15 r- 



10 



5 - 





 10 



o 



c 



5 - 





 10 



30 



Period 2 (08 Mar 78 -25 Sep 78) 



y=-0.18(x)+13.i 



/■=-0.92 



s(y.x)=0.43 



I 



Period 3 (26 Sep 78 -28 Dec 78) 



y=-0.1ii(x)+1205 

 r =-0,81 

 sfy.x) = 0.65 



40 



50 

 Body moss (kg I 



60 



70 



Figure l. — Feeding rate versus individual body mass for eight 

 adult female northern fur seals for Periods 1-3. Standard error 

 of estimate isy.x) is indicated by the broken lines. 



In Period 1, when water temperature averaged 

 8.8° C, the smaller seals required a greater 

 percentage ration than the larger animals, as 

 shown by the slope of the line in Figure 1 ( - 0.327). 

 In Periods 2 and 3, when water temperatures were 

 similar, the variation in feeding rate versus body 

 mass was less, and the slopes of the lines also were 

 similar, as shown in Figure 1 ( - 0.18 and - 0.144, 

 respectively). 



The above equation allows the feeding rate of 

 captive adult females to be predicted with reason- 

 able accuracy, given water temperature and body 

 mass. The artifact introduced by captivity was to 

 allow the seals to enter and leave the water at 

 will. Future studies should be made using adult 

 females that are confined to the water and not 

 allowed to haul out for a length of time (and at a 

 water temperature) that simulates the pelagic 

 phase of the life cycle. 



Acknowledgments 



Michael A. Bigg, Department of Fisheries and 

 Oceans, Pacific Biological Station, Nanaimo, B.C., 

 Canada, reviewed the manuscript. Figures and 

 tables were prepared by Paul Gaj and Laurelyn 

 Schmidt, Sea Research Foundation, Inc., Mystic 

 Marinelife Aquarium, Mystic, Conn. 



Literature Cited 



BIGG, M. A., I. B. MACASKIE, AND G. ELLIS. 



1978. Studies on captive fur seals. Progress report no. 

 2. Can. Fish. Mar Serv. Manuscr. Rep. 1471, 21 p. 

 SCHEFFER, V. B. 



1962. Pelage and surface topography of the northern fur 

 seal. N. Am. Fauna 64, 206 p. 



captivity follows a predictable pattern, implying a 

 precise mechanism for weight control that is 

 seasonally synchronized. Our findings are further 

 confirmation of this. Food intake (and therefore 

 body mass) was greatest from late autumn to late 

 spring. Changes in mass reflected variations in 

 blubber thickness, because all animals were fully 

 mature. 



Changes in water temperature probably account 

 for the seasonal variation in food consumption 

 shown by our seals, although individual differ- 

 ences in metabolism probably were important. 



Stephen Spotte 



Sea Research Foundation, Inc. 

 Mystic Marinelife Aquarium 

 Mystic, CT 06355 



Department of Mathematics and Physics 

 Thames Valley State Technical College 

 Norwich, CT 06360 



Gary Adams 



*Bigg, M. A. 1979. Studies on captive fur seals. Progress 

 report no. 3. Submitted to Standing Scientific Comm., 22d 

 Annu. Meet., North Pac. Fur Seal Comm., 35 p. 



184 



