FISHERY BULLETIN: VOL. 84, NO. 4 



Gulf of Alaska 



Based on all samples collected in the Gulf of 

 Alaska, the main diet of northern fur seals was 

 Pacific herring when energy content was con- 

 sidered, but Pacific sand lance, Ammodytes hexap- 

 terus, was most important when caloric values were 

 not considered (Fig. 8A). However, there were 

 subregional differences in diet. Off southeastern 

 Alaska, collections were made in Sitka Sound dur- 

 ing February and March where the diet was almost 

 exclusively Pacific herring (Fig. 8B, C). In the north- 

 ernmost area of the region the diet consisted chief- 

 ly of capelin, Mallotus villosus, but also to a lesser 

 degree of both walleye pollock, Theragra chalco- 

 gramma, and Pacific sand lance (Fig. 8C). Off 

 Kodiak Island during April to July, the diet was 

 mainly Pacific sand lance and capelin (Fig. 8B, C). 

 Gonatid squids (Gonatidae) were the primary foods 

 of northern fur seals in oceanic waters of this region 



from April to June. Rockfishes and salmonids were 

 also eaten by northern fur seals in offshore and 

 northern inshore areas of the region (Fig. 8C). 



Western Alaska 



Of the 309 stomachs with food collected in this 

 region from May to October 1958-74, 239 were 

 taken during June, with most of these collected 

 south of Unimak Pass. The main foods of the north- 

 ern fur seals were Pacific sand lance and capelin, 

 as off Kodiak Island, with the energy content of each 

 having little effect on their relative importance (Fig. 

 9). Other important prey were Atka mackerel, 

 Pleurogrammus monopterygius, salmonids, walleye 

 pollock, and the squid Berryteuthis magister. Sable- 

 fish, Anoplopoma fimbria, and Pacific herring were 

 also eaten by northern fur seals south of Unimak 

 Pass during summer months. 



GON 



HER 



CAP .POL 



Prey species 



SND OP 



B 



100 



75 - 



S 50 



Figure 8.— Composition (percent) of diet of northern 

 fur seals by prey species in the Gulf of Alaska during 

 1958-74 (A) for pooled February-July samples (N = 

 1,163), using modified volume (dark bars) and energy- 

 adjusted modified volume; (B) by month using modified 

 volume; and (C) by subregion with pooled February- 

 July samples using modified volume. Key: CAP = 

 capelin; GON = gonatid squids; HER = Pacific her- 

 ring; MF = miscellaneous fish species; MS = 

 miscellaneous squid species; OP = other prey; POL = 

 walleye pollock; ROC = rockfishes; SAL = salmonids; 

 SND = Pacific sand lance; US = unidentified squid. 



100' 



75- 



50 



25- 



HER 



• • • • 



'.SND*. 



  ■_■_•_■. 



*p6l>: 



HER 



CAP 



Mv/;i*y^ 



CAP 



SND 



