Chapter II — Species of Special Concern 



Monitoring Haul-Out Sites in Bristol Bay — As 



noted above, most walruses migrate north with the 

 edge of the pack ice as it retreats in spring. Howev- 

 er, some walruses, principally adult males, move 

 south to Bristol Bay in the southeastern Bering Sea, 

 where they remain throughout the summer. To help 

 determine the status and trend of this segment of the 

 walrus population, the Service, the Togiak National 

 Wildlife Refuge, the Alaska Department of Fish and 

 Game, and more recently the Bristol Bay Native 

 Association have cooperated in a long-term effort to 

 monitor three major summer walrus haul-out sites 

 located on the northern coast of Bristol Bay. The 

 three haul-out sites are at Round Island, Cape Peirce, 

 and Cape Newenham. As noted in the previous 

 annual report, counts at these sites in 1997 indicated 

 that at least 9,400 walruses were present in northern 

 Bristol Bay, a number that was 15 percent greater 

 than the average annual estimate over the previous 

 five-year period. 



In addition to these three haul-out sites, another 

 major walrus haul-out site is at Cape Seniavin along 

 the south shore of Bristol Bay on the Alaska Peninsu- 

 la. This site has been surveyed infrequently and 

 information on the number of walruses using the site 

 has been limited. To develop a better estimate of the 

 number of walruses using Bristol Bay in summer, all 

 four major haul-out sites around Bristol Bay were 

 monitored continuously for one month during the 

 summer of 1998. These are the only major land- 

 based walrus haul-out sites in the United States and, 

 for the first time, all four sites were monitored at the 

 same time. Preliminary results indicate that more 

 walruses use Cape Seniavin than previously thought. 

 As of the end of 1998, monitoring data had not yet 

 been fully analyzed to determine a maximum count of 

 walruses hauled out at one time at the four sites. 



Telemetry Studies — In 1995 the U.S. Geological 

 Survey initiated a multi-year study to develop satellite 

 tracking techniques for walruses. Its purpose is to 

 improve understanding of at-sea habitat-use patterns of 

 walruses. After successful trials on 8 animals in 

 Bristol Bay during 1995, 8 walruses were tagged in 

 1996, 18 in the summer of 1997, and 14 in 1998. All 

 tags were attached to adult males at haul-out sites in 

 northern Bristol Bay, most at Cape Peirce, but some 

 at Round Island, and a few at Cape Newenham. 



Time-depth recorders also were attached to five 

 animals in 1997 and to three animals in 1998 to 

 document dive patterns and feeding activity. In 

 addition to providing new insights on the distribution, 

 movement, and ecology of walruses using Bristol Bay, 

 the results are expected to help resolve questions 

 about the proportion of time walruses spend hauled 

 out in order to develop correction factors for use in 

 evaluating aerial survey results. 



The results of work to date have identified pre- 

 ferred feeding areas in central Bristol Bay. They also 

 suggest that, although animals used different haul-out 

 sites in Bristol Bay, there was a strong indication of 

 site fidelity. For example, animals tagged at Cape 

 Peirce appeared to haul out principally, though not 

 exclusively, at that site. To date, tags have continued 

 transmitting for up to 198 days, and some animals 

 have been tracked from their summer habitat in 

 Bristol Bay to the winter breeding grounds off St. 

 Lawrence Island. 



At the end of 1998 it was the Commission's 

 understanding that the U.S. Geological Survey was 

 considering substantially reducing the number of 

 satellite tags it would deploy in 1999, while expanding 

 efforts to test new drugs to immobilize walruses and 

 summarizing study findings for publication. Also 

 being considered were studies to evaluate whether 

 analyses of stable isotopes in walrus vibrissae might 

 be used to determine walrus movement patterns more 

 cost effectively than satellite tagging. 



Assessments of Age-Sex Composition and Repro- 

 duction — Morphological differences in tusks and 

 facial features of walruses have been found useful for 

 identifying the age and sex of individual walruses. 

 With such differences, observers can generally assign 

 specific ages to observed animals younger than age 

 four and also can assign older animals to broader 

 multi-year age groups. Using this ability, researchers 

 on a series of vessel-based walrus surveys conducted 

 early in the 1980s attempted to determine the age and 

 sex composition of the walrus population and the 

 survivorship rates of young animals. Among other 

 things, the studies found that roughly one-third of the 

 mature females were accompanied by calves of the 

 year and another third were accompanied by animals 

 born in the preceding calving season. 



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