Stone and Jessop: Feeding habits of Alosa pseudoharengus 



163 



Feeding activity 



Feeding activity, as indicated by 

 mean stomach fullness index 

 values, varied by season/geo- 

 graphic area (F 3 1910 =46.20, P< 

 0.001). Mean stomach fullness 

 was highest for Summer-Fundy 

 and Winter-Shelf collections and 

 lowest for Winter-Fundy and 

 Winter-Georges collections (Ta- 

 ble 4). The proportion of feeding 

 fish was highest during summer 

 in the Bay of Fundy (80.6%) and 

 lowest during winter on Georges 

 Bank (33.6%). Stomach fullness 

 was significantly higher at bot- 

 tom depths greater than 200 m 

 for all but the Winter-Shelf col- 

 lections, where mean fullness 

 did not differ among depth 

 groups (Table 4). Similarly, the 

 proportion of feeding fish was 

 highest in areas exceeding 200 m 

 deep for all collections. 



Alewife feeding activity varied 

 throughout the diel period dur- 

 ing winter (F 1 1(m =24.97, P< 

 0.001) and summer (F 5 196 = 7.98, 

 P<0.001) with maximum full- 



%N 



%V 



Winter-Shelf 



100-| < 101 m (n = 49) 



60 



20- 



20- 



60 



100 



Summer-Fundy 



100-1 < 101 m (n = 33) 



Chaot 



%N 



%v 



60 



20- 



20" 



60 



100 



Jzj_P" 



%N 



%v 



%N 



%V 



Legend 



Eup 



Cop 



Pter 



Amp 



CruLar 



FIshLar 



Chaet 



Mys 



Poly 



%N 



%V 



ness in both seasons occurring 

 near mid-day (Fig. 7). In winter, 

 feeding activity was extremely 

 variable: mean fullness was high 

 during early morning (0001- 

 0430 hours), declined until dawn 

 (0730), increased sharply until 

 early afternoon (1330), declined 

 again in late afternoon (1630) 

 and then increased after sunset 

 before falling off again prior to 

 midnight. During summer, diel 

 feeding activity was much more 

 constant, although sample sizes were smaller and 

 stomach fullness more variable. Feeding activity in- 

 creased gradually after sum ise, peaked by mid-mo 71- 

 ing ( 1000), then declined throughout the afternoon and 

 evening until just prior to midnight (2200). Although 

 alewives fed actively at night during winter, peak feed- 

 ing generally occurred during the day in winter and 

 summer. 



Daily ration 



Daily consumption of alewives in the field was about 

 1.22% BW at 7.16°C during winter and 1.88% BW 



%N 



%V 



i = 20% FO 



i = 20% FO 



Figure 3 



Relative importance of prey categories in the diet of alewives, Alosa 

 pseudoharengus, obtained from groundfish research surveys off Nova 

 Scotia (1990-91), ranked from highest Index of Relative Importance (left 

 to right), by depth range, for Scotian Shelf (winter) and Bay of Fundy 

 (summer) collections. (Symbols as in Fis;. 2). 



at 7.43°C during summer (Table 5). The winter daily 

 ration of alewives generally decreased from 1.95% 

 BW for fish less than 151 mm FL to 1.13% BW at 

 151-200 mm FL, 1.19% BW at 201-200 mm FL and 

 1.00% BW at larger than 250 mm FL. 



Discussion 



Our study clearly indicates that alewives off Nova 

 Scotia feed primarily on euphausiids, particularly 

 Meganyctiphanes norvegica; much smaller contribu- 

 tions are made by other prey. Alewives from the 



