492 
Fishery Bulletin 99(3) 
Table 4 
Horn’s overlap index values for total numbers and biomass of prey consumed by YOY walleye pollock and Pacific herring caught 
separately in summer and together in autumn in Prince William Sound, 1994-1995. No summer sympatric fish were available and 
autumn allopatric fish were not caught in the same year. Overlap greater than 0.60 indicates similar diets (see text). C = central; 
NE = northeast. 
Sampling period and target catch 
By prey 
Region 
Overlap in number 
By prey By prey 
species category 
Overlap in 
By prey 
species 
biomass 
category 
Interspecific diet overlap 
July 1995 allopatric fish 
1995 
C, NE 
0.79 
0.82 
0.76 
0.83 
October 1995 sympatric fish 
1995-96 
NE 
0.16 
0.22 
0.44 
0.64 
1995-97 
NE 
0.43 
0.48 
0.53 
0.69 
Average 
NE 
0.31 
0.43 
0.55 
0.69 
Intraspecific diet overlap 
November 1994 sympatric fish 
1994-96 
NE 
0.69 
0.94 
0.08 
0.39 
1994-97 
NE 
0.86 
0.91 
0.88 
0.91 
Average 
NE 
0.87 
0.97 
0.88 
0.95 
Allopatric-sympatric fish 
October 1995 herring 
0.51 
0.89 
0.56 
0.93 
November 1994 pollock 
0.87 
0.91 
0.56 
0.73 
