720 



Fishery Bulletin 89(4), 1991 



Figure 1 



Size of prey ingested by age-0 and age-1 walleye pollock 

 at station 95 (56°11.17'N, 162°18.36'W), in the south- 

 eastern shelf region of the Bering Sea, 3 August 1985. 

 Age-0 data are plotted, including and excluding copepod 

 eggs. Prey widths (in mm) were as follows: copepod eggs 

 0.11-0.20, Calanus marshallae 0.61-1.70, Pseudocalanus 

 sp. 0.11-0.70, Centropages abdorninalis 0.31-0.60, Metri- 

 dia sp. 0.51-0.60, Acartia sp. 0.21-0.40, Tortanus discau- 

 datus 0.31-0.50, amphipods 0.21-1.8, euphausiid furcilia/ 

 juveniles 0.21-3.50, mysids 0.41-0.50, decapod larvae 

 0.21-0.90. Fish scales were not included in this analysis, 

 as their ingestion was deemed incidental. 



by age-1 pollock, which ranged from 137 to 212mm TL 

 (x 162.8mm, SD 16.32) (Fig. 1). Prey-size distribu- 

 tions were significantly different regardless of whether 

 copepod eggs were included (P<0.001, Kolmogorov- 

 Smirnov test; Conover 1980). Taxa of prey ingested by 

 the two age-classes also differed (Table 1). Small cope- 

 pods (0.21-0.50 mm width) and copepod eggs (0.11-0.20 

 mm width) comprised the bulk of the prey ingested by 

 age-0 fish, while larger copepods and euphausiid fur- 

 cilia (0.71-1.30 mm width) comprised the bulk of the 

 prey ingested by age-1 fish. 



Although euphausiid furcilia and juveniles made a 

 substantial contribution to the diet of both age-classes, 

 age-0 fish ingested smaller and/or earlier furcilia stages 

 than did age-1 fish. Copepods comprised a major por- 



