THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 269 



Between 4 and 14 June 1960, the late Tom O'Brien and I camped 

 on Simeonof and Little Koniuji Islands. We circumnavigated 

 Simeonof and made other dory trips to several beaches on Little 

 Koniuji and Herendeen Islands. Also, v^e walked more than 

 15 miles on beaches. At least 80 percent of the beachline that we 

 searched was adjacent to favorite sea otter feeding and resting 

 areas. 



We searched beaches carefully but were able to find remains of 

 only one adult male sea otter on Simeonof and fragments of one 

 juvenile skeleton on Little Koniuji. Both animals had been dead for 

 several months. Considering that during aerial surveys of these 

 same areas on 10 April 1962 we counted 549 otters, the observed 

 mortality there was low. 



Mortality observations in the Shumagin Islands and data pre- 

 sented in the sections on Body Measurements, Food and Feeding 

 Behavior, and Distribution and Numbers, when compared with 

 similar data from Amchitka, indicate that the Shumagin popu- 

 lation (4 otters per square mile of habitat) was not overutilizing 

 food resources as was demonstrated for the Amchitka population 

 (19 otters per square mile of habitat) and that winter-spring 

 starvation and accompanying mortality did not occur. 



MORTALITY ON THE SANAK ISLANDS 



The Sanak Islands include Sanak, Caton, and a number of small 

 islets and rocks. The population density of this area was estimated 

 to be about two otters per square mile of habitat (see Distribution 

 and Numbers). 



In 1960, O'Brien and I spent from 20 to 23 June exploring this 

 area. We landed via dory on Caton Island and seven smaller islets 

 (Leda, Wanda, Elma, Telemitz, Peterson, and Mary Islets, and 

 Princess Rock). We searched more than 10 miles of beach and 

 found the skeletal remains of only one adult female otter, indicat- 

 ing that little winter-spring mortality had occurred. 



Discussion 



The analysis of data obtained from two classes of populated sea 

 otter habitat were presented. The criterion of population density 

 was the number of otters per square mile of water less than 30 

 fathoms deep. It was shown that at Amchitka the population was 

 crowded during the study period, having about 19 otters per 

 square mile. The outer Shumagin Islands and Sanak Islands were 

 not crowded, having respectively about four and two otters per 

 square mile. The estimated annual winter-spring mortality at 



