THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 299 



When the food supply was limited on Amchitka and several 

 otters were held simultaneously in a pool, we found that large 

 juveniles, weighing 20 lb. (9 kg.) to 30 lb. (14 kg.), maintained 

 health and vigor when fed a minimum daily average of about 6 lb. 

 (3 kg.) of food per animal and that adults could subsist on a 

 minimum average of about 8 lb. (4 kg.) fed daily per animal in 

 morning, noon, and evening feedings. Given these quantities, the 

 animals were always hungry and tended to rob food from each 

 other. Stullken and Kirkpatrick (1955) found that when captives 

 held in dry bedding were given only about 12 to 15 percent of 

 their body weight per day enteritis developed. 



The northern fur seal which, unlike the sea otter, has a thick 

 blubber layer in addition to its fur, was found to require only 

 about 7 percent of its body weight in food per day (Scheffer, 

 1950b). 



C onclusions 



When food was offered daily in excess, the average daily con- 

 sumption by a female during 602 days was about 23 percent of the 

 body weight. The daily consumption varied greatly. Consumption 

 per day ranged from about 5 percent to 40 percent of the body 

 weight. This animal appeared to be in excellent health during the 

 study period. 



When a captive male was offered food that was limited to 20 

 percent of his body weight each day, he consistently ate the 

 amount offered and remained vigorous and healthy. 



At Amchitka when a sufficient number of fish could not be 

 caught, otters were held temporarily in apparent good health on 

 less than the optimum food requirement. Food representing 15 

 percent of the body weight per day was near the minimum tempo- 

 rary requirement. 



COST OF FOOD 



Inquiries have been received concerning the economic possibility 

 of operating a sea otter ''fur farm.*' Aside from the high expense 

 of catching and transporting the animals and building suitable 

 quarters for them, the cost of feeding would be an important con- 

 sideration. 



For 1 year a record was kept at the Seattle Zoo of the cost to 

 feed an adult female sea otter (Susie). The information was 

 given to us by Zoo Director Frank Vincenzi (letter, 8 April 1963) 

 and is summarized below : 



