THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 19 



be recognized in the natural environment. Seldom, however, may 

 the sex of all adult or subadult otters seen during a period of 

 observation be positively identified. 



During hunting it was demonstrated that recognition of sex in 

 the field is impractical when obtaining skins is the primary 

 objective. Between 31 July and 3 August 1963, officials of the 

 Alaska Department of Game shot 20 sea otters of adult size. 

 Mothers accompanied by pups were omitted from the kill in the 

 hope that a high proportion of males would be obtained. Only 

 one male (5 percent of the kill) was taken in the * 'female areas" 

 where this collection was obtained. 



Body Measurements 



Stullken and Kirkpatrick (1955) described some of the physical 

 characteristics of the sea otter and reported on physiological 

 studies of captive otters. My observations are intended to supple- 

 ment theirs. 



Body weights and lengths of sea otters captured or found dead 

 on Amchitka beaches, or shot in waters near Amchitka, and of 

 otters taken in other Alaska areas are discussed in this section. 

 Because no anatomical feature is known to reveal the exact age 

 of a sea otter, juveniles and subadults are omitted and only data 

 from newly born and adult animals are presented. Sea otters 

 were recognized as adults by observations of adult dentition, suture 

 closure and sagittal crest development of the skull, and of the 

 baculum size in males. 



Total length was obtained by measuring, with a steel tape, each 

 animal from tip of nose to tip of tail as it lay flat on its back. 

 Only the total length is considered in the following discussion. 

 (The mean tail length was found to be 24.5 percent of the total 

 length. The range in 10 adult males was 22.3 to 29.2 percent and 

 in 10 adult females 22.0 to 26.1 percent.) Some animals killed 

 during the Alaska State harvesting operations could not be meas- 

 ured immediately after death. When an animal in rigor mortis 

 was measured, an attempt was made to stretch it to full length. 

 Some of these, however, were probably measured as being slightly 

 shorter than they would have been when relaxed. 



The scales most frequently available were spring scales of 

 50- and 100-lb. capacity. The data as shown in tables were con- 

 verted to kilograms. Small young were usually weighed on a 

 15-kg. capacity balance. 



