walleye pollock was similar to that of small walleye 

 pollock (Fig. 2). Intermediate-sized fish also fed pre- 

 dominately on euphausiids in the winter and spring 

 and more on mysids in the summer and fall. However, 

 seasonal variability in diet was not as great as for 

 small walleye pollock. Too few large walleye pollock 

 were collected in three of the seasons to demonstrate 

 seasonal changes in their foods. 



Some of the seasonal differences found in foods of 

 small walleye pollock may be explained by the 

 availability of euphausiids and copepods. In two 

 seasonal studies of zooplankton in the Auke Bay 

 vicinity, 1962-64 (Wing and Reid 1972) and 1973-75 

 (Carlson 1980), euphausiids (excluding small larval 

 forms) were least abundant and copepods were most 

 abundant during the late spring and summer. Similar 

 seasonal patterns were found in the foods of small 

 walleye pollock: The percent volume of euphausiids 

 was lowest in the summer, whereas copepods were a 

 significant food only during the summer. However, 

 results of the zooplankton studies also differ in some 

 respects from my results: In 1973-75, euphausiids 

 were most abundant in plankton in the fall (Carlson 

 1980), but in my 1979-80 study, they were relatively 

 scarce in the stomach samples during the fall. Con- 

 current studies of walleye pollock foods and 

 zooplankton abundance are needed to better under- 

 stand the causes of seasonal variations in the diet of 

 small walleye pollock. 



Acknowledgments 



I thank my colleagues in the Marine Investigations 

 section of the Auke Bay Laboratory for their assis- 

 tance in this study, especially Bruce Wing, who 

 helped identify the invertebrates. 



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David M. Clausen 



Northwest and Alaska Fisheries Center 

 Auke Bay Laboratory 

 National Marine Fisheries Service, NOAA 

 P.O. Box 155, Auke Bay, AK 99821 



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