779
NOAA Technical Report NM FS SSRF-779 Opportunistic Feeding of the Northern Fur Seal, Ca//orhinus ursin us , in the Eastern North Pacific Ocean and Eastern Seri ng Sea
Hiroshi Kajimura
February 1984
u.s. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service NOAA TECHNICAL REPORTS -
National Marine Fisheries Service, Special Scientific Report-Fisheries
The major responsibililles of the National Marine Fisheries Service (NMFS) are to monitor and assess the abundance and geographic distribution of fishery resources. to understand and predict fluctuations in the quantity and distribution of these resources, and to establish levels for optimum use of the resources. NMFS is also charged with the development and implementation of policies for managing national fishing grounds, development and enforcement of domestic fisheries regulations. surveillance of foreign fishing off United States coastal waters, and the development and enforcement of international fishery agreements and policies. NMFS also assists the fishing industry through marketing service and economic analysis programs, and mortgage insurance and vessel construction subsidies. It collects. analyzes. and publishes statistics on various phases of the industry. The Special Scientific Report-Fisheries series was estahlished in 1949. The series carries reports on scientific investigations that document long-term cclntinuing programs of NMFS. or intensive scientific reports on studies of restricted scope. The reports may deal with applied fishery problems. The series is also used as a medium for the publication of bibliographies of a specialized scientific nature. NOAA Technical Reports NMFS SSRF are available free in limited numbers to governmental agencies, both Federal and State. They are also available in ,,,change for other "ientific and technical publications in the marine sciences. Individual copies may be obtained from D822, User Services Branch, Environ mental SCience Information Center, NOAA, Rockville, MD 20852. Recent SSRF's are:
.,ulf menhaden. BrnOOrlia palronus, purse seine fishery: Catch, !Ishing 733. Possible management procedures for increasing production of sockeye ],'IIV!lV .mJ age and size compos!lion. 1964-73. By William R. Nicholson. salmon smolts in the Naknek River system. Bristol Bay, Alaska, By Robert J. \larc], 1'1',. lilT 8 p .. I fig .. 12 [abies. Ellis and William J. McNeiL April 1979, iii + 9 p .• 4 figs., 11 tables,
'23 khthv'oplankton compOS!llon and plankton volumes from inland coastal 734. Escape of king crab, Paralilhodes camlschalica. from derelict pots. By "Ia[er, c)f 'clutheastern Alaska. April-November 1972. By Chester R. Mattson William L. High and Donald D. Worlund. May [979. iii + 11 p .• 5 figs .• 6 and Brllce l Win;!. April 1978. iii + II p .. I fig .. 4 tables. tables.
~~·1 t "lima! l:ll ;1\ er3g.e daily instantaneous numbers ('If recreational and COffi 735. History of the fishery and summary statistics of the sockeye salmon, On n'CiClal ii'hc'rmen and boaters In the SL Andrew Bay system. Florida. and adja corhynchus nerka, runs to the Chignik Lakes. Alaska. 1888-1956. By Michael c."" ,."bla! \\a[:". 19"3. Bv Doyl<' F. Sutherland. May 1978. iv + 23 p .. 31 L. Dahlberg. August 1979. iv + 16 p .• 15 figs., II tables. ;~', lahk·.., 736. A historical and descriptive account of Pacific coast anadromous salmonid ~ca" 'lui h1lwm-\\ ater temperature trends in the Gulf of Maine and on rearing facilities and a summary of their releases by region. 1960-76. By Roy (ic,', "." 'linl.. 1963·"5. Bv Clarence W. Davis. May 1978. i, + 17 p., 22 figs .. J. Wahle and Robert Z. Smith. September 1979. iv + 40 p., 15 figs., 25 tables. ~ "lr,lL'" 737. Movements of pelagic dolphins (Slenelia spp.) in the eastern tropical Pa ..... 2(1. rill' liui: L1f i\laine temperature structure between Bar Harbor, Maine, and cific as indicated by results of tagging. with summary of tagging operations • Y.lIIll,·utl·, ·',·'.a Sco[la. June 1975-No,ember 1976. By Robert J. Pawlowski. 1969-76. By W. F. Perrin, W. E. Evans. and D. B. Holts. September 1979, iii 1',',c·n.I'", I ~-~. iii + 10 p .. 14 figs .. I table. + 14 p .• 9 figs .. 8 tables.
f 'pl'IlJabk bathythermograph observations from the NMFS/MARAD 738. Environmental baselines in Long Island Sound. 1972-73. By R. N. Reid. "'II:.;t r ),'P,)rtUl1\tv Program for 1975. By Steven K. Cook, Barclay P. Collins, A. B. Frame. and A. F. Draxler. December 1979. iv + 31 p .• 40 figs .• 6 tables. ,,.1l1 Ch"'[lne S. Cart,. January 1979. i, + 93 p., 2 figs .. 13 tables. 54 app. figs. 739. Bottom-water temperature trends in the Middle Atlantic Bight during spring :~~. \',-'nIL'ai sectIons of semimonthly mean temperature on the San Francisco and autumn. 1964-76. By Clarence W. Davis .. December 1972. iii + 13 p., 10 HC"h'llllu ,c)u[e: Frum expendable bathY1hermograph observations. June 1966- figs., 9 tables. Ileccmbet IY'C,. B, J. F. T. Sauro L. E. Eber, D. R. McLain, and C. E. Dorman. lanu:m 19'9. III + ,5 p .. 4 figs .. I table. 740. Food of fifteen northwest Atlantic gadiforrn fishes. By Richard W. "29 Rderence, for the llldentification of marine invertebrates on the southern Langton and Ray E. Bowman. February 1980. iv + 23 p .. 3 figs .• II tables. ,\[LlJlIl( ,'c)ast ,;f the LTlIted States. By Richard E. Dowds. April 1979. iv + 37 p. 741. Distribution of gammaridean Amphipoda (Crustacea) in the Middle At '30. Surface Circulation in the northwest Gulf of Mexico as deduced from lantic Bight region. By John J. Dickinson, Roland L Wigley. Richard D. Bro Jfli' honks Bv R"hcrt F. Temple and John A. Martin. May 1979. iii + 13 p., deur, and Susan Brown-Leger. October 1980. iv + 46 p .• 26 figs .• 52 tables. y ri~ ... 4 tables. 742. Water structure at Ocean Weather Station V, northwestern Pacific Ocean. -11 \nnc)latcJ blhl,ugraphy and subject index on the short nose sturgeon. Aci- 1966-71. By D. M. Husby and G. R. Seckel. October 1980, 18 figs., 4 tables. (l{'I/\('r hrt>\'/ru\-rrulll By James G. Hoff. April 1979, iii + 16 p. 743. Average density index for walleye pollock. Theragra cha/cogamma. in the ~"' ·\'\I.;>-\/llt,'llll)/ the :"\lHthwes{ Atlantic mackerel, Scomberscombrus, stock. Bering Sea. By Loh-Lee Low and Ikuo Ikeda. November 1980. iii + 11 p., Ilv Im,;1\ f) .\llc!c"c)J). \prtl 1979. iv + 13 p., 9 figs .. 15 tables. 3 figs., 9 tables. NOAA Technical Report NMFS SSRF-779
Opportunistic Feeding of the Northern Fur Seal, Cal/orhinus ursin us , in the Eastern North Pacific Ocean and Eastern Bering Sea
Hiroshi Kajimura
February 1984
U.S. DEPARTMENT OF COMMERCE Malcolm Baldrige, Secretary National Oceanic and Atmospheric Administration John V. Byrne, Administrator National Marine Fisheries Service William G. Gordon, Assistant Administrator for Fisheries The National Marine Fisheries Service (NMFS) does not approve, rec ommend or endorse any proprietary product or proprietary material mentioned in this publication. No reference shall be made to NMFS, or to this publication furnished by NMFS, in any advertising or sales pro motion which would indicate or imply that NMFS approvell, recommends or endorses any proprietary product or proprietary material mentioned herein, or which has as its purpose an intent to cause directly or indirectly the advertised product to be used or purchased because of this NMFS publication. CONTENTS
Introduction ...... : ...... 1 Background ...... 1 Present treaty ...... 1 General distribution at sea ...... 2 4 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : D~~~:~~~~~:~r~ ' 4 Laboratory procedure...... 4 Fur seal feeding at sea ...... 4 Fishery resources significant to fur seals ...... 6 California ...... : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 10 Bering Sea ...... 11 Oregon ...... 11 Washington ...... 12 British Columbia ...... 12 Gulf of Alaska ...... : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 12 Western Alaska ...... , ...... 13 Principal forage species of fur seals ...... 13 California ...... : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 13 Northern anchovy ...... 15 Pacific whiting ...... : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 16 Market squid ...... 16 Pacific saury ...... 18 Rockfishes 18 Jack macke~e'I ' : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 19 Sablefish ...... 20 Oceanic squid ...... 20 Bering Sea ...... 20 Walleye pollock ...... 22 Capelin ...... 23 Atka macketel ...... 25 Oceanic squids ...... 26 Pacific herring ...... 27 Deepsea smelts ...... 29 Pacific sand lance ...... 29 Greenland turbot ...... 30 Discussion and summary ...... 31 Acknowledgments ...... 32 Literature cited ...... 33 Appendix figures 1-13 ...... 36-48 Appendix table 1 ...... 49
Figures
1. The general ocean distribution and breeding islands of the northern fur seal ...... 2 2. Fur seal sightings in the North Pacific Ocean by Japan, Canada, and the United States, 1955-79 ...... 3 3. General trends in the percentage of stomachs containing food in relation to time of collection ...... 5 4. Locations off California where northern fur seals were collected, 1958-66 ...... 6 5. Locations in the eastern Bering Sea where northern fur seals were collected, 1958-74 ...... 6 6. The seven collection areas of northern fur seals, 1958-74 ...... 7 7. Principal forage species of northern fur seals off California, 1958-66 ...... 9 8. Principal forage species of northern fur seals in the eastern Bering Sea, 1958-74 ...... 9 9. Principal forage species of northern fur seals off Washington, 1958-74...... 9 10. Principal forage species of northern fur seals off British Columbia, 1958-72 ...... 10 11. Principal forage species of northern fur seals in the Gulf of Alaska, 1958-68 ...... 10 12. Principal forage species of northern fur seals in western Alaska, 1958-74 ...... 10 13. Basic pattern for CalCOFI stations in survey areas off California and Baja California...... 14 14. Commercial landings of forage species significant to northern fur seals off California...... 14 15. Food web involving commercially important and abundant fish, birds, mammals, and squid ...... 15 16. Locations off California where northern fur seals were collected whose stomachs contained northern anchovy, 1958-66 ...... 15
iii 17 . The distribution of anchovy subpopulations and total spawning biomass ...... ~ ...... 16 18. Locations off California where northern fur seals were collected whose stomachs contained Pacific whiting, 1958-66 ...... 16 19 . Seasonal depth distribution of Pacific whiting ...... 17 20 . Locations off California where northern fur seals were collected whose stomachs contained market squid, 1958-66 . . . 17 21. Locations off California where northern fur seals were collected whose stomachs contained Pacific saury, 1958-66 . . . 18 22 . Eastern Pacific stock of Pacific saury ...... 18 23 . Locations off California where northern fur seals were collected whose stomachs contained jack mackerel, 1958-66 . . 19 24. Distribution of the jack mackerel resource ...... 19 25. Bathymetric distribution of sable fish ...... 20 26. Locations off California where northern fur seals were collected whose stomachs contained Onychoteuthis sp., 1958-66 ...... , ...... 20 27. Stations successfully trawled during the 1975 eastern Bering Sea baseline survey...... 21 28 . Locations where northern fur seals were collected whose stomachs contained walleye pollock, 1958-74 ...... 22 29 . Apparent density of walleye pollock in various regions in the eastern Bering Sea and the Gulf of Alaska ...... 24 30. Locations where northern fur seals were collected whose stomachs contained capelin, 1958-74...... 24 31. Locations where northern fur seals were collected whose stomachs contained Atka mackerel, 1958-74 ...... 25 32 . Locations where northern fur seals were collected whose stomachs contained Gonatus sp., 1958-74 ...... 26 33 . Locations where northern fur seals were collected whose stomachs contained Berryteuthis magister, 1958-74 ...... 26 34. Locations where northern fur seals were collected whose stomachs contained Gonatopsis borealis, 1958-74...... 27 35 . Distribution of squids and fi sh in the stomachs of sperm whales from the Bering Sea and the Gulf of Alaska, 1960 and 1963 ...... 28 36. Locations where northern fur seals were collected whose stomachs contained Pacific herring, 1958-74 ...... 29 37 . Locations where northern fur seals were collected whose stomachs contained deepsea smelt, 1958-74 ...... 29 38. Locations where northern fur seals were collected whose stomachs contained Pacific sand lance, 1958-74 ...... 30
Tables
I. Fis hes eaten by fur seals in the eastern North Pacific Ocean and eastern Bering Sea, 1958-74, by area ...... 7 2. Squids eaten by fur seals in the eastern North Pacific Ocean and Bering Sea, 1958-74, by area...... 8 3. Principal forage species utilized by fur seals in the eastern North Pacific Ocean and the eastern Bering Sea, 1958-74, by area ...... 9 4. Food of fur seals off California ...... 11 5. Food of fur seals off Oregon ...... 11 6. Food of fur seals off Washington ...... 12 7. Food of fur seals off British Columbia ...... 12 8. Food of fur seals in the Gulf of Alaska ...... , ...... 13 9. Food 0; fur seals in western Alaska ...... 13 10. Food of fur seals in the eastern Bering Sea...... 21 II . Summ ary of estimates of absolute population size for eastern Bering Sea walleye pollock ...... 23 12. Summary of annual catch of walleye pollock from the eastern Bering Sea by trawl fisheries, 1964 to 1979 ...... 23
iv Opportunistic Feeding of the Northern Fur Seal, Callorhinus ursinus, in the Eastern North Pacific Ocean and Eastern Bering Sea
HIROSHI KAJIMURA'
ABSTRACT
Tbe PribUof Island population of nortbern fur seals, CalloThinus uTsinus, feeds on a variety of prey throughout its subarctic range from California to tbe Beriug Sea. A total of 53 species of fisb and 10 species of squid has been Identified from tbe stomacbs of fur seals taken during 1958-74. Some fur seal prey species are commercially fIShed "bUe otbers are uot of commercial importance but are important forage food for many otber predators including otber mariue mammals, seabirds, and flSbes. Tbe season and location are important considerations. as are the migratory cbaracteristics of forage species, wben studying tbe diet of fur seals in tbe eastern Pacific. Evidence sug· gests tbat fur seals are opportunistic feeders preying on tbe most available species throughout their range.
INTRODUCTION States. Japan, Russia, and Great Britain (for Canada) formed the Convention for the Preservation and Protection of Fur The northern fur seal, Callorhinus ursinus, feeds on a vari Seals which prohibited pelagic sealing. Since then under inter ety of fishes and squids throughout its range in the eastern national management, the Pribilof Island fur seal population North Pacific Ocean and the eastern Bering Sea. Small school has recovered and now numbers about 1.3 million animals or ing fishes are usually the principal forage species over the con nearly 80070 of the world population of this species (Lander tinental shelf region and oceanic squids are important seaward and Kajimura 1982). The food of the northern fur seal was of the continental slope in deepwater areas. Fur seals are first reported from seals collected in 1895 by Alexander (1896) found from California to the Bering Sea in nearly all months as a part of the Jordan Commission investigations. of the year, with a few exceptions, and with peak abundance varying by time and area. Present Treaty Evidence presented here suggests that fur seals are opportu nistic feeders preying on the most available species throughout The present Interim Convention on Conservation of North their range. The information used in reaching this conclusion Pacific Fur Seals was signed February 1957 by Japan. Canada. was obtained primarily for the area off California and the east the U.S.S.R., and the United States, and protects fur seals as ern Bering Sea, focusing on the· principal forage foods of fur did the Convention of 1911. The two broad objectives of the seals as based on stomach content volume and the relative 1957 Convention are: 1) To achieve and sustain maximum pro abundance of fishery resources available in the area. The prin ductivity of the fur seal resource and 2) 10 determine the rela cipal forage species of fur seals for other areas between Cali tionships between fur seals and other living marine resources. fornia and the Bering Sea will also be discussed. but in lesser The terms of the present Convention during 1958-63 required detail. each member country 10 conduct pelagic research and collect a minimum number, or "quota." of seals each year. At this Background time. when most of the seals were collected, it was necessary 10 find areas of seal concentration and to collect as many as pos FollOwing the purchase of Alaska by the United States in sible to meet the quota required by the Convention. Effort was 1867, the most critical period for the survival of the northern therefore directed toward collecting seals-thereby sacrificing fur seal, Callorhinus urs;nus, occurred between 1879 and 1909 the quality of systematic surveys to determine the density. dis when no effective international conservation agreement ex tribution, or relative abundance of fur seals by time and area. isted. During this period, almost 1 million fur seals (mostly The quota required by the Convention was modified after pregnant females) were taken at sea. Between 1889 and 1909 1963. Initially, hunting was carried out in areas where seals the number taken at sea was almost twice that taken on the were known to be seasonally abundant during the days of Pribilof Islands (the northern fur seal breeding islands of St. pelagic sealing and research voyages prior to 1958; marginal Paul and St. George) in the eastern Bering Sea. Because of the areas where seals were known to be scarce were generally LlDrestricted harvest of females at sea, the Pribilof Island fur neglected. ;eaI population declined from about 2 million in 1880 to ap At present it is known that most fur seals found in the east proximately 300,000 animals in 1909. In 1911 the United ern North Pacific Ocean are from the Pribilof Islands (St. Paul, St. George, and Sea Lion Rock; Otter and Walrus Islands have no fur seal rookeries) in the eastern Bering Sea. 'NOrthwest and Alaska Fisheries Center National Marine Mammal Labora which are the principal breeding grounds of the northern fur ~.:.~nal Marine Fisberies Service, NOAA, 7600 Sand Point Way NE .• -.WA98I1S. seal. Fur seals from the western Bering Sea (Commander ~r Islands), the western North Pacific (Kurile Islands), and the cruises (19S8-74); other sightings are from NMFS prop-_ Okhotsk Sea (Robben Island) do not contribute significantly which include the Platforms of Opportunity Program (POp). to this population. Two additional rookeries in the eastern Outer Continental Shelf Environmental Assessment Progrlll North Pacific Ocean are off southern California on San (OCSEAP), and Dall's Porpoise Program. Miguel Island and nearby Castle Rock near the southern limit Some northern fur seals are found throughout their range II of the fur seal's range. The San Miguel colony of fur seals was the eastern North Pacific Ocean in nearly all months of till discovered in 1968 with about 100 fur seals (Castle Rock col year with periods of peak abundance varying by time and area. ony was discovered in 1972). By 1979 this San Miguel-Castle Many immature seals of both sexes remain at sea during tilt Rock colony had grown to more than 3,000 animals. first year or two of life and do not return to their island of The U.S.S.R. manages rookeries on islands in the western birth until ages 2 or 3 yr. Most fur seals spend about half tile North Pacific Ocean used by about 485,000 seals that return year at sea (November through May-June) and the remainder annually to breed on the Commander Islands (Medny and Ber (July-October) on and around their home islands during tbt ing Islands) in the western Bering Sea, Robben (Tyuleni) Is breeding season. land off Sakhalin Island in the Okhotsk Sea, and on a few of Fur seals are most frequently seen from about 70 to 130 laD the Kurile Islands. Recoveries of tagged animals have shown from land and usually in greatest numbers along the contineo that seals from the eastern and western breeding islands do in tal shelf and slope throughout their range primarily because of termix to some small extent at sea and on the breeding islands. abundant food resources in this area. Most fur seals are stiD OD Figure I shows the general ocean distribution and breeding is or near the Pribilof Islands in October but by the end of lands of northern fur seals in the eastern and western North November only about 30"'0 or less of the population remains Pacific. near the Pribilof Islands at a time when the first seals have completed their North Pacific (Gulf of Alaska) crossing and GENERAL DISTRIBUTION AT SEA are beginning to appear off the coasts of southeastern Alaska, British Columbia, and Washington. During research cruisa Northern fur seals occupy the subarctic waters of the North off California, Oregon, and Washington, the first seals were Pacific Ocean extending southward to the California-Mexican sighted on 5 December and on 25 and 27 November, respec border (lat. 32 oN) in the eastern Pacific and to about the mid tively. dle of Honshu Island, Japan, (lat. 36°N) in the western From January to March, fur seals are found along the con Pacific. Very few fur seals have been sighted south of these tinental shelf and slope, entering coastal waters in pursuit of latitudes. The 57,927 fur seal sightings shown in Figure 2 are prey, from the Gulf of Alaska south to California. Fur seals from sighting data obtained primarily from pelagic fur seal continue to increase in abundance during December and Janu cruises with supplemental data from other sources to provide a ary off Washington and California. In February and March, picture of fur seal distribution at sea. Sightings of seals in the seals are most abundant from California to Sitka, Alaska. The western North Pacific Ocean area are primarily from the Japa numbers of fur seals wintering off California reach a peak dur nese pelagic fur seal research cruises (1958-78), the National ing late January through March and decrease as they begin Marine Fisheries Service (NMFS) Dall's Porpoise Program their northward migration starting in late March. Most seals (1978-80), and from salmon research cruises of U.S. vessels have left this area by early June. (1955-72). Sightings of seals in the eastern North Pacific Ocean In April fur seals are widely dispersed from Kodiak Island, area are primarily from Canadian and U.S. pelagic fur seal Alaska, to California with the population reaching its peak in
144 ODE 164 00£ ,'6 00101 I S6 00 101 1 J6 DO W 11 6 DO w
60 ~O N
40 DON
2 0 DON
Figure I.-The general ocean distribution and breeding islands of the northern fur seal (modUted from: Fiscus, C. H. 1980. Range of the northern fur seal. Unpubl. rep., 7 p. Natl. Mar. Mammal Lab., Northwest and Alaska Fish. Cent., Natl. Mar. Fish. Sen., NOAA, 7600 Sand Point Way NE., Seattle, WA 98115).
2 .. Gulf of Alaska during May. The northbound migration dant during the breeding season. Off California. solitary seah _ March-June. fint in the southern limits of the range off represented 30 to SO'" of the total sightings. whereas off :MIIonda and proceeding past Washington in April and May, Washington they comprised 3(}.64"" Larger groufls of Ufl to :III Oulf of Alaska in May and June, and westward into the 20 seals have on occasion been sighted usually during sflring ..... Sea in June. In June. fur seals are scattered throughout migration but groups of this size are unusual. A few groufls of :III North Pacific Ocean. Fur seals are in the eastern Bering seals numbering more than 20 have been seen off Washington _ and on or near the breeding islands of St. Paul, St. and California when they were actively feeding on large JeorJe. and Sea Lion Rock (Pribilof Islands) in greatest num schools of prey. ,.. during July. August. and September (most age groups of The SUbarctic water mass Ouctuates seasonally-north in JOth sexes). summer, south in winter. Seasonal and annual variations in In tbe eastern North Pacific Ocean. any discussion of fur temperature, salinity, dissolved oxygen. and water movement ;eal distribution at sea refers primarily to females because they patterns occur on a worldwide basis. The role of such ocean -epresent about 90070 of the pelagic catch (with some variation currents and other oceanic factors in the distribution and ,y time and area). Older females (age 5 yr and older) are gen migration of fur seals in the eastern North Pacific Ocean ha' ll'IIly more abundant off California than off Washington, yet to be examined systematically; however. some data are ¥bile the younger seals are not fully represented (Append. available. During our 1958-74 studies. the largest number~ of .,... A-I to A-tO). Females of all ages (and young males 1-4 yr fur seals were collected where surface water temrc:rature\ »ld) are found in the Gulf of Alaska and the eastern North ranged from 10° to 14 °C off California. 7°_12 °(, off Washing· ;'acific Ocean during winter and spring. Only the younger im ton. 5 0 _9°C in the Gulf of Alaska. and gO_10 °C in the Bering nature males (ages 1-5 yr) have been found south of Alaskan Sea (Kajimura 1980'). Upwelling of water from the deflth\ i, vaters with a few exceptions. Nearly all of the older males win an imflortant oceanic and coastal flrocess which occur~ when er in Alaskan waters-primarily in the Gulf of Alaska, north the surface layer is transported offshore (due to the stre,s of IUd south of the eastern Aleutian Islands, and probably in the wind parallel to the coast on the sea surface) and 1\ then re kring Sea. The catch of males diminished south of lat. 46°N placed by nutrient-rich water from below . The western l'Oa\l Washington-Oregon border) as shown by summaries of the of North America is among the world's major upwelllO!l nonthly age and sex composition in Appendix Figures A-I to regions. Here. uflwelling flrobably IOnuence\ product 1\ II Yand \-10. Of 3,612 fur seals taken off California, only 2070 or only concentration of primary flroducers and 10oplanKton. Thl' 10 ;6 animals were males of ages 1-5 yr and only one seal was 5 yr turn innuences the distribut ion and rel'ruitment of fl,h \Ind., lid. The seals on which these percentages were based were which become available 10 the fur seal. and uilimatcly tht' dl" aken prior to 1967, and the San Miguel Island males would at tribution of seals because they winter and feed nit the \\e\lern hat time not have contributed to the offshore population. No coast of North America. LUempt has been made to verify the distribution of older males teeause poor weather conditions during late autumn, winter. IUd early spring in the Gulf of Alaska and Bering Sea would everely curtail vessel operations and reduce sightings or
·atches. I l\ajimura, H . lYI\O . DI",lrlt"1lJllllfl .HlJ rtl1t't.JtIlHl .'1 n(l nr ', ("T ~ '~ ! ~ H •.(".,;\ If Jii •. Fur seals congregate in tight social groups on land but at sea ,hlnusurslnu..')lnlhcca~lC'rnPa":lfi.: InH ~.J Jl mllT.J.W H 1 .'tn~J('!."·\ 1',-,(": hey are often solitary. Solitary seals predominated in all areas A. . f . 'or~ . and \1 . l'. B 1lltl. f-urthC'r aIlJh ... !, (d pcl.t)lh, IIH "c.al J .. I.I " dlr.. ! C"J t1 , (he lInlied 5lalc' .Ind (anaJa J uron~ I'I<~ . ·~ . 1'." I. r ,., ~ 1 , nr , ; ~ i " r ..... , ; Appendix Table A-I). The frequency of solitary seals was \1ar. \tammall an., ~ l)rth"<.·,t .tnJ ..\I~ .. lJ h'h (en t . ,,- •• : : \t .. r I :, h '« \ . lighest in the Bering Sea (38-68070) where seals are more abun- NO AA . 760(1 S.lnJ P,,,nl \l,"a ' .... ' . '>calilc . W .\ 'I~ I I (
BERING SEA , ',.'
._- ._-
3 DATA COLLECTION annual growth lines. F~)f tho~e teeth that do not show annual growth layers clearly, a technique reported by Pierce and KaJI. Field Procedure mura (J 980) on aCId etching and highlighting for defining growth layers wIll be of use in age determination. Purse seine vessels (Append. Fig. A-II) were used by the The stomach was cut open by slicing the entire length of the United States for conducting pelagIc research, with only a few stomach lining, cutllng with care so food organi ms would not exceptions. This type of vessel wllh the wheelhoue and Oying be damaged. When the stomach contained whole fish or bridge forward of armd hip permitted greater vISIbIlity for squids, the contents were placed dire tly into a weIghing pan. sighting and following seals. The sizes of the chartered vessels I f the contents were largely liqUid they were pia ed in a ieve to were between 19.4 and 29.4 m (65-96 ft) regi tered length wIth drain Thc content wcrc then tran jerred into the weighing a cruising speed of about 8 to \0 kn, with fuel, water, and food ran. The ~tomach IImng v;a nn ed to obtain all food partI storage capability to stay at sea for at least I mo. The vessel cles, as otoliths and quid beak often adhered to the tomach complement normally consisted of eight men, Including four wall. 'xce ~ OUld wa drained from the y,.elghlng pan prior to crew, a captain, engineer, deckhand, and a cook with four each weighing. large tomach required two or more weIgh· wildlife biologists aboard. The vessel crew aSSisted the thrce to lOgs as dId the "olumetflc meLlsun.:ment . four scientists in all phases of re earch including sighting, tomach content welghlOg < \0 g (or dlge ted fi h, sqUId tracking, shooting, and recoverIng seals. Fur seals were shot remain , otolith, quid beak and pen , or vertebrae frag with 12-gauge shotguns u 109 magnum load of OO-bu kshot. ments) were recorded a "tra e" amount unle a'" hole pe The scienti t or biological crew collected the biologIcal data imen or fle hy part \erc pre ent. For content Ith a eIght and samples from each animal collected at ea. of 100 g or Ie s, the \olume "'as not mea ured but wa a Igned Biological data collected from each eal included ex, a value a though the content had the ame den Jlya ",ater length, weight, and any external irregularities which werc (e.g. , if ",eight equal g, the \olume equal 55 cm'). Weight recorded on field data cards (Append. Fig. A-12l before any and volume < 1 g \\ere ehe ed early In the program and biologIcal specimen were removed from the anImal. Both up lound not to \ary Igmficantly .• 'onrood item uch as roc' , per and lower jaws were cut off, and these sections boiled until pebbles, hell, et . v\ere not entered on ood data heet as the teeth could be easily removed. The four canine \\ere part of the total \\eight and volume. toma h content volumes labeled and tagged for final processing in the laboratory where (cc) ",ere obtalOcd by the \\ater dl placement method III large age was deterntined. graduated beakcr apable of holdIng 2, ce. Upon opening the abdominal cavity, if the seal was a number \as a Igned to each pe Imen and re orded on a female, the reproductive condnion wa determined bj exam food c rd ( ppend. Fig. -13). \-\'hen the tomal.:h ",as ining the uterine horns. The entire female genItal tract wa opened, weIght and volume of content were entered on thl then removed as was the entire stomach and presen ed 10 10 010 card and the content IdentJ led. When t"'o or more peCles Formalin for detailed examlnatJon in the laboratory. could not be easil} eparated, the e. ammer estimated their proportionate \.olume to the neare t 51t'0. The ",eight and \01- Laboratory Procedure ume of each indiv idual pecie \\.ere calculated by multIplYing e timated percentage times total \\elght and volume. peclmen The examination of femalp reproductIve organs in the lab were identified by companng them "'ith kno"'n pre en'ed oratory consisted of a thorough macroscopic examination of whole pecimens or kno'" n skeletal material in the laboratory the uterine horns to verify field diagnosis. The ovaries were collection and by u mg variou cephalopod and fi h identifica then sliced (1 mm thickness) and examined for Graafian foll! tion key . dIrect count of complete specimen, quid beaks cles (size and ovulation) and the presence or absence of cor (dorsal and ventral), and fish keletal remains uch as total pora albicantia or corpora lutea indicating past and pre ent skulls, otoliths, or number of vertebrae approximating a com reproductive history. Age specific pregnancy rates are a major plete fish keleton was u ed to e timate the number of quid factor in assessing the overall health of the fur seal populatIon and fi h in the tomach. Length and weIght mea urement of (pups born) as an indication of its present status and in estI prey were taken whenever possible (measurement example: mating future herd size for making management deciSIOns . snout to fork of tall; length of all vertebrae of fi h, snout to The ages of all seals collected are determined by counting hypural plate, and dorsal mantle length of quid). the annual growth layers in the dentine of the canine teeth which appear as alternate clear and opaque layers under trans FUR SEAL FEEDING AT SEA mitted light (high intensity lamps) and with the aid of magni fiers and dissecting microscopes. The ages of most young fur Although fur seals are usually olitary at ea, they tend to seals through age 6 yr can be determined with acceptable ac congregate loosely in areas of abundant food supply and are curacy by counting the external growth increments on the up most frequently seen from about 70 to 130 km from land and per canine; however, for older seals, the ages are determined near the continental shelf and slope. Fur seal densities are by counting the internal annuli from longitudinal half sections often greatest near sea valleys, submarine canyons, seamounts, of canine teeth. and along the continental shelf and slope where abrupt All canine teeth of fur seals taken at sea were sectioned lon changes occur in depths and upwellings of nutrient-rich water, gitudinally (lengthwise), just off center, with a bandsaw. Lapi which influence productivity and concentrate primary pro dary equipment utilizing horizontal grinding wheels of various ducers and zooplankton. This, in turn, gives rise to the attrac coarseness was used to grind the rough surface as close to mid tion, distribution, and recruitment of fishery resources which line as possible. The plane of cut and the degree to which the then become food for fur seals and other predators in th tooth is ground to the midpoint is critical in obtaining readable marine environment.
4 Fur seal feed primarily at night, perhap inOuen db ' the that many forage pe ie rise toward the urla e after dar d become readily available to fur eals and other pretl tor hi h feed primarily in the epipelagic and m pela i 7. n , he did vertical migration of cephalopod ..... a. con Irmed b ' udle<; conducted by Roper and Young (197 ) and P r t • (1977). This vertical migration of squid make them ce k to fur eal foraging In the epipelagic and me opela ne<; and the water over the continental shelf. ccamc <;qUld e ~ome of the principal forage food of fur eals throu hout elf entire range in the eastern North Pacific ean and ea t n Bering ea. Bathylagids, deep ea smelts, also borne allable to fur eals because of their vertical migration ward~ the urface at night. Anchovies also dl play dlel vertl· I movements, ri ing to the surface at mght and disper in a wn approache when they chool lightly and return to eper depths. On occasion, anchovie form large den e ur e schools during daylight hours. four \cals eeking food are not limited to prey that are found ar the surface as depth-time recorders placed on fur se I in c wild re orded depths of dive to 208 m (624 ft) which la ted rSAmm.' In the maJonty of fur eal to mach examined, the quantity tal volume) of food in stomachs i generally highest in I ur Is collected oon after daylight. It gradually diminishes b) d-a ftcrno n and increase again towards dusk as the seal 'rcase their feeding activitie . The graph hown In Figure 3 IS tamed when the fra tion of fur eal tomachs containing d I~ plotted against time (hour) of collection. f' ur seals usually swallow small prey whole below the surface d bring larger prey to the surfa e where they break them into
R l entry, NatIonal Manne Mammal Laboratory. trlC' enter, Mrs, NOAA, 7600 and POInt Way commun March 19 2.
100 r------, 0
10
EMPTY STOMACHS G 6 1970 and 1972 (Marine Mammal Biological Laboratory 1971 ; cies that are important during yearly collections are not evi 7 Fiscus et al. 1973 ). This information does not show in pooled when amples are combined over many years of coli data (combined years) because these data are generally con autlon must be e erci ed in examining data on to cealed by the more abundant (dominant) species over the com contents of fur seals during the early year of pelagic reseal bined years of collection. (1958-63). DUring the e year an annual and relatively hI Because of such circumstances, the locality and time of col quota for the collection of fur seals was In effect which m lection dictate to a great degree the occurrence of certain prey or less dictated intensive sampling in areas where eals con species in the stomachs of fur seals. Consequently knowledge trated. s a result, when concentrations of eal were encou of the oceanographic conditions in the collection area, as tered, as many animals as po ible were collected to achi related to time and seasonal movements of prey, is needed as annual research quota. Examination of tomach conten an aid in understanding the feeding habit of fur eals. The u ually revealed that eal from one locality were feedmg dominant food of fur seals collected eaward of the continen the same prey. ollection of large number of eal from 0 tal shelf over deep water is usually oceanic sq uid (quids and area may thu bias the importance of a particular prey Spec! deepsea smelt in the Benng Sea) whIle nearshore collection in that area (I.e., off alifornia) for the eason. It must made over the shelf mdicate fi h as the primary food-the ex recogmzed that the time pent collecting ample in one I ception being the neritic market qUId, Lo/i?,o opa/escens, ity precluded olle~ting cal on predetermined random tr \ 'hich is usually found over the contmental shelf and in coa tal ect to obtain repre entative ample. The location of r waters and seldom over deep water. orne principal prey pe- eal collected off alifornia and in the eastern Benng hown In Igure 4 and 5.
'Marine Mammal Biological Laboratory. 1971. Fur eal In\rstig3I1ons. 1970 Unpubl. manuscr . 155 p. atl. Mar Mammal Lab ... onh"e t and Alaska I h Cent .• Natl. lar Fish. Sen.. OM. 7600 and Point \', a SE. Seattle, \', A ,. 98115. sa Fiscus. C H .. H. Kajimura. and A. A. Wolman 1973. Pan II PelagiC fur eal investigations. 1972. In Marine Mammal 01\ ISlon. Fur seal tn\Cstl~allon . 19 2. p. 29-47,67-91. Unpubl. rep. U.S. Dep. Commer. ~OAA . atl. tar. fish Serv • Northwest Fish. Cen!., Seattle. Wash (A,;ul. atl. tar. Mammal Lab . ~onh· west and Alaska Fish. Cent.. atl. Mar Fish. Sen NOAA.7600 and POint \', ay NE • Seattle WA 98115.)
56
..... +i \\ i +. + +··~ir\~~+( Bering Sea : '~rEunk' +~+~+ \
+.+ t.
t73 171 \
Figure S.-LOC1ItJon in tbe eastern Bering Sea b .. ~ 4,659 nortbern (ur sail collected. 1953-74.
FI HERY RE OURCE SIG IFICA T TO FUR SEALS
Figure 6 illustrate the even areas into \\ hich the easte orth Pacific region was divided for the purpo e of cond tmg the dietary tudie reported here. For the areas hown Figure 6, the boundaries (in parenthese ) are as follows: C fornia (Jat. 32° to 42 °N); Oregon (Iat. 42 ° to 46° ; Washi ton (Iat. 46 ° to 49 °N); British Columbia (Iat. 49° to 54°30' long. I46°W); Gulf of Alaska (Jat. 54°30 ' to coast and 10 158 °W, and lat. 49° to 54°30 'N between long. 146° 158 °W); western Alaska (west of long. 158°W and north lat. 49°N, and north to the Alaska Peninsula and Aleutian \ . '\ lands); eastern Bering Sea (north of the Alaska Peninsula Aleutian Islands). The list of fishes and squids consumed by fur seals throu out their range in the eastern North Pacific Ocean and in Figure 4.-LocatiODS off California where 3,613 northern fur seals were coUected, eastern Bering Sea is shown in Tables 1 and 2. The princi 1958-66. prey species of fur seals in each of these areas as based
6 stomach content volume generall d not ch e ~en though the ranking by volume within thi II t m ~ han e for 61 OOM each area (Table 3). The four principal prey peC1 on umed, CA NA DA based on percentage of total stomach content .. olume b month for California, Oregon, Washington, Bnu holum- bia, Gulf of Alaska, western Alaska, and the tern Ben Sea are shown in Tables 4 to 10. The leading four prey species con umed by fur al dun 51 OON each of the collection years off allfornia (195 -59, 1 I,
WASHINGTON 1964-66) contributed 82 to 99070 of the total toma h ontent "------,----, volume during these years (Fig. 7). Similarly for the Benn I OREGON Sea, the principal prey specIes contributed 75 to 99tro of the ~-T --\--,-....L.1I1 41 oot! total stomach content volume from collection made In I 1962-64,1968, 1973-74 (Fig. 8). In the other area the pnnClp forage species contributed 64 to 99070 of the total lood volume off Washington (Fig. 9); 66 to 95% off British olumbla ( 'I J1 """ 10); 89 to 99% in the Gulf of Alaska (Fig. II); and 77 to 99 125 oow "5 OOW 17500W 165 OOW 155 oow 145 OOW '35 OOW off western Alaska (Fig. 12). Six prey species formed the major food of fur al off h- Figure 6.-Tbe seven collection areas of nortbern fur seals, 1958-74. fornia during the collection period and, as sho .... n to th fol-
Table I.-Fisbes eaten by fur seals in tbe eastern Nortb Pacific Ocean and eastern Bering Sea, 1958-74, by 1IlH.
Location location
:E'" .E'" co .. E -"'" -"'" E C ::l ~ ~ C ~ 0 '0 :;;: 0 '0" 00 :;;: ., :< < "§'" U CI)'" '"§ ..c c ~ c c .... E c ... 0 0 00 0 .;; 0 t .2 00 :.c ~ ;; .2 00 .§. c .... ., .§ u ...... ~ ~ ~ ·c :; ., 'a E :; ii Food items u 0 ~ c:o 0 ~ c:o Food items ..,) 0 ~ :0 0 :$ ~ Entosphenus tridentatus x x x x x x x Trachipteridae x x Squalis acanthias x Trachipterus altivelis x Hydrolagus colliei x x Trachurus symme/rlcus x x Clupeidae x x x x SClaemdae x A losa sapidissima x x x Brama japonica '( Clupea harengus pallasi x x x x x x x Medialuna californtenslS x Engraulis mordax x x x Scomber japonicus x Salmonidae x x x Sebastes spp. x x Oncorhynchus spp. x x x x x x x S. alutus O. gorbuscha x x x x S. entomelas x O. keta x x x x x S. jordant x O. kisutch x x x Anoplopoma fimbria x O. nerka x x x Hexagra!nmldae O. tshawytscha x x x Pleurogrammus monopteryglus Salmo gairdneri x Conidae Osmeridae x x x x x Cyclopteridae Hypomesus pretiosus x x x Aptocyclus ventricosus Mallotus vil/osus x x x x Trichodontidae Thaleichthys pacificus x x x x x Trichodon trichodon Bathylagidae x x Ammodytes hexapterus Tactostoma macropus x Bathymasteridae Scopelosaurus sp. x Bathymaster signatIL< Paralepis atlantica x x Anarhlchadldae Myctophidae x x x x x Anarhlchas onentallS Tarletonbeania crenularis x x x Zoarcidae Symbolophorus californiensis x Tetragonurus CUYlerl Lampanyclus sp. x A IherinopslS californtenslS Anoloplerus pharao x Pleuronecuformes Cololabis saira x x x x x Olhanchth_H sp. Gadidae x x x x x Pleuronectldae Gadus macrocephalus x x x x A thererthe.s stomlas MerlucclUs produclUS x x x x Hlppo~/ossus rll'noleplS Microgradus proximus x L.,opsella eHilS Theragra chalcogramma x x x Remhardll hp~ lossold Ponchth,s notatus Gaslero leus aculealus '( x " mdenufiro lo .....ing paragraphs, it may be concluded that these prey species Beginning in 1975 , bbth the United States and Canada sus were the most available food resource utilized by fur seals off pended the collection of specimens at sea, pooled their data, CalifornIa Similarly for the eastern Bering Sea, the principal and undertook a joint analysis on all aspects of the pelagic foods of fur seals were the most available food resource uti phase in the life history of this species. Two preliminary re lized by fur seals m the collection area. The abundance, lis ports utilizing the pooled data have been completed on topics tribution, and availability of the major prey species will be such as migration, distribution, growth, reproduction (preg dl cussed to demonstrate the opportunistic feeling of fur seals nancy rates), life table, and feeding habits (Kajimura et aI. 8 9 primarily off California and in the eastern Bering Sea and to a 1979 , 1980 ). Detailed fur seal feeling data tables will be lesser extent for the other areas. The first major report on the food of northern fur seals was that of Lucas (1899) for the Bering Sea and subsequently by 'Kajimura, H., R. H. Lander, M. A. Perez, A. E. York, and M. A. Bigg. 1979. others as more information became available in later years. Preliminary analysis of pelagic fur seal data collected by the United States and Can The food and feedmg habits of the northern fur seal in the ada during 1958-74. Unpubl. rep., 247 p. Nat!. Mar. Mammal Lab., Northwest eastern , orth PaCIfic and eastern Bering Sea are well described and Alaska Fish. Cent., Natl. Mar. Fish. Serv., NOAA, 7600 Sand Point Way from the extensive pelagic research conducted throughout this NE., Seattle, WA 98115. (Submitted to 22nd Annual Meeting of the North Pacific Fur Seal Commission.) region by Canada and the United States during 1958-74. Both 'Kajimura, H., R. H. Lander, M. A. Perez, A. E. York, and M. A. Bigg. 1980. countries have reported findings in their respective annual Further analysis of pelagic fur seal data collected by the United States and Canada reports and in the five joint reports of the North Pacific Fur dunng 1958-74. Part 1, 94 p. and Part 2,172 p. Unpubl. rep. Natl. Mar. Mammal Lab .. Northwest and Alaska Fish. Cent., Natl. Mar. Fish. Serv., NOAA, 7600 Seal Commission (NPFSC) (1962,1969,1971,1975, and 1980) Sand Point Way NE., Seattle, WA 98115. (Submitted to 23rd Annual Meeting of for the period 1958 through 1976. the North Pacific Fur Seal Commission.)
Table 2.-Squids eaten by fur seals in the eastern North Pacific Ocean and Bering Sea, 1958-74, by area.
Species Species
rea and )car Area and year
( We (ern Alaska 1958 ,x 1960 x 1962 x x 196 x x x x x Bering Sea x 1960 x 1962 x x X 196) x x 1964 x 1966 196 11171 .\ 1,/74 Table3.-Principal forage species utilized by fur seals in the eastern North Pacific Ocean and the eastern Bering Sea, 1958.74, by area. June July BerryteuthlS Berryteuthls maglseer magister Gonaropsis Location borealis ..Atka ,., mackerel b Capelin os Capetm :0 os os Pollock E gj C ""gj "" 25 os a os 50 75 25 50 '0'" ~ OJ .§ to ~ (/) L u C C ..... August a a E 00 September S 00 ~ .... ~ .§ Pacific Gonatopsis OJ os ~ OJ herring ~ -;; OJ borealis U ~ ~ Forage species 0 ~ 0 ~ Capelin Capelin Berryteuthis Fish: magister Gadidae Clupea harengus pallasi X X X X X Pollock Pollock Engraulis mordax X X X 25 50 25 50 Oncorhynchus spp. X X X X L ~ Percent October Mallows villosus X X X x Sand lance Thaleichlhys pacijicus X X Berryteurhis Cololabis saira X X X magister Gadidae X Gadus macrocephalus X Capelin Merluccius prOduCIUS X X X x 25 50 75 100 Theragra chalcogramma X X X x June-October Trachurus symmelricus x Combined months Gonatopsis X Sebasles Spp. x x x x borealis • Fteq. (percent) Anoplopoma fimbria x x x X Berryteuthis Vol. (percentl magister Pleurogrammus monoplerygius x x X Capelin Ammodyles hexaplerus x x X Cephalopods: Pollock Lo/igo opalescens x x x L25 50 Onycholeuthis sp. x x X Percent Onychoteuthis borealijaponicus x GOnaIUSSp. x Figure 8.-Principal forage species of northern fur seals in the eastern Berryteuthis magister x x x Bering Sea, 1958·74. Gonalopsis borealis x Unidentified squid x January February Sablefish Capel in January February Rockfish Salmon LO/'90 opaleseens ~ Dnvchoteuth" sp ~ Salmon Anchovy Onycholeurh,s sp Pacific saury Pacific herring Rockfish PaCifiC whiling PaCifiC whiting 25 50 25 Anchovy ~ Anchovy ! March April 25 50 75 25 50 75 Salmon Salmon Percent Percent March April Pacific herring Anchovy Lotigo opafescens Jack mackerel Anchovy Pacific herring Pac ific saury Anchovy Rockfish Rockfish Pac ific whiting Lo/igo opalescens 25 50 25 Anchovy ~ PaCific whiting l May June 25 50 25 50 Percent b L Percent Pacific whiting Salmon May June Sablefish Salmon LO/'90 opalescens ~ '''~'''" ~ Anchovy Onychoteuthis sp. Onychoteuthls.. sp Jack mackerel Rockfish Pacific herring PaCifiC hemng PaCifiC whiting 25 50 25 50 75 Pa cific whiting Anchovy ~ December·June 25 50 75 25 50 December Combined months ~Percent Percent Salmon January- June Capelin Anchovy Loligo opalescens c:::J Freq. (percent) Eulachon _ Vol (percent) Vol. {percent' Pacific saury Sabtefish Rockfish ~ ~ '''.,.-' Pacific whiting Pacific herring Pacific hemng Anchovy ~25 50 25 Percent Percent 25 50 ~Percent Figure 9.-Principal forage species of northern fur seaJs off Washington, Figure 7.-Principal forage species of northern fur seals off California, 1958·66. 1958·74. 9 .hJnuary February Loligo opJlescens Cod Sablefish Sableflsh May June Paclf c herring Rockfish Pollock Atka maCkerel ~ Berryeeuthis Berryteuthis Polock Pacific herring magisrer magister ~25 50 25 50 75 100 Capel in Capelin March April Sand lance Sand lance Cod Rockfish E25 50 25 50 Pacific ...vhiting Eulachon July BerryreurM; ~August Pollock Sablefish magiseer Salmon ~ CapellO Pacific herring Pacific herring Pacific herring SableflSh Atka mackerel b25 ~25 50 75 PaCifiC herring Capelin May June 25 50 Sableflsh 25 50 75 PaclflCsaUry ~ Percent Pacific whiting Cod September $a'-non Atka ~ack.rel F: ~rnng ~~:;~oteuthls Capel In Pacific boreallJapon/cus ~~~~!!~~!i~i!~~~. 25 50 75 100 25 50 25 50 75 b May-September January-June Percent Combined months Combined months Atka mackerel Sableflsh Berryteuthis n Freq. (percent) o Freq. (percent) magister iL • Vol (percent) Onycnoteuth;s _ Vol. (percent) borealijapon;cus Capelin Salmon Sand lance 1 PacI C hernng 25 50 ~25 50 Percent Percent Figure 10.-Principal forage species of nortbern fur seals off British Columbia, Figure 12.-Principal forage species of nortbern fur seals in western 1958-72. Alaska, 1958-74. February March found in these two reports, the annual reports, the NPFSC C: pelln Capello ~ reports, and in Lander (1980). Pa IfiC he og ~ Pacific herring ~ The discussion in this report will focus on the principal prey 50 100 50 100 species of fur seals based on stomach content volumes and May relative abundance of fishery resources off California and in Berryreuthis ROCkf magister the eastern Bering Sea and, to a minor degree, on some princi natIJ Pollock pal prey species in other areas of collection. P.,lIock Capelin pe 0 Sand lance California 25 50 75 b25 50 75 June July Three species-the northern anchovy, Engraulis mordax, Salmon Pacific whiting, and market squid-were among the four lead Squid ing forage species consumed during the 6 yr of collection off Sand lance California, and the Pacific saury, Cololabis saira , was among CapellO the leading species during 2 yr. These four species were prob 50 75 ~25 50 February July Percent ably the most abundant prey available to fur seals off Califor ComblMd months nia during those years. Other species also presumably abundant and available to fur seals at the same time include jack mackerel, Trachurus symmetricus, rockfishes, Sebastes spp., sablefi sh, ~ Anoplopoma fimbria, and the oceanic squid, Onychoteuthis sp. The market squid is generally found over the continental shelf whereas Onychoteuthis sp. inhabits deeper offshore waters. As can be seen in Tables I and 2, the distributions of many prey species overlap in several areas and some species are co nsumed throughout their eastern Pacific range. f UO' II l'nnClp~1 lora t P<""" of northern fur ,ea" in the Gulf of The northern anchovy, jacksmeit, Atherinopsis californien 'I Io.a. 1958-68. sis, Pacific whiting, rockfish, and squid were the leading prey 10 )ecies of fur seals collected off California during February to Bering Sea .pril 1952 (Taylor et al. 1955). lacksmelt was not an impor mt food of fur seals during the 1958-66 California collections The principal prey species utilized by fur seals in the eastern Ithough this species occurred in stomachs of fur seals during Bering Sea include Pacific herring, Clupea harengus pallasi, anuary, February, March, and April collections (Table 4). capelin, Mallotus villosus, walleye pollock, Theragra chalco The fur seals collected off California were taken before the gramma, Atka mackerel, Pleurogrammus monopterygius, and iscovery of the San Miguel Island population (the samples oceanic squids of the family Gonatidae-inclucting Gonatus 'ere collected during 1958-66). Thus, the San Miguel Island spp., Berryteuthis magister, and Gonatopsis borealis. Deepsea opulation, which numbered about 100 animals when dis smelts of the family Bathylagidae, Greenland turbot, Rein overed in 1968, would not have affected our findings or the hardtius hippoglossoides, and salmon, Oncorhynchus spp., ~sults of the 1958-66 surveys. The population of seals from were represented among the principal forage species during )e San Miguel-Castle Rock colony (which has grown to about some annual collections but when all years' data were com ,000 animals in 1979) may now play an important role as bined by month for the Bering Sea their cumulative total vol ear-round residents in California waters. umes were not large enough to place them among the principal species. Salmon occurred among the principal forage species food of fur seals in 1960 and deepsea smelts in 1963, 1968, 1973, and 1974. Table 4.-Food of fur seals off California, January-June 1958-66. Months Oregon Jan.' Feb. Mar. Apr. May June Dod items The collection of fur seals off Oregon were made while the [sh: research vessel was enroute between Washington and Califor Entosphenus tridentatus x x nia during 1959, 1961, 1964, and 1965. Although the sample Squalus acanthias x sizes were small, a total of 14 species of fish and 7 species of Clupeidae x Alosa sapidissima x x x squids was identified in the stomachs of fur seals. The princi Clupea harengus pallasi x x x x x pal prey species included northern anchovy, Pacific whiting, Engraulis mordax 3 rockfish, and squids (Table 5). Oncorhynchus spp. x x Hypomesus pretiosus x x Thaleichthys pacijicus x x Tactostoma macropus x Paralepis atlantica x x x Myctophidae x x x x Table S.-Food of fur seals off Oregon, January and March·May 1958-65. Tarletonbeania crenularis x x x Symbolophorus californiensis x Months Cololabis saira x x x x Merluccius productus 222 2 Food items Jan.' Mar. Apr. May Trachipteridae x x x Trachipterus alrivelis x x Fish: Enrosphenus rridentarus x Trachurus symmetricus x x 4 x Alosa sapidissima x Sciaenidae x Clupea harengus pallasi Brama japonica x Engraulis mordax x Medialuna californiensis x x Oncorhynch'/S spp. Scomber japonicus x Scopelosaurus sp. Sebastes spp. x x x 2 x Myctophidae Sebasres jordani x x Tarleronbeania crenularis A noplopoma fimbria x x 4 x Cololabis saira x Atherinopsis californiensis x x x x Merlucclus producrus 2 x Cirharichrhys sp. x x x Trachiprerus alrivelis x Pleuronectidae x x x x Trachurus symmerricus Lyopsetta exilis x x Sebasres spp. Porichrhys norarus x x x x A noplopoma fimbria Unidentified x x x x x x Lyopsella exi/is ephalopods: Unidentified x x Ocyrhoe ruberculara x x x Cephalopods: Loligo opalescens 4 x 4 2 x 4 Loligo opalescens Onychoreurhis sp. 3 4 x x Onychoreurhis sp. Onychoteuthis borealijaponicus x x x x x x Onychoreurhis boreailjaponicus x Mororheurhis robusra x x A bra/iopslS sp. Abraliopsis sp. x x x x x Gonatldae Gonatidae x x x x x Gonarus sp. Gonarus sp. x x x x x x BernreurhlS magISter Berryreurhis magisrer x x Chiroteuthldae Gonaropsis borealis x x X Unidentified SQUId 2 4 Unidentified squid x x x x x x Stomachs \\Jlh food tomachs with food 399 1,006 558 268 265 81 172 222 161 69 107 35 198 405 255 77 75 15 , umerals indicate the ranking of principal prey species based on percentage of total stomach content volume. 11 Washington than in any of the othe_r six areas (Table 6) . Surveys and collec tions were conducted from late November through early June Among the seven designated collection areas (Fig. 6), the with March, April, and May receiving the most time coverage. ocean area off Washington had the most extensive time cover April was the only month in which collections were made dur age as well as the most variety of prey species eaten by fur seals ing every collection year from 1958 through 1974. The principal prey species utilized by fur seals off Washing Table 6.- Food of fur seals off Wasblngton, December-June 1958-74. ton included the Pacific herring, capelin, eulachon, northern anchovy, rockfi sh, salmon, Pacific Whiting, sable fi sh, and the Months oceani c squid Onychoteuthis sp. These principal prey species Food items Jan.' Feb. Mar. Apr. May June Dec. contributed from 64 to 99 0/0 of the total food volume (Fig. 9) . Fish: Entosphenus tridentatus x x British Columbia Hydrolagus colliei x" x Clupeidae x x Alosa sapidissima x x x x urveys and coll ectIons in British Columbia waters occurred Clupea harengus pallasi " x 3 2 from January through June, 1958-68, with extensive lime cov Engraulis mordax "\ 2 2 x erage primanly during May and April. Salmonidae X x x x x x x The principal prey pecies of fur seals taken off Brillsh Oncorhynchus spp. 2 3 4 4 Columbia included the Pacific herring, eulachon, salmon, O. gorbuscha 2 3 4 " O. keta 2 4 sablefish, rockfish, walleye pollock, Pacific cod, Gadus O. kisurch 2 4 4 x macrocephalus, Pacific whiting, Pacific saury, and squids, L. O. nerka 2 4 opalescens and Onychoteuthis borealijaponlcus (Table 7). O. tShawytscha 2 4 The e principal prey species contributed from 66 to 95% of the Salmo gOlrdneri x " total food volume (Fig. 10) . Osmeridae x x " x x Hypomesus pretiosus "\ x Mallotus villosus 4 Table 7.-Food of fur seal off British Columbia, JanuaJ"}-Juoe 1958-72. Thaleichthys pacijicus x" " "x " " Bathylagldae " " " Paralepis atlantica x " Myctophidae x Food items Jan. Feb. pro May June Tarletonbeama crenularis "x " Cololabis saira x " Fish Gadidae Entosphenus trldentatus .W"erluccius productus x x " 4 Hvdrolagus colliel x Microgadus proximus " Clupe.dae x Theragra chalcogramma Clupea ilarengus pallasl 2 Gasterosteus aculeatus x " Oncorhynchus spp. Trachipteridae " o keta 3 Trachipterus altivellS "x Osmendae Trachurus symmetricus x Hypomesus pretiosus Bramajaponica Thaleichthys paclficus " Sebastes spp. 3 x" Cololabis saira 4 Sebastes entomelas x Gadidae ). A noplopoma fimbria 4 x x Gadus macrocephalus 4 4 Hexagrammidae !>lerlucclus productus 3 2 Ammodytes hexapterus x x Theragra chalcogramma , 2 Zoarcidae Gasterosteus aculeatus , Tecragonurus cuvieri "x Sebastes spp. 2 "x 4 Pleuronecuformes x A noplopoma fimbria 3 2 4 Pleuronectidae x x x x Ammodytes hexapterus " ). U nidenti fied x x " x x Pleuronectidae x x Cephalopods: UOIdentified x x " Octopoda Cephalopods: Lo/igo opalescens x x "x x x x Loligo opalescens 4 Onychoteuthis sp. x x x x 2 2 Onychofeurhis borealijaponicus x" Onychoteutilis borealijaponicus x x x x x Gonatidae x Moroteuthis robusta x Gonatus sp. x Abraliopsis sp. x x Berry teurhis magister x x x Octopoteuthis sp. x x x Unidentified squid x x x x x Gonatidae x x x x x x x Stomachs with food 19 89 79 44 170 62 Gonatussp. x x x x x Stomachs with trace 2 27 31 5 39 5 Berryteurhis magister x x x x x " Stomachs \\~thout food 20 86 58 60 156 33 Gonatopsis borealis x x x x ' Numerals indicate the ranking of principal prey specie based o n percentage of Chiroteuthidae x x x x total stomach content volume. Chiroceutilis sp. x x x x Unidentified squid x x x x x x x Stomachs with food 273 257 569 1,082 647 32 78 Stomachs with trace 94 105 226 325 222 12 36 Gulf of Alaska Stomachs without food 209 187 688 1,014 475 17 38 'Numerals indicate the ranking of principal prey species based on percentage of Surveys and collections in the Gulf of Alaska occurred pri total stomach content volume. marily during 1958 through 1968 with greater time coverage 12 ccurring during May and June when fur seals were expected Table 9.-Food of fur seals in western Alaska, May-September 1958-74. n this area in greater numbers enroute to the Pribilof Islands_ The principal prey species utilized by fur seals in the Gulf of Months aska included Pacific herring, capelin, salmon, walleye Food items May' June July Aug. Sept. ollock, Pacific sand lance, Ammodytes hexapterus, rockfish, Fish: tka mackerel, and squids, Gonatus spp. and B. magister Entosphenus tridentatus x able 8). These principal prey species contributed from 89 to Clupea harengus pallasi x 0/0 of the total food volume based on percentage of the total Salmonidae x 4 Oncorhynchus spp. omach content volume of seals taken in this area (Fig. 11). x 4 x 0. gorbuscha x 0. keta x 0, kisutch x Table 8.-Food of fur seals in tbe Gulf of Alaska, February-July 1958-68. 0, nerka x 0. tshawytscha x Months Osmeridae x Mallotus villosus 2 2 x Feb.' Mar. Apr. May ood items June July Gadidae x 'ish: Gadus macrocephalus x Theragra chalcogramma Clupeidae x 4 x x x Clupea harengus pallasi x x 4 Sebastes spp. x A noplopoma fimbria Oncorhynchus spp. x x 2 4 2 Pleurogrammus monopterygius O. gorbuscha 2 4 2 x Cottidae O. keta 2 x Cyclopteridae O. kisutch 2 x 0. tshawytscha x Trichodon trichodon x Ammodytes hexapterus Osmeridae x x x Bathymaster signatus Mallotus villosus 2 2 2 x A theresthes stomias Thaleichthys pacificus x x x Unidentified x x x x Myctophidae x x Cephalopods: Anotopterus pharao x Gonatidae x x x x Cololabis saira x Gonatus sp. x Gadidae x x Berrytheuthis magister 3 3 x 4 Gadus macrocephalus x x x Gonatopsis borealis x x x Microgadus proximus x x Unidentified squid x x Theragra chalcogramma 2 x Stomachs with food 7 350 30 35 15 Gasterosteus aculeatus x x Stomachs with trace III 10 6 I Sebastes spp. 4 x Stomachs without food 14 276 22 51 18 Sebastes alutus x x A noplopoma fimbria x x 'Numerals indicate the ranking of principal prey species based on percentage of Cyclopteridae x x total stomach content volume. Trichodon trichodon x Ammodytes hexapterus x 2 Pleuronectidae x x A theresthes stomias x x x U nidenti fied x x x x PRINCIPAL FORAGE SPECIES OF :ephalopods: FUR SEALS Octopod a x Loligo opalescens x x Onychoteuthis sp. x x California Gonatidae x x Gonatus sp. x x x The relative abundance of fishery resources available in the Berryteuthis magister 4 x x California Current System have been determined from egg and Gonatopsis borealis x x larvae surveys conducted by the California Cooperative Unidentified squid x x x x 3 Oceanic Fisheries Investigations (CaICOFI). The basic pattern :tomachs with food 33 205 225 505 328 24 itomachs with trace I 9 22 53 68 4 for the stations of the CalCOFI survey areas off California :tomachs without food 30 100 118 599 474 68 and Baja California since 1950 are shown in Figure 13. The sampling method, gear, and surveying techniques used for col 'Numerals indicate the ranking of principal prey species based on percentage of otal stomach content volume. lecting data on fish eggs and larvae to determine distribution and abundance of fishery resources in the California Current System were summarized by Ahlstrom (1966) and Kramer et N estern Alaska al. (1972). Based on surveys conducted by CaICOFI, the major fishery resources (arranged in order of their relative abun Surveys and collections in the western Alaska region were dance) were determined to be: 1) Northern anchovy, 2) Pacific nade primarily during June 1958, 1960, 1962, 1968, and 1974. whiting, 3) rockfishes, 4) jack mackerel, 5) Pacific saury, and The principal prey species utilized by fur seals in this region 6) L. opalescens. These fishery resources were considered to be ncIuded the fishes Pacific herring, capelin, salmon, walleye among the most underutilized fishery resources off California )o\lock, sablefish, Atka mackerel, and Pacific sand lance as (Ahlstrom 1968). "'ell as the squid B. magister (Table 9). These principal prey The California marine fish fauna consists of about 554 spe :pecies contributed from 77 to 99% of the total stomach con cies of which 439 are found in coastal waters (to 120 m depth), ent volume for this area (Fig. 12). 48 are meso- or bathypelagic species, and 67 are deepwater 13 fi hes (Miller and Lea -:1972). In addition, 40 species of pelagic cephalopod are known to inhabit the waters off southern California and Baja California, Mexico (Young 1972) . Th abundance of these species (cephalopods) is greatest in outh ern California, gradually declining northward correlated wit increasing latitude and decreasing minimum urface tempera ture. They contribute only a small percentage to the commer cial catch of fish (Horn 1980). Among the top 10 commerci fish landings in California, tunas contribute approximatel 55070 (primarily caught out ide of California). Also among th top 10 are 4 of the major forage species of fur seals which tot 34070: Anchovy 24070, jack mackerel 6070, L. opa/escens 31110 and rockfish 1070 (Oliphant 1973). The commercial landings 0 forage species significant to fur seals feeding off California ar shown in Figure 14. The prey of fur seals along with other fish and invertebral play an important role in the complex food web off Californi (Fig. 15). The prey species, including squids, anchovy, Paci 1 whiting, and rockfish, shown in the food web, are also amon the most abundant species in the California Current Syste Antonelis and Fiscus (1980) summarized the known prey pinnipeds inhabiting the CalCOFI study area and indicate th there is a wide range in the list of prey consumed in the area b these pinnipeds. Many consume the same prey but differ pr marily by foraging in different zones. Ainley and Sang (1979) reported that most seabirds feed as secondary and Ie • I lire 13. litlSic pattern fo r California Cooper1llhe Oceanic Fisheries Investiga tiary carnivores and that certain of their prey characteristical II n Ie I (H II talion in , une) area, orf California and Baja California. occur as the predominant items in the diets of other mari v • ROCKF SH I-igure 14.- Commercial landin!(; of fOr1l!(e species significanl northern fur ,uls oft California (from he) 1971). 14 ~ WHALE .\~ .; r-;, .. r~~:~~ • ~~.' Mon,,,,, ~~. + +•••• + ...~~. . p • +. • + * Pt. ConcePtIon Figure IS.- Food web in volving commerciaUy impon ant and abundant flsb, birds, mammals, and squid Lo/igo opa/escens (modified from Morejobn et aI. 1978). Figure 16.-Locations off CalIfornia wbere 843 nortbern fur seals were coUected wbose stomacbs contained nortbern ancbovy. 1958-66. birds in the eastern North Pacific Ocean. Seabirds are oppor tunistic feeders, foraging on smaller abundant schooling orga nisms such as euphausiids, squids, clupeids, and engraulids. Ainley (1980) described seabirds as marine organisms (similar fisheries also shows its acceptance as food for a wide vanety of to fish and marine mammals) because t hey are full-time parti fishes. cipants in marine energy cycles as they derive all their food The largest concentrations of anchovies are usually found from the sea. Seabirds however, travel above the sea's surface between San Francisco and Magdalena Bay, Baja California, instead of being confined to water, spending some time on with general distribution from the Queen Charlotte Islands, land to raise their young, as do pinnipeds. British Columbia, south to Cape San Lucas, Baja Cali forma, Mexico. The anchovy biomass increased tremendously dunng 1952-6Z from about 640,000 to over 6 million tons (Fig. 17) . Northern anchovy.-The northern anchovy is one of the Since 1962, the anchovy biomass has remamed high, fluctu major forage species utilized by fur seals wintering off Califor ating between 5 and 8 million tons in a population consistmg nia and has been among the top four forage species consumed of three subpopulations (Fig. 17). North of the CalCOFI sur by fur seals during every monthly coll ection (January through vey area, large concentrations of the anchovy have also been June) off California (Fig. 7). The locations where fur seals reported along the Oregon and Washmgton coasts. The an were taken whose stomachs contained anchovy is shown in chovy is also one of the principal forage prey of fur seals off Figure 16. The northern anchovy is also the most abundant Washington during February, March. and Apnl (Fig. 9). Al and largest fi shery resource in the California Current System though most fishes and squids rise toward the surface after based on CalCOFI surveys and on acoustic-mid water surveys darkness, the anchovy is also known to form large dense ur (Ahlstrom 1968 ; Frey 1971 ; Mais 1974). Anchovies, which are face schools during daylight hours. extremely abundant off southern California are heavily preyed The known or suspected predators of anchovies including upon by most predatory species (fishes, seabirds, squids, pin marine birds, mammals, fishes, and invertebrates have been nipeds, and whales) in the California Current (Fig. 15). This summarized by Huppert et al . (1980). During pelagic fur eal species contributed 74 070 of the total stomach content volume operations off California, Pacific whitesIde dolphm , Laf!f? in fur seals taken off California in 1966 (Marine Mammal Bio norhynchus obliquidens. California ea hons. Za/ophus calt logical Laboratory 1969) . Anchovy are also cannibalistic, feed /orn ian us, fur seals, and seabIrds have been ob en'ed feedmg ing on their own larvae and eggs (Hunter and Kimbrell 1980). in the same chool of anchovies. In man} m tance . concentra The extensive use of anchovy as bait in commercial and sport tions of birds in the distance u uall} mdlcated hool of an- 15 I • CHO Y BIOM' ~S \ "- . ~ " \ z \; \ U 9 C~UFORr-.'A z 0 " ..J ~ tv' I' r· '- ./ 0 1955 1960 1965 25' ,"'. Figure 17.-The distributiou of anchovy subpopulations (from Huppert et aI. 1980) and tota! spawning biomass (from Vrooman and Smitb 1971). chovies at the surface and, when approached, fur seals or other marine mammals were usually found. Pacifi c whiteside dolphins and Dall's porpoise, Phocoenoides dalli, collected off California were also feeding on anchovy, Pacific whiting, Pacific saury, and a variety of squids (Kajimura et al. 1980). Rice (1977) reported northern anchovy as the dominant food of sei whales, Balaenoptera borealis, off California during June, July, and August. Rice also reported that anchovies oc curred in 70/0 of the stomachs of fin whales, Balaenoptera Figure 18.-Locations off California wbere 658 northern fur seals were collected physalus, and 60% of the stomachs of humpback whales, whose stomachs contained Pacific whiting, 1958-66. Megaptera novaeangliae. Although sperm whales, Physeter macrocephalus, are year-round residents off California, they apparently do not feed on anchovi es as large forage species ap 19). It is during this period, when feeding fish are over the con pear to be more to their liking, especially larger oceanic squids tinental shelf and slope, that the whiting is subjected to the (Rice and Wolman 1970'°). foreign fishery. Although there is no major U.S. fishery for whiting off the western coast of North America, the species Pacific whiting.-Pacific whiting has been among the lead has been the subject of an intensive foreign fishery in this area ing forage species consumed by fur seals off California during since 1966. Dark et al. (1980) estimated the total whiting bio April and 1ay and second in importance during January, Feb mass at about 1.2 million tons (average annual foreign commer ruary, and March (Fig. 7). All months combined, whiting was cial catch of 167,000 tons) based on bottom trawl and midwater second only to northern anchovy as the leading forage species hydroacoustical trawl surveys conducted during July-September consumed by fur seals off California. The geographic occur 1977. This survey also indicated the whiting biomass is nearly rence of whiting in stomachs of fur seals is shown in Figure 18 . evenly distributed over fishing areas known as the Vancouver, Pacific whiting is a schooling fi sh that is distributed over the Columbia, and Eureka grounds and less abundant to the south continental shelf and slope from the Gulf of California to the over the Monterey and Conception grounds. Gulf of Alaska. Egg and larval studies by CalCOFI also indi Pacific whiting, which are cannibalistic, make pronounced cate that whiting is consistently ranked second to anchovy in diel vertical migrations to feed on anchovy, rockfish, and annual estimates of relative abundance in the survey area (Ahl- market squid. Fiscus (1979) summarized the known or sus trom 1969). Spawning occurs primarily during \vinter and pected marine mammals and other predators which forage on early spring (December to April) in deepwater areas along the whiting. coasts of southern California and Baja California, Mexico. The whiting undertake an annual migration northward in the Market squid,-The market squid is an important forage spring and summer and southward beginning in autumn (Fig. food of many fishes, seabirds, and marine mammals and is an important link between zooplankton and the hi gher trophic levels in the pelagic environment of the California Current Sys Rice, D. \\., and A. A \ olman. 1970. Sperm whales In the eastern North tem (Fig. 15). Young (1972) reported that the market squid is Pa"fi, Progres, report on research, 1959-69. Submitted to Scientifi c Committee, perm" hale blOlog) and stock assessment meeting, Honolulu, Hawaii, Doc. probably the most abundant squid off the California coast. r .\ , I r (A\all '1all. ~ I ar Mammal Lab., Northwest and Alaska Fish. Cent. , The market squid (a schooling species) is one of the leading at! lar Fish en., ~O."'.A. '600 Sand Point Way NE., eattle, WA 98 115.) forage species of the fur seal off California as evidenced in col- 16 .+ ++ + ~ Eureka +, Seasonal Depth Distribution of Pacific Whiting + + ++ '00 + + + + ++ ~ 200 + +++ •~ ~ ~ 300 ~ < ~ ' 00 500 ,.. INT ER SPRING SUMMER FALL Figure 19.-Seasonal depth distribution of Pacific whiting (from Alverson and Figure 20.-Locations off California where 326 northern fur seals were collected Larkins 1969). whose stomachs contained market squid, 1958·66. lections made during January, March, April, and June (Fig. Studies of the feeding habits of the market squid in Mon 7). Its occurrence in stomachs of fur seals is shown in Figure terey Bay show changes in diet with location and depth but 20. Among the eight taxa of squids identified in stomachs of with no changes with respect to size of squid or sex. Squids fur seals taken off California, the market squid and oceanic were found to be feeding primarily on euphausiids, copepods. squids, Onychoteuthis sp. and O. borealijaponicus, were iden megalops larvae, mysids, and amphipods as well as on fish and tified most frequently. other cephalopods (Karpov and Cailliet 1979). Cannibalism IS The market squid population is considered to be large as are common among squids in the pelagic environment and the most cephalopod populations in the eastern North Pacific mature squids probably feed exclusively on fishes and cephalo Ocean. Although the life history of the market squid is rela pods. tively well known (Fields 1965), the life histories of other Most pelagic marine mammals feed to varying degrees on pelagic cephalopod fauna of the eastern North Pacific Ocean squids which are available in the epi- and mesopelagic zones are poorly known. whereas some of the deep diving mammals, such as the sperm Based on CalCOFI surveys, the market squid ranked third whales, have diets which consist of 90070 squids from the among cephalopods in abundance (Okutani and McGowan greater ocean depths. Laevastu and Fiscus (1978)" conserva 1969). Squid larvae found in greatest abundance were Abrali tively estimated the annual consumption of squids by the opsis jelis and Gonatus jabricii. Abraliopsis sp. and Gonatus North Pacific sperm whales to be about 30 million tons and spp. were also consumed by fur seals taken off California. estimated 220 million tons of squids being consumed annualb These species of squids normally inhabit the epi- and meso by all predators in the North Pacific marine ecosystem. Clarke pelagic zones seaward of the continental shelf waters. (1977) estimated the worldwide squid consumption by sperm The market squid is neritic, being found over the continental whales to be about 320 million tons. Okutani (1977) reported shelf and in coastal waters but very seldom over deep water. worldwide squid species (includmg cuttlefish) numbenng be· The known geographic range of the market squid is from tween 450 to 500 species belonging to 30 families. Hecate Strait, British Columbia, into Puget Sound, Washing ton, and south to Guadalupe Island and Turtle Bay, Mexico (Berry 1912; Okutani and McGowan 1969). A few occurrences " Laevastu, T., and C. H. Fiscus. 1978. Re\1e" of cephalopod resource« on I'le of this species have been identified in stomachs of fur seals eastern North Pacific. Processed rep., 15 p. ~orth"est and I~ 'a FIsh Crnl taken in the Gulf of Alaska in 1958 and 1962. NaIl. Mar. Fish. Serv., NOAA, 2725 Momlake Bhd. E . Seattle. \\ A 9 11~ 17 Pacific saury.-Pacific saury is one of the leading forage foods of fur seals off California during February and March ', 'J' (Fig. 7). Its geographic occurrence in the stomachs of fur seals 50° taken off California is shown in Figure 21. CANA.DA Typically oceanic, the Pacific saury ranges across the entire UNlno STATtS North Pacific Ocean from Japan to North America; the east ern Pacific saury stock is located principally in waters from northern Baja California, Mexico, to Wa hington (Fig. 22). The population is considered to be large (fifth most abundant species) as determined from CalCOFI urveys (Ahlstrom 1968). The population of the saury is evaluated on the basis of egg and larval estimates, predator-forage indice , and from visual observations. Such indicators give abundance e timate of 450,000 to 1.5 million tons (Ahlstrom 1968; SmIth et al. 1970; Inoue and Hughes 1971). Pacific saury, in common with the northern anchovy and market squid, form an important link between lower and A W... tU". 19S1·9 higher trophic levels as they provIde forage for a large variety B .. ,,", 0 ~abn. 19$8 C .. JoI hn .p .... ina aroWlcb of fishes and marine mammals in the ea tern North Pacific April·July. 1958 9 .l figure 22.-Eastern Pacifi tock of Pacific aUr) (from Inoue and Hugbes 1971) . ( \ 30%. Immature aury were reported by Frey (1971) to be a \ major food Item of the albacore tuna, Thunnus alalunga. Mais (1974) reported that a high percentage of successful night lIght tations contained the saury (48!l10). Thi wa inter l preted to be indicative of a large aury population but the I study concluded that commercial concentrations were infre quent and erratIc, re ulting in a failure in the development of a commercial fishery off CalifornIa. The rea on for this lack of ~ . den e commercIal concentratIons \\as attributed by Trumble (1973) to the lack of large thermal boundarIes comparable with that of the cold water-warm water boundary of the Kuroshio f Oya hio Current in the western Pacific Ocean . .~ Although Pacific saury eggs were found during all months of the year on CalCOFI surveys, 92% of the eggs were col ." t ~., <:, . ~ lected from February to July. Of these, 65070 were taken during ... +.... +. Monterev April, May, and June (Ahl trom 1968). The coastal water be '\+ ... + ++ .. + + ...+ ..t + tween lat. 26° and 40° constituted the principal spawning \ grounds in the survey area. Areas off southern California and "'~* .;,vi \.,++,: :+. Baja California, Mexico, were reponed to be nursery grounds * ' .;;$' containing mostly juveniles dispersed over a wide area. The ..... ~t;..* + t . , largest concentrations of saurie were reported to be at dis + Pt. lAncpotlon tances of 64 to 193 km offshore (Frey 1971). Fur seals were *. , " most often seen from 70 to 130 km offshore near the continen 1 ++ it. 0. \::::;:::0 0 tal shelf and slope. '~ Rockfishes.-Rockfishes ranked fourth in both volume and frequency as forage food of fur seals off California in 1965 (Fiscus and Kajimura 1967). All of the rockfish were immature juveniles (vertebral length from 47 to 99 mm); one seal stom ach contained 137 of these small rockfish. Rockfish were most Figure 2l.-Locations off California where 336 northern fur seals were collected numerous in stomachs from seals collected off Monterey, whose stomachs contained Pacific saury, 1958-66. Calif. (Jat. 36 °38 ' N, long. 121 °55 ' W). 18 Rockfishes of the family Scorpaenidae form one of the im portant and largest fish families off California. Rockfishes are also considered a much underutilized fishery resource of CciIi fornia in terms of abundance (Frey 1971). This family is repre sented by three genera in California, with at least 55 species of t + Sebastes spp., a single species of Scorpaena, and 2 species of Eureka Sebastolobus (Phillips 1964; Frey 1971) . No estimate of the rockfish biomass has been made. It is known in general terms as a large resource, and because rock fish are a highly desirable food resource they are subjected to both commercial and sportfishing pressure. The larvae of Sebastes spp. have consistently ranked third or fourth in abun dance in the CalCOFI survey area (Ahlstrom 1968). The com mercial catch reached a maximum of 8 million kg in 1958 but .t since has dropped to about 4 million kg (Fig. 14). CalCOFI ++ +-. .. + surveys show that the larvae of various species of rockfish oc ++ ++ cur in great abundance and are widely distributed along the + +.-. / .... + + + + coast as far as 500 km offshore. During their pelagic existence, Monterey rockfishes sometimes form a large and important part of the diet of chinook salmon, Oncorhynchus tshawytscha; albacore; and petrale sole, Eopsetta jordani (Phillips 1957). Perhaps because of the numerous head spines of rockfishes, fur seals have always beheaded the adult rockfishes before swallowing them as only bodies have been found in their stom Pt. Conception achs. This was generally the situation off Washington when rockfish was the principal prey species during February, + °o~ March, and April (Table 6). As previously mentioned, most rockfish taken by fur seals off California were juveniles. Lar val and juvenile rockfish were available from the surface to 140 m depth during CalCOFI survey cruises (Ahlstrom 1965). Jack mackerel.-Jack mackerel is among the leading forage species of fur seals collected during April and June off Califor Figure 23.-Locations off California wbere 114 nortbern fur seals were collected nia. The principal locations where this fish occurred, as Indi whose stomachs contained jack mackerel, 1958-66. cated in stomachs of fur seals, are shown in Figure 23. The jack mackerel was second only to the anchovy in frequency of occurrence in midwater trawl catches conducted by CalCOFI scientists, with the highest catch rates and largest catches made in the southern and northern California regions (Mais 1974). Jack mackerel larvae are abundant in offshore regions from March through July (Kramer and Smith 1970). Although the jack mackerel is widely distributed through the eastern North Pacific Ocean from Baja California, Mex ico, to the Aleutian Islands (Fig. 24), it occurred in only one stomach of a fur seal north of California during 1958-74, probably because jack mackerel prefer warmer water and migrate into the Gulf of Alaska only in summer. Very few seals have been collected during summer in areas outside the Bering Sea. 40· Jack mackerel exhibit both coastal (north-south) and inshore offshore movements. The larger and older fish are found off shore in deeper water, whereas the younger fish are generally found over rocky banks and shallow coastal areas (MacCali et 30· al. 1980). Juvenile jack mackerel stay inshore (0-90 km) for the 1 and 2 Gillnet catches 3 and 5 Eggs and larvae first 3 to 6 yr of their lives, gradually moving farther offshore 4 Night light stations with increasing age and size. Young fish commonly school beneath floating kelp in the open ocean (Mais 1974). Fur seals, which are often found in association with floating kelp, may be attracted by these juvenile jack mackerel. The entire jack mackerel resource of the eastern Pacific Ocean was estimated between 2.1 and 4.8 million tons and the Figure 24.-Distribution of tbejack mackerel resource (modified from MacCall et California and Baja California resource at 1.4 to 2.4 million a1. 1980). 19 tons (Ahl trom 1968) . Ahlstrom' eSllmate is comlderably Oceanic quid.- The Ul:eanlC qUld~ Onycholeulhi\ p. and higher than MacCall et aI.' (1980), who e timated the current o horea/ljapOntCU5 wer'c comhlncd In thi~ report for ali for· pawning bioma to be I to 2 million tons, with 1.5 million ilia (shov.n a OnychotC'uthH p. in r igurc 7) as important tons as the working e tlmate. food of lur \Cab during January and f'ebruary, According to Young (1972), 0. horea/ljaponicu<; i\ the only pecIc found ablefi h.-The sablefi h IS distributed throughout the here, 0 hankHl repla ing it In ubtroplcal and tropl(al water. North Pacific Ocean from the Bering ea south to northern Okutanl and Mc(,ov.an (19fi9) nportcd that 0 bankHl.",a Baja California and along the Alan coa t from Kamchatka the rilth mmt abundant qUid In the alC or 1 urvey area and outhward to the northea tern coa t of Japan. This species was wa~ pre ent throughout Ihe entire allforllla urrent Sy tern. among the prinCipal prey of fur eals taken in v.aters off ali The occurrenlC of thl qUid In toma h 01 fur eal taken fornia dUring May (Fig. 7) and it was also important to fur olf ahfornia arc hO\\n In r I urc 2fi . eal In area north of ahfornia (Table 3). In water~ 01 r ali forma, mall Immature sable fish are common In Inshore water, particularly in pring and summer. Fur seals, howe'.er, vacate the area about this lime to return to the Pribliof Is l~nds. ablefish generally move to deeper v.ater as they In· crt!ase In age and Ize \\ith adult inhabiting the deeper \\ater along the continental slope and beyond throughout much 01 the ea tern orth Pacific Ocean. Sablefi h occupy a \\ide range of depths, \\lth adult II h showing daily diurnal movement from depths belo\\ 1'i0 m. Juvenile fish inhabit the near urface and coastal \\ater to depths < 150 m (Fig. 25). ablefi h were located In greate t number between 366 and 823 m off the coasts of Oregon and Washington (Heyamoto and lton 1965). Although there are no bioma e timates for sablefish oft California, thi specie is the mo t abundant roundfi h taken by otter tra\\ler ; Frey (1971) reported that It could \\Hh tand a greater rate of exploitation. Lov. et al. (1976)" reported that the relative distribution of e ploltable ablefish biomds for , '. .~~. , , the California-Vancouver and Bering ea Region I 13~0 each .. .. -the Aleutian Region 71170, \\ith the highest concentration .~ located in the Gulf of Ala ka contributing 67~0. Sablefish spawn from December to April, with peak adl\IlY . , M/, occurring during January and Februar} in deep \\ater (250-750 -';,~j •. m). There is no evidence of a spa\\mng migration The} are •..If:- • .~ . relatively fast growing, attaining an average length of about 33 s : ... cm at the end of their first year and enter the fi her) near the end of their second year when about 43 cm in length (Fre) .~ . \ .. 1971) . Fur seals prey on the mailer ablefish before the) move *-:' into deeper water as mature fish. " "Loy,. L. L.. G K Tanonaka, and H. H. ShIppen. 1976. Sabletlsh of the north eastern Pacific Ocean and Bering Sea. Processed rep .. 115 p. Nonhy,est and Alaska Fish Cent, atl Mar. Fish Sen.., NOAA. 2725 \lontlake Bhd. E. eat Figure 26.-Localion .. off Cilliromia .. here 448 northern fur >eab .. ere collected tie, WA 98112. ..ho e >lomach, conlained OnJ<,holeurhis po, 1958-66. Bering ea ,...... ------~--~------~-~Surfon E99~0 Larvae I Ju er- .?s ~ 100 55 II to 4 yeo .- The Bering Sea marine fish fauna i made up of about 3 Do" , / ' 200 109 pecies of fish repre entlng about 40 famille (Qua t and Hall 300 - 64 O,u,nolldo,l, I ',", / 1972; Wlhmovsky 1974) From thl group, fur eals are known movemenl / / 400 .... 218 E ~ 0 to prey on fish species from 17 famlhe . Some have occurred 500 ~ -273 = ::l; ~ only rarely in the stomach of ampled eal while some species 20 (able to.-Food of fur seals In t.be etISIem Bering Sea, June-October 1958-74. 91070 of the stations fished): econd, reen nd tur Months curred in 78% of the station fi hed): ele\'enth, P Ii he (occurred In 37% of the tat ion fi hed); and pclin en oed items June' July Aug. Sept. Oct. teenth place occurred in 22ct1o of the tlon Ii hed Pere If ct ish: al. 1976"). Principal forage ie of fur I Entosphenus tridentatus x trawl catches include Atka mackerel, P lfic Clupea harengus pal/asi x 4 x sea smelt, salmon, and sauids. Salmonidae x x in Oncorhynchus spp. x x x Although we know tnat tra .... l are elective (due to the O. gorbuscha x ability to sample all substrates and Incomplete 0. keta x x water column) and that estimates of standm O. nerka x x sentative only for those species which are x x x x Osmeridae trawl, the total fish biomass for the Benng ea .... a Urn ted Mallotus villosus 2 3 3 Thaleichthys pacijicus x x x x at 4.4 million tons (Pereyra et al. footnote 13). I h of fMu, Bathylagidae x x x lies Gadidae and Pleuronectidae accounted for 0 er 0 of Myctophidae x the Bering Sea fish catch. Based on tra .... l urve ,the hI Lampanyctus sp. x biomass of fish was reported at the outer heir region, u re Gadidae x x 2 2 and 3 (Fig. 27), which represented 63ct1o of the Ii h blom Gadus macrocephalus x x Theragra chalcogramma 3 of the entire survey area. The average Ii h Latch rate .... Sebastes spp. x est in subarea 2. A noplopoma fimbria x x x Ichthyoplankton surveys conducted in the e~ tern Berm Hexagrammidae x x Sea are not as extensive as those conducted b Ie P I off Pleurogrammus monopterygius 2 x x x 2 California. Waldron (1981), in summarizing ichthyorlankton COllidae x x Cyclopteridae x x studies conducted in the Bering Sea ince 19 5 by J ap n, the Aptocyclus ventricosus x U.S.S.R., and the United States, reported that the lar of Trichodontidae x over one-third of the genera, over one-half of the famlh , nd Trichodon trichodon x only about one-fifth of the species of fish present as dult III Ammodytes hexapterus x x x x x the Bering Sea have been collected and Identified. Much of the Bathymasteridae x x Anarchadidae x ichthyoplankton surveys m the past ha\e entered on alle e Anarhichas orientalis x x pollock. These surveys also show pollock (\anae and ) to Pleuronectidae x x x be the most abundant taxa accounting for more than 9Sct:o of x Hippoglossoides stenolepis the catch (Waldron and Vinter 1978"). Reinhardtius hippoglossoides x x x Unidentified x x x x x In the Bering Sea, as for the waters off California, the I tephalopods: tion of fur seal collection influence the importan e of dIffer Gonatidae x x x x ent prey species as the prinCipal forage food. If fur eaJ re Gonatus sp. x x x x Berryteuthis magister 4 4 2 x Gonatopsis borealis x 3 x 4 "Pereyra, W. T., J. E. Reeves. and R G BakkaJa 1976 Dmtenal fi h Urudentified squid x x x x 3 shellfish resources of the eastern Benng Sea tn the baseline cear 19 Pr tomachs with food 69 924 1,441 375 29 rep., 619 p. Nonhwest and Alaska FIsh. Cent , all ltu Fish 17 364 560 145 3 itomachs with trace 2725 Montlake Blvd. E., Seattle, WA 98112. 74 651 929 144 14 IlOmachs without food "Waldron, K. D., and B. M. Vinter 1978. I,hthyoplan ton oflhc castcm Her 'Numerals indicate the ranking of principal prey species based on percentage of ing Sea. Processed rep., 88 p . Nonh" est and Ala! 8 fI h Cent, atl tar F Serv., NOAA, 2725 Montlake Bh·d. E., Seattle, \\ A 112 tal stomach content volume. Dther species of pelagic cephalopods known to inhabit the ~ering Sea are deepwater species and therefore are probably at available to fur seals. Three families of fish-Salmonidae, Gadidae, and Pleuro r ectidae-support the major commercial fisheries for finfish the eastern Bering Sea. Pacific salmon, of course, are im ortant in the Bristol Bay salmon fishery and northward into he Kuskokwim-Yukon area. The other two families make up e commercially important trawl fishery resource in the east rn Bering Sea. The relative abundance of the commercially port ant trawl or bottom fish resources in the Bering Sea is latively well-known based on commercial fish catches and rom U.S. research vessel surveys. The noncommercial specIes e not as well documented. The rank order by frequency of occurrence (11'0) of the 20 a t common fish species in the eastern Bering Sea (based on ra" I catches) includes four of the principal forage pecie of .,gurr2 .- lJIti ur seals. In order these are: First, walleye pollock (0 curred in 21 taken near the Aleutian Islands and Passes, the principal prey move to the spawning areas along the outer shelf west an appear to be the Atka mackerel and capelin. If seals are taken northwest of Unimak- Island in spring and to the outer and beyond the shelf over deep water, the forage species will likely central shelf in summer. In 1973 and 1974 when sampling wa be oceanic squids of the family Gonatidae or deepsea smelts of limited to an area around the Pribilof Islands, walleye polloc the family Bathylagidae. Fur seals taken over the shelf are (and gadids which were most likely walleye pollock) were tho likely to be feeding on walleye pollock, Pacific hernng, and leading forage species of fur seals, contributing 82 and 860/0 of Greenland turbot. The principal forage specIes utilized by fur the total stomach content volume. ur seals forage on pecle seals in the eastern Bering Sea are shown in Table 3. other than walleye pollock when taken nearer the Aleutian Is lands and the Aleutian Passes or beyond the helf over deep Walleye pollock.-Walleye pollock has been among the water. leading prey species (Fig. 28) during the 7 yr that fur eals were Walleye pollock is the most important demer al fish popula collected in the eastern Bering Sea (Niggol et al. 1960"; Fiscus tion In the eastern Bering ea in terms of bIomass and landin et al. 1964, 1965; Fiscus and Kajimura 1965; Marine Mammal in the fishery and is the most abundant and most frequently Biological Laboratory 1970; Kajlmura et al 1974'6; and Kajl occurring species in the eastern Benng ea. It biomass fro mura and Sanger 1975"). The walleye pollock occur as the the 1975 urvey wa e timated at 2.4 million metric tons (t) or leading prey species when fur seals are collected on the helf or 41070 of the total fauna available to the trawl gear. Total bio near the shelf edge. This fish wa al 0 the mo t frequently rna s for all pecie wa e tlmated at 5.9 mIllion t (Pereyra el eaten prey of fur seals as reported by Lucas (1899). aJ. footnote 13) . Vanous e lImates of ab olute population ize V alleye pollock are widely di tributed over the continental of eastern Benng ea walleye pollock based on re earch sur shelf III the eastern Bering Sea, forming chool near bottom veys, commercial fisherie catch data, and model e timates are during daylight and then dispersing into the water column at shown in Table II. Thl emlpelagic fi h is al 0 the target of night (Smith 1981). Smith also reported that the ea onal the large tingle specIe fi hery in the orth Pacific Ocean, movements of walleye pollock show that the. helf population \.\'here the commercial catch reaked at more than I. million I retreat to deep water along the outer helf edge In winter. They in 1972 and e 'ceeded more than 1_2 million t In 1970 through 1976 (Table 12) . Thl re ie ha a \.\'Ide dl tnbutlon extending from centra 'Niggol, K., C. H. Fiscus, T. P. O'Brien, and F. Wilke. 1960. PelagJc fur seal 10· California north\.\'ard through the Benng ea, ea of Okhotsk, \,estigations-Alaska 1%0. Unpubl. rep., 60 p. U .. Fish Wild!. en.,. tar. Mam· mal BioI. Lab., Seattle, Wash. (Avail. Natl. Mar Mammal Lab, 'orthwest and and the ea of laran (Hart 1973). ot only IS it abundant in Alaska Fish. Cent, Natl. Mar. Fish. Serv , NOAA, 7600 and POlOt Way E., the Bering ea (Fig. 29), it i also rerorted abundant at time Seattle, WA 98115.) near Kodiak I land. n 0 km long choolof pa\.\'ning walleye "Kajimura, H., G. Sanger, and C. H. Fiscus. 1974. Part 5. Pelagic, Bering ea. rollock (one to everal kilometer wide and 5 m deep) \.\'a In Marine Mammal DiviSIOn, Fur seal investigations, 1973, p. 31-47,71-95. Un publ. rep. Northwest and Alaska Fish. Cent.. atl. Mar. Fish. erv., OAA,7600 sighted on the we t ide of helikof trait by the MF urve} Sand Point Way NE .. Seattle, WA 98115. yes el ~lll1er Freeman in mid-March 19 0 (Fitzgerald 19 0). 'Kajimura, H., and G Sanger 1975 . Part 5 Pelagic-Benng Sea In Marine 1975 ~IF tra\.\'1 survey of the ea tern Benng ea found Mammal Division, Fur sea!lOvestigations, 1974, p. 38-54, 102-112. Unpubl. rep Northwest and Alaska Fish. Cent., atl. Mar. Fish Serv NOAA, 7600 and fi h den ity hlghe t in the area north of nimak I land ( ub Point Way NE., Seattle, WA 98115. area 2) of all subarea sampled. The pre ence of a large bio- .. .. . + Bering Sea .. ". 'f'+ 1'+ + p~ .. r .<:J /' '5 00\1 16,' 0(\1 16J 00\1 1')9 0" .... Figure 28.-Locations where 503 northern fur seals were collected whose stomachs contained walleye pollock, 1958-74. 22 Table ll.-Summary of estimates of absolute population size for eastern Bering Sea walleye pollock (from Smitb 1981). Estimated population Source Region and time period' Method' (X 10't) Based upon research survey data Pereyra et al. 1976' Eastern Bering Sea shelf, Unimak Pass 2.426 to 61 ON (August-October 1975) Bakkala and Smith 1978' Eastern Bering Sea shelf, Unimak Pass 0.679 to 59°N (April-June 1976) Okada 1978'; Nunnallee 1978' Aleutian Basin (June-July 1978) 0.840 Based upon commercial fisheries data Chang 1974 Eastern Bering Sea shelf, INPFC areas 2.3-2.6 I and 2 (1%9-1970) Chang 1974 Eastern Bering Sea shelf, INPFC areas 2 2.3-2.4 I and 2 (1970) Low 1974 Eastern Bering Sea, primarily INPFC 3.45-5.83 areas I and 2 (1964-1971) Based upon model estimates Laevastu and Favorite 1977' Eastern Bering Sea shelf 8.235 'A description of INPFC (International North Pacific Fisheries Commission) statistical areas is given in Forrester et al. (1978). 'Estimation methods: I = "area swept" (Baranov 1918; Alverson and Pereyra 1969); 2 = "cohort analysis" (Pope 1972); 3 = "model fitting" based upon commercial fisheries data. ' Pereyra, W. T., J. E. Reeves, and R. G. Bakkala. 1976. Demersal fish and shellfish resources of the eastern Bering Sea in the baseline year 1975. Processed rep., 619 p. Northwest and Alaska Fish. Cent., Natl. Mar. Fish. Serv., NOAA 2725 Montlake Blvd . E., Seattle, WA 98112. 'Bakkala, R. G., and G. B. Smith . 1978 . Demersal fish resources of the eastern Bering Sea: spring 1976. Processed rep., 234 p. plus 534 p. append. Northwest and Alaska Fish. Cent., Natl. Mar. Fish. Serv., NOAA, 2725 Montlake Blvd . E., Seattle, WA98112. 'Okada, K. 1978. Preliminary report of acoustic survey and mid-water trawl on pollock stock of the Aleutian Basin and adjacent waters in summer of 1978 . Unpub!. manuscr., 13 p. [In Jpn., Engl. summ.] Jpn. Fish. Agency, 2-1, Kasumigaseki, Chiyoda-Ku, Tokyo, Jpn. 'Nunnallee, E. P. 1978. Report on observations aboard the Japanese research vessel Tomi Maru 52 during a Bering Sea (Aleutian Basin) pollock survey conducted in June-July 1978. Unpubl. manuscr., 31 p. Northwest and Alaska Fish. Cent., Nat!. Mar. Fish. Serv., NOAA, 2725 Montlake Blvd. E., Seattle, WA 98112. ' Laevastu, T., and F. Favorite. 1977. Preliminary report on dynamical numerical marine ecosystem model (DYNUMES II) for eastern Bering Sea. Processed rep., 81 p. Northwest and Alaska Fish. Cent., Natl. Mar. Fish. Serv., NOAA, 2725 Montlake Blvd. E., Seattle, WA 98112. Table 12.-Summary of annual catcb (metric tons) of walleye pollock from the mass of fish in this area throughout most of the year may be eastern Bering Sea by trawl flSberies, 1964 to 1979.' (From Smith 1981.) due to its richness as a foraging area as well as to the fact that it is generally ice-free throughout the year. Zooplankton, such as Republic of China, copepods and euphausiids, and planktivorous fishes, like Year Japan U.S.S.R. Korea Taiwan Poland Total capelin and Pacific herring, are abundant throughout the year. 1964 174,792 0 0 0 0 174,792 1965 230,551 0 0 0 0 230,551 1966 261,678 0 0 0 0 261,678 Capelin.-Capelin, a member of the smelt family Osmeri 1967 550,362 0 0 0 0 550,362 dae, is one of the principal forage species of fur seals in the 1968 700,981 0 1,200 0 0 702,181 eastern Bering Sea (Fig. 8). This fish occurred among the lead 1969 830,494 27,295 5,000 0 0 862,789 1970 1,231 ,145 20,420 5,000 0 0 1,256,555 ing four prey species consumed by fur seals during 1960-64 1971 1,513,923 219,840 10,000 0 0 1,743,763 (Niggol et al. footnote 15; Fiscus et al. 1964, 1965; Fiscus and 1972 1,651,438 213,896 9,200 0 0 1,874,534 Kajimura 1965). The occurrences of capelin In 1960-63 were 1973 1,475,814 280,005 3,100 0 0 1,758,919 primarily near the Aleutian Islands (Unimak Pass) and in 1964 1974 1,588,390 1,252,777 309,613 26,000 0 0 in seals taken north of the Pribilof Islands (Fig. 30). Capelin, 1975 1,136,731 216,567 3,438 0 0 1,356,736 1976 913,279 179,212 85,331 0 0 1,177,822 however, were not among the principal prey species when am 1977 868,732 63,467 45 ,227 944 0 978,370 piing was limited to an area around the Pribilof Islands in 1973 ' 1978 821,306 92,714 62,371 3,040 0 979,424 and 1974 (Kajimura et al. footnote 16; Kajimura and Sanger ' 1979 (774,630) (60,000) (85,000) (5,000) (25,000) (950,000) footnote 17). 'Bakkala, R., L. Low, and V. Wespestad. 1979. Condition of ground fish resources Capelin are distributed both in the North Atlantic and the in the Bering Sea and Aleutian area. Unpubl. manuscr., 107 p. Northwest and Alaska North Pacific Oceans. In the North Pacific, capelin are found Fish. Cent., Natl. Mar. Fish. Serv., NOAA, 2725 Montlake Blvd. E., Seattle, WA from off Washington (Strait of Juan de Fuca) north\\ard to 98112. In ' Preliminary estimates. arctic Alaska and Kamchatka and the Okhotsk Sea south ' Foreign fishing allocations (Pileggi and Thompson 1979). ward to Korea (Hart 1973). This fish IS considered an arctic 23 110' ,60" ,'>0' " .. ..,. .o~, 4' \ • "~~ )( 0 if':i. ~ ., / •• 110' Figure 29 .-Apparenl den II, (U lim' ) of walle). pollock on 'anou rtgioo In lb. ttrn Benng Sea and the Gulf of AIa;kallS uggC$ted from:'loMJ bottom ' .... I ~Uf".} f 197:l-78J al d.plh of 400 m and less (modined from Iton 1981J . J + Gulf of Alaska 6 + I SJ 001". L -+ - .. .. Pr ibi lof Is. • .. -~ .. ~~~--.- .' --~ ~....:. Bering Sea ... 111 CO \l 161 00-' lCiJ 00 1,' 159 co ... Figure 30.-Locations where 920 northern fur seals were collected whose stomachs contained capelln, 1958-74. 24 species with its center of abundance in the Bering Sea (along Atka mackerel.-Atka mackerel was second only to capelin the Aleutian Islands) or Arctic Ocean (Hart and McHugh as the principal forage species based on percentage of total 1944). Capelin are a bathypelagic (benthopelagic) fish during stomach content volume for seals collected in Unimak Pass most of the year and are located near the bottom, moving in and beyond the shelf area between the Aleutian and the Pribi shore as the spawning period approaches (Andriyashev 1954; lof Islands during 1962 (Fiscus et al. 1964). When sampling Trumble 1973; Macy et al. 1978'8). In some parts of the range, was limited to a distance of 55 krn around the Pribilof Islands capelin spawn from April to October, spawning on beaches in 1974, Atka mackerel was the third ranking principal forage composed of fine gravel at high tide. In southern British Co species of fur seals. This species was found in the stomachs of lumbia, this fish spawns in late September andl or early Octo seals taken south and west of St. George Island along the shelf ber (Hart and McHugh 1944; Hart 1973). edge in 1974 (Fig. 31). Capelin ranked 17th by frequency of occurrence (010) of the Atka mackerel is distributed from off California northward 20 most common taxa in the eastern Bering Sea survey con to the Bering Sea and in the Sea of Japan (Miller and Lea ducted in 1975 (Pereyra et al. footnote 13). Little is known as 1972). During the breeding season it is concentrated in waters to the relative abundance of capelin in the Bering Sea but the off the Aleutian Island chain from Attu to Unimak Islands, species was observed in large numbers along the Alaska coast the Alaska Peninsula, the Shumagin Islands, and Kodiak Is in shallow water at about the same time as spawning Pacific land and is widespread in the open ocean at other times. Ever herring (Barton and Steinhoff 1980). Based on the analysis of mann and Goldsborough (1907) reported that at Atka Island fur seal feeding studies and because it is also an important link the larger males arrive first in May to await the females' arrival in the food chains of the North Pacific and Bering Sea for on the spawning grounds which is always near the various many fishes, marine mammals, and seabirds (Ainley and San passes in the Aleutian Islands. They also reported that sea ger 1979; Kawamura 1980; Kajimura et al. 1980), capelin is lions, killed at various times throughout the winter, frequently probably a large and important resource in the North Pacific had stomachs filled with Atka mackerel, an indication that Ocean and associated seas. Based on an ecosystem model, some fish stay near the Aleutian passes year-round. Larkins Laevastu and Favorite (1980) estimated the pelagic fish spe (1964) reported Atka mackerel catches incidental to high seas cies, consisting primarily of capelin and Pacific sand lance, salmon gillnet sampling as the fourth most abundant species biomass to be 4.3 million t for the Bering Sea. Capelin was also caught. Chum, Oncorhynchus keta, sockeye, o. nerka, and found in stomachs of humpback whales (Nemoto 1957). Cape pink salmon, O. gorbuscha, were numbers 1, 2, and 3, respec lin is not fished commercially but is considered an excellent tively. Atka mackerel catches were more abundant in gillnet food by those who capture them on the spawning beaches. catches in the southern Bering Sea-Aleutian areas than in the During an ichthyoplankton survey of the Bering Sea in 1977, northern or southern portion of the Gulf of Alaska. capeiin was the only smelt collected and its larvae were among Ichthyoplankton surveys in 1955-78 were summarized by the largest caught, ranging from 31 to 65 mm in length. The Waldron (1981) who reported that Atka mackerel larvae were larvae are known to move offshore to deeper water after caught at 118 stations on 11 cruises in winter, spring, and sum hatching but little is known of the deepwater phase of the lIfe mer from late February to August. These larvae were distrib cycle of this fish. Eighty-six percent of the capelin were caught uted from the Aleutian Islands to lat. 62°N and from long. at night, primarily over the continental shelf within about 140 160 0 W in Bristol Bay to long. 175°E. In 1977, larvae of the km (75 mi) of Unimak Pass. The larvae of this species were the family Hexagrammidae were the second most numerous larvae sixth most abundant taken (Waldron and Vinter footnote 14). caught with Atka mackerel larvae consisting of about 29% of the Hexagrammidae catch (Waldron and Vinter footnote 14). The larvae were relatively large, ranging from 12 to 30 mm in " Macy, P. T., J . M. Wall, N. D. Lampasakis, and J. E. Mason. 1978 . Resources length, and were caught at stations throughout the survey area of non-salmonid pelagic fi shes of the Gulf of Alaska and eastern Bering Sea, Part during April and May over the shelf and extending well I. Unpubl. manuscr., 33 5 p. Northwest and Alaska Fish. Cent., Natl. Mar. Fish. Serv., NOAA, 2725 Mont1ake Blvd. E., Seattle, WA 98 112. beyond the continental slope. The highest abundance was !CI :os .. <:1 ... Pribilof Is. + ! t + ... +++: ... .. \ .. t Bering Sea , 59 or ~ 167 oow ,6J 00'11 115 CO'J '" 00'11 Figure 31.-Locations where 133 northern fur seals were collected whose stomachs contained Atka mackerel, 19S-74. 25 reported over the shelf during April and over the outer shelf in ing Sea but throughout their range wherever seals are taken May. seaward of the continerltal shelf over deep water (Table 2). The To take advantage of the Atka mackerel's breeding habits, one exception is the market squid, Lo/igo opalescens, which is the commercial fishery for this species is centered near the found principally on the shelf. In the eastern Bering Sea, only Aleutian Islands (most abundant near Atka Island area) and squids of the family Gonatidae have been identified in stom near the Shumagin Islands and Kodiak Island. Commercial achs of fur seals, Although only gonatid squids have been catches by Soviet vessels were reported at about 21,000 t in found in stomachs of fur seals, eight other families of squids, 1977 and the catch quota for the Aleutian area was set at which include 14 to 15 additional species, have been identified 24,000 t in 1979 (Bakkala et al. 1979). The commercial catch of from stomachs of sperm whales taken in the Bering Sea-Aleu Atka mackerel in the Gulf of Alaska averaged 20,600 tons per tian Island areas (Okutani and Nemoto 1964; Kodolov 1970). year in 1974-78 (Alton 1981). Squids of the famIly Gonatidae are found 10 the subarctic Atka mackerel and Pacific saury are the most commonly waters of the North Pacific Ocean and Bering Sea and include found fish prey of humpback and sei whales in the eastern about 12 species representing three genera: Gonatus, Berry North Pacific Ocean. The former is considered one of the leuthls, and GonatopslS (Young 1972; Okutani 1973; aito et favorite foods of humpback whales in waters off the western al. 1977; Anderson 1978; Bublitz 1981). In the Bering Sea, Aleutians and south of Amchitka Island (Nemoto 1957). squids representing each genera have been identified in fur seal Based on U.S. pelagic fur seal studies, it appears that fur seals stomachs. These are Gonatus spp., Berryteuthis magISter, and collected in the Aleutian Islands passes during the summer Gonatopsis borealis (Figs. 32, 33, 34) . The latter two species months (June through October) prey principally on Atka have been among the prinCIpal forage species of fur seals col mackerel. lected during June to October 1958-74 in the Benng Sea (Fig. 7). Oceanic squids.-Oceanic squids constitute some of the Berryteulhis magister \.\as also among the prinCIpal forage principal forage foods of fur seals not only in the eastern Ber- specIes of fur seals 10 the western Alaska area (Fig. 8). Al- 58 0010 .. ·c Pribilof Is .r-, ./ 56 00'" ~ ~ 'r"---~- C'" ~.,..~ , 't' ~ ("):._ ;' '. Bering Sea 54 00 101 11 S 00'11 II OO w 161 00 01 ' J 00 <1 Figure 32.-Locations were 151 northern fur seals were collected "hose stomachs contained Gonatus sp., 1958-74 . .. Bering Sea .. 167 00\1 Figure 33.-Locations where 377 northern fur seals were collected whose stomachs contained Berryleuthis magister, 1958-74. 26 though gonatid squids have occurred throughout the fur seals' the Bering Sea-Aleutian area shown in Figure 35 gives some in range, squids of this family were not among the four principal dication of the distribution of squids. forage species in the areas south of Alaska. Based on estimated catch per unit of effort (CPUE) data by Oceanic squids of the family Onychoteuthidae, Onycho Japan and the United States (in subareas 2, 3S, and 3N (Fig. 27) leuthis sp. and Onychoteuthis borealijaponicus, are principal in the 100 to 400 fathom (183-732 m) depth zone commonly prey species of fur seals off California, Washington, and Brit fished by Japanese and U.S. vessels), the estimated squid bio ish Columbia (Figs. 7, 9, 10) . mass ranged from 16,842 to 27,037 t. The commercial catch of The oceanic squid fauna of the North Pacific Ocean and the squids was about 9,000 t in 1978 and has dropped to about Bering Sea are poorly known but the population of some 5,000 t in recent years (Bakkala footnote 20). The gonatid pelagic squids can probably be considered large based on in squid B. magister is fished near the shelf edge while O. boreali formation obtained from the analysis of stomach contents of japonicus is fished near the Aleutian Islands. 19 marine mammals and seabirds. Sanger (cited in Mercer 1981 ) presented information on the trophic relationship of seabirds Pacific herring.-Pacific herring is important in the food and squids based on stomach contents of seabirds collected in web throughout its range as it is one of the primary forage the Gulf of Alaska and the Bering Sea from 1975 through 1978. foods of many animals in the marine environment including Sanger estimated that consumption of squids by seabirds dur fishes, marine mammals, and seabirds. Pacific herring has ing the summer in Alaska was at least 53,000 t. The population been among the principal forage foods of fur seals in the east of the two species of gonatid squids, B. magister and G. bore ern Bering Sea, southeastern Alaska (Sitka Sound), and espe alis, can be considered a major resource based on fur seal feed cially important to fur seals off Washington and British Co ing data coUected during 1958-74 in the eastern Bering Sea. lumbia, Canada (Tables 6, 7). Even in the first feeding stuclies of fur seals in the Bering Sea, The importance of Pacific herring as forage food of fur seals It was revealed that quids were princIpal forage species (Lucas off the Washington-British Columbia coast (Fig. 36) can be at 1899). Currently B. magister is fished commercially by Japan tributed to an abundant adult herring population estimated at along the shelf edge in the Bering Sea.'o Fiscus (1982) sum about 350,000 tons and the fact that the main feeding grounds marized the known predation by 25 marine mammals on squids for juvenile and immature herring was located off the Strait of and the pos ible predation by 20 other marine mammals in the Juan de Fuca and in Hecate Strait (Hourston and Haegele eastern orth Pacific Ocean and Bering Sea. He also discussed 1980). About 200,000 tons of adults (19 billion fish) are found the species of sqUIds that may be suffiCIently abundant enough in several major concentrations of individual schools (each '0 support a commercIal fishery. containing up to 10,000 tons) scattered along the edges of Sperm whales are known to feed primarily on squids and banks extending along 100 mi of coast off the Strait of Juan de should give a good indication of the a ailable benthic squid Fuca. These aggregations move north or south during the sum fauna of the area. KawakamI (1980), 10 revlewlOg sperm whale mer presumably following their food supply with adult herring feeding, reported that the frequency of sqUIds 10 sperm whale returning to their offshore feeding grounds in April and May. stomachs was between 71 and 94a,to of total stomach contents The abundance of herring in this area is probably the principal In sperm whales taken In the Bering Sea-AleutIan area and reason that Pacific salmon are also leading forage prey of fur 32% for the Gulf of Alaska. The occurrence of qUId and fish seals off Washington and British Columbia (Figs. 9, 10). Both in stomachs of sperm \\ hales taken 10 the Gult of Alaska and herring and salmon apparently feed on the rich zooplankton in the area. The Hecate Strait population (100,000 tons) is "'vIercer, R. W. (editor). 19S1 Proceeding of the sqUId workshop. NWAFC thought to be similar (Hourston and Haegele 1980). Processed rep SI-II, 34 p. onbwe5t and Alaska Fish. Cent.. atl. Mar. Fish. In the Bering Sea, Pacific herring was one of the principal Serv., OAA, 2725 Montlake Blvd E., Seattle, WA 9S112 . foods consumed by fur seals taken during August (Fig. 8), lO R. G Bakkala, onhwest and Alaska Fish. Cent., NMFS, NOAA, 2725 'II1ontlake Blvd . E ,Seattle, WA 9S112, pers. commun. October 19S1 north and east of St. Paul Island. This fish represented 31 a,to of 53001'1 -.d ,-/ r + ( 55 001'1 -.+ S4 OOH 16J OO w ,59 OOW 11:; cc ... '1' 00 .... 16' 00101 FIgure 34.-Locations where 473 northern fur seals were collected whose stomachs contained Gonatopsis borealis, 1955-74. 27 1960 ~ ',,- '; ,:7-p -, ( 0 J 60 N \ It >- -'-~~f1~(~~ R I' i ,,' -1 ' .~ ~ ' ,- Number of animals /-;.,-. '" 0 • squids C fish 0 40~ 500 C 20~ 39 ':) 5 ~ 19 0 1 ~ 4 1963 60 0 N 00 o 0 0 0 0 00 00 00 o 0 O O~ 00 00 0 0 0 0 p' 0 0 0 0 ~,o"'.tf' ~~"'C>'- 0 40~ o o 20~39 00 o 10~19 o 5~9 o 1~4 0 0 160 E 180 0 160 W 1400 W Figure 3S.-Distributioo of squids aod fisb io tbe stomachs of sperm whales from the Beriog Sea aod the Gulf of Alaska, 1960 and 1963 (from Okutaoi and Nemoto 1964). the total stomach content volume in 1964 (Fiscus and Kaji sonal distribution in the eastern Bering Sea (Wespestad 1978'1; mura 1965). The migration of herring in the Bering Sea is such Wespestad and Barton 1981). that in August, herring migrate back to their major winter Pacific herring was the. principal forage fish eaten by fur grounds located northwest of the Pribilof Islands and in late seals taken in Sitka Sound in 1958 contributing nearly 46% of March, they leave the wintering ground and migrate towards the coast where they spawn on intertidal vegetation during " Wespestad, V. O. 1978 . Exploitation, distribution and life history features of Pacific herring in the Bering Sea. Processed rep., 25 p. Northwest and Alaska Fish. spring and early summer. Temperature apparently plays a Cent., Natl. Mar. Fish. Serv., NOAA, 2725 Montlake Blvd. E., Seattle, WA major role in influencing the time of spawning and the sea- 98112. 28 58 CO ... Pribilof Is. • t Bering Sea .' . 17 .! CC\I " . Figure 36.-Locations where 628 northern fur seals were collected whose stomachs contained Pacific herring, 1958-74. Figure 37 .-Locations where 169 northern fur seals were coll ected whose tomach\ contained deepsea smelt, 1958-74. the total stomach content volume for seals taken in this area 22 (Wilke et al. 1958 ). As shown in Figure 11, herring was the fish were not among the principal forage prey of seals taken principal food during February and March as based on sam off Washington in 1972. ples which came mostly from Sitka Sound. Jordan and Gilbert (1899) described a new species of bathy Pacific herring is distributed in coastal waters from Baja lagid which they named Therobromus callorhinus "seal fish" California, Mexico, northward along the North American because it was described from vertebrae found in stomachs of coast into the Arctic Ocean and southward along Asian coastal fur seals taken in the Bering Sea. Chapman (1943) subse waters to Korea, Japan, and the Sea of Okhotsk (Hart 1973). quently identified this "seal fish" as a species of Bathy/agus. In the eastern North Pacific, the major concentrations of her The identification of bathylagids in stomachs of fur seals taken ring abundance are reported from Puget Sound, Washington, in the Bering Sea in 1963 was the first reported occurrence northward to Dixon Entrance and in the Bering Sea (Wespestad since T. ca/lorhinus "seal fish" was reported by Lucas (1899) and Barton 1981; Hourston and Haegele 1980) . from seals collected over deep water in the same area. Lucas Pacific herring are taken by commercial fisheries in south reported "seal fish" as the third most frequent prey eaten by eastern Alaska, Prince William Sound, and the Kodiak Island fur seals; walleye pollock and squid ranked numbers 1 and 2 areas where concentrations of herring become abundant on the ahead of the "seal fish." The "seal fish" were from deep spawning grounds (Reardan 1981a, b). At present the commer water areas between lat. 54°43' and 55°29 'N, and long. cial herring fishery in Alaska and British Columbia is primarily 167°41' and 170°53 'W. for eggs-on-kelp (kazunoko kombu), sac-roe (kRzunoko), and Species of the genus Bathy/agus of the family Bathylagidae the bait fishery. The first two fi~hery products are exported to are bathypelagic offshore in the northeast Pacific Ocean rang Japan and the bait is generally used in the domestic commer ing from Baja California, Mexico, and north into the Bering cial and sport fishery. There is no important food fishery for and Okhotsk Seas (Hart 1973). Chapman (1943) and Rass herring in Alaska but, in British Columbia, a small portion of (1967) reported bathylagid fishes (genus Bathy/agus) a WIde the catch is sold for human consumption and as animal food spread in the world oceans from the Bering and Norwegian to aquariums and zoos. Seas to Antarctica. Fishes of this family are small In size (length 12-25 em), usually found in deep water, and called Deepsea smelts (Bathylagidae).-Deepsea smelts or "seal black or deepsea smelts (Hart 1973). fish" are important food of fur seals in the deepwater areas of Fedorov (1973) listed the depths and habitat for the four the Bering Sea occurring in every collection year since 1963 . species of bathylagids found in the Bering Sea as folio" s: Fishes of the family Bathylagidae ranked fourth in importance Mesopelagie-Bathy[agus ochotensis, 30 to 1,000 m; bathy by volume as food species in 1963, 1964, 1968, 1973, and 1974 pelagic-Leurog[ossus stilbius schmtdti, 0 to 1,800 m; B. (Fiscus et al. 1965 ; Fiscus and Kajimura 1965; Marine Mam pacificus-50 to 1,604 m; and B. milleri-60 to 1,420 m 1- mal Biological Laboratory 1970; Kajimura et al. footnote 16; though there is no estimate on the relative abundance of the e Kajimura and Sanger footnote 17). The "seal fish" was first species, Grinols (1965) listed B. pacificus occurrence a com reported by Lucas (1899) and were found in stomachs of seals mon and the remaining three species as not rare. taken from the deepwater areas of the Bering Sea (Fig. 37). The 10 occurrences of bathylagids off the Washington coast in Pacific sand lance.-Pacific sand lance IS one of (he pnnll May 1972 were also from seals taken over deep water. These pal forage foods of fur seals In the western Gulf of Al ka region during May, June, and luI) (Fig. 38). In 195 , 1960. and 1962, fur seals fed on sand lances near Sanak I land and " Wilke, F., K. Niggol, and C. H . Fiscus. 1958. Pelagic fur seal investigations on Portlock, Albatross, Shumagin. and Da~ld on Bank ~a1ifornia, Oregon, Washington and Alaska, 1958. Unpubl. rep., 96 p. U.S. Fish (Wilke et al. footnote 22; Niggol et al. footnote 15: and FI cu Iidi. Serv., Mar. Mammal Res. , Seattle, Wash. (Avail. Natl. Mar. Mammal et al. 1964). The Kodiak Island helf regIon I an area of abun Lab., Northwest and Alaska Fish. Cent., Natl. Mar. Fish. Serv., NOAA, 76(X) dant zooplankton and high biological productmt) (Kendall et Sand Point Way NE., Seattle, WA 98115 .) 29 Gulf of At IJ • I p, 1 0 8' ng ' .. fl· . fj~u,,·JH .- t o(Olwn .. h." 581 nnnh m fur fcd .. hu ~nd I~n 1 al 1980- ). The abundance of sand Ian e In lhl regIon I prob t \ I: n 10 \ r nd high r lrophl lev el pn:dalor tndudlllg ably due to Ideal oceanographic onditlOn , the fllh LOoplank almon, halJbul, cablflj, and mannc mammal ( Inle> and ton which i the primarj food of sand lance. and the ;1\ ailabl angcr 1979; Hart 1913). rhl p ic \\a reported a one of sandy bottom habitat needed by thi pecIc. the fa~onte 10 d of mlll)..:c (pIked) \\hale olf Japan ( mura The Pacific sand lance is distnbuted III coa,tal \\ater~ from and a)..:llIra 1956). southern CalifornIa north\\ard to the Bering ea. lellllan 1 - lands, Kurile and ommander Islands. and O)..:hots)..: and Greenland lurbot.- 1;\ cn pl:('ie 01 natl I he of the famll, Japan Seas (Hart 1973). Thl fi his \\ldel)' distributed through Ph!UrOneClidJe arc among the 20 mo t common fi h ta a in the the high latitudes of the orthern Hemi phere. The tlantk eatern Benng ea (based on tra\\l ur\ey condu led in 19 5). species, American sand lance-A mmodyres american LIS. Fur eab, howe\ er. generally ha\ e no! preyed on the e demer- which is commonly called sand eel. I fished commercially; the al pecle to an} great e\tent. Thi is probably becau. e of the North Pacific specIes is not fished but probably could support fur eals' habit of -\\allo\\ing Ii h \\hole. The general hape of a commercial fishery. Although no estimate of the relatIve natfi he \\ould make it difficult for fureal to \\allow tho e abundance of this fish is available for the Gulf of Alaska, Lae that are old er than the juvenile stage. The onl, e\ eption i vastu and Favorite (1980) estimated capelin and sand lance ju\enlle Greenland turbot. Other pecie of pinmped (north biomass at about 4.3 million t for the Bering Sea. Sand lance ern ea hon. Eumeroptas jubarus. and harbor eal. Phoca in common with many of the other smaller fishe , form large vitulina), do feed on the e t1atfi he . schools both inshore and offshore and is an Important link be- The first occurrence of Greenland turbot was noted III stom achs of fur seals taken north of the Pribilof I lands III 1963 and has occurred as prey of fur seal from the arne general area in " Kendall. A. W., Jr., J. R. Dunn, R. J. Wototira with J. H. Bowerman, Jr. , subsequent collection in 1964, 1973 , and 1974 (Fiscus et al. D. B. Dey. A. C. Matarese. and J. E. Munk. 1980. Zooptankton, including ichlhy 1965; Fiscus and Kajlmura 1965; Kajimura et a!. footnote 16; oplankton and decapod larvae, of the Kodiak shetf. NWAFC Processed rep. 80-8, 393 p. Northwest and Alaska Fish. Cent., Natl. Mar. Fish. Serv., NOAA, 2725 and Kajimura and Sanger footnote 17). In 1973 . this fish was Montlake Blvd. E., Seattle, W A 98112. the fourth ranking principal finfish foraged by fur seals. The D~~ ______~ ______rincipal occurrences of this fish in fur seal stomachs were group of species based on size. Some election may also ccur rom an area south and west of St. George Island near the on the basis of factors such as taste and texture; howeHr. helf edge and north of St. Paul Island. One fur seal collect ~d these factors can only be studIed through exrerimenta[i n. t lat. 58°03 'N, long. 169°47 'Won 24 August 1963 contained The important point is that within the et of specie~ kno\\ n [0 500 individual juveniles of this species while another seal col occur in the fur seal diet the available evidence POInts to p_ ected in the same general vicinity (lat. 58 °03 ' N , long. portunistic feeding. 69°50 'W) contained 98 individuals indicating the possibility Location is also important in considering dIet of fur seals, as hat this area is a nursery ground for this species. The size of prey species generally differ in abundance from area to area hese fish ranged in length from 45 to 60 mm (tip of snout to (north-south; inshore-offshore) and seasonally. The mIgrator) end of hypural plate) for 14 specimens. patterns of forage species must also be considered since they Among the 20 most common fish species in the eastern Ber may be available to fur seals only at certain times of the year. ing Sea (based on research trawl surveys), Greenland turbot For example, off Washington, Pacific whiting migrate mto the ranked second in frequency of occurrence. This fi sh occurred area in the spring and become available to fur seals. Generally In 78070 of the stations fished in 1975 (Pereyra et al. footnote speaking, the migration of fur seals is probably not mfluenced 3). In ichthyoplankton surveys the larvae of this species was by the movement of migratory fishes on which they feed al he third most abundant flatfish larvae caught. The larvae though the evolution of fur seal migration may have resulted /oNere large, ranging in length from 16 to 22 mm and were pri from preference to feed upon selected prey species. There is no marily taken from the Aleutian Islands northwestward to documentation concerning this subject. Taylor et al. (1955) orth of St. George Island (Waldron and Vinter footnote 14). and NPFSC reports (North Pacific Fur Seal Commission 1962, In the eastern Bering Sea, adult Greenland turbot are con 1969, 1971, 1975, 1980) have shown that a small percentage of idered deepwater flounders that mainly occupy continental Pri bilof Island fur seals intermingle with Asian seals, an indi slope waters whereas juveniles generally occupy the shelf area . cation that food is probably not a major factor in the mIgra Bakkala et al. (1979) reported that the highest trawl survey tion of fur seals. Local movement and distribution IS probably catches for this species occurred northwest of the Pri bilof simply a result of the abundance of the forage species In the Islands. area. Fur seals move to and feed in areas where food is abun The Greenland turbot is an amphiboreal species occurring in dant and depart in search of other areas of concentrated prey the North Atlantic and North Pacific Oceans. In the North when it becomes scarce. Pacific Ocean, adults generally occur primarily in the northern Northern fur seals occupy the subarctic waters of the North portion of the species' range, in deep waters of the Pacific Pacific Ocean southward to the California-Mexican border Ocean from Baja California, Mexico, to Honshu Island, (lat. 32°N) in the eastern Pacific and to about the mIddle of ~apan, through the Okhotsk and Bering Seas (Hubbs and Wili Honshu Island (lat. 36 °N) , Japan, in the western Pacific. In movsky 1964; Hart 1973). Relatively few adults have been the eastern Pacific, the Pribilof Island population (the major taken by trawl fisheries in the warmer portions of its range. breeding islands) numbers about 1.3 million animals or nearly 80070 of the world population of this species. The U.S.S.R. DISCUSSION AND SUMMARY controls the breeding islands used by the remaining fur seals (population of about 485,(00) in the western Pacific. Although northern fur seals feed on a variety o f fishes and The eastern Pacific populations of northern fur seal are squids throughout their range, evidence presented on the found throughout their range from California to the Benng abundance and distribution of the principal prey species sug Sea in nearly all months of the year with few exceptions and gests that fur seals are opportunistic feeders preying on the with peak abundance varying by time and area. Most of the most available species in the area. The principal prey species Pribilof Island fur seals spend about half the year at sea for this study were selected based on the percentage of total (November through May-June) and the remainder on and stomach content volume (fourth largest) by month for each of around the islands during the breeding season. Fur seals are the seven collection areas. most frequently seen in greatest numbers along the continental In examining the variety of prey consumed by fur seals through shelf and slope throughout their range primarily because of out the eastern Pacific range, about 53 species of fish and 10 abundant food resources in this area. Fur seals feed on a van species of squid have been identified from the stomachs of fur ety of fishes and squids throughout their range and as a gen seals. From this total, about 14 species of fi sh and 6 species of eral rule, smaller schooling fishes are usually the princiral for squid are considered the principal prey of fur seals. The list of age species over the continental shelf region and oceamc sqUId principal prey species of fur seals in each of these areas, as are important over deepwater areas seaward of the ontinental based on percentage of total stomach content volume, gener shelf and slope. ally does not change over time even though the ranking by vol Fur seals feed primarily at night, perhaps due to the fact that ume within this list may change. Some species are important in many forage species rise toward the urface after dar~ and more than one area. Some are fished commercially while become readily available to fur seals which feed pnmanl} in others are not of commercial importance but are important the epipelagic and mesopelagic zones. In the majonty ot t ur forage food for many other predators including fis hes, sea seal stomachs examined, the total volume of food in tomach birds, and other marine mammals. is generally highest in fur seals collected soon after daylight. The predominance of single food items in the stomachs of generally diminishes by mid-afternoon and increa e agalO fur seals may reflect the availability and abundance of fish towards dusk as the seals resume theIr feeding actl illc . fur squid species more than it reflects the selection or preference seals usually swallow the smaller prey w hole below the urface of one particular species over another. It is obvi ous that the and bring the larger prey to the surface where the} fIr t brea prey that fur seals are observed to eat is selected from a larger them into smaller pIeces. 31 The leading four prey species consumed by fur seals during Pacific sand lance; cap~lin; squid, B. magister; Atka mackerel; the six collection years off California contributed 82 to 99070 of walleye pollock; Pacific salmon; Pacific herring; and sablefish. the total stomach content volume. From a total of 26 species The major fish-squid resources as related to the principal of fish and 8 species of squid identified in stomachs of fur seals forage species of fur seals off California and in the Bering Sea taken off California, only 6 species of fish and 2 species of were discussed and included the known distribution, abun squid are considered the principal prey of fur seals in this area. dance, and migratory movements for each prey species as an These principal forage species included northern anchovy, aid in understanding the feeding habits of fur seals. In addi Pacific whiting, the market squid, Pacific saury, jack mack tion the principal forage species of fur seals off Washington, erel, rockfishes, sablefish, and the oceanic squid, Onychoteu British Columbia, the Gulf of Alaska, and western Alaska this sp. The first three species were among the four leading for were brieOy discussed. age species during every monthly collection off California. The major fish-squid resources off California (as deter Similarly for the Bering Sea, the principal prey species con mined from bottom trawl, midwater hydroacoustical, and tributed 75 to 99070 of the total stomach content volume during CalCOFI surveys) in order of relative abundance are I) north the seven collection years. From a total of 23 species of fish ern anchovy, 2) Pacific Whiting, 3) rockfishes, 4) jack mack and 3 species of squid identified in stomachs of fur seals taken erel, 5) Pacific saury, and 6) market squid. in the Bering Sea, only 5 species of fish and the 3 species of The northern anchovy was the most abundant, and the larg squid were considered the principal prey of fur seals in this est fishery resource in the California Current System followed area. These principal forage species included walleye pollock; by the Pacific whiting whIch consistently ranked second to an capelin; Atka mackerel; oceanic squids Gonatus spp., Berry chovy in annual estimates of relative abundance in the area teuthis magister, and Gonatopsis borealis; and Pacific hernng. surveyed. Although there was no estimate of rockfish biomass, Deepsea smelt of the family Bathylagidae and salmon were it is known in general terms to be large. The jack mackerel, among the principal forage species during annual collections whIch is of widespread occurrence off California, was second but not when all years' data were combined by month for the only to the anchovy III frequency of occurrence III midwater Bering Sea. Salmon occurred among the principal forage food trawl catches. Pacific saury was considered to be the fifth most of fur seals in 1960 and deepsea smelt in 1963,1968,1973, and abundant species as determllled from CalCOFI surveys. The 1974. Greenland turbot was important in 1973. market squid, found over the continental shelf, was reported Off Oregon, the collections of fur seals were relatively small as probably the most abundant squid off the CalifornIa coast. as seals were collected while vessels were enroute between The rank order by frequency of occurrence (%) of the 20 Washington and California. Of the 14 species of fish and 7 most common fish taxa III the eastern Bering Sea trawl catches species of squid identified in stomachs of fur seals taken in this included four prinCIpal forage species of fur seals. In order area, Pacific whiting, rockfish, northern anchovy, and squids these are: First, walleye pollock (occurring in 91 % of the sta were the principal foods. tions fished); second, Greenland turbot (occurring in 78% of the stations fished); eleventh, Pacific herring (occurring in Off Washington, the principal forage species contributed 64 37% of the stations fished); and seventeenth, capelin (occur to 99% of the total food volume. From a total of 33 species of ring in 22% of the statIons fished). The principal forage fish and 10 species of squid identified in stomachs of fur seals species of fur seals not among the trawl catches included Atka taken in this area, only 8 species of fish and 1 species of oce mackerel, Pacific sand lance, deepsea smelt, salmon, and anic squid were considered the principal prey of fur seals. The oceanic squids. principal prey species included Pacific herring, rockfish, Based on the principal prey species of fur seals (as deter northern anchovy, capelin, eulachon, salmon, Pacific whiting, mined from stomach contents) and the relative abundance of sablefish, and squid, Onychoteuthis sp. the fish-squid resources off California and the eastern Bering Off British Columbia, the principal prey species contributed Sea (based on ocean surveys), we must conclude that fur seals 66 to 95% of the total food volume. From a total of 15 species are opportunistic feeders, foraging on the most abundant fish of fish and 4 species of squid identified in stomachs of fur seals squid species available to fur seals in an area. Opportunistic taken in this area, 9 species of fish, the market squid, and the feeding by fur seals on the most abundant and available spe oceanic squid were considered the principal prey of fur seals cies prevails throughout their range in the eastern North off British Columbia. The principal forage species included Pacific Ocean and eastern Bering Sea. Pacific herring; eulachon; salmon; squids, Loligo opa/escens and O. borea/ijaponicus; sablefish; rockfish; walleye pollock; NOTE ADDED IN PRESS Pacific cod; Pacific whiting; and Pacific saury. In the Gulf of Alaska, the principal prey species contributed The 1983 Draft Environmental Impact Statement (DEIS) on 89 to 99% of the total food volume. From a total of 21 species the Interim Convention on Conservation of North Pacific Fur of fish and 5 species of squid identified in stomachs of fur seals Seals24 shows a decline in the Pribilof and Robben Island pop taken in this area, 7 species of fish including Pacific sand ulations of fur seals to 975,000 and 84,000, respectively. The lance, capelin, Pacific herring, walleye pollock, Atka mack Commander Islands (325,000), Kurile Islands (54,000), and erel, rockfish, and salmon were the principal fishes while San Miguel Island (4,000) all show population increases. Gonatus spp. and B. magister were the principal squids. In the western Alaska region, principal prey species contrib uted 77 to 99% of the total food volume. From the 19 species of fish and 3 species of squid identified in stomachs of fur seals "National Marine Fisheries Service. In Prep. Draft Environmental Impact taken in this area, 7 species of fish and 1 species of squid Statement on the Interim Convention on Conservation of North Pacific Fur ranked as principal prey. The principal forage species included Seals. U.S. Dep. Commer., NOAA, NMFS, Wash., D.C. 32 ACKNOWLEDGMENTS I am especially grateful to Kazuhiro Mizue, University of okyo, and to Kazumoto Yoshida, Far Seas Fisheries Re earch Laboratory, for the thesis suggestion, encouragement md deep personal interest, and for their generous assistance li ven me to make this possible. I am also appreciative for the support and opportunity given )1(' to complete this study by Michael F. Tillman, Director. 'iational Marine Mammal Laboratory. and by Charles Fow er, Manager, Northern Fur Seal Research Program, National '-brine Mammal Laboratory. I am also indebeted to my colleague and friend, Clifford H. Fiscus, whom I have had the pleasure to be associated with, ~nd to work under his general supervision while engaged in an3Imo, B C.) pelagic fur seal research. BARTON, L. H , and D L Sill H J/ t 1980. Assessment of paWnIn hemll!! ( tu~ "arrll Special thanks and credit are due to Rae Mitsuoka for her selected COa5tal ",aters In tbe ea5tan Bcrin ti mely translations; James Peacock and Melody Tune for lnf Lean I 7,60 P many of the graphics; to Jerry Hornof and Freya Skarin for BERRY S S. computer plots; and to Pat Cook, librarian, for her assistance 1912. A rencw of the ccpbalnro 34 OKUTANI, T. Akad. Nauk SSR 84, 237 p. [In Russ.] (Trans!. 1969,393 p., by Inst. Mod. 1973 . Guide and keys to squid in Japan. [In Jpn., Engl. abstr.] Bull. Tokai Lang., Inc., for U.S. Dep. Def., Naval Oceanogr. Off. , Washington, D.C.) Reg. Fish . Res. Lab. 74:83-111. REARDEN, J. 1977. Stock assessment of cephalopod resources fished by Japan. FAO 1981a. Herring: an uncommon common fish, Pan I. Alaska 47(6): 17-19 Fish . Tech. Pap. 173,62 p. 66. OKUTANI, T., and J. A. McGOWAN. 1981b . Herring: an uncommon common fi sh, Part 2. Alaska 47(7):16-19, 1969. Systematics, distribution, and abundance of the epiplanktonic squid 54,55. (Cephalopoda, Decapoda) larvae of the California Current, April, 1954- RICE, D. W. March, 1957 . Bull. Scripps Inst. Oceanogr. Univ. Calif. 14,90 p. 1977. Synopsis of biological data on the sei whale and Bryde's whale in the OKUTANI, T., and T. NEMOTO. eastern North Pacific. Rep. Int. Whaling Comm., Spec. Issue 1: 92-97. 1964. Squids as the food of sperm whales in the Bering Sea and Alaskan Gulf. ROPER, C. F. E., and R. E. YOUNG. Sci. Rep. Whales Res. Inst. Tokyo 18 :111-122. 1975. Vertical distribution of pelagic cephalopods. Smithson. Contrib. OLIPHANT, M. S. Zoo 1. 209, 51 p. 1973 . California marine fish landings for 197 1. Calif. Dep. Fish Game, SMITH, G. B. Fish Bull. 159,49 p. [1981.] The biology of walleye pollock. In D. W. Hood and J. A. Calder OMURA, H., and H . SAKIURA. (editors), The eastern Bering Sea shelf: Oceanography and resources, Vol. 1, 1956. Studies on the little piked whale from the coast of Japan. Sci. Rep. p. 527-551. U.S. Gov. Print. Off., Washington, D.C. Whales Res. Lnst. Tokyo 11 :1-37. SM ITH, P. E., E. H. AHLSTROM, and H . D. CASEY. PEARCY, W. G., E. E. KRYGIER, R. MESECAR, and F. RAMSEY. 1970. The saury as a latent resource of the California Current. Calif. 1977 . Venical distribution and migration of oceanic micro nekton off Ore Coop. Oceanic Fish. Invest. Rep. 14:88-130. gon. Deep-Sea Res. 24:223-245. TAYLOR, F. H. c., M. FUJINAGA, and F. WILKE. PHILLIP, J . B. 1955. Distribution and food habits of the fur seals of the North Pacific 1957. A revie" of the rockfishes of California (FamIly Scorpaenidae). Ocean. U.S. Dep. Inter., Fish Wildl. Serv., Washington, D.C., 86 p. Calif. Dep. Fish Game, Fish Bull. 104, 15 8 p. TRUMBLE, R. J. 1964. LIfe history studies on ten species of rockfish (Genus Sebastodes). 1973 . Distribution, relative abundance, and general biology of selected Calif. Dep. Fish Game, Fish Bull . 126, 70 p. underutilized fishery resources of the eastern North Pacific Ocean. M.S. PIERCE, K. ., and H. KAJIMURA. Thesis, Univ. Washington, Seattle, 178 p. 1980 Acid etching and highlighting for defining growth layers In cetacean VROOMAN, A. M., and P. E. SMITH. teeth. In W F Perrin and A. C. Myrick, Jr. (editors), Growth of odontocetes 1971. Biomass of the subpopulations of northern anchovy Engraulis mordax and Slfenians. Problems In age determinatlon, p. 99-103 Rep. Int. Whal Girard. Calif. Coop. Oceanic Fish. Invest. Rep. 15:49-51. mg Comm , Spec. Issue 3. WALDRON, K. D. PILEGGI , J., and B. G. THOMPSO . [1981.] Ichthyoplankton. In D. W. Hood and J. A. Calder (editors), The 1979 Fisheries of the United States, 1978. U.S. Dep. Commer., NOAA, eastern Bering Sea shelf: Oceanography and resources, Vol. 1, p. 471-493 . atl. Mar. Fish. Serv., Curro Fish . tat. 7800, 120 p. U.S. Gov. Print. Off., Washington, D.C. PlNKAS, L, M. S OLIPHANT, and 1. L. K. lVERSO . WESPESTAD, V. G., and L. H. BARTON. 1971 . Food habits of albacore, blue fin tuna, and bonito in California waters. [1981.] Distribution, migration, ~nd status of Pacific herring. In D. W. Calif Dep. Fish Game, Fish Bull. 152, 105 p. Hood and J. A. Calder (editors), The eastern Bering Sea shelf: Oceanography POPE, J. G. and resources, Vol. 1, p. 509-525. U.S. Gov. Print. Off., Washington, 1972. An Investlgatlon of the accuracy of vmual population analysis using D.C. cohon analySIS . Int Comm. orthwest Atl Fish, Res. Bull. 9:65-74. WILlMOVSKY, N. J. QUAST, J C, and E. L. HALL. 1974. Fishes of the Bering Sea: the state of existing knowledge and require 1972. LIst of fishes of Alaska and adjacent waters with a gUIde to some of ments for future effective effort. In D W. Hood and E. J. Kelly (editors), their literature. U.S. Dep. Commer., NOAA Tech. Rep NMFS Oceanography of the Bering Sea with emphasis on renewable resources, p. SSRF-658, 47 P 243-256. Univ. Alaska, Fairbanks, Inst. Mar. Sci., Occas. Pub!. 2. RASS, T S. (editor) YOUNG, R. E. 1967. Pelagichesk,ye i batipelagicheskiye ryby morovogo okeana (The 1972. The systematics and areal distribution of pelagic cephalopods from It pelaglc and bathypelaglc fishes of the world oceans) Tr. In st. Okeanol., seas off southern California. Smithson. Contrib. Zool. 97, 159 p. 35 60° N GULF OF ALASKA '", .. _f> Brlflsh C oh... mbl' 50~ '0' ~ Sample size COLUMBIA • Y • ...• ,~., ...... f ,.. nO '''', . ~lO'10, l 50· N ~ 1~.L~ " .A ... -; .. w W.,hlnglo 0\ Sample size .....'n • OREGON 40° N ultlOt'l"lt.l CALIFORNIA 30· N JANUARY 180· 160· W 140· W 120· W Appendix Figure I.- Age and ~n compo~illon or northern fur ,.aI, rOlltrltd durin\( J . nuar) 19S8 74 In Iht ..,Itm North Parlfil o.-..n . .... 01.: !!!, "~!u-' "' ~-', I, uri.bl, . .-- '~ 'J - ~ 600 N 24 '" Gulf of Alaska 20 y .. 16 Sample size 12 12 Males • 51 Females 0 .. - COLUMBIA • 24 6 ..." . .,,,,., ...... ~ . 20 Bntish Columbia 16 50C N 12 Sample size 31 Males • w --.J 24 Washington OREGON 20 16 12 Sample size 40° N CALIFORNIA 10 15 20 Age [years) 12 California 10 Sample size JMales • 1409 Females 0 300 N FEBRUARY 1800 1600 W 1400 IN 1200 W Appendix Figure 2.-Age and sex composition of northern fur seals collected during February 1958-74 in the eastern North Pacific Ocean. Note: the vertical scale is variable. 60° N 60 I British Columbia so' 40l Sam ple size Sample size 28M,I", • t 6 45M,," • 177f~.IPlO ~ 92F,,,, .. lnO lO< : 11 ~IO J 10 4b-d),., .qn, ~ IV IS 10 10 ~ A~I"''''''II • COLUMBIA • "...• ,~.,....c... '" ""''': lO,. l Wash ng10n 50° N 1,21 Sample size 101 M,I.... • 1061flll"Uin w 00 :i ~b~ 10• ,. Oreg('n OREGON \4,1 .. . 8F .....~1 1 6 >r 40° N CALIFORNIA n ...... "'qr "... , 11 rf Caillon,. '1'., I. ' .• Sample size ~ rI 10 "", ,,," • 30° N ~ '1 ;:~~.-. z< 1 ~ MARCH 1800 1600 W 1400 W 1200 W Appendix Figure 3.-Alle and sex composiUon or northern rur ""als collected durin9 March 1958-14 in the eastern North Padfic <>eean. Note: the nrtlcaJ scale Is .arlable. \ ~ ~ 600 N 60 British Columbia 50 _'0 y ! Sample size ~Sample size 59 Males _ 61 ~ 30 2SMaies • .. 281 Females 0 19 Ft'males 0 .~ :20 10 10 15 20 10 15 20 Agelyursl Agelvears) COLUMBIA ... - 2'1 Washington • , ...." { .. ,,,,., ...... 20j 16 500 N Sample size 293 Miles • " 1809 Females 0 w 'D 14, Oregon I' OREGON "1 r 101 _I r ~ '.m". ,;,. :I ~ ~~L~~' : ~400 N 15 \""0"''' Age lv~arsl " I California 10 _ • . Apr.1 16M,ll'S • 330 Fem,lrs C , ~\J300N 10IlltiL 15 10 APRIL A~(ve,,"l I 0 0 1400 W 120 W 1800 160 W Appendh Figure 4, - Age and Se"( composition of northern fur seals collected during April 1958-74 in the eastern North Pacific Ocean. Note: the vertical scale Is variable. 600 N Gull of Ala~ka -f1 Sample sIZe ; -4 ••to' ~ ty " WeU~fn A,a\ke .0, ... - 16" • e, '" v OREGON Sample s .ze "l 40° N Somple Sl20 ... 300 N MAY 1800 1600 W 1400 W 1200 W App~ndb•• 'au". S.' - A". and,..., compo,'dun til nurth .. r" 'ur ..... 1.. l' nll ..' ," rct d",.-In" M., 1~" . '7 .. 'n ,h ...... -" .""," .. ,....h ,· ...- .t...... " .•.. "i .....: .h ...... rtk •• _ ...... 60° N Bering Sea 10 8 Gulf of Alaska 2 1 nlllllih Sample size 17 Males 118 Females •0 y Sample size .. 131 Males • IL- 678 Females C 10 15 20 Agelyears) " Western Alaska 10 10 15 20 Age (years) 24 ~- COLUMBIA • British Columbia I .." . .,,~.,...c.... Sample size 20 ":' 87Malel • ~39Ffmalr C 16 2 C 12 Sample size 50° N ISMail's • ~ 80 Females a :. 8 10 15 20 Age (yealS) -""" 10 15 10 Age (years) 306 WashIngton 24] OREGON 20 16 Sample size 12j 18Males _ 31 Females a 8, 40° N 4j CALIFORNIA n 10 15 10 AgetyearsJ 24 CalIfornia 20 Sample size 3 Mal ... s 300 N JUNE 1800 1600 W 1400 W 1200 W Appendix Figure 6.-Age aod sex composition of northern fur seals collected during June 1958-74 in the eastern North Pacific Ocean. Note: the vertical scale is variable. 0 12 60 N Bering Sea '0 331 Gulf of Alaska Sample size 211 Males • " 1365 Females 0 ., 20 .. " 12 Sample size 18 Malel • 74 Females 0 Western Alaska ~ • '6 COLUMBIA I,.., • ':. ",~., Sample size ...... 12 ... SMiles • 44 Fem.les a 500 N f$ Aqelvearl!" 400 N CALIFORNIA 300 N JULY 1800 1600 W 1400 W 1200 W A.o,,"",nct\x ""ltlul'e '7._AIlC! 1iQ)~T""'UU'UI!i"nun" nnnncn. -n. ~ ._ ~~ ..~;- __. .~« uunntl Julll 195&.74 In ,h" ("au'ern Nor,h p .. -.:lne O,"L;'~. -'_._ ... n_ . • _It ...... ~_ ...... ~ _ ~ 600 N 10 Bering Sea _8 !! Sample size GULF OF ALASKA 196 Ma les • 2177 Females 0 .... 31.4 " Western Alaska ~ 20 • I ..., • COLUMBIA ... { ..,,~.,~. 16 12 Sample size a Males • 78 Females 0 500 N .j>. W OREGON 40° N CALIFORNIA 300 N AUGUST 0 180 0 160 W 1400 W 1200 W Appendix Figure 8.-Age and sex composition of northern fur seals collected during August 1958-74 in the eastern North Pacific Ocean. Note: the vertical scale is variable. 12 Bering Sea 60· N 10 ~8 Sample size 49MIIC!1 • GULF OF ALASKA I, 471 FMn.IM 0 .. .. Western Alaska 20 lSi ~ • Sam ple size COLUMBIA I ..." 1M.!" • ;,.'''''''~' r'j )1 F..., .. lnD . ~ . 40· N CALIFORNIA 30· N SEPTEMBER 180· 160· W 140· W 120· W Appendix figure 9 , ARt and '" compo.'l'on or nOMhun rur ,nl. colln'l.d durlna .... pl.mb<"r I 600 N Bering Sea GULF OF ALASKA Sample size ~ • 6 ...., , • ,.,'iII".,.,...· ,:' 500 N Washington 12 .j:>. VI 10 400 N OCTOBER NOVEMBER 300 N DECEMBER 0 0 180 160 W 1400 W 1200 W Appendix Figure to.-Age and sex composition of northern fur seals collected during October. November. and December 1958-74 in the eastern North Pacific Ocean and Bering Sea. Note: the verti cal scale is variable. I u~ b, Ih l olltd lalt' r.. , oodu(lm p ta 46 FIELD RECORD OF FUR SEAL ADUL T : Cruise number ___ Vessel ______Field numkr ______ Date collected LocatIon (state) Example: 18 November 1969 ------ Distribution Sq.: Horiz Vert _____ N .. ______W. Time Water Temperature °c Sex Age Example: 1430 Nearest degree Number in group _____ Tag ______ Length ______cm (nearest) Weight kg. (one decimal, zero or numbe r) Nulliparous _____ Primiparous _____ Multiparous ______ Ovaries: left __ right __ Follicle size: left right (mm) (mm) Uterine horn condition: (L) __ (R) Nulli young (L) (R) Nulli mature (L) (R) post partum (L) (R) nonpregnant parous (L) __ (R) __ Nipple crypts: clean __ dirty __ Visibility ______ FETUS: (yes) __ (no) __ Normal ____ Aborted ____ Resorbed _____ Sex ____ Length cm. Weight ____ grams (one decimal, zero or number) REMARKS: ______ Parts saved: Snout _ _ ___ Stomach ______GT ______Other ______ Initials of examiner ____ Revised 1970 GPO ~96-795 Appendix Figure 12.-Form used to record biological data collected from individual northern fur seals. 47 FOOD HABITS - rUR SlALS 'A(ll __ TOlAl SICJm h Conl.ntl c ... c", .. ,.... N., 1.0 No V ... "",,, ...... ' , I !W1'11 1 3 • • 11 Il .. '- RoundwOrm, tYftl__ fNOJ_ COllECTION OATA ( ..... (D IV Hw' CoIlectrd ___~ _____ FIElO NUMBER -\pp~ndh figure 1.1. I-urm u .....:d 10 n°\.ord lomY h (onltnt IIr nOrlhtrn fur oj 48 Appendix Table I.-Grouping of northern fur seals off California, Wash- ington, and the Bering Sea, 1958-74. Total Number of seals per group in the water number Area/year 2 4 Total of seals ------Percen tage------California 1958 33.8 28.5 19.6 9.2 6.3 97.4 1,990 1959 29.7 19.5 13.7 8.0 4.3 75.2 5,132 1961 31.4 28.7 17.0 8.7 6.2 92.0 1,926 1964 29 .8 23.7 18.7 12.7 3.6 88.5 979 1965 50.6 23.7 14.3 6.5 3.1 98.2 1,114 1966 31.3 22.4 16.9 10.5 5.9 87.0 2,704 Washington 1958 56.8 30.6 6.5 3.5 97.4 229 1959 64.0 25.2 6.1 1.2 2.3 98.8 644 1961 41.5 27.9 12.7 4.9 5. 1 92. 1 1,068 1964 64.2 26.9 8.9 100.0 67 1965 31.6 25.3 15 .2 9.4 7.8 89.3 513 1967 43.3 25.4 14.0 9.1 4.8 96.6 835 1968 40.8 24.9 13.6 9.3 5.1 93.7 1,078 1969 37 .7 26.9 12.1 8.5 8.8 94.0 1,136 1970 29.5 27.0 19.0 9.3 6.6 91.4 1,886 1971 39.9 23.9 18 .4 9.7 2.3 94.2 1,323 1972 37.9 29.2 11.7 9.0 4.1 91.9 849 Bering Sea 1960 44.0 30.6 11.8 5.8 2.4 94.6 2,120 1962 43 .7 30.4 14.4 5.2 2.9 96.6 6,111 1963 38.4 26.1 14.3 7.3 4.1 90.2 5,790 1964 56.2 28.1 11.7 2.9 0.8 99.7 1,799 1968 68.0 22.2 7.0 1.8 1.0 100.0 1,509 1973 58.6 25.3 10.1 3.1 0.4 97.5 2,430 1974 57.7 33.6 6.8 0.9 0.3 99.3 1,752 49