PEREZ and BIGG: DIET OF NORTHERN FUR SEALS 



30,- 



BER 



SAL 



CAP POL ATK 



Prey species 



SND 



OP 



Figure 9.— Composition (percent) of diet of northern fur seals by prey 

 species in western Alaska during 1958-74 for pooled May-October samples 

 (N = 309), using modified volume (dark bars) and energy-adjusted modified 

 volume. Key: ATK = Atka mackerel; BER = Berryteuthis magister; 

 CAP = capelin; OP = other prey; POL = walleye pollock; SAL = 

 salmonids; SND = Pacific sand lance. 



Eastern North Pacific 



Northern anchovy (20%) and Pacific herring (19%) 

 were the main species eaten by the northern fur 

 seals in the eastern North Pacific when data from 

 all regions and months were pooled (Fig. 10). These 

 prey were the most important whether energy con- 

 tent was considered or not, although importance in- 

 creased when the caloric values were included. 

 Salmonids (6%), capelin (8%), Pacific whiting (7%), 

 walleye pollock (2%), Pacific sand lance (8%), and 

 rockfishes (4%) were also commonly eaten. The re- 



maining diet was made up of a wide variety of squids 

 (mainly market squid, 6%; onychoteuthid squids, 

 6%; and gonatid squids, 5%) and other fishes (mainly 

 Pacific saury, 4%; sablefish, 2%; and Atka mackerel, 

 2%). Squids were the primary food species in oceanic 

 waters between California and the Gulf of Alaska, 

 and fishes were the main prey in the neritic areas. 

 Although not eaten in large amounts, salmonids and 

 rockfishes were the main fishes consumed in oceanic 

 areas between Washington and the Gulf of Alaska 

 (Figs. 6C, 7C, 8C). 



O 



■D > n. 



£ > ° 



*o-= 



Ox 

 Z O 



uiZ 

 I cc 



o» 



<o 



Figure 10.— Composition (percent) of diet of northern fur seals by prey species in 

 the eastern North Pacific (excluding the Bering Sea) during 1958-74 using modified 

 volume (dark bars) and energy-adjusted modified volume. Data from all months and 

 years were pooled (N = 5,624). 



965 



