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Fishery Bulletin 96(2), 1998 
Inside water (IRI) Outside waters and 
(partitioned into inlets and passages) outer coast inlets (IRI) 
■■ Calanoid copepods Euphausiids r l Hyperiid amphipods 
CFJ Decapod larvae ESS Fishes F 13 Tunicates 
Figure 4 
Index of relative importance (IRI) of principal prey of juvenile pink salmon in inside and outside waters and 
outer coast inlets of southeastern Alaska in 1983 and 1984 and outside waters and outer coast inlets of northern 
British Columbia in 1984. 
and chum salmon; both ate hyperiid amphipods, fish, 
and Oikopleura dioica. The third-highest diet overlap 
in all pooled samples was between chum and sockeye 
salmon ( C A =0.73); both species consumed fish, hyperiid 
amphipods, and euphausiids. 
Temporal diet overlap The degree of diet overlap 
among salmon species pairs varied by time period when 
habitat was not considered. In August 1983, diet over- 
lap, based on the consumption of hyperiid amphipods, 
was greatest for pink and chum salmon juveniles 
( Q =0.95; Table 5), O. dioica, and euphausiids. Diets of 
juvenile pink and sockeye salmon overlapped signifi- 
cantly ( C A - 0.72) on the basis of hyperiid amphipods 
and euphausiids. Alesser, but still significant, diet over- 
lap (C ? = 0.62) occurred between sockeye and coho 
salmon on the basis of hyperiid amphipods, decapod 
larvae, and fish. 
Diet overlap was lower in July 1984, when samples 
included waters outside of British Columbia, than in 
August 1984. Diet overlap was significant for combi- 
nations of pink, chum, and sockeye salmon, but not for 
combinations including coho salmon (Table 5). The 
greatest overlap occurred between pink and chum 
salmon ( C A =0.80), pink and sockeye salmon ( C A =0.79), 
and chum and sockeye salmon ( C A =0.73), which was 
principally due to similar proportions of hyperiid am- 
phipods and juvenile fish. The relative importance of 
larvaceans accounted for the greatest difference in the 
diets of these three species: O. dioica made up nearly 
20% of the IRI for chum salmon, compared with less 
than 3% for pink and sockeye salmon. 
In August 1984, the diets of pink, sockeye, and chum 
salmon overlapped greatly, whereas coho salmon diet 
did not overlap with that of any other species (Table 5). 
Diets of pink and sockeye salmon overlapped almost 
