290 
Fishery Bulletin 96(2), 1998 
Table 3 
Stomach contents of juvenile salmon in marine waters of southeastern Alaska and northern British Columbia in 
1983 and 1984. 
N is numerical percentage, W is dry weight percentage, FO is frequency of occurrence percentage of fish with prey item 
i , and IRI 
is percent of total IRI for all prey taxa. 
IRI = 
(N + W)FO. Taxa are omitted if IRI is <1% for all salmon. 
Pink salmon 
Chum salmon 
Sockeye salmon 
Coho salmon 
Chinook salmon 
N 
W 
FO 
IRI 
N 
W 
FO 
IRI 
N 
W 
FO 
IRI 
N 
W 
FO 
IRI 
N 
W 
FO 
IRI 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
(%) 
All periods combined 
Calanoids 
5.6 
0.9 
47.9 
3.7 
5.4 
0.8 
32.9 
3.0 
9.0 
0.5 
41.5 
4.2 
Decapods 
3.8 
4.0 
48.6 
4.7 
2.4 
3.6 
36.6 
3.1 
5.4 
2.6 
43.2 
3.6 
52.0 
0.1 
56.3 
25.3 
11.2 
0.2 
38.5 
4.8 
Euphausiids 
5.2 
5.5 
46.2 
6.0 
6.0 
5.9 
39.8 
6.1 
16.5 
4.3 
57.4 
12.6 
12.8 
0.1 
35.8 
3.9 
52.6 
0.2 
33.3 
18.3 
Hyperiids 
45.2 
5.8 
90.3 
39.6 
29.5 
5.7 
73.6 
28.0 
46.2 
3.7 
90.1 
36.5 
22.9 
0.1 
46.4 
6.8 
1.5 
0.2 
7.7 
0.1 
Tunicates 
32.2 
0.1 
35.2 
13.6 
52.5 
0.1 
46.7 
30.1 
16.4 
<0.1 
13.1 
2.3 
Teleosts 
1.3 
76.0 
39.1 
31.2 
0.9 
82.7 
28.6 
28.3 
2.9 
87.2 
47.0 
40.3 
8.4 
99.5 
73.2 
63.8 
30.2 
99.0 
71.8 
76.4 
Total 
93.3 
92.3 
98.8 
96.7 
98.7 
98.6 
96.4 
98.3 
99.5 
96.1 
99.8 
99.8 
95.5 
99.5 
99.6 
August 1983 
Calanoids 
6.4 
2.9 
62.6 
6.6 
2.0 
4.7 
39.7 
3.1 
10.9 
4.6 
52.7 
6.0 
0.4 
<0.1 
10.1 
<0.1 
Decapods 
4.3 
8.6 
60.9 
8.9 
0.9 
12.1 
32.6 
4.8 
1.1 
8.3 
30.9 
2.2 
46.4 
0.5 
63.1 
26.4 
Euphausiids 
4.9 
14.1 
52.9 
11.4 
5.3 
32.7 
46.2 
18.4 
17.0 
39.0 
76.4 
31.5 
5.8 
0.6 
36.9 
2.0 
Hyperiids 
37.0 
12.4 
71.0 
33.6 
31.5 
28.0 
64.7 
38.5 
58.5 
30.7 
94.5 
55.1 
41.5 
0.6 
59.7 
21.7 
Tunicates 
38.7 
0.2 
48.7 
20.3 
56.8 
0.5 
60.9 
28.8 
8.7 
0.1 
14.5 
0.9 
0.1 
<0.1 
6.0 
<0.1 
Teleosts 
0.4 
56.7 
29.9 
16.6 
0.2 
20.2 
19.6 
4.6 
0.3 
16.7 
21.8 
2.7 
2.7 
96.4 
61.1 
49.1 
Total 
91.7 
94.9 
97.4 
96.7 
98.2 
98.2 
96.5 
99.4 
98.4 
96.9 
98.1 
99.2 
July 1984 
Calanoids 
15.0 
0.8 
39.0 
7.3 
23.4 
1.4 
28.0 
11.0 
12.1 
0.4 
4.3 
5.6 
0.7 
<0.1 
7.1 
<0.1 
Decapods 
4.7 
1.9 
42.0 
3.3 
1.1 
2.1 
26.9 
1.4 
8.8 
0.8 
32.1 
3.2 
54.3 
0.1 
65.7 
27.6 
Euphausiids 
7.0 
5.0 
46.3 
6.6 
4.8 
8.1 
37.6 
7.7 
23.0 
3.4 
62.3 
17.0 
16.6 
0.1 
33.7 
3.8 
Hyperiids 
45.2 
4.3 
68.3 
39.4 
26.0 
6.3 
53.8 
27.1 
37.8 
2.0 
70.4 
28.9 
6.1 
0.1 
25.4 
0.8 
Tunicates 
11.9 
<0.1 
17.6 
2.5 
34.3 
0.1 
29.0 
15.8 
9.1 
<0.1 
7.5 
0.7 
4.1 
<0.1 
5.3 
<0.1 
Teleosts 
3.6 
84.2 
39.0 
38.4 
3.9 
77.4 
32.3 
35.0 
4.2 
92.0 
45.9 
43.9 
15.5 
99.7 
84.0 
67.6 
Total 
87.4 
96.2 
97.5 
93.5 
95.4 
98.0 
95.0 
98.6 
99.3 
97.3 
100 
99.8 
August 1984 
Calanoids 
2.3 
0.7 
37.9 
1.3 
3.8 
0.3 
25.1 
1.5 
4.7 
0.5 
32.7 
1.8 
0.2 
<0.1 
2.7 
<0.1 
Decapods 
3.2 
3.9 
43.4 
3.7 
5.0 
2.9 
42.9 
5.0 
4.5 
5.3 
61.2 
6.4 
58.3 
0.1 
42.7 
24.7 
Euphausiids 
4.8 
3.7 
39.3 
3.9 
7.3 
2.4 
29.7 
4.2 
9.6 
3.8 
41.5 
5.9 
19.7 
0.1 
32.4 
6.3 
Hyperiids 
50.1 
5.0 
65.3 
40.8 
27.9 
3.0 
53.1 
22.6 
47.5 
5.1 
68.7 
36.5 
10.3 
0.1 
24.0 
2.1 
Tunicates 
34.4 
<0.1 
34.7 
14.4 
52.8 
<0.1 
37.1 
28.9 
28.3 
<0.1 
19.7 
5.9 
<0.1 
<0.1 
0.1 
<0.1 
Teleosts 
1.1 
85.1 
38.5 
35.5 
0.8 
90.8 
28.0 
37.3 
3.1 
83.1 
47.6 
43.4 
10.7 
99.6 
72.9 
66.8 
Total 
95.9 
98.4 
99.6 
97.6 
99.4 
99.5 
97.7 
97.8 
99.9 
99.2 
99.9 
99.9 
most important prey group (IRI=36.5%) and had the 
highest FO and average count (Table 3). 
Coho salmon The prey spectrum of juvenile coho 
salmon (112-309 mm FL; x =222 mm; SD=35.1) en- 
compassed 25 taxonomic groups, including eight iden- 
tifiable fish families (Table 2). Teleosts made up 
99.5% of the total prey weight, with a mean number 
of 8.4 fish consumed by 73.2% of the coho predators 
(Table 3). Juvenile fishes were the principal compo- 
nent of coho salmon diet in all habitats except in the 
outside waters during August 1983 (Fig. 7), when 
decapod larvae were more important (IRI=66%). The 
IRI for prey fish ranged from 51% to 81% in the other 
habitats, with Pacific sand lance ( Ammodytes 
hexapterus) the most prevalent species. Other iden- 
tifiable prey fish (in order of importance) included 
walleye pollock (Theragra chalcogramma ), rockfish 
( Sebastes spp.), flatfish (Pleuronectidae), Pacific her- 
ring ( Clupea pallasi), smelt (Osmeridae), prickle- 
backs (Stichaeidae), and sculpins (Cottidae). Fish 
were more important in 1984 than in 1983 and higher 
in Alaska than in British Columbia. 
Chinook salmon The prey spectrum of juvenile 
chinook salmon (139-324 mm FL; x =224 mm; 
SD=58.4) encompassed 14 taxonomic categories and 
four identifiable fish families (Table 2). Fish were 
the most important prey: IRI’s ranged from 28% to 
100% among habitats (data not shown). Fish made up 
99% (biomass) of chinook salmon stomach contents in 
pooled samples, with a mean of 30.2 individuals con- 
