354 



Aluskii — Our Living Resoiiires 



Fig. la. Distribution of sea otters 

 before fur hardest began in 1741 

 and populations that sur\'ived the 

 harvest, providing the nucleus lor 

 recovery of the species. Width ol 

 shaded area is not relative to sea 

 otter habitat. 



Fig. lb. Current distribution of 

 sea otters including locations ol 

 successful translocations. 



P Kunlls. 



O Pre-1791 distribution 

 • Fur tiaivest survivors 



Russia 



Seaof /'?fja'=„, P„b,lofls.'--r 

 Okhotsk f i ' Mednyls, ^ 



/ * Bristoltoy ^^^. 



Ralls T' -'"W ( Kodiakis, Pnnce ' 

 Delarolls, / Shumagin Is. William 



Kamchatka Sandman 



Peninsula feels 



Pacific Ocean 



Punla Abreo|os .- i '■ 

 (southem limit) "^ 



'„„ . , Bering Sea 

 , Benng Is. ...,- 



Pnbilolls.— -'-. .A,- 



. Aleutian IslanOb 

 JSakhalin i/\ ^ -. ^..- 



^ Kamchatka 

 'Kuril Is. Peninsula 



Hokkaido 



Pacific Ocean 



Successful translocations 

 I Current dislribution 



Canada 



Southeast Al 



San Nicolas ls.€~ 



between sea otters and humans is that sea otters 

 prey on and often limit some benthic inverte- 

 brate populations. Because some of these inver- 

 tebrates are also used by humans (Estes and 

 VanBlaiicom 1985). human perceptions about 

 the effects of sea otter foraging on invertebrates 

 sometimes differ. By limiting populations of 

 herbivorous invertebrates (e.g.. sea urchins 

 [Echinoidea]) otters help maintain the integrity 

 of kelp forest communities. At the same time, 

 sea otter predation on other marine inverte- 

 brates can lead to direct competition with 

 humans for resources. These interactions add 

 complex dimensions to the conservation and 

 management of sea otters, in large pail because 

 of wide-ranging social, ecological, and eco- 

 nomic consequences of sea otter foraging. 



Long-term data on abundance and distribu- 

 tion are available for relatively few sea otter 

 populations. Here we summarize such data 

 from three populations: Bering Island. Russia; 

 Prince William Sound, Alaska: and Olympic 

 Peninsula. Washington. The Bering Island pop- 

 ulation resulted from natural emigration and 

 represents complete recovery. Prince William 

 Sound represents near recovery of a remnant 

 population, whereas the Washington population 



was established via translocations from Alaska 

 and is just beginning to recover. We will com- 

 pare growth rates and current status among 

 these populations. Because of its unique status 

 and growth characteristics, the California sea 

 otter is not treated in this article. 



Population Surveys 



Annual skiff surveys were conducted at 

 Bering Island from 1979 to 1993 (except 1990; 

 Burdin et al. in press). Surveys from skiffs, air- 

 planes, and helicopters were conducted in 1950, 

 1959, 1972, and 1984-85 in Prince William 

 Sound (Johnson 1987: Irons et al. 1988). In 

 Washington, skiff surveys augmented with 

 ground counts were conducted from 1977 

 through 1987, and aerial surveys augmented 

 with ground counts were conducted from 1989 

 to 1993 (Jameson et al. 1986; Jameson 1993). 

 Instantaneous growth rates were calculated by 

 regressing the natural logs of survey counts over 

 time. 



Population Status 



Bering Island 



Bering Island was recolonized by sea otters 

 from nearby Medny Island about 1970. Growth 

 occurred by progressive expansion around the 

 island, with complete occupation of available 

 habitat by 1983. The abundance of sea otters 

 increased at an average of 22% per year, from 

 500 sea otters in 1979 to an estimated 3,835 in 

 1990 (Fig. 2). More than 20% of the population 

 died at Bering Island during the winter of 1990- 

 91 (Burdin et al. in press), suggesting that the 

 number of sea otters exceeded available food 

 resources. Little opportunity exists for emigra- 

 tion as the nearest unoccupied habitat is several 

 hundred kilometers from Bering Island. 



Prince William Sound 



Although no surveys were conducted before 

 1959, at least 150 sea otters were observed in 

 southwestern Prince William Sound in 1951 

 (Lensink 1962). Sea otters had spread through- 

 out all available habitat in the sound by 1985, 

 although growth was still apparent in the east- 

 ern part of the region (Johnson 1987). The over- 

 all growth rate in Prince William Sound 

 between 1911 and 1985 was on average about 

 8% per year (Fig. 2). No density-dependent 

 mortality event, such as observed at Bering 

 Island, has been documented for Prince William 

 Sound. Limited unoccupied habitat that could 

 provide space for dispersing animals is still 

 available both to the east and west of Prince 

 William Sound. 



