356 



Alaska — Oitr Liviit\; Resources 



For further information: 



James L. Bodkin 



National Biological Service 



Alaska Science Center 



1011 E. Tudor Rd. 

 Anchorage. AK 99503 



Johnson, AM. 1987. Sea otters of Prince William Sound. 



Alaska. U.S. Fish and Wildlite Service. Alaska Fish and 



Wildlife Research Center. Anchorage. 1S7 pp. 



(Unpublished rep.) 

 Kenyon. K,W. 1969. The sea otter in the eastern Pacific 



Ocean. U.S. Fish and Wildlife Service North .American 



Fauna 68. .^.Si pp. 



Lcnsink. C.J. 1962. The history and status of .sea otters in 



Alaska. Ph.D. thesis. Purdue University, West LaFavette. 



IN. 188 pp. 

 Riedman, M.L., and J. A. Estes. 1990. The sea otter 



(Enlixcira liitris): behavior, ecology and natural history. 



U.S. Fish and Wildlife Senice s'iological Rep. 90(14). 



126 pp. 



Pacific 

 Walruses 



by 



Gerald W. Garner 



National Biological Service 



Figure. Distribution of Pacific 

 walruses in the Bering and 

 Chukchi seas of Alaska and Russia 

 (Fav 1982). 



Pacific walruses {Odohcnus niMininis cliver- 

 i>ens) live in tiie Bering and Chukchi seas of 

 Alaska and Russia (Figufe). The population is 

 subject to a Native subsistence harvest in Alaska 

 and a commercial and subsistence harvest in 

 Russia. Total annual harvest ranges between 

 5.500 and 10.300 walruses (Fay et al. 1989). 

 The Marine Mammal Piotection Act requires 

 management of the population within an opti- 

 mal sustainable population range, and the sub- 

 sistence harvest by Alaskan Natives cannot be 

 regulated unless the population is declared 

 depleted. 



Pacific walruses are an important source of 

 meat and ivory for Native peoples of Alaska and 

 the Chukotka Peninsula, Russia. The species is 

 long-lived, has a relatively low reproductive 

 rate, and occupies a position near the top of the 

 marine food chain. Thus, besides being a very 

 \ isible species, the walrus may be an indicator 

 of the health of the Airtic marine ecosystem. 

 The United States and the fomier Soviet Union 

 initiated cooperative surveys throughout the 

 entire range of the shared population in 1973 

 and have since conducted periodic surveys at 5- 

 year intervals. 



^jy ■ 



U.S.-Russian Walrus Surveys 



Walruses are gregarious and often form large 

 groups when resting on sea ice or land. This 

 behavior is called "hauling-out," and land sites 

 where large groups traditionally congregate to 

 rest are commonly called "haul-outs." The 

 cooperative U.S, -Russian surveys used aerial 

 counts of walruses on sea ice in the Russian and 



U.S. sectors, aerial and photographic counts at 

 Russian land haul-outs, and ground and aerial 

 counts at U.S. land haul-outs (Estes and Gilbert 

 1978: Estes and Gol'tsev 1984). Aerial surveys 

 were conducted in the U.S. sector during 1975, 

 1980, and 198.S, and were extended to include 

 sea ice within the Russian sector during 1990 

 (Gilbert et al. 1992). Biologists altered each 

 subsequent aerial survey to increase the preci- 

 sion of the estimates (Johnson et al. 1982; 

 Gilbei-t 1986. 1989; Hills and Gilbeil 1994). 



Because of the ongoing efforts to improve 

 the surveys, specific techniques varied among 

 years but the basic design was to fly a series of 

 north-south transects beginning at the edge of 

 the polar ice pack and ending where concentra- 

 tion of ice was sufficient to exclude walruses. 

 Transects were arranged systematically and 

 stratified to achieve maximum coverage of the 

 Chukchi Sea. Transects were located approxi- 

 mately between Pt. Barrow, Alaska, and the 

 mternational border in 1975. 1980. and 1985. 

 and throughout the entire Chukchi Sea during 

 1990. Most land haul-outs also were surveyed 

 from aircraft, either by counts made directly by 

 observers or from photographs. Some haul-outs 

 were visited and counted by observers on the 

 ground. 



Biases were evident in the survey data, and 

 lack of precision was common in all surveys 

 (Estes and Gilbert 1978; Johnson et al. 1982: 

 Gilbert 1989; Gilbert et al. 1992). Surveys, 

 however, were continued because biologists 

 believed that, despite these faults, the surveys 

 would indicate population trends and were the 

 best available method for assessing population 

 size (Johnson et al. 1982: Gilbert 1986). Also, 

 researchers recognized that an unknown and 

 variable part of the walrus population was not 

 available for counting because the number of 

 walruses that were hauled out on land or ice var- 

 ied significantly from day to day (Estes and 

 Gilbert 1978; Gilbert 1989; Gilbert et al. 1992). 

 None of these surveys used a con'ection factor 

 for this unobserved fraction, and no attempts 

 were made to classify walruses by age or sex. 

 Even though population trends cannot yet be 

 reliably determined by these surveys, 

 researchers believe that long-term data from the 

 surveys will eventually provide more definitive 

 information about the status and trends of wal- 

 rtis populations. 



