Stone and Jessop: Feeding habits of Alosa pseudoharengus 



161 



cally less than in other areas. Hyperiid amphipods, 

 (Parathemisto gaudichaudi), ranked second in im- 

 portance (%V=10), followed by crustacean larvae 

 (furciliae), calanoid copepods, and fish larvae, 

 (Ammodytes dubius). During summer in the Bay of 

 Fundy, alewives fed heavily on euphausiids (%V=95) 

 but also consumed chaetognaths, mysids, and poly- 

 chaetes (second, third, and fourth in importance). 



Rankings of IRI values (excluding euphausiids) for 

 Winter-Georges, Winter-Shelf, and Summer-Fundy 

 samples were not significantly correlated (u^O.22, 

 P=0.701), indicating seasonal and geographic differ- 

 ences in the dietary importance of these lesser prey 

 categories. Winter-Fundy samples contained too few 

 prey categories to be analyzed. 



Diet composition by depth range 



For Winter-Shelf and Summer-Fundy collections, 

 the proportion of euphausiids in the diet increased 

 with increasing depth (Fig. 3). At bottom depths less 

 than 101 m on the Scotian Shelf, euphausiids com- 

 posed 64% of total volume and 22% of total number; 

 at 101 to 200 m, %V = 83 and %N = 23 and at depths 



greater than 200 m, %V = 96 and %N = 95. During 

 summer in the Bay of Fundy, euphausiid consump- 

 tion increased with depth such that at less than 101 

 m, %V = 82 and %N = 35; at 101 to 200 m, %V = 97 

 and %N = 97; while at depths greater than 200 m, 

 both %V and %N = 100. Other prey categories gen- 

 erally decreased in number with increasing depth 

 as did their relative proportion. For both Winter- 

 Shelf and Summer-Fundy collections, prey diversity 

 and abundance were greatest where bottom depths 

 were less than 101 m. 



Multiple correlations of IRI values for prey cat- 

 egories (excluding euphausiids) between the three 

 bottom-depth interval groups were not significant 

 (u>=0.54, P=0.12) for Scotian Shelf collections and 

 reflect the decreasing number of prey categories 

 with increasing depth. For Summer-Fundy samples, 

 the Spearman rank correlation of IRI values for the 

 two shallower depth-intervals was not significant 

 (r s =-0.35, P>0.05) and euphausiids were the only 

 prey at depths greater than 200 m. 



Depth-related differences did not occur in the 

 euphausiid-dominated diet of alewives from the 

 Winter-Fundy and Winter-Georges collections at 



