large-scale and annual food requirements. coromercial fishing may prevent restoration of' the Before large-scale whaling started, the daily whale populations. As a rule, many commercial fish- requirement of food for the whale~ was 55,000- ing operations are in traditional whale feeding ar- 100,000 tons. Out of this amourit, bowheads con- eas.In the savarin, Anadyr, and Korf-Karagin areas sumed 54-60'7e, gray whales 16-18'7r, and fin whales during the feeding periods for whales, people also 11-15O< . The share of the rest of the v hales was less fish for pollock, herring. cod, salmon, and other corn- than 15".f. The annual requirement of food was 11.6- rnercial fishes. The nursery grounds of small pol- 21.4 million tons Table 1!; 7-9% was fish and 3-4ric lock Vavarin area!, which is an important item on cephalopods, so the major food, at more than 80ci<. the whales menu il.owry et al. 1988!. are worked was plankton This ratio is understandable since the by tens or sometimes hundreds of commercial boats. main consumers of plankton were bowheads, gray Tankers, trans-shipping boats. and other subsidiary whales, and fm whales, and the share of the toothed fleet come there all t.h.e time. The disturbance of whales in the yearly food rcrnoval was only 5-6',r. whales in such areas is very high, and as a result in Distribotinrt,Abtrndarrce, and TrophicRe/actions oi Bering.sca Cr i;iceins recentyears one rarely sees feeding whales in ar- 1988,Radchenko and Sobolevsky1992! and their easof commercialfishing, The commercialfishing port,ionin the total biomassof the epipelagicfish fleethas forcedthe whalesout ofthe traditionalfeed- was more than 80'rcin the 1980s.The biomassof ing areasinto lessproductive parts of the Bering pollockin the openBering Sea was fairly signifi- Sea.This appliesespecially to the balaenoptcrid cant Bulatov and Sobolevsky 1990!. At the saine whales,for whomfish arean importantpart of the time, as the commercialfishing statistics indicate, diet.Perhaps this is whytheir recoveryis slow. in the 1970sand 1980sthe voliirnc of fishing kept Cornrnercialfishing will not havea negativeef- growing,especially in the Russiarieconomic zone fecton abundance of the right whales,especially the Shuntovet al. 1988!,but the number of balaenop- bowhead.In fact, the removalof pollock,which con- terid whales in those years still stayed low, At sumesmostly plankton, will to someextent lower presentthe annual foodrequirement of fish by thecompetition and the pressure of the intense food BeringSea cetaceans is in t.herange of 260-400tons, competition,In addition,the foragingareas of the The problem of the relationship betweenhu- bowheadare muchlarger and their distribution in- mansand whalesis getting morecomplicated every cludes,besides the BeringSea, the Chukchiand yearbecause of mtensiveexploitation of the shelf Beaufort,seas. The Balaenopterid ae occupied a much andincreasing pollution of the waters.The solution smallerfeeding area in the BeringSea originally, for this must involvesetting someinternational reg- sowhen t,hey were forced out of t.beregion where ulations for the preservationof whales,AVe cannot pollockgathered, they foundthemselves in worse forgetthat they are an important.link in the rna- circumstancesthan before.This is probablya sig- rine ecosystemand the destructionof its balance nificant factor slowingdown anyincrease in abun- may lead to negative consequerices. dant e of balaenopterid whales. The problemof the interactionof marinemam- REFERENCES mals and fishing has been discussedr'n the last 20 yearsrZernskiy et al. 1979;Sobolevsky 1984, 1990; Alton,34,S. 1974. Bering Sea benthos as a foodre- Beverton1985; Lowry et al. 1988!.Totally opposite sourcefor demersal fish populat,iona. In: D.W. pointsof viev havebeen expressed, ranging from Hood and E.J. Kelley eds,!, Oceanographyof the stabilizingrole of marinemammals in ecosys- the Bering Seawith emphasison renewabl.ere- tems Zemskiyet al. 1979!to thedamage caused by sources. Univ. Alaska Inst, Mar. Sci., Occas whalesand sealsto commercialfishing. True, the Publ. 2, Fairbanks, pp. 257-277. amount of stated annual food requirementin the BeringSea varies significantly depending on the Arsenev,V,A. 1939. Distribution and migrationsof authors,but theyall indicatethe importantrole of the far-eastern white whale. Izv. Tikhookean. cetaceansin the removalof largeplankton and fish Nauchno-Issled. Inst. Rybn. Kohoz. Okcanogr. biomassfrom the ecosystem Frost and Iawry 1981; TINRO! 15. 111 pp. In Russian.! Sobolevsky1983a, 1983b; Laevastu and Larkins 1981!.At presentthe annualfood consumption by Arsenev,VA. 1961.Distribution of whales in the BeringSea cetaceans is 2-3times less than in the Bering Seaand opportunitiesfor development mid-nineteenth century, so any alleged harm to rna- of whaling.Tr. Soveshch.Ikhtiol. Korn.Akad. rine mammals has been reducedto the same degree. Nauk SSSR 12;112-124. In Russian. ! In the presentwork wc did not.calculate thc commercial kinds of' fish consumedby the v hales. Bakkala,R.G., and V.G. %espestad. 1983. %alleye 92Veplan to do that in the future Herc,we consid- pollock.In; R.G.Bakkala and I.. Low eds.!,Con- ered it necessaryto put downsome thoughts in de- dition of groundfish resourcesof the eastern fense of the whales. In the 1980sin the Bering Sea BeringSea and Aleutian Islands region in 1982. epipel.agiczone, in the layerwhere the right and U.S.Dept. Commerce, NOAA Tech. Mem. NMFS balaenoptcridwhales feed, the biomassof the ma- FfNWC-42, pp. 1-28. jor speciesof nekton including rnesopelagic fishes risingto the surfaceat night!was about 34 million Berzin,A.A. 1959.Feeding of spermwhales Phy- tons Radchenko 1994i. The share of the main seter catodon! in the Bering Sea. Izv. Tik- whales'food objects poflock,herring, cape/in>was hookean.Nauchno-Issled. Inst., Rybn, Khoz, 69''I or 23.5 million tons. Pollock, playing an impor- Okeanogr. TINRO! 47;161-165. In Russian.! tant part in the whales'diet, iLowry et a}.1988!, in the 1970s had a leading position in the fish groups Berzin,A.A. 1981.Contemporary condition ofbow- iBakkala and 8'espestad1983, Soholevsky et al. head stocks. Priroda 6:81-83. iln Russian. ! Ectilogyot the Oertng~,S<,trA Rct ien ni RussianI trerattjre
Berzin, A.Aand A.A. Rovnin. 1966, Distribution bov head whale Bafaert a rnysticetus! population and migration of whales in the northeastern by the pelagic whaliiig industry, 1848-1914. Rep. Pacific Ocean, Bering and Chukchi seas. Izv. Int. Whaling Cotnin. Spec. Issue 5:107-141. Tikhookean. Nauchno-Issled. Inst. Rybn. Khoz. Okeanogr. TINRO! 58:179-207. t In Russian, Bogoslovskaya, L.S., L.M. Votrogov, and I.M. Krup- nik, 1984. Bowheads in Chukchi waters: History Berzin, A.A., and V,I.. Vladirnirov. 1986. ontcrnpo- and contemporary status of the population. In: rary abundance of cetaceans in the fur-eastern Morskiye rnlekopitayushchiye l Marine mam- seas. In: Tezisy 9 Vsesoyuznogo soveshchaniya malsj. Nauka, Moscow, pp. 191-210 In Russian. t po izucheniye, okhrana ratsiona 1'noye ispol'zovaniye morskikh mlekopitayushchikh Breiwick, J,M., D.J. Rugh, D.E. Withrow, et al. 1989. Abstracts of the 9th Soviet L'nion Conference Preliminary population estimation of gray on Studies, Preservation, and Rational Exploi- whales during the 1987-1988 southward migra- tation of Marine Mammals]. Akad, Nauk SSSR, tion. Rep. Int. Whaling Comm. SC/'40/PS 12. Arkhangelsk, pp. 32-33. In Russian.! Bulatov, O.A., and Ye,I, Sobolevsky. 1990. Distribu- Berzin, A.A., and V.L. Vladimirov. 1988. Results of tion, stock condition, and fishing opportunities research on the distribution and abundance of for pollock in the open Bering Sea. Biol. Morya cetaceans obtained on the whale catcher boat Vladivostok. i 5:61-72, In Russian.! "Dobry" in October-November of' 1987. In: Sbor- nike Nauchno-issledovatel'skikh rabot po mor- Burns, J.J. 1984. Living resources. In: W.E. Wester- skirn mlekopitayushchim severnoi chasti Tikhogo meyer and K.M. Schusterich leds.t, United Okeana ]986-1987 [Scientific research on north- States arctic interests: The 1980s and 1990s. Vol. ern Pacific marine mammals in 1986-] 987]. Akad. ]. Springer-Verlag, New York, pp. 75-104. Nauk SSSR, Moscow, pp, 11-17. In Russian,! Frost, K.J., and L.F. I owry. 1980. Feeding of ribbon Berzin, A.A., and A.V. Yablokov. 1978. Stock sizes seals Phocu fosciota! in the Bering Sea in and struct.urea of the common exploited species sprin.g, Can, J. Zoo]. 58:1601-1607. of cetaceans in the world ocean. Zool. Zh. 572!: 1771-1785. In Russian. ! Frost. K.J., and L.F. I,owry, ]98]. Foods and trophic relationships of cetaceans in the Bering Sea. In: Berzin, A,A.. and A.V. Yablokov, 1984. Condition of D.W, Hood and J,A. Calder eds.!, The eastern the gray whale stocks. In: Morskiye mlekopit- Bering Sea shelf'. Oceanography and resources, ayushchiye Marine mamma Is], Nauka, Moscow, Vol. 2. Ui.S. Dept,. Conirnerce. NOAA, Once of pp. 223-233. In Russian.! M arine Pol l uti on Assessment; distributed by Iiniv. Washington Press, Seattle, pp. 825-836. Beverton, R.J.H. 1985. Analysis of inarine maintnal- fishery interaction, In: J,R. Beddington. R.J,H. Iva hin, M.V., L.A. Popov, and A.S. Tsapko. 1972. Beverton, and D.M. Lavigne eds.!. Marine Morskiye inlekopit,ayushchiye i spravochntk t mammals and fisheries, London: George Allen IMarine inamnials a reference book!]. P.A. Moi- & Unwin, London, pp. 3-33. seev ed.h Izd. Pishch. Prom. lFood Industry Press!, Moscow. 303 pp. In Russian, I Blokhin, S.A. 1984. Populat.ion st,at,usof gray whales t Eschrichti us rnbustush In: Morskiye m!ekopit- Kawakarni, T, 1980, A review of sperm whale food. ayushchiye [Marine mammals I. Nauka, Moscow, Sci. Rep, Whales Res. Inst, Tokyo 32:199-2]8. pp. 223-233. In Russian.> Kleinenberg, S.K., A.V. Yablokov. V.M. Bel'kovich. Blokhin, S.A. 1990. Results of gray whale Eschrich- and M.N Tarasevich. 1964. Bclukha: Opyt tius robusfus! research nn the California- monograficheskogo issledovaniya vida White Chukotka population in 1980-]988, Izv, whale Delphinaprerus icucris!: Iiivestigation of Tikhookean. Nauchno-Issled. Inst. Rybn. Khoz. the speciesl. Izdatel stvo Nauka. Moscow, 455 Okeanogr. TINROi 112:61-73. pp,
Bockstoce, J.R., and D.B. Botkin. ]980. The histor- Klumov, S.K. 1978. Sperm whale nutrition in the ical status and reduction of the western Arct.ic North Pacific. In: Morskiye mlekopitayushchiyc 27't Oistrifiutiort ALundance,arrrf Trophic kefationc nt Hr ring Sca Cetacearis
lMarine mammals]. Nauka, Moscow, pp. 175- Rice,D.W, 1968. Stomach contents and feeding be- 213. In Russian. I havior of killer whales in the eastern North Pa- cific. Norsk Hvalfangst-Tidende 57!:35-38. Laevastu, T., and H.A. Larkins, 1981. Marine fisheries ecosystem:Its quantitative evaluation and Rice, D,Wand A.A. Wolman, 1971.Life history and management. Fishing News Books, Farnharn, ecologyof the gray whale,k;schri< hti us robust- England, 162 pp, Russian translation, 1987, us. Am. Soc. Mammal. Spec. Publ. No. 3. 142 pp. Agropromizdat, Moscow, 164 pp, Scarnrnon,C.M. 1874. The marine mammals of the Lowry, L.F., K.J. Frost, and T.R. Loughlin. 1988, northwestern coast of North America. John H. Importance of walleye pollock in the diets of Carmany and Co., San Francisco, Reprinted marine mainmals in the Gulf of Alaska and 1968. Dover, New York, 319 pp, Bering Seaand implications for fishery manage- rnent, In: Proceedings of the International Syrn- Shuntov, V.P. 1988. Biological resources of the far- posiurnon Biologyand Managementof Walleye eastern seas; Research and development oppor- Pollock. Un.iv. Alaska Sea Grant Report 89-01, tunities. Biol. Morya Vladivostok. I 3 3-14, IIn Fairbanks, pp, 701-726. Russian.!
Mathisen, O.A. 1959. Studies on Steller sea lion Shuntov, V.P.,A,F, Volkov, and A.Ya. F.fimkin. 1988, Fumetopiasj ubatus! in Alaska. Trans. N. Am. Structure and contemporary state of the pelag- Wildl. Conf. 24:346-356. ic fish groups of the western Bering Sea, Biol. Morya Vladivostok.! 2:56-65. In Russian.! Nasu, K. 1974. Movement of baleen whales in relation to hydrographic conditions in the northern Sleptsov, tVI.M. 1955, Exploited cetaceans of the part of the North Pacific Ocean and the Bering northwestern Pacific, Okhotsk, and Bering seas. Sea. In: D.W. Hood and E,J, Kelley eds.!, Ocean- Tr. Inst. Okeanol. Akad. Nauk SSSR 14:70-95, ography of the Bering Sea with emphasis on In Russian.! renewable resources. Univ. Alaska Inst, Mar. Sci. Occas. Publ. 2, Fairbanks, pp. 345-361. Sleptsov,M,M, 1961.Feeding areas of whales in the Bering Sea.Tr. Inst. Morfol. Zhivotnykh 34:65- Nemoto, T. 1957, Foods of baleen whales in the 78. In Russian,! northern Pacific. Sci. Rep. Whales Res. Inst Tokyo 12:33-89. Sobolevsky,Ye.I. 1983a.Significance of marine rnam- mals in the trophic chains of the Bering Sea, Ohsumi, S. 1976, Population assessrnentofthe Cal- Izv, Tikhookean. Nauchno-Issled. Inst. Rybn. ifornia gray whale. Rep. Int. Whaling Comm. Khoz. Okeanogr. f TINRO> 107:120-132. In Rus- 26;41 3-425. sian.!
Omura, H, 1958, North Pacific right whale. Sci. Rep. Sobolevsky, Ye.l. 1983b. Marine mammals in the Whales Res. Inst. Tokyo 13:1-52. Okhotsk Sea: Distribution, abundance, and role as consumers of other animals. Biol, Morya Radchenko, V.I. 1994. Composition, strucf,ure, and Vladivostok.! 5:] 3-20, In Russian.! dynamics of the nekton groups of the Bering Sea epipelagic zone.Avtoreferat kand. diss. biol. Sobolevsky, Ye,I. 1984. Marine mammals in the Ja- [Candidate thesis], Vladivostok, 24 pp. In Rus- pan Sea: Distribution, abundance, and role as sian. ! consumers of other animals. In: IVIorskiye rnle- kopitayushchiyc [Marine mammals]. Vladivos- Radchenko, V.I., and Ye.I. Sobolevsky. 1992. Season- tok, pp. 39 53. al dynamics of the spatial distribution of pollock Thcragro chrrlcogramma i in the Bering Sobolevsky, Ye.I, 1990. Marine mammals and their Sca. Vopr. Ikhtiol. 32!:84-95. In Russian.! role in the ecosystems of the far-eastern seas. Ecologyuf the Bering Sea:4 Rei e
In: Tezisy dokladov X Vsesoyuznogo sovesh- Vladimirov, V.L. 1993. Sovremennoye rasprede- chaniya po morskim inlekopitayushchim [Ab- peniye, chispennost' i populyatsionnaya struk- sti acts of Proceedings of the Tenth Soviet Union tura kitov dal'nevostochnykh rnorey [Contem- Symposium on Marine Mammalsl. Moscow,pp. porary distribution, abundance, and population 280-281. I ln Russian.! structure of far-eastern whales]. Dissertatsiya kandidata biologisheshikh nauk v forms nau- Sobolevsky, Ye,I., V.P. Shuntov, and A.F, Wolkov. chogo doklada [Candidate thesis], Vladivostok, 1988. Composition and present status of pelag- 28 p. In Russian.! ic fish communities in the western Bering Sea. In: Proceedingsof the International Symposium Zeh, J.E., P. Turet, R. Gentleman. and A.E. Raftery. on Biology and Management of Walleye Pollock. 1988.Fstimate of bowhead whale Baloena mys- Univ. Alaska Sea Grant Report 89-01, Fair- ticetus! population size based on 1985 visual and banks, pp. 523-536, acoustic data. Rep. Int. Whaling Comm. 38:349- 364. Sokolovsky, A,S,, and S.Yu. Glebova, 1985, Popula- tion structure and productivity of eastern Bering Zeiuskiy, V.A., I.S. Studenetskaya, and A.V. Yablok- Sea pollock, Izv, Tikhookean. Nauchno-Issled. ov, 1979. Marine mammal resources:History of !nst. Rybn. Khoz. Okeanogr, TINRO! 110:29- exploitation, current status, and future devel- 37. {In Russian.! opment. In: Biologicheskiye resursy Mirovogo Tomilin, A.G. 1957. Zveri SSSR i prilezharhchikh okeana [Biological resources of the World ocean]. Moscow, pp. 150-164, In Russian.! stran. T. 9. Kitoobraznyye [Mammals of the USSR and adjacent countries. Vol, 9, Cetaceans]. Izdatel'stvoAkad. Nauk SSSR,Moscow, 756 pp, Zenkovich, B.A. 1937, The food of the far-eastern In Russian.! whales, Dokl. Akad. Nauk SSSR 16{4!:239-242. In Russian,! Townsend, C,H. 1935. The distribution of certain whales as shown by logbook records of Ameri- Zenkovich, B.A. 1938.Fin whale Balaenripterophys- can wha[eships. Zoologica New York! 19!:3-50. ali s I of the far-eastern seas. Priroda 6:123-126. In Russian.! Vadivasov, M,P, 1946. USSR whaling in the far-eastern region, Izv. Tikhookean. Nauchno-Issled, Zimushko, V.V., and S.A, Iienskaya. 1970. Gray Inst. Rybn. Khoz. Okeanogr. {T!NRO,I 22:239- whale foods at the foraging areas. Ekologiya 254, In Russian.! 3:80-84. { In Russian. t br o!r>p!of he Berkip .Sea:3 Revieiv ol Russianl rlerature
Statusof the Northern Fur Seal Callorhinus ursinus!Population of the CommanderIslands
A.l. Boltnev KamchatkaResearch Institrrte of Fisheriesarid Oceanography KarnchatIVIRO! Petropavlovsk-Kamchatski, Russia
AeSTRACT eries, which have intensified in recent decade~, re- In this research wc analyzed basic demographic and duce the food supply for maririe rnarnmals and dis- life history parameters of the northern fur seal Cal- turb their lives by forcing them to move from lorhiir as irrsirrus! on the Commander Islands for the traditional areas of occupancy lAlverson 1992t In period 1958 to 1994, Data discussed in this paper order to preserve marine mammals, scientists from include birth weight, mortality of pups at the rook- ditYerentcountries are concernedwith determining eries, abundance of mature males, and growth rates the degree of influence that contemporary fisheries of fur seals during lactation and maturation to 5 have on the condition of' the food base for marine years of age. mamma]s. and the connection between the abun- Evidence is presented that the increase in abundance of marine mammals and natural fluctuations dance of fur seals on the Commander Islands in the of ocean bioresources or relationship to anthropo- 1950s was caused by the immigration of fur seals genic forces Lowry et al. 19S2. 1989; Merrick er.al. from the I'ribilof Islands, where the stocks experi- 1987; Trites 1992k enced the first stage of a decline in abundance, On The northern fur seal is a convenient object for the Commander Islands, after rapid population modeling the influence of the environment on growth in the 1950s and early 1960s two cycles in marine mammals, but the analysis is comp! icated abundance of fur seals occurred: the population de- by the direct impact of humans on fur seal popu- clinedduring 1967-1975,grew slowly during 1976- lations sealing industry t The main purpose of rhis 1986, and declined again until 1992 when increased paper is to analyze the changes in abundance of numbers of both adults and pups began appearing. northern fur seals on the Commander Islands since the signing, in 1957, of the Interim Convention for I NTRODU CTION the Conservation of North Pacific Fur Seals by Japan, Canada, Russia. and the United States, Northern fur seaLsinhabit the open waters of the which initiated regular research on the biology of northern Pacific boreal zone. Their main rookeries northern fur seals and inonitoring of the stocks. The in Russia are located on the Cornrnander Islands, goal of this paper is to extract the natural fluctua- Kuril Is!ands, and Robben Tyuleniy l Island; and in tions in stock abundance, iinrelated to the eAects the United States on the Pribilof Islandr, Alaska, of the sealing industry, in order to use the results and San Miguel Island, California, Females give in analyzing long-term changes in oceanic ecosvs- birth in late June and July, and nurse the pups ap- tems. proximately until the rniddle of November. Males and females leave the rookeries in October and No- vember to winter in the ocean, and return to the MATER!ALSAND METHODS rookeries only for reproduction. Data were collected from 1958 to 1994by scientists Northern fur seals, with other marine mammals, fromthe marinemammal research laboratory of the are the apex trophic link in the North Pacific eco- former Kamchatka Division of the Pacific Ocean system. Their abundance is limited significantly hy Scientific Research Institute of Fisheries and Ocean- the food supply Castellini 1991!. Commercial fish- ography TINROt Statusoi the NorthernI ur Sc«I Population of the f ommanrler Islands
The number of mature males at the rookeries 4ppop Q Cottttttatttter Is. rookeries Northern was determined visually using binoculars every fifth Netthwestern - SOtitheaste~ti day. In the discussion we use only maximum male Utiio abundance. The data on the abundance of harem males, obtained in 1988-1990 with some deviations from the standard recording methods, were deter- ie mined by the method of a moving average. The abun- o 25,OPO-I dance of pups was determined mostly by individual counts; pups on the Northern rookery were counted 2P,PPP D once every third year. Between individual counts, E the number of pups was estimated from the maxi- z tsppp mum number of females at the rookery t method of re G.A. Nesterov!. Al] the dead pups were counted in- 1P,PPP r / di vid u ally. / I s,ppp The height of the age ridges in the canine teeth / of 2- to 5-year-old bachelors, obtained at the rooker- 0 ies during harvests, was used to estimate annual 1955 1960 1965 1976 1975 1960 1965 1996 19952600 changes in fur seal growth rat,e as a function of environmental conditions along with such parameters Year as weight of newborn seals, weight of pups after the harem season, and weight of pupa at the end of nurs- Figure I. Ãumber of fur seal pups on the Cornrttander Islands. ing. Newborn pups were found at the rookeries from a mobile observatory station, Pupa were weighed in the first 10 days of August during mass pup tagging, and in early November while searching for the the short period from 1958 to 1965, pup abundance young of the year. The weight of the pups was taken increased about 1,5 times Figure 1!. The popula- with a spring scale with an accuracy of 0.2 kg. Ca- tion increase prompted the seals to establish the nine teeth were collected for analysis in various Northwestern rookery on Bering Island and to re- years. Measurements of the age ridges in the teeth occupy the I trilie rookery on Medniy Island, which were performed with sliding calipers along the large had been abandoned in the 1930s. outer curve of the tooth, and the height of the age By the rnid-1960s, population growth slowed. ridge was calculated as a difference between two Trends differed among the rookeries: at the newly measurements: the distances f'rom the top of the established rookeries abundaiice kept, increasing, tooth to the first and to the second age ridges. The while the number of pups at the old rookeries weighing of pups and measuring of teeth were done Northern and Southeastern dropped significant- by G.A. Nesterov. ly. The total nuinber of pups dropped even lower than Age composition was determined on the basis of in the late 1950s, before the period of population data from females tagged at birth. This was done increase. with binoculars and a 60-power telescope. Data pro- Overall, the abundance of fur seal pups on the cessing allowed for tagging factors and tag losses Coniinander Islands has decreased. Since the mid- I Vladimirov and Lyskin 1984!. 1970s it has fluctuated around the level of the rnid- 1960s. A slight increase in the birth rate in the late RESUI.TS 1970s to early 1980s was due mostly to an increase in the abundance of pupa at the Northern rookery fncrease in abundance of Bering Island. The decline in birth rates at the The kiwest number of fur seals on the Cominander Northwestern and Southeastern rookeries complete- Islands was recorded in l 911 by Suvorov 912!, who ly Leveledthe population growth. However, the de- discovered about 3,000 pups on both islands and cline in birth rate at the Northern rookery in the estimated stock abundance at. 11,000. After a 5-year late 1980s, along with a low birth rate at the other ban on cominercial hunting at t,he rookeries. the rookeries, had a negative effect on the birth-rate number of fur seals slowly grew; to 15,000-17,000 indices for the entire population. The demographic jn 191.7, 2l.000 in 1930, 30,000 in 1934, and so on parameters of the 1994 year-class allow one to as- IBoytsov 1934, Barabash-Nikiforov 1936, Il'ina sume some positive tendencies, At present, more 1 950I. The beginning of regular observations of the than 70,000 pups are born at the Commander Is- stock coiricided with the period of its growth. Over lands rookeries. Frtrlogs«l the HerIOIrSea: A RevieaOf Russian I iterature
Commanderls rookeries i CommanderIs 50 2,500
40 2.000
30 "I1.5OO E E O. 20 < 1,00 0 0 Cl 10 500
1955 1960 1965 1970 1975 1960 1965 1990 1995 2000 1955 1960 1965 1970 1975 1960 1965 1990 1995?000 Year Year
Figure 2. Percentageof dead fur seat pupa on he Com- Figure J. Rum her of fur seal harem males on the Com- mander Istarrds. mander Isla rufs.
Mortalityof pupsat the rookeries males tr = 0.57k the indicator of which is the nurn- The mortality rate for newborn pups on the rooker- ber of newborn pups. In this sense, the insignifi- ies of the Commander Islands increased in the mid- cant decrease in the abundance of harem males in 1960s, then fluctuated at 10-16% of the birth rate the late 1980s, with a relatively high total number until, in the last 6-8 years, it decreasedsignificant- of' males over 7 years old, was caused by the slight ly, to 4-8%. The overall rookery mortality rate is decreasein the number of productive females. which mostly influenced by the high mortality of the pupa is shown by the abundance curves of the pupa. up to 40% of pups born! at the Northwestern rook- At present the total number of mature males on ery, due to development of a hookworm I'Uncinaria the CommanderIslands is about 9,000. including lr4casi1 epizootic there in the early 1970s i Starostin over '3,00A harem males. 1972i, Except for the Northwestern rookery, fluctuations in pup mortality were synchronous at all the Annualvariations of the growthrate rookeries on the Commander Islands t Figure2!. Pup inortality cycled twice during the research period, The weight of a pup at birth reflect.sthc diet of the with high mortality rates on the rookeries in the mother during pregnancy,especially during the last mid-1960s and in the mid-1980s. month, v hen development of the fetus requires the rnaxirnum amount of energy ITrites 1991!. Varia- tion in weight among newborn fur seals is signifi- Abundance of mature males cant: the coefficient of variation is 26.8~i for males The abundance of matur e males I 7years and o]der! and 24.7% f'or femaleswith an averageweight of on the Commander Islands has peaked three times: 6,1 and 5,5 kg, respectively IBoltnev 19941.Howev- in the mid-1960s, mid-1980s, and early l 9906.The er, the variation among newborns does not, mask peaks were most distinct at the Bering Island rook- interannual differences in mean birth weights Fig- eries, and less apparent on 18edniy Island rFigures ure 5 t The vseight of newborn pups was greatest in 3 and 4I. 1983. It decreased through the late 1980s and The rnaxirnum abundance of harcrn males by reachedits lowestin 1989.Since 1990 the weightof themselves has experienced the same three cycles, newborn fur seals has been increasing. repeating exactly the pattern of abundance of calves The weight of fur seal pupa in early August I Fig- and total mature males. Their abundance is relat- ure 6 i, aAer the end of the pupping period. increased ed, first to the total number of mature males r = in 1982-1984, declined to a mininiurn in 1991, and 0,90!, and second to the number of productive fe- then increased rapidly, practically reaching the his- ZOO .Statvsof thetk!orthem Fvr Seal Population nf the Comm,4ncls
~ Cammen
~ 4,000 E D 9 000 0 er > 2.000- E Z
5.0 r 1980 1982 1984 1986 1988 1990 1992 t 994 1996 1955 '1960 1965 1970 1975 1980 1965 1990 1995 2000 Year Year
Figure 4. I
torical maximum of 1974 N. Starostin, pers. coin- 12 mun.!.The weight of the pups in November,when most of them have finished nursingand they leave the islands for wintering, was about 3 times greater than their weight at birth. Before leaving the CII rookeries, pups feed only on their mothers'inilk, -10 16 Consequently,annual variation of their weight in ee C3 November is a crucial indicator of conditions dur- E ing lactation.Pup weight in Novemberdeclined from 0 18-20 kg in 1985 to 13-15 kg in 1991, but has been Or i2 ID increasing since 1992 Figure 6!, <2r Growth during the first 3 years of life, as inea- er.8 er o sured by the annual increase of dentin in fur seal 8 er canine teeth, has peaked twice Figure 7!: it in- 0 creased in the late 1960s, then fell; froni the mid- 19708 through the rnid-19808 there was another increase, and in the late 1980s another decxease. 4 1965 1970 1975 1960 1985 1990 1995 2000 Also there were two cycles in the long-term fluctuations of growth of 4- to 5-year-old animals Figure Year 8!: the first coincided with the second for 1- to 3- year-olds,and the secondstarted in the early 19908 Figure 6. Weight of fur seal pup»
Agestructure of thefemales at the Northernrookery The age structure of the fur seal population at the Northern rookery on Bering Island is complex and requires further research. However, using the pro- Fro!ogry of tire BeringSea: A Reviewof Russianliterature 281
20 Fireiyear Or kfe
6.5 EVl ;e 18 err a! 14 6.0 E Q 12 0 a8C err rs 10 orr! 5.5C Eo rr! o 8 '6 Ol Z
T 5.0
1984 'l985 19S6 1987 198s 1989 1990 1991 1992 1993 1960 1965 1970 1975 1980 1985 1990 1995 Year Year Figure 9. Percentageof 2- to 5-year-oldfur sealfemales Figure 7. Incrementalgrowth offurseal teethin thefirst on fVortherrrrookery, Bering Island. and secondyears of life, northern and South- eastern rookeries, Bering Island.
portion of young females present as a measure of the reproductive potential of the population Fris- man et al, 1985!, data characterizing the survival rate of 2- to 5-year-old fur seal females in recent years are given in Figure 9. It is apparent that the percentageof young females at the rookery has been steadily declining since the mid-1980s. CE4.0 o!
DlSCUSSION 'D8a rr> For the last three decades the basic statistical parameters describing the northern fur seal popula- Vrrr a tions ol the Commander Islands have undergone sr 3.0 periodic fluctuations, we can define four periods: a period of rapid population growth during 1958-1966, V! I a decline during 1967-1975, a period of slow growth Z during 1976-1986,and another decline during 1987- 1992, 1 In the first period the abundance of pups and 1965 1970 1975 1980 1985 1990 1ggs mature males increased. At the garne time, howev- Year er, the mortality rate of pups at the rookeries also increased iFigure 2>.Unfortunately, we do not have Figure 8. Incremental growtli of fur seal teeth in the any data on growth of fur sealsduring this period. third throughfift'h years ofli je, ¹rthern and In the second period the abundance of mature Southeastern rookeries, Bering Island. males rapidly decreased,the total number of pups decreased,and the mortality rate of newborns decreased at all rookeries except Northwestern. A hookwormepidemic was developingthere. andthe mortality rate of pups reached 40% of the total number of newborns.Apparently this wascounteracted 282 Statusot the XorthemFur Seal Population of the ConimanderbtanCh by the increase in pup growth rate, even though the growth rates of the 2- to 5-year-old fur seals were 5.0 obviously decreasing in the early 1970s. The third period was characterized by a rapid 4.0 increase in the number of inature males and a slow increasein the abundanix. of pups;the mortality rate dd of pups at the rookeriesnot affectedby the epidein- 30 ic went up again by the end of the period, The growth CL rates for fur seals increased. O. The fourth period showed a lessdrastic decrease o 2.0 in the abundance of mature males, and weak tendencies toward a decrease in birth rate. The mor- E tality of pupa at the rookeries fell, and the effects of Z 1.0 the hookworm epizootic on the inortality rate at the Northwestern rookery was greatly reduced. The growth rates of the pupa declinedand becamemin- 00 imal in 1991. At the end of the period, the growth rates of immature males also decreased,The age structure of females changed toward a lesser pro- 1900 1920 1940 1980 1980 2000 portion of the younger animals, which is a result of Year reduced survival during the sea stage of their lives. The growth of the population of fur seals on the Figure IO. Xumberoffur sealpups on the PribilofIslands Commander Islands in the late 1950s and early Briggs and I'ouster I984, Fou.'ler pers. 1960sis difficult to explain. The intensive develop- commun.!. ment of fisheries during that time led to a rapid decline of marine resources Alverson 1992! and was probably one of the main reasonswhy t heabundance ~ndnlot Islands of fur seals and Steller sea lions Fttrnetopiosj uba- 000 ttts! at the Pribilof and Kuril islands decreased York I si. ' Si. and Hartley 1981, Briggs and Fowler 1984, Fris- rnan et aL 1985, Merri ck et al, 1987, Loughlin et al. 10,000 1992!. The most likely explanation for the conspic- Q uous growth of the Commander Islands population E S,OO0- of fur seals is immigration from other populations, E especially the abundant Pribilof population. ra 6.000i The nuinber of fur seals on the Pribilof Islands in the 1950s was estimated at 1.8-2 million Fig- 0 4,000 ures 10-12!. One can probably agree with the conclusion of York and Hartley 981! that one of the E main factors influencing abundance in the 1950s and Z 2000 19608 was the commercial harvest of female seals. The decline of environmental conditions and competition with fisheriesexacerbated the process. However, that was when the rookeries on the Commander Islands started to expand and two new 1900 1920 1940 1960 1980 2000 rookeries were created This expansion coincided Year with the abundancepeak for fur sealson the Pribilof Islands. one of'the largest populations, and the time Figure II. %umber of fur sealharem maler,oa the Pribilof of its intensive exploitation Figures 13 and 14! when Isla ride r Brig gs a ad Fou. ler I 984, Fou'ler pers. 100,000 and inore seals were obtained every year, commun. J. including 30,000-4G,GGGfemales. According to data on tagged aniinals recovered at the Coinmander Is- lands during that period, the Pribilof fur sealscon- tributed most to the creation of new rookeries. At that time they comprised up to 20% of the popula- Ecologyof tht Bc.ring.Sea: A Reviewof IVussianliterature
25,000
10 20.000 7! 08 E 1s.opp col06 O 10.000 Ct C5 E 0.4 E 0 5,000~ Z 0.2 E
1900 1920 1940 '1960 1980 2000 1910 1920 1930 1940 1950 1960 1970 1980 1990 Year Year Figure12. ?htalnumber of fur sealadult maleson the Figure14. Harvestof fur seal maleson the Prtbdof Is- Pribilof Islands Briggs and Fouler 1984, lands, 1917-1984 tAriggs and Fou,ler 1981. Fouler pers. commun. 8 Fowler pers. comm un. t
40,000 tion on the Commander Islands Chugunkov 1966; Chelnokov 1982, 1990a i. 35,000 One of the reasonsfor the migration of fur seals may have beenthe increasedanxiety of' the young 7p 30,000 ones. Researchershave acknowledgedthis factor as stimulating sealsto leavethe rookeries Chelnokov 25,000 1990b!. During harvest of females, the impact is a> 20,000 greatly increased,since it affectsnot only the bachelors of the rookery, but a]so directly the reproduc- E 15.000 tive feme.les. 0 10,000a> Another important factor affecting the seals J2 choiceof a reproductionarea is the availability of E Z 5,000 sufficient food resources for thc successful rearing of pups,The foodsupply was probablylimited during those summersat the Pribilof Islands, and fur sealsstarted migrating to other regionsand stay- 1950 1955 1960 1965 1970 1975 1980 1985 ing there for reproduction,This is supportedby the growth rates of the Pribilof Is!ands fur seals esti- Year mated from teeth collected during harvest; Trites Figure13. Harvestof fur sealfemales nn thePribilof Is- and Bigg 19921. lands. 1958-1984 Briggs and Fou'ler I984, The increasedmortality rate of pupa at the Com- Fowler pers. comrnunu. mander Islands rookeries in f.he mid-19606 could be due partly to the large proportionof immigrants. Sealimmigrants inhabit the least preferablespots at the rookeries,and their pups have low weights and a low survival rate Boltnev 1990a. 1990b >. !ther factors, suchas the density of a rookeryand the foodsupply for fernales during lactation,could have contributed to increased pup mortality. This i. sup- Statusof tIre Alorthernt.ur,Seal Popo!ativrl ot the CommanderIslands
25 7,000 Pribilof I Sc Paul 8,000 20 St Geo
0 a>5,0CO o< o 9 CO 15 0 4,000 O. D. p 0 ~ 3,000 t5 I a 10 OP 2,000
1,000 0 Z' pQ p
8 1910 1920 r930 1940 1950 1980 1970 1980 1990 r955 1960 1965 1970 1975 1980 1985 1990 1995 2000 Year Year
Figure I5. Percentageofdeadfurseal pupsonthePrilrilof Figure I6.."tlumber of fur seals harvested on the Com- Islandr Briggs and Fou ter I984, I"ololer perK mander Islands, 1957- I994. commun.J.
portedhy mortality at the Pribilofrookeries Fig- er, the harvest continued through 1973,when a lack ure 15k wheremortality of pupaincreased signifi- of males at the rookeries forced the hunters to stop cantly in the 1950s and gradually decreasedafter the industry on Bering Island and limit it to Mcd- the mid-1960s; and the data mentioned above Trites niy Islanrl, The decreasein the number of pups at and Bigg 1992l. the Northernand Southeastern rookeries during the The increase in abundance of fur seals on the mid-1970s was caused partially by the continuing CommanderIslands in the early 1960s was appar- migration of females to the neighboring Northwest- ently a result of intensivereconstruction of the spe- ern and Urilie rookeries, as well as the decrease in cies' distribution. The Commander Ir lands pup abundanceduri ng that period on all of the Com- population was augmented greatly by irnrnigrants mander Islands rookeries. from the Pribilof Islands, which determined its com- Harvest restrictions in 1973-1978 caused the positionat that moment and for the following years. increase in the number of mature males in the late Unfortunately, the terrmnation of large-scale seal 1970s. However, the increased birth rate at the tagging on the Pribilof Islands made it impossible Northern rookery, which determined an increase of' to follow the seal migration process in detail after this parameter f'or the entire populat,ion, along edth 1968. One can only surmise that the eA'ect of the the faster growth rates of pups during nursing, was Pribilof Islands population on the Commander Is- a sign of some positive changes in the environment. lands population went down after the rnid-1960s, It might have been a result of an increased biomass as suggestedby the last data on the tag returns on of pollock from the abundant year-classesof the late the Commander Islands out of four generations of 19708 Balykin 1989, Zolotov and Antonov 1989. fur seals that were tagged in the late 1980s on the Wespestad and Dawson 1991!. However, the trend Pribilof Islands, in pup abundance in the early 19808 differed from The current decrease in the abundance of har- one rookery to another. At the Urilie rookery, abun- ern males is related to excessiveharvest of the pop- dance was stable, while at the Southeastern and ulation l Figure 16l. Calculations showed that in Northwestern rookeries it was decreasing. It is dif- some year-classes of seals practically all males were hcult to determine any difference in the f'ceding ar- killed tFrisman et al, 1985!. The take exceeded eas for fur seals from these rookeries. The 11,000 per year, and after 1965 abundance declined explanations are probably to be looked for in the due to the decrease in the number of males. Howev- internal populat>onstructure. The young Urilie and Frol
Northwestern rookeries were not, fully developed, 12,OOO and the Vorthwestern rookery was affected by the hookwormepizootic which killed up to 40'7rof all 10,00O the newborn pups 4,ooo survival of the pupa Sobo}evsky1988; Boltnev Q 1990a, 1990bh m 2,00o The decline in pup growth rates in the late 1980s E is a result of inadequate nutrition of' t.he females during lactation, and coincideswith fluctuation in the biomass of basic food resources in the ocean Ba- lykin 1989,Zolotov and Antonov 1989,Wespestad Z 174517501755176017651770 1775 17so 17651790 and Dawson 1991!, Slow growth rates of pupa will affect their survival and eventually lead to a de- Year crease in the abundance of young seals at the rookeries Figure 9h and lead to a decline in the Figure 17. 7Vumberof fur seals harvestedon the t.'ooi- reproductivepotential of the populationin the fol- mander Islands irr the early years of the rn- lowingyears, Thc 1992-1994increase in the growth dustry, 1748- 178 7. rates of pupa is promising and could be the beginning of a newperiod in the populationincrease. At least,the sutnrnernutrition offemales has improved Data found in the archived documents ol that around the Corninander Islands. Compared to 1992 time allow one to estimate the commercial pressure N = 72!, during the 1994 seasonthe weight of fe- on the Commander Islands population right af'ter males increased by over 3,5 kg P < 0.001't During discoveryof the islandsas insignificant Figure 17i, the summer of 1994,females obviously fed very well; It had increased 5-7 times by the 1770s,when a new we observed them vomiting extra food, which was methodf' or preparingpelts was found. In 1779,Rus- mostly squid, aA.ercoming out of the sea a number sian merchants Shelikhov and Golikov organized of times. export of sealskinsto China thc cit,yof Kyakhtul. Accordingto Slyunin 1895I andSuvorov I 1912I. the ACKNOWLEDGMENTS industry operated regularly after that. and the amount of harvest kept increasing. Mostly 3- to 4- The author would like to thank G.A. Nesterov, D.I. month-old animals of both sexes i silver"' seals I were Chugunkov.F.G. Cholnokov all KamchatVIRO!, killed.The pelts were 1.aken only from the backsI seal VV. Fotnin, V.V.Vertyankin, and.V.S. Nikulin for "tails"!. Thepressure of hunting was aggravatedby their contribut,ionafrom long-term monitoring of the the fact that anybody who wanted to could hunt ~ un- Commander Islands fur seal population, and Dr. regulated industry!. Lntil the end of' the eigh- C,W. Fowler for data on the Pribilof Islands fur seal teenth century,20,000-30,000 fur sealswere taken popu1 ation. everyyear. In 1776,however, Gregory Pribilof discovered the islands which were later named after him, with the tremendousnumber of fur sealsin- APPENDIX habiting them, Consequently, most of the pressure fell on those islands. and at the end of the eighteenth Historyof theFur Seal Industry on the century the seal industry was monopolized.Start- Commander Islands ing in 1799,the Russianand American Company Theexploitation of the fur sealson the Commander pufation of the Coinrtianrl'ertsfaorls
60.000 abundance in the 1880s was at a maximum: from 1.3 to 2 million on the Cominandcr Islands Greb- 60,000 nitskiy 1882, 1902; Voloshinov 1889!. Hutchinson, Kole, & Co. exploited the rookeries severely for 20 > so,ooO years, without regard to the condition of t,he population. During their last year of operation, the cotn- ~ 30.000 pany killed over 100,000seals, officially stating on]y half of that in the report Suvorov 1912!. At the end of the nineteenth century, a period of 20,000 fu.rseal harvesting in the open.sea started. Pelagic sealing was later termed "predatory" because two 0E 010,000 seals perished or were lost in the sea for each one that was retrieved Suvorov1912!. Cozninercial pelagic and rookery sealing at the end of the last century quickly overtaxedthe fur sealstock and put it on the edge of total extermination, The switch of ZS40 11660 16601 900 19' 1940 1960 'l960 the leaseholder in 1891 Russian Company of Seal Year Hunting! andin 1910 KamchatkaCompanyofSeal Hunting! caused a forced decrease in the number of F'tgure 18. Xumber of fur seals harvested on fhe Coin- killed animals, most likely without any reduction mander Islands tn later years of fhe indusfry, of the intensity of the operation. Naturalists who 1855-196I. visited the rookeries at, that time reported a disastrous decline in fur seal abundance over the entire area Stejneger 1896, Suvorov 1912!. In 1911, after years of negotiation, the North Pacific Fur Seal Conventionwas signedby Great thoughon a moremodest scale, happened i nIrkutsk Brit,ain for Canada!, Japan, the United States, and in 1820 and led to a general decrease in abundance Russia, The fur seal rookeries at. the Pribi]of and of fur seals1 Suvorov1912!. It is not clear,and prob- Coinmander islands and Robben Island started re- ably wiB never become clear, whether this decrease coveringslowly. A 5-year hunting ba» was put on really happened or was assumed from the decineof all populations. This saved the fur seals from total the industry. It is possible that the limitations on extermination. Further growth of the Commander sealing were causedby the inonopoly in the seal in- Islandspopulation occurred slowly, maybe because dustry, whoseultimate goal wasto keepthe prices of the sealing industry. But its pressure was not so high. Similarly, in 1843 through 1847 RAC allowed great, increasingonly in the 1960safter the popu- a 5-yearperiod of intensive sealing, after which this lation had reached a certain level. Calcu! ations Fris.- activity stayed limited until Alaska was sold. Be- man et al. 1985! indicate that at that time the mal es sidesthe economic regulations onthc industry,RAC were killed off completelin many year-classes.That proposed some sophisticated methods of comtncrcial led to a rapid decreasein the abundance of harem exploitation of f'ur seals using the special features tnalesin 1973and to another 5-year hunting ban of their biology. One of the important characteris- on Bering Island, tics of this period is t,he shift to selectivehunting The resumption of the industry in 1979 caused for 3- to 4-year-old male seals, which increased the another decline in the abundance of harem males reproductivepotential greatly becauseof the poly- at the rookeries.However, because of the expense gamous nature of fur seals Sulkovskiy 1882, Vo- of pelt preparation abroad and the loss of the tech- loshinov 1889, Slyunin 1895, Suvorov 1912!, nologyin Russia, the operation v as stopped in 1985, After Alaska was sold in 1867,IIutchinson, Kole It.resumed again in 1987on BeringIsland, but there k Co., the company that leased the fur seal harvest they harvested 3- to 4-month-old male seals, and onthe CommanderIslands, intensified sealing sub- beginningin 1993,young-of-the-year of both sexes, stantially, and on the average, 30,000-40,000male putting off the harvest until the last moment bef'ore fur seals were taken each year Figure 18!. Proba- sealsleave for wintering, On Medniy Island, hunt- bly as a result of previouslimitations on sealing, ing for bachelor tnales resumed in 1990. Frnl<>g~y n the Bering>Sea. 3 f'evieivot' Russian iterature
Chelnokov, F.G. 1990a. The fraction of Pribilof Is- REFERENCES lands fur seals in the harvest on the Command- Alverson, D.L, 1992.A review of commercial fisher- er Islands. Izv. Tikhookean, Nauchno-lssled, ies and the Steller sea lion Furrrctopias juba- Inst.. Rybn. Khoz, Okeanogr. TINRO! 112:116- tus!; The conflict arena. Rev. Aquat. Sci. 117. In Russian.! 6,4!: 204-2;i 6. Chelnokov, F.G. 1990b. The effect of the anthropo- Balykin, P.A. 1989. WesternBering Seawalleye genic factor on the fur seal rookeries, Izv. pollock populat,iondynamics and stock condi- Tikhookean. Nauchno-Issled. Inst. Rybn, Khoz. tions. ln: Proceedings ot the International Syrn- Okeanogr. TINRO! 112:114-115. In Russian. ! posium on the Biology and Management of Walleye Pollock. Univ, Alaska Sea Gran.t Report Chugunkov, D.I. 1966.Local populations of fur seals 89-01, Fairbanks, pp. 559-568. inhabiting Bering and Medniy islands Izv. Tikhookean. Nauchno-Issled. Inst, Rybn. Khoz. Barabash-Nikiforov, I.I. 1936. Pinnipedia of the Okeanogr. TINRO! 58;15-21. < In Russian. I Commander Islands. Tit Vses, Nauchno-Issled. Inst. Morsk. Rybn. Khoz. Okeanogr. VNIRO! Dorofeev, S,V, 1964. Northern fur seals ."allorhi- 3:223-237. In Russian. ! rzus ursinus L.!. Izv, Tikhookean. Nauchrio- Issled. Inst. Rybn. Khoz. Okeanogr. TINRO! Boltnev, A.I. 1990a. Spatial structure of northern 54:23-50. In Russian, ! fur seal rookeries. Izv. Tikhookean, Nauchno- Issled. Inst. Rybn. Khoz. Okeanogr. TINRO! Frisman, Ye.Ya.,Ye.I. Skaletskaya, and A.Ye. Kuzin, 112:29-34. In Russian.! 1985. Matematicheskoye rnodelirovaniye di- narniki chislennost.i severnogomorskogo kotika Boltnev, A.I. 1990b,Causes of mortality in newborn i optimal'noye uprav92eniyekotikovyni khozyay- seals. Izv. Tikhookean, Nauchno-Issled. Inst, stvom I Mathematical modeling of northern fur Rybn. Khoz. Okeanogr. TINRO! 112;35-38. In seal populat,ion dynamics and the opt,imum Russian.! management of the fur seal indu~tryl. Vladivos- Boltnev, A.I. 1994. Pre-natal maternal investment tok, 156 pp. In Russian.! in off'spring of northern fur seal, Callorhirius Grebnitskiy, N.A. 1882, Notes on the Commander urs ious Otariid ae, Pinnipedi a!. Zool. Zh. Islands. In: Sbornik glavneyshikh ofitsial'nykh 73I3!:126-135. In Russian.] dokumentov po upravleniyu Vostochioy Sibir'yu Boytsov, L.V, l934. Kotikovoye khozyaystvo [Seal- [Collection of major official documents on the ing industry]. Vneshtorgizdat, Moscow,195 pp. management of eastern Siberia]. Irkutsk. 3!:41-125, I ln Russian. i In Russian.!
Briggs, L., and C.W. Fowler. 1984. Tables and fig- Grebnitakiy,N.A. 1902.Komandorskiye ostroi a lThc ures of basic population data for the northern Commander Islands1. St. Petersburg, 41 pp. ln fur seals of the Pribilof Islands. Background pa- Rllss1arl. I per submitted to 27th Meeting of the Standing Scientific Committee of the North Pacific Fur Il'ina, Ve,D, 1950. Ostrovnoye zverovod.tvo ! For Seal Commission, 29 March-9 Apri l. Moscov; 35 farming on the islands]. Moscow, 301 pp. iln Russ i an. ! pp.
Castellini, M, 1991 Report of the inarine marnrnal Loughlin, T.R., A.S. Perlov, and V.A. Vladirnirov. v orking group. In: Is it food?Addressing ma- 1992. Range-wide survey and estimatioii of to- rine mammal and seabird declines. Workshop tal number of Steller sea lions in 1989. Mar. summary. Univ. Alaska Sea Grant Report 93- Marnrnal Sci. 8!:220-239. 01, Fairbanks, pp. 4-13, Lowry, L.F.. K.J. Frost., D.G. Calkins, G.l.. Sw'artz- Chelnokov,F.G, 1982,Mixing of ComnianderIslands man. and S. Hills. 1982. Feeding habits. food fur seals with fur seals from other populations, requirements, and status of Bering Sea inarinr Vopr, Geogr. Kamchatki Petropavlovsk-Karn- mammals. North Pacific Fishery Management chatski! 8;74-76. In Russian. ! Council, Anchorage, Alaska, Doc. 19, 292 pp. Statu~ot fhe IVorthemFur Se,i!Popo ition of the Cotimiancler slat>cA
Lowry,L,F., K.J. Frost, and T.R. Loughlin. 1989. of eastern Siberial, 3!:41-125. Irkutsk, In Importance of walleye pollock in the diets of Russian.! marine mammals in the Gulf of Alaska and Bering Sca, and implications for fishery man- Suvorov,Ye.K. 1912.Komandorskiye ostrova i push- agernent. In: Proceedings of the International noy promysel na nikh The fur industry on the Syniposiumon the Biologyand Managementof CommanderIslands J. St. Petersburg,324 pp. < In WalleyePollock. Univ. Alaska Sea Grant Report Russian,! 89-01, Fairbanks, pp. 701-726. Trites, A.W. 1991.Fetal growth of northern fur seals: Merrick, R.L., T.R. Loughlin, and D.G. Calkins. I.ife history strategy and sources of' variation. 1987. Decline in abundance of the northern sea Resource Ecology and Department of Zoology, lion, Eumetopiasjubatus, in Alaska, 1956-86. University of British Columbia, pp. 1-33. U,S, Natl. Mar. Fish. Serv. Fish. Bull. 85:351- 365, Trites,A.W. 1992. Northern fur seals:Why havethey declined? Aquat. Mamm. 18:3-18. Slyunin, N,V. 1895.Prornyslovyye bogatstva Kam- chatki, Sakhalina i Komandorskikh ostrovov Trites, A.W., and M.A. Bigg. 1992. Changes in body [Corninercial resources of Kamchatka, Sakha- growth of northern fur seals from 1958 to 1974; lin, and the Commander Islands]. St. Peters- Density effects or changes in the ecosystem'? burg, 117 pp. In Russian.! Fish. Oceanogr. 1;127-136.
Sobolevsky, Ye.I. 1988. Populyatsionnaya morfo- Vladirnirov, V.A., and V,N. Lyskin. 1984, New data logiya lastonogikh. Izmenchivost' i prostranst- on distribution and population structure of thc vennaya struktura vida lPopulation morphology northern fur seals Callorhitius ursi ti.usL.!, Zool. of the Pinnipedia.Variability and spatial struc- Zh. 632!:1883-1890, I'n Russian.! ture of the speciesl. Nauka, Moscow,216 pp. In Russian. ! Voloshinov,N.A. 1889, Morskiye kotiki [Fur sealsJ. St. Petersburg.Part 1, 23 pp.;part 2, 24 pp. In Russian.! Starostin, N.M. 1972, Hookworm diseases of the Bering Island fur seals. In; Tezisy dokladov 8 Wespestad,V.G., and P.Dawson, 1991. Walleye pol- Vsesoyuznoykonferentsii po prirodnoy ochago- lock. In: Assessment and fisheries evaluation vosti bolezney zhivotnykh i okhrane ikh chislen- report for the groundfish resourcesof the Bering nosti [Abstracts of papers of the 8th Soviet Union Sea-Aleutian Islands region as projected for Conference on the Nat.ural Origins of Animal 1992.North Pacific Fishery Management Coun- Diseasesl. Kirov. 2:131. In Russian.! cil, P,O. Box 103136, Anchorage, AK 99510, 27 pp- Stejneger, L. 1896. The Russian fur-seal islands, U.S. Commission on Fish and Fisheries. Wash- York,A.E.. and J,R. Hartley. 1981.Pup production ington, D,C148 pp. following harvest of fernale northern fur seals. Can. J. Fish. Arluat. Sci. 38:84-90, Su]kovskiy, PG. 1882. Notes on the commercial in- dustries on the Cornrnander Islands and l,he at- Zolotov, O.G., and N.P. Antonov. 1989, Condition of titude of the inhabitants of those islands, the walleye pollock stock in the Pacific v aters gathered from materials available at the Depart- off Kamchatka and the northern Kuril Islands. ment of Eastern Siberia Management. In: In: Proceedingsof the Iiiternational Symposium Shornik gla vneyshikh ofitsial'nykh dokumentov on the Biology and Management of Walleye Pol- po upravleniyu Vostochioy Sibii''yu [Collection lock. Univ. Alaska Sea Grant Report 89-01, of major oAicial documentson the rnanagernent Fairbanks, pp. 549-557. Lctoicy»of the Gering Sea:A Reviewot RussianLiter iture
Distributionand Seasonal Feeding Behavior of SpottedSeals Phoca largha! in the BeringSea
Ye.l.Sobolevsky marine Biology Institute, Russian Academy of Sciencesof the Far East Vlnrli uostok, Rus.sin
ABSTRACT and increased pressure on separate parts of the ec- The distribution of spotted seals Phoca largha! in osystern exist. the Bering Sea is described, Seasonal feeding behavior of P. largha in different areas of the Bering MATERIALS AND METHODS Sea is analyzed. Common prey species that provide a main portion of the seal's menu werc recorded. ln this study we used published data Gol'tsev 1969; Ashwell-Erickson and Elsner 1981; Kosygin et al. 1985; Lowry et al, 1986, 1988; Burkanov et al. 1988; lNTRODLfnIOS Perez and McAlister 1993! and results of our per- The distribution of P, largha in the Bering Sea sonal research on pinnipeds. changes according to season. Usually, aggregations From seasonal changes in the distribution of P. of these seals are observed in spring, and during lnrgha Tikhomirov 1964, Fedoseevet al. 1988,Sa- summer-fall the seals stay along the coast. Phoca dovov 1990!, we defined seven regions in the Bering largha has a varied diet and prefers such prey as Sea Figure 1!: 1. Karagin; 2. Olyutorsk-Navarin; 3. common species ol' fishes walleye pollock, sand Anadyr; 4. northern; 5. central; 6, southeastern;and lance, capelin! and invertebrates small crab and 7. Cornrnan der-Aleutian. octopust Estimates of abundance of P. largha in differ- Phoca largha is one of the common seals in the ent seasons v"ere based on counts reported for the Bering Sea, where it has three large populations: Bering Sea in previous studies I Braham et al. 1984. Gulf of Anadyr, Karagin Bay, and eastern Bering Fedoseev et al, 1988, Perez and McAlister 1993 t Sea. Efforts of Russian and American scientists have Estimates of seasonal f'ood consumption took assembledsigniticant information about the life his- into account the difTerent age groups of t.heanimals. tory, distribution, and food consumption of P, lar gha Pupsand juveniles prefer to eat shrimps. small in different seasons Gol'tsev 1971; Sobolevsky 1983, crabs, and Euphausiidae in surnrner and fall, while 1990;Bukhtiyarov et al, 1984;Kihal'chich and Dzha- stomachs of adults usually contain fish. octopus, and rnanov 1986; Burkanov et al. 1988; Sadovov and shrimps Gol'tsev 1969, Bukhtiyarov et al. 1984, Grachev 1990!. Research conducted in various years Bukhtiyarov 1986, Trukhin et al. 1991!. Data on Braham et al. 1984, Bukhtiyarov 1986, Sadovov composition. abundance,and biomassof pelagicfish- 1986, Trukhin 1988! provides more detailed consid- es in the various regions of' the Bering Sea are de- eration of the seasonal distribution and trophic as- rived from previous TIVRO hydrobiological and sociations of P, largha. ichthyological studies Shuntov et al. 1988, 1993: Phoca largha is used as a model for studying Radeb en ko and Sobole v sky 1992t the influence of animals of the highest trophic level Estimates of seal biomass were based on their seals, whales! on the local biota in separate areas total abundancein difTerent regions considering the of the Bering Sea. Such studies are critical to irn- age structure iTrukhin 1988,Sadovov 1990 i andlif» proving forecastsfor the managementof animal pop- periods of animals: during fall and mntcr the aver- ulations and research problems of monitoring in age body mass has been estimated at 60 kg and dur- such regions, where the rigid trophic relationships ing summer at 50 kg. The biomass of ivveniles was 290 Oistribotian and SeasonalI-ceding Behavior of Spc>ttctclSea!5 i n the Beri»gSea
65
60'
55
170 E 170W 1 SO'
Figure 1. Regionsdefined for studyof feedingbehavior of spottedseals, Phora largha, in the Bering Seat 1, Karagcnc2. Olyutorsk-Savarin; 3, Anadvr; 4. northern; 5. central; 6. snutheastei n; 7. Commander-Aleutian.
calculated separately with an average bodymass of form aggregations in the central region of the Bering lo-25 kg depending on season. Sea and south of the ice edge Braharn et al. 1984, An estimateof the consumptionZ, of eachkind Fedoseev et al. 1988!. of foodj in the region a during seasont was provid- From winter through spring the distribution of ed for the regions during each season spring, surn- P. /argha depends on the condition of the ice fields, mer, fall, winter! by the following expression; their mobility, and t,he southern border of the ice Fay 1974, Sobolevsky 1988, Sadovov 1990!. In Z, = b,xreo,r,10 spring and early suminer spotted seals congregate in the Gulf of Anadyr, Korf-Karagin region, Olyu- where t; is the time period in days!; r, is the daily torsk-Navarin shelf, waters of Karagin coast, and ration during seasont in % of biomass!; e is the the southeastern Bering Sea Braham et al, 1984, part of the j-type food in ration during seasont in Sadovov 1986, Sadovov and Grachev 1990!. In the s !in the region a; 6, is thebiomass during seasont northern and central regions of the Bering Sea P. tin kg!; and x is the abundance thousands speci- largka do not form large groups, and they are rare- rnens! in the r egion during seasont. Calculations of ly seen there during that period. Z were carried out by Dr. A.I. Abakumov. With the disappearance of the sea ice, the distribution of P. largha changes. The seals begin to DISTRI8 UVIOL congregatein placeswith the most stable ice. In Ma.y and June large areas of the Bering sea becomefree The dist,ribution of P. targha in the Bering Sea has of ice, In June isolated ice floes can be observed in an irregular character, since the seals prefer to con- Karagin and Olyutorsk bays, the Gulf of Anadyr, gregate in bays and coastal shelf zones,They do not and in the northern region of the Bering Sea. Ecologyot' the HcringSea; 8 Reviewot Russianliterature 79l
Spring Summer
5
Winter
5 5 S4 K 3 x 3 C 0 0C e 1 1 I 0 0 -' ~+ b b bC gl Q ~~b ~bj cj b gjb gx+ b%S+ %i Q c yb gled~l7 b qC ~k + ~ bQ ~C L! se P ~+ps ~cb p 0~ G + c ,c, .8 g> ~c' i~' e gc' bs P~ e yO CP C2
Figure 0, Consumption ofimportant fish speciesbv P. largha by seasan.'ee Figure I far definitionsof regionsl-7.i
In the summer I'. lorgha are scattered along the occur until spring, at the time ofreproduction, when coast, On some islands and in small bays animals the seals form dense concentrations Braham et al. may form rather large groups. During the spawn- 1984, Fedoseev et al. 1988! and their spatial struc- ing migrations of salmon, P, largha aggregate near ture differs from that of November-December Sobo- rivers, At that time salmon play a very important levsky 1&88 i, role in seal feeding, and many fish are injured by P. largha Chugunkov et al. 1984!. In late summer and early fall most of the seals SEASONALCHANCES IN DIET leave the river mouths. Seal rookeries have been In all regions thc diet of P. largha usually consists located on the coast of islands far from the spawn- of fish, shrimp, small crab, and octopus. However, ing rivers. The absence of huinans leaves seal num- there are some variationa in diet among the regions bers undisturbed in summer periods. during the seasons,In spring the most common spe- The spatial distribution of P. largha is rnain- cies found in the stomachs of P. lorgha in Karagin tained until new ice forxns. When small bays freeze Bay and the Ohutorsk-Navarin region are;mall up at. the beginning of the ice period, the seals leave walleye pollock, sand lance, shrimp. and octopus the coastal area and scatter among the ice fields. lFigures 2 and 8>. In the northern region of the In early winter P. lorgha do not form large con- Bering Sea the role of Arctic cod and walleye pol- centrations on the ice. Such dist,ribution does not lock has been growing. In the central Bering Sea 292 Distributior!and Seasonal Feeding Behavinr of SpottedSr .!Is in theDerri!g Sea
Spring Summer
5 5 a4 Othe g4 Other K 3 IE3 topuses Octopuses vl 2 VP 8 allcrabs all crabs I- t P-0 ps 0 t 2 3 4 5 6 7 1 2 Region
5 5 Other p4 Other e,4 x 3 x 3 Octopuses t52 82 ll crabs K SisalI Crabs r- i ps 0 0 't 2 3 4 5 6 7 i 2 3 4 5 6 7 Region Region
Figure 3 Coneuirtptionofirrtportaiit irivertebratefoodsby P.lrtrgha by season. 8ee Figure 1 for defi rtitiorts 0/'regions /-7,t
walleyepollock is the basicfood of P. larghri. In the andshrimp dominatein the diet. In the central and southeasternregion capelin and small walleyepol- southeasternregions small walleye pollock, small Lock are the main foods Figure 2!. crabs,and shrimpsdominate Figures2 and 3!. In In summer the diet of P. Lrirghaincludes the var- all regionsthe young ol' P. lrxrgh.riconsume large iousspecies of salmon, which at that timeare found quantitiesof octopus,small crab, and shrimp Fig- in mostregions of' the BeringSea Birrnan 1985, ure 3!. 1Vlostfood is eaten by the main P. larg/to con- Sobolevskyet al. 1994,Shuntov et al, 1995!.Dur- centrations during the summer in the Karagin, ingtheir spawningmigrations, salmon are frequent- Anadyr,and southeasternBeing Searegions Fig- ly foundin stoinachsof P. lrrrgha.At this time P. ures 2 and 3!. /arghrr congregatenear the spawning streams. In fall the majority of P. /argha feed near the Youngspotted seals, which wereborn the previous coa.st,where the important fooiLs,up to 40-50%,are spring,bemn to feedindependently of their moth- smallwalleye pollock, sand lance, capelin, Arctic cod, ers. Their basic foods are small crab and shrimp and various speciesof shrimp and small crab Fig- !Hukhtiyarovct al. 1984!.In additionsome algae ures 2 and 3!, In fall the invertebrate foods are a.bun- was found in seal stomachs. Fish, including sand dant alongthe coast.Generally, food of P. larg/ta in lance,capelin, and somesculpin, comprise only a summer and fall are the same. In winter the amount smallpart of the diet of youngspotted seals. of fish in the diet of P, ktrghtr increases Figures 2 Adult spottedseals in summerconsume mainly and 3!. In someregions walleye pollock, capelin, fish and crab Figures2 and3!. In the Karaginand sandlance, Arctic cod,and shrimp are the prevail- Olyutorsk-Navarinregions small walleye pollock are ing food items. dominantin the diet, and in the Anadyr regionwall- An analysis of annual food consumptionhas eyepollock, sculpin, and shrimp are commonly eat- shownthat the highestlevel of consumptionof fish en. In the northern Bering SeaArctic cod, capelin, and nonfirh food itents occurred in t.he Karagin. Ecologynt the Benng.Sea:A Reviewof RussianLiterature 79 j
Fish tinued to occupy the leading position in the Bering 35 Non-fish foods Sea ecosysteins Shuntov et al. 1993!. lt is known that, due to high abundance, ma- 30 rine inammals play an important rnle in the Bering o 25 Sea ecosysterns Laevastu and Larkins 1981!. The o 20 diet of P, largha in the ocean is rather diverse, with ~~15 pollock, sand lance, capelin, and invertebrates having the dominant position in the diet. Research on o10 inammals and fish Kibal'chich and Dzhamanov 1986, Burkanov et al. 1988, Fadcev 1989, Radchen- I- 1 2 3 4 5 6 7 ko et al. 1990, Sobolevsky et al. 1991, Shuntov et al. 1993! indicates that aggregations of seals are ob- Region served in the most productive regions of the Bering Sea, with large concentrations of fish, small crab, Figure 4. Annual consumption of fish and invertebrate octopus, and shrimp. foods by P, largha by region. See Figure 1 for It is necessary to emphasize that the character definitions of regions 1-7.! of changes, occurring in fish compositions, connect,- ed with the number changes ol' the common fish species,will reflect t.hespecific character of largha feeding and the prevalence of such fish speciesin the stomachsof seals.Adult sealsprey upon the most Olyutorsk-Navarin, and Anadyr regions regions 1, abundant food the most accessible in various sea- 3, and 61, and the lowest level in the northern and sons of the year. Therefore, the seals are the con- central Bering Sea and Commander-Aleutian re- surners of the doininant fish species in pelagic zones gions regions 4, 5, and 7; Figure 4!. The proportion of t.he Bering Sea. of fish in the diet of P. largha is usually higher than that of other items. REFERENCES Ashwell-Erickson, S,, and R. Elsner. 1981. The en- DISCUSSION ergy cost of free existence for Bering Sea harbor An analysis of seasonal changes in feeding demon- and spotted seals,ln: D.W.Iiood and J.A. Colder strates an essential distinction in the food spectruin eds.!, The eastern Bering Sea shelf: Oceanog- in the regions of the Bering Sea Figures 2-4!. A more raphy and resources. Vol. 2. U.S. Dept. Com- diverse array of food items is observed in coastal rnerce, NCAA, Off'ice of Marine Pollution regions along the western and eastern coastsof the Assessment; distributed by IIniv. Washington Bering Sca than in the central part. Press, Seattle, pp. 869-899. Studies of fish of the Bering Sea show fluctua- tioiis in abundance and body mass of important com- Bakkala, R.G., and V.G. Wespestad. 1983. Walleye mercial fishes and invertebrates Kachina 1981, pollock. In: R.G. Bakkala and L. Low eds. !, Con- Fadeev 1986, Bulatov and Sobolevsky 1990, Rad- dition of groundfish resources of the eastern chenko 1994!. In the early 1980sthe food base was Bering Sea and Aleutian Islands region in 1982. sand lance, capelin, Arctic cod,and walleye pollock. U.S. Dept. Commerce, NOAA Tech. Memo. During the last years the important part of the P. NMFS F/NWC 42;1-28. larghtr diet has been small poflock. Probably the fluctuations of food ration are directly coniiect,ed wi h Birma.n, I,B. 1985. Morskoye period zhizni i voprosy the abundance of common commercial fishes. Dur- dinamiki stada tikhookeanskikh lososeye [Ma- ing the 1950s and 1960s herring formed the impor- rine life history and problems of populatio~ dy- tant part of fish composition in the Bering Sea riarnics of the Pacific salmons],Agropromizdat, Wespestadand Barton 1979,Kachina 1981!. In the Moscow,2f!8 pp. In Russian. i 198Gsthe leading position has beenpollock Fadeev 1986, Sobolevskyet al. 1989,Radchenko 1994!, due Braharn, H.W., J.J. Burns, G.A. Fedoseev.and B.D. to successful pollock recruitment at the end of the Krogman. 1984.Habitat partitiomng by ice-as- 1970s Bakkala and Wespestad 1983. Dawson 1989 i. sociated pinnipeds: Distribution and density of During recent years this species,despite an appre- seals and walruses in the Bering Sca, April 1976. ciableedecrease in abundance by 3-4 times!, has con- In: F,H. Fay and G.A. Fedoseev!eds. h Soviet- 794 Oistributionanr! Neasonaj Feeding Hc'hart'or of SpottedSeafs tn the beringSea
American cooperativeresearch on marine mam- I"adeev, N.S. 1989. Spatial and temporal variability rnals. Vol, 1. Pinnipeds. NGAATech. Rep.NMFS of the eastern Bering Sea walleye pollock size 12:25-47. composition in relation to its migrations. In; Proceedingsof the International Symposiurn on Bukhtiyarov, Yu,A, 1986. Present food rations of the Biology and Manageinent of Walleye Pollock. seals in the Okhotsk and Bering seas. In: Tezi- Univ. Alaska Sea Grant Report 89-01, Fair- sy dokladov 1X Vsesoyuznogosoveshchaniya po banks, pp. 497-508, izucheniyu, okhrane i ratsional'nomu ispol'zovaniyu morskikh mlekopitayushchikh Neports Fay, F,H, 1974. The role of ice in the ecology of rna- of the 9th All-Union Conference on Study, Pro- rine mammals of the Bering Sea. In: D.W. Hood tection, and Rational Use of Sea Mammalsl. and E.J. Kelley eds,!, Oceanography of the Arkhangelsk, pp, 67-68. In Russian. ! Bering Seawith einphasis on renewable resources, Inst.. Mar. Sci., Univ. Alaska, Fairbanks, Oc- Bukhtiyarov, Yu.A., K.J, Frost, and L.F. Lowry. 1984, cas. Publ, No. 2:383-399. New information on foods of the spotted seal, Phoca largha, in the Bering Sea in spring. In: Fedoseev,G.A., Ye.V,Razlivalov, and G,G, Bobrova. F.H. Fay and G.A. Fedoseev eds.!, Soviet-Arner- 1988. The distribution and abundance of ice ican cooperative research on marine mammals. seals on ice fields of the Bering Seain April and Vol. 1. Pinnipeds. NOAA Tech. Rep. NMFS May in 1987. !n; Nauchno-issledovatel'skiye 12:55-59. raboty po morskim mlckopitayushchim severnoy chasti Tikhogo okeana i 1986-1987 Scien- Bulatov, O.A., and E,I, Sobolevsky.1990. Distribu- tific research on sea rnamrnals of the northern tion, condition of the stock, and prospect for pol- Pacific Ocean in 1986-1987]. Vses. Nauchno- lock fishing in the open part of t,he Bering Sea, Issled. Inst. Morsk. Rybn. Khoz. Okeanogr, Biol. Morya 5;65-72. In Russian.! VNIRG!, Moscow, pp. 44-70. In Russian.!
Burkanov, V.N., A.R. Seinenov, S.A. Mashagin, and Gol'tsev, V,N, 1969, The food of the largha seal in Ye.V. Kitayev. 1988. Data on abundance of ice the Bering Sea during the spring-summer seals in Karagin Bay, Bering Sea, in 1986-1987. period. In: Tezisy dokladov !V Vsesoyuznogo In: Nauchno-issledovatel'skiye raboty po rnor- soveshchaniya po izucheniyu morskikh mleko- skim rnlekopitayushchirn severnoy chasti pitayushchikh IReports of the 4th All-Union Tikhogo okeana i 1986-1987l Scientific research Conferenceon Study oi' SeaMammals!. Moscow, on sea marnmalr, of t,he northern part of the pp. 129-132. In Russian.! Pacific Ocean in 1986-198'7l. Vses. Nauchno- Issled. Inst. Morsk. Rybn. Khoz. Okeanogr, Gol'tsev, V.N. 1971. Foods of the largha seal. VNIRO!, Moscow, pp. 71-80. In Russian.! Kkologiya 2;62-70. In Russian.!
Chugunkov. D.l., M.V, Dobrynina,and PV. Andriy- Kachina, T.F, 1981.Herring of the wester n Bering enko. 1984, Destruction of salmon by largha Sea; Biology, trade, and rational use. I.egkaya i seals Phoca largha!. In: Morskiye rnlekopitay- pishchevaya prornyshlennost', Moscow, 120 pp, ushchiye Dal'negoVostoka l Seamammals of the In Russian. ! Far East], Izdatel'stvo Tikhookean, Nauchno- Issled. Inst. Rybn. Khoz. Okeanogr. TINRO!, Kibal'chich, A.A., and G,Kh, Dzhamanov. 1986.Data Vladivostok, pp. 31-38. In Russian. i on pinniped biology in t,he northern Bering Sea during the winter period research vessel Za- Dawson,P.K. 1989.Stock identification of Bering Sea kharoeo, 1984l, In: Naukno-issledovatel'skiye walleye pollock. In: Proceedingsof the Interna- raboty po morskim rnlekopitayushchim sever- tional Symposium on Bering SeaFisheries, July noy chasti Tikhogo okeana v 1984-1985 I Scien- 19-21. 1988, Sitka, Alaska. U.S, Dept. Commerce, tific research on sea rnarnrnals of the northern NOAATech. Memo. NMFS F/NWC 163:184-206. Pacific Ocean in 1984-1985]. Vses. Nauchno- lssled, Inst. Morsk. Ryhn. Khoz. Gkeanogr. Fadeev, N.S. 1986. The Bering Sea. In: Biolog- VNIRO1, Moscow, pp. 53-60. In Russian.! icheskiye resursv Tikhogo okeana [Biologica! resources of the Pacific Gceanl. Nauka, Moscow, Kosygin, G M., A.T, Atsepkov, V.M. Kogay,ct al. 1985. pp. 389-405. In Russian. I Nastavleniye dlya zveroboynogopromysla [Man- fr o/og> rrf the Bering Sea:A Aevieivor Russia!rLiterature
ual for animal tradel. Tikhookean. Nauchno- in 1984-1985]. Vses. Nauchno-Issled. Inst. Issled. Inst. Ryhn. Khoz. Okeanogr. TINRO!, Morsk. Rybn. Khoz. Okeanogr. VNIRO!, Mos- Vladivostok, 117 pp. In Russian.! cow, pp. 73-81. In Russian.!
I,aevastu, T., and H.A. Larkins. 1981, Marine fish- Sadovov, VN, 1990. Materials on distribution and eries ecosystem:Its quantitative evaluation and biology of ice-inhabiting seals in the Bering Sea management. Fishing News Books, Farnharn, in 1986-1988. In: Morskiye rnlekopitayushchiye England, 162 pp. Russian translation, 1987, [Marine mammals!. Moscow. pp. 29-48. In Rus- Agropromizdat, Moscow, 164 pp. sian,!
Lowry, L,F,, K.J, Frost, and J.J. Burns. 1986. As- Sadovov. V.N., and A.I. Grachev. 1990. The distri- sessment of marine mammal-fishery interac- bution of ice.-inhabiting seals in the western tions in the western Gulf of Alaska and Bering Bering Sea during exploitation in 1986-1988. Sea: Co~sumption of comrnerically iniportant Tezisy dokladov X Vsesoyuznogosoveshchaniy a fishes by Bering Sea pinnipeds. Final Report to po izucheniy u, okhrane i ratsion al'nornu National Marine Fisheries Service, Contract No, ispol'zovaniyu morskikh rnlekopitayushchikh NA-85-ABH-00029, 26 pp. lReports of the 10th All-Union Conference on Study, Protection, and Rational Use of Sea Mam- Lowry, L.F., K.J. Frost, and T.R. Loughlin. 1988. mals]. Moscow, pp. 266-267. In Russian.! Importance of walleye pollock in t.he diets of marine mammals in the Gulf of Alaska and Shuntov, V.PV.V. Lapko, A.A. Valanov, and A.V, Bering Sea, and implications for fishery man- Startsev. 1995. I nt,erannual changes in anadro- agernent. In: Proceedings of the International mous migration of salmon in the western Bering Symposium on the Biology and Management of Sea and adjacent waters of the Pacific Ocean, Walleye Pollock. Univ. Alaska SeaGrant Report Biol. Morya 21!:37-44. ! In Russian.! 89-01, Fairbanks, pp, 701-726. Shuntov, VP., A.F. Vo]kov, and A.Ya. Efirnkin. 1988. Perez, M.A., and W.B, McAlister. 1993. Estimates The state and modern condition of fish comrnu- of food consumption by marine rnarnmals in the nities in the epipelagic zone of the western eastern Bering Sea. U.S, Dept, Commerce, Bering Sea, Biol. Morya !:56-65. In Russia~. ! NOAA Tech. Memo, NMFSAFSC 14, 36 pp. Shuntov, VP., A.F. Volkov, O.S. Temnykh, and Ye.P. Radchenko, V.I. 1994, Sostav, struktura i dinamika Dulepova. 1993. Mintay v ekosistemakh nektonnykh soobshchestv epipelagiali Beringo- dal'nevostochnykh morey I Pollock in the ecosys- va morya [Content, structure, and dynamics of terns of the far-eastern seasj. Vladivostok, nektonic communities in the epipelagic zone of 426 pp. In Russian.! the Bering Sea]. Avtoref. kand, diss. [Candidate thesisl, Vladivostok, 24 pp, In Russian.! Sobolevsky,Ye.I. 1983.The importance of sea mammals in trophical bonds of the Bering Sea. Izv. Radchenko, V.I., and Ye.l. Sobolevsky. 1992. Season- Tikhookean. Nauchno-lssled. Inst. Rybn. Khoz. al dynamics of spatial distribution of' pollock Okcanogr, ! TINRO! 107:120-! 32. <'In Russian. ~ Theragra chalcograrnrnoi in the Bering Sea Vopr. Ikhtiol. 32!;84-95. In Russian.! Sobolevsky, Ye.I. 1988. Populyatsionnava mor- fologiya lastoriogikh l Populatiori morphology of Radchenko, V, I., Ye.I. Soholcvsky, and L.V. Chcbluk- pi nnipeds], Nau ka, Moscow, 216 pp. ova. 1990. Size-space structure of pollock in t,he western Bering Sea, Depon. VNIER. 27/07l90, Sobolevsky.Ye.l. 1990.Sea mammals and their role N 1125, In Russian.! in ecosysterns of the far-eastern seas. In: Tezisy dokladov X Vsesoyuznogo soveshc..hariiyapo Sadovov, V.N, 1986, Data on pinniped biology in the morskirn rnlekopitayushchim l Reports of the Bering Sea research vessel Zokharouo, 1984!. 10th All-Union Conference on Sea Mammalsl. In: Naukno-issledovatel'skiye raboty po mor- Mo. cow, pp. 280-281. ! In Russian.! s ki m inlekopitayushchi m s eve rnoy eh asti Tikhogo okeana v 1984-1985I Scientific research Sobolevsky,Yc.I., L.V. Cheblukova,and VI. Radchen- on sea rnarnmals of the northern Pacific Ocean ko. 1991. Spatial distribution of pollock, Thern- Distributionand Seasonal Fecdi tig behavior otSpotted Se,ils ui theHeritig Sea
grachalcogramma, in the western Bering Sea. Trukhin,A.M. 1988. Data on biology of larghaseals Vopr.Ikhtiol. 31!;776-775. In Russian,! in the Bering Sea, In: Nauchno-issledo- vateVskiyerahoty po morskiminlekopitayush- Sobolevsky,Ye,I., V.I.Radchenko, and A.V, Startzev, chim severnoy chasti Tikhogo okeana i 1994. Distribution and feeding of keta, Onco- 1986-1987[Scientific research on seamammals rhyrichusketa, during the autumn-winter peri- of the northernpart of the PacificOcean in 1986- od in the westernBering Seaand Pacificwaters 19871,Vses. Nauchno-Issled. Inst. Marek. Rybn. of Kamchatka,Vopr. Ikhtiol. 34!:35-40. In Khoz. Okeanogr. VNIRO!, Moscow,pp, 38-44, In Russian.! Russian. ! Sobolevsky,Ye.I., V.P, Shuntov, and A,F. Vol kov, 1989. Trukhin,A,M., A.I. Makhnyr',and V.A.Pavlyuch- Thecomposition and the presentstate of pelag- kov.1991. Prese~t food of sealsin the BeringSea ic fish coinmunitiesin the westernBering Sea. duringthe spring-summerperiod. In: Biologiya In: Proceedingsofthe InternationalSymposium rybi bespozvonochnykhsevernoy chasti Tikhogo onthe Biology and Management ofWalleye Pol- okeana[Bio!ogy of fishesand invertebratesof lock. Univ. Alaska Sea Grant Report 89-01, the northernPacific Ocean]. Izdatel'tsvo DVGU, Vladivostok,pp. 128-142. In Russian,! Fairbanks, pp. 523-536. Tikhomirov,E.A. 1964. On thedistribution and bi- Wespestad,V.Gand L.H. Barton.1979. Distribu- ology of pinnipeds of t,he Bering Sea,Izv. tionsand migrationsand stat,usof Pacificher- Tikhookean.Nauchno-Issled. Inst. Rybn.Khoz. rin,g.In: Fisheriesoceanography of the eastern Okeanogr. TINRO! 52:277-285, In Russian.! BeringSea shelf. Seattle, pp, 166-212. Lcologvof the BeringSea: A Reviewot RussianLiterature 297
Historical Trends in Abundance of Steller SeaLions Eumetopiasj ubatus! in the Northwest Pacific Ocean
A.l. Boltnev Kamchatka ResearchInsti tute of Fisheries and Oceanography KamchatXIRO! Pet rap a r-'lotisk-Karnchatski, Rue si a
O.A. Mathisen Juneau Center,School of Fisheries and OceanSciences, Uniuersity of Alaska Fairbanks Juneau, Alaska
ABSTRACT the Commander Islands, Kamchatka, Sakhal in and Some historical trends in the abundance of Steller the Kuril Islands, and the Sea of Okhotsk. sea lions Fumrtopias jubatus! in the western re- In waters of the Russian Far East, Steller sea gion of t.he North Pacific Ocean are analyzed here. lions occur practically everywhere from Vladivostok Long-term study by biologists from KamchatNIRO to Chukotka, There are five major reproductive rook- and Kamchatrybvod revealed that sea lions moved eries, all located on the Kuril Islands: Lovushki, to the Commander Islands in the first, half of the Srednego,Brat Chirpoev, Raykoke. and Antsiferovo 1960s and created a stable reproductive rookery on Figure 1!. Births at those five rookeries accounted Medniy Island. for about 98% of the pups born in the Far East in the early 1980s Perlov 1982!!.Some small reproduc- INTRODUCTION tive rookeries are on Iony Island St. Jona Island i and the Iamskiy Islands in the Sea of Okhotsk Fig- The Steller sea lion is endemic to the North Pacific, u.re 1!; Cape Kozlova. on the Kronotskiy Peninsula Their rookeries are.spread north for great distances of Kamchatka, and the Commander Islands at. along the American and Asian coasts from Califor- Southeastern Cape, Medniy Island Figure 2!. nia to Japan. In the last few years, studies of Stell- er sea lion biology have attracted careful attention by many world scientists because of' a disastrous KURIL ISLANDSAREA decreasein the number of sea lions. Currently, most The Kuril Islands have extremely complex and unof the data we have are related to Steller sea lions stable weather. In summer few days are without fog, in the eastern Pacific, The amount of available data gale force wind, or strong surf. Frequently the from the western part of the inhabited area is not weather prevents scientific work. sufficient to answer some essential questions. AVhat According to Captain Snow 902!, an enthusi- were the trends in abundance in the western region astic researcher of the Kuril Islands, up to 100.000 during the period when a significant decrease in the sea lions used to haul out on 18 Kuril rookeries. He American population of Steller sea lions was ob- was the first to record the locations of the Steller served, and what are they now? Is it possible that sea lion rookeries on the Kuril Islands. However, part of the Steller sea lion population migrated west hir estiinate of the number of sea lions is cornpara- from the eastern Pacific Braham et al. 1980, Mer- ble to the expression"a lot." becausehe did not.ac- rick et al. 1987!? To answer these and other ques- tually count them, tions, we analyzed the available information on The first attempt to count sea lions at. the Kuril Steller sea lions from the Russian part of the area rookeries was undertaken by Klurnov ~ 1957t In two 298HistoricalTrrnds in Abundance of Stellar Sea Lions in theNorthwest Vacit'ic 55'h! Ocean
50'
45
140-E 145' 150' 155" 160 FigureL LocationsofSteller sea lion rookeries and hauloutsin the Sea of Okhotsk and Kuril 1slands,Russia. tAdapted from Laughlinet a!. 1992./ E<.ologyottheBeringSea:8Revir.~ ofRussian Literalurt. 60'N
55"
50
150'E 155' 160 1 65' 170'
I'rgure 2. Locat tons of Stetler sea Lionrookertes and houlotrts on the CoznrnanderIslands and Kamchatka Panrnsotn, Russra. Adapted from l.ooghtin et oL 7992.! HistnriCS!Trends in AbundanCeOf Stefier Sea i iOnSin the,'siOrthweatPaCifrC Ocean trips aboardthe vesselKrylatka in 1955and 1956, Table 1. Number of Steller sea lions on the Kuril he described23 rookeries with a total of 15,000- Islands, 17,000sea lions Table 1!.He did not go ashore,but examined thc rookeries through binoculars from Adults Pupa and pupa only Source aboard the vessel. From long-term regular observa- Year tions,Voronov 974! estimatedthe number of &tell- 1956 15,000- ? Klumov 1957 er sea lions on the Kuril Islands in 1959-1962 as 17,000 10,989individuals, The most completecount was 7 Voronov 1974 carriedout by Belkin 966!, who led threelarge 1959-1962 10,989 expeditionsin 1962-1964.The most extensive one 1963 18,429 3,687 Belkin 1966 occurred during 19 May-20 August 1963,About 11,027 1,940 Perlov 1970 1,500miles of the coastwere explored,the topogra- 1967 phyof all theKuril rookeries was observed, and the 13,347 1,976 Perlov 1970 total number of sea lions was determined.Overall, 1969 11,080 3,232 Maminov et al. 1991 Belkincounted 3,687 pupa and 15,905 adults, A com- p]etecount of Steller sea lions on the Kuril Islands 1975 6,082 1,976 Kuzin et al. 1984 was alsoundertaken in 1968by Perlov970!, who 1981 5,550 1,672 Kuzin et al. 1984' counted 13,347adults and pupa,and in 1983by 3,120 904 Kuzin et al, 1984' Maminov Kuzin et al. 19841,who reported6,073 1982 adultsand pups. In the yearsbetween those stud- 1983 6,073 2,001 Maminov et al. 1991 iesit v as only possibleto do partial countsof the 1984 3,865 670 TINRO archives' sealions, but from that informationit couldbe seen that the Kuril population of Steller sea lions de- 1986 4,297 1,359 TINRO archives creased in numbers. ].989 3,615 1,445 Loughlin et al, 1992' In the mid-1970s Perlov 975! optimistically 1994 394 574 KamchatN IRO estimated,mainly from data of the 1950sand early archives 1960s,the total numberof sealions in the Russian portionof the northwestPacific as 27,000. includ- '>ueompletesurvey. ing 20,000in the Kuril Islands,2,000 in theSea of 'PlusS4 dead. Okhotskon Iony Islandand the IamskiyIslands, 1,100on the Kamchatkacoast, 3,500 on theCorn- manderIslands, and 700on Tyuleniy Robben! and walked around the rookery. Overall, 1,510pups were Sakhalin islands. However, his estimates seem un- counted, Rasaet al. 9551 reported that in 1932aII realistically high. 00%! of the pupswere killed; in 1933,53ok were In 1989,656 males, 2,959 females and bachelor killed; and in 1942-43,again 100%.After that the bulls,1,445 live pups, and 34 dead pupa were count- rookeriesprobably never really recovered. Accord- ed on the Kuril Islands Loughiin et al. 1992!. In ingto Perlov977!, in the mid-1970sthere were 1994, E.N. Kalinichenko, an employeeof Kamchat- four rookerieson Iony Island, with 72 males,459 NIRO, countedsea lions on the Kuril Islandsfrom females,341 bachelorbulls, and 337 pupa, andon a boat,The preliminarydata, with a countof 3,794 Matykil Island IarnskiyIslands! t,here were 66 sea lions including 574 pups, indicate a continuing males,400 females,:30 bachelor bulls, and 270pupa. decrease in abundance Table 1!. Accordingto Voronov9741, only 750to 1,050Stell- er sea lions hauled out at the small bachelor rook- SEA OF OKHOTSK eries on the Sakhalin coast Shmidt Peninsula, TyuleniyIsland, and Opasnosti Rock!. In 1989,1,500 In the 1930s the Sea of Okhotsk population appar- sea lions were counted on Iony Island, 900 on thc ent]y was in better conditionthan today Table21. Iamskiy Islands, 200 on Tyuleniy Isla.nd,and 300 Accordingto Freiman 936!, there weretwo rook- on OpasnostiRock Loughlin et al, 1992!. erieson Bol'shoyTalok Island, I amskiyIslands, wdth about 2,000 Steller sea lions.Nikulin 937! reported that about 7,000 sea lions inhabited the Sea of EASTCOAST OF KAMCHATKA Okhotsk, However, in 1933 all the pups at one of PENINSULA the rookeries on Iony Island were killed: that way "complete. counting was accomplished.At other The nutnber of Steller sea lions on the east coastof rookeries.the pupswere countedby a scientistwho Kamchatkaduring 1982-1984in summerwas esti- Fcofog>of the'Bering Sea; A Reviewof Russianliterdture
Table2. Estimatednumbers of SteUersea lions iu the RussianFar East,
lony I. 8c Robben Commander Source Year l urnsk iy Is, Island Kamchatka Islands Nrkulin 1937 1933 4,500 Barabash-Nikiforov 1936 1935 1.000 Nesrerov 1964 1957-1962 4,000 Khromovskikh 1966 1964 4,000 Khr omovskikh 1966 1'965 10,000 Vlymrin and Fomin 1978 1968 10,850 Mymrin et al. 1979 1970-1975 10.000-15,000 Perlov 1975 19?5 2,000 700 1,100 3,500 Mvmrin et al 1979 1977 4,578 Burkanov 1986 1982-1984 6,357-8,260 Burkanov 1988 1982-1984 10,000- 14,000 Vcrtvankin and Nikulin 1988 1987 2,415 Loughlin et al. 1982 92989 2,913 200 3,082 890
matedat 6,357-8,260by Burkanov986l, Laterhe increase in abundance,according to S.V,Marakova, described 27 sea lion rookeries, 20 of which were in was observedin the war years 941-1945!, and in regularuse. He estimated the total number of Stellar the 1950s the number of Steller sea lions stayed at sea lions on Kamchatka in the 1980s at 10,000- about 4,000 in winter Nesterov 1964!. Khro- 14,000 Burkanov 1988!.There is onereproductive movskikh < 1966I countedabout, 10,000sea lions on rookeryon CapeKozlova Kronotskiy Peninsula!, Commander rookeries in the spring of 1965. whereabout 100pupa were born in 1994 according During the 1940sand 1950sSteller sea lions to E.N. Kalinichenkok In the late 1980s the nurn- visited the islandsregularly in the summer,as v ell ber of sealions on the Kamchatkacoast decreased as the winter, and femaleswere seenmore often. A Table2>, and in 1989only 2,600-2,800sealions were newbornpup wasfound for the first time on the counted Loughlin et al. 1992!. SoutheasternCape rookery of Medniy Island in 1962,and newbornsea lions were seenthere regularly starting in 1969i Figure3 i.In the sameyears, CoMMANDER IsLANDs reproductionwas noted on Ariy KamenIsland new- Grebnitskiy 902i wrote that Steller sea lions bornpups and pregnant females i Chugunkov1968. ceasedtheir permanenthabitation of the Comrnand- 1971!. Steller sea lions have ber.n noticed regularly er Islandsin approximatelythe 1830s,even though onCape Monati, Bering Island, since 1983, and in previouslythey reproduced there. He believed they 1986Chugunkov discovered a sealion pup on t.he arrivedperiodically from fall to springand only in BeringIsland northwesternrookery Vertyarrkin small groups. and Nikulin 1988!. According to Chelnokov 978, Beginningin the 1930s,the numberof Steller 1983!, the increase in. numbers at the Southeastern sealions on the CommanderIslands increased rap- Caperookery on MedniyIsland stopped after 1968 idly, Accordingto Barabash-Nikiforov936!, sea Figure3, Table3b but it wasnot a resultof hunt- lion rookeriesformed in winter on Ariy KarnenIs- ing or redistribution over thc other rookeries. landand CapeMonati on BeringIsland, and on the Accordingto Myrnrin and Fomin 978 i, in the northwestand southwestextrermties of MedniyIs- winter of 1968 the number of sea lions on the Com- land Table2!. The numberof animals varied from niander Islands totaled 10.860 individuals Table 2 1 50 to 1,000and more.He alsoreported that harem In the early 1970siMyrnrin et al. 1979!there w'ere rookeries did not appear,even though in 1932a preg- three rookeries on Medniy Island and five on Bering nant. female was killed, and that the nat,ives cap- Island. with a to1.alof 3,000-5,000 to 10,000-15,000 tured up to 100-150sea lions yearly for their meat sealions depending on the season.The nati ves killed and fur. In the following yearshunting was proba- 50-60to 200-300yearly. Then the numberof seali- bly reducedto 10-20sea lions II'iira 19501A new ons on the Commander Islands started decreasing >listorica/ Trend» iii 4l>undarrce of Stol!or Sc;1I.ieriis in th» Xortlriveot P icific Ocean
Table 3. Number of Steller sea lions on Southeast- ern Cape rookery, Medniy Island, Com- 40 rnander Islands. 3.5 Ferns!es and Adult males Q sc 30 Year young males l bulls! Pups 200 2.5 1953 330 117 E 1954 910 122 2.0 150 s E 1955 1,010 HO so 1959 700 g 15 1oo < 1960 1,000 77 10 1962 2,300 87 E 1965 2,341 117 0.5 1966 1,804 79 2,H76 86 0 0 1967 1950 1960 1970 1980 1990 2000 1968 2,898 66 Year 1969 2,496 79 1970 894 Figure 3. %umber of Steller sea lions on Southeastern 1971 1,310 Caperookery, 1!fedniy I~land, Commander Is- 1972 3,475 laiids t Vertyanki n and K ku ti n 1988; 1973 2,903 26 KumchatVIRO archives; Z. Mamaeo, pers. commun.!. 1974 2,976 1975 1,786 15 1976 1,942 31 1977 1,917 19 and by 1977 totaled 4,578 individuals. In the fol- 1978 1,283 lowing years the decline continued and, according 1979 600 to Vertyankin and Nikulin 988!, the number 1980 1,165 reached 2,415 individuals in 1987, A larger number 1981 1,200 of sealions appeared at the rookeries in spring and 1982 950 summer than in winter. In 1989, 890 sea lions were 1983 720 counted on the Cornrnander rookeries, including 185 1984 HOO pupa Loughlin et al. 1992!, 1985 800 140 1986 890 CONCLUSIONS 1987 1,200 The decline in the abundance of Steller sea bona in 1989 426 the northwest Pacific and Sea of Okhotsk is obvious 1991 299 75 222 and has beenwell documented Loughlin et al. 1992!. 1992 290 86 219 However. we would like to look closely at some of 1995 326 66 248 the details of the process.Thus, in the rnid-1960sa Sources'KarochatHIRO, archrsal data', Cheluokov i97S; Vertvuarclo rapid increase, more than 300'7r,in the number of and Vikolinisaa i datafor 1978-l987!;E. Maroaavpere comraunifnr !99n sea lions on the Commander Islands was recorded Nesterov 1964, Khromovskikh 1966!. One must acknov,ledge immigration of someanimals from the eastern Pacific, to at least the Commander Islands. It is difficult to explain the changing abundance i Figure 3, Tables 2 and 3! any other way. The mi- Ecololl>of tbi l3er!'r!gSea: A Reviewot RussianLitera rrre 303
Vl 10 somedomesticated sea lions feeding next to the fish- 0 ing boats.She and the fishermenfed the sea lions OR during fish processing.Well-fed sea lions refused O pollock,but neverrefused herring, Alverson992! E concluded from available sources that the main item O.6 in the Steller sea lion diet is f'at fish. In the 1970s c 9 and 19SGssea lions had to switch to pollock because 0.4 E of a shift in the North Pacific ecosystem Naumen- cO ko et al, 1990!, According to fishing statistics from E Oe the North Pacific and Bering Sea Figure 4!, in the C CD early 1960sthe wes .emregions had more herring O.o reserves than the eastern regions, and every year 1955 1960 1965 1970 1975 195 ! this difTerence increased until the late 1970s, when Year commercial herring fishing stopped for lack of fish Alverson 1992!. It is possible that Steller sea lions Figure4. Commercialherring landingsfrom the north. kept movingtoward the westernareas of the ocean eaat Ond northicest Po in- closely connected with the migration of fur seals formation before the early 1980s Burkanov 1986!. from the Pribilof population,which was declining Onecan only supposethat the abundanceof Steller during that period Briggs and Fowler 1984!. sea lions on the Commander Islands reflects their Although the major decreasein the number of abundance all over Kamchatka, and that the nurn- marine marnrnals occurred in thc 1970s Casteifini ber of them was high in the early 19809 partly for 1991!, rnigr.ation of fur seals and Steller sea lions to the samereason: migration from the eastern Pacific. the Commander Islands in the 1960s indicates that Similar migrations of marine mammals proba- even then factors unfavorable to marine marnrnal bly took place in the past, in response to eve!ical populationsexisted, causing them to leaveareas of changes in the ocean ecosystem. This is supported traditional occupation. by Grebnitskiy'si 1902!report that in the middle of' One might surmise that la.ck of food was one the nineteenth century Steller sea lions reproduced factor, especially during the reproductive period. on the Cornrnander Islands, hut later practically Judging by the number of bachelorrookeries Lough- disappeared and only appeared individually. We hn et al. 1992!, Steller sea lions, unlike seals, haul couldprobably agree with Alverson ,1992!that the out on ]and islands, rocks, capes! close to feeding intensive developmentof fishing in the North Pa- areas during their foraging migrations, cific in the past three or four decadesis one of the KamchatNIRO biologist L, Sharaphetdinova, import.ant f'actors determining the conternporarv who worked in the 196Gs in the western Bering Sea, abundance of Steller sea lions and other marine told one of us about an unplanned "experiment."with mammals, 304 H stodcal Irendr in Abundance of Steller Sea Liuris in tbe Nor h inst Pacif'i c Ocean
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