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Fishery Bulletin 103(2) 



The estimated abundance of sea otters decreased by 

 91-94% in the NAPa study area, which ranged from 

 4236-7240 in 1986 to 374 in 2000 (Table 1). Estimated 

 abundance increased by 95-385% in the NAPb study 

 area, which ranged from 897 to 2238 in 1986 to 4354 in 

 2001. Overall, abundance estimates in the NAP study 

 area declined by 27-49% between 1986 and 2000. With- 

 in the NAP area, sea otters were distributed primar- 

 ily near the coast rather than further offshore as was 

 observed in 1986 (Fig. 3). In May 2000, the majority 

 of sightings occurred in the Port Moller and Nelson 

 Lagoon areas, which had contained few otters during 

 the 1986 surveys. Estimated abundance within the SAP 

 study area declined by 93-94%, from 13,900-17,500 in 

 1986 to 1005 in 2001. Similar to the NAP results, areas 

 that had previously supported dense aggregations of 

 sea otters were largely vacant in 2001 and the areas of 

 highest concentrations were in bays and lagoons. 



Coastline survey analyses 



Between 1986 and 1989 there was considerable variabil- 

 ity in sea otter counts at islands in the south Alaska Pen- 

 insula study area (Table 2). Some areas had increased 

 (Sanak, Caton, and the Pavlof Islands) while others 

 decreased (Deer Island, Shumagin Islands). However 

 by 2001, sea otter counts and density had decreased 

 at nearly all islands and net losses of over 100 otters 

 occurred at Deer, Dolgoi, Goloi, Unga, and Nagai islands. 

 Overall, sea otter counts at these islands declined from 

 2174 in 1986 to 402 in 2001— a 63% decline in density. 

 In April and May 2001 we surveyed approximately 

 3800 km of coastline from Cape Douglas to False Pass 

 (Table 3). Sea otter density in 2001 was 35% lower than 



in 1989 for the three westernmost coastline segments 

 from False Pass to Castle Cape (1782 km of coastline). 

 To the east of Castle Cape, sea otter density was 4% 

 greater in 2001 than in 1989 (2018 km of coastline). 

 These results indicate that an eastward extent of the de- 

 cline along the Alaska Peninsula may occur in the area 

 of Castle Cape. Overall, sea otter density declined by 

 12.4% along the coastline of the Alaska Peninsula from 

 False Pass to Cape Douglas between 1989 and 2001. 



Discussion 



When compared to surveys conducted in 1986, our results 

 indicated that sea otter abundance has declined severely 

 in the SAP and NAPa study areas along the Alaska 

 Peninsula, whereas sea otter abundance increased in 

 the NAPb study area (specifically Port Moller) and east 

 of Castle Cape along the south side of the Peninsula. To 

 determine the geographic extent and magnitude of the 

 sea otter population decline, current data were needed 

 to assess population abundance and trends along the 

 Alaska Peninsula. 



Variations in survey methods limited our ability to 

 assess population trends for the Alaska Peninsula prior 

 to 1986. In 1976, the sea otter population along the 

 NAP was estimated to be 17,000 and continued range 

 expansion was expected (Schneider, 1976). In 1982- 

 83, seasonal estimates of sea otter abundance in the 

 NAP study area varied between March (1454), August 

 (10,325), and October (1880) which led Cimberg et al. 2 

 to speculate that there was a large-scale seasonal mi- 

 gration of sea otters between the Bering Sea and North 

 Pacific Ocean. Sea otter distribution and abundance 



