Pinkas et al. (1971). The numerical component 

 of their formula was deleted because of the dis- 

 parity in size of harbor seal prey items. The 

 modified IRI was calculated as percentage of 

 occurrences multiplied by percentage of volume. 



Results 



Food was present in 269 of the 548 stomachs. 

 Fishes composed 74.5*^, cephalopods 21.5%, and 

 decapod crustaceans 4.0% of the occurrences 

 (Table 2). A minimum of 27 species of fish were 

 identified belonging to 13 families. Cephalopods 

 included both octopus and squids of the family 

 Gonatidae. Decapod crustaceans were primarily 

 shrimps with one occurrence of a crab. The five 

 top-ranked prey of harbor seals in the Gulf of 

 Alaska were walleye pollock, octopus, capelin, 

 eulachon, and Pacific herring (Table 3). 



Regarding prey utilization by area of collection 

 (Table 4), sample sizes were small and collections 

 did not span all seasons (Table 1). Either walleye 

 pollock or octopus was the top-ranked food in all 



Table 2. — Stomach contents of 269 harbor seals collected in 

 the Gulf of Alaska, all areas and seasons combined. [% under 

 Occurrences = Percentage of occurrences and 95% confidence 

 limits.] 



Table 2.— Continued. 



Occurrences 



Volume 



Occurrences 



Volume 



Prey 



No. 



ml 



Cephalopocia: 

 Octopus sp., octopus 

 Gonatidae. squids 

 Decapoda: 

 Stirimps 

 Crabs 

 Rajidae: 



Raja spp.. skates 

 Clupeldae: 



Clupea h. harengus. Pacific 

 herring 

 Salmonidae: 



Oncorhynchus spp.. salmon 

 Osmeridae: 

 Mallotus villosus. capelin 

 Thaleichthys pacificus, 



eulachon 

 Hypomesus pretiosus, 



surf smelt 

 Unidentified Osmeridae, 

 smelts 

 Gadidae: 

 Eleginus gracilis, saffron cod 

 Gadus macrocephalus . 



Pacific cod 

 Microgradus proximus. 



Pacific tomcod 

 Theragra chalcogramma . 

 walleye pollock 

 Zoarcldae: 



Lycodes spp.. eelpouts 

 Scorpaenidae: 



Sebastes spp., rockfishes 

 Hexagram midae: 

 Hexagrammos spp., 

 greenlings 



97 



77 

 20 

 18 

 17 



1 



29 



9 

 67 

 40 



22 



4 



1 



134 



5 



28 



7 



94 



6 



4 



21,5=3.9 

 17.1±3.5 

 4.4r2.0 

 4.0±1,9 

 3.8=1.9 

 0.2 = 0.5 



0.7 = 0.9 



6.4 = 2.4 



2.0=1.4 

 14.9±3,4 



8.8 = 2.7 



4.9 = 2.1 

 0.9= 1.0 



0.2 = 0.5 



29.7 = 4.3 



1.1 = 1.1 



6.2 = 2.3 



1.6=0.7 



20.8 = 3.9 

 1.3=1.2 

 0.9=1.0 



0.4 = 0.7 



20,433 



18,753 



1,680 



3,800 



3,400 



400 



2,780 



6,560 



4,477 

 23,034 

 10,687 



1 1 ,837 



460 



50 



26,603 



395 



3,240 



1,030 



21,938 



60 



810 



400 



20.0 

 18.3 

 1.6 

 3.7 

 3.3 

 0.4 



2.7 



6.4 



4.4 

 22.5 

 104 



11.6 



04 



 0.1 



26.0 



0.4 



3.2 



1.0 



21.4 



1 



0.8 



0,4 



Prey 



No. 



% 



ml 



% 



Cottidae: 



Dasycottus setiger. 



spinyhead sculpin 

 Enophrys bison, buffalo 



sculpin 

 Myoxocephalus spp., 



sculpins 

 Unidentified Cottidae, 



sculpins 

 Trichodontidae: 



Trichodon tnchodon. Pacific 



sand fish 

 Bathymastendae: 

 Bathymaster signatus. 



searcher 

 Ammodytidae; 

 Ammodytes hexapterus. 



Pacific sand lance 

 Pleuronectidae: 

 Atheresthes stomias . 



arrowtooth flounder 

 Eopsettajordani. petrale sole 

 Glyptocephalus zachirus . 



Rex sole 

 Hippoglossoides elassodon . 



flathead sole 

 Lepidopsetta bilineata . rock 



sole 

 Limanda aspera. yellowfin 



sole 

 Lyopsetta exilis. slender sole 

 Parophrys vetulus. English 



sole 

 Unidentified Pleuronectidae 

 Unidentified fish remains 



Totals 



10 22=1.5 



2 0,4 = 0.7 



1 0.2 = 0.5 



2 0.4 = 0.7 

 5 1.1 = 1.1 



10 



19 

 23 



3 



1 



1 



5 



1 



6 

 2 



2 



2 

 17 



2.2=1.5 

 07=09 



4.2 = 2.0 



5.3 = 22 



0.7=09 

 0.2=0.5 



0.2 = 0.5 



1.1 = 1.1 



0.2=0.5 



1.3=1.2 

 0-4=0.7 



0.4 = 0.7 

 0.4 = 0-7 

 3.8=1.9 



451 100.0 



1.912 1.9 



240 0.2 



1 ,430 1 .4 



242 02 



3,025 3.0 



40 0.1 



463 0.5 



2,615 2.6 



150 0.1 



130 0.1 



1,650 1.6 



65 0.1 



620 0.6 



5,320 5.2 



102.332 100.1 



Table 3. — Rankings by modified Index of Relative Importance 

 (IRI, see text footnote 3) of major prey of harbor seals collected 

 in the Gulf of Alaska. Only those prey with IRI 3= 2 are included. 



Rank 



Prey 



Modified 

 IRI 



Occur- 

 rences 



Volume 



Co) 



445 



313 



92 



57 



41 



20 



13 



13 



9 



7 



7 



4 



2 



2 



2 



20.8 

 17.1 

 8.8 

 4.9 

 6.4 

 6.2 

 5.1 

 3.8 

 2.0 

 4.4 

 2.2 

 2.2 

 0.7 

 4.2 

 1.6 



21.4 



18.3 



10.4 



11.6 



6.4 



3.2 



26 



3.3 



4.4 



1.6 



3.0 



1.9 



2.7 



0.5 



1.0 



marine areas and eulachon was dominant in the 

 estuarian and freshwater habitats of the Copper 

 River Delta. Walleye pollock was the top-ranked 

 item in the eastern areas: northeastern Gulf of 

 Alaska, Prince William Sound, and the Kenai 

 coast. In the western areas: Lower Cook Inlet, 

 Kodiak, and the Alaska Peninsula, octopus had 

 the highest ranking. In Lower Cook Inlet, octopus 

 and shrimps made up over 60% of both total 



546 



