BOWMAN: FOOD OF SILVER HAKE 



TABLE 7. — Geographic breakdown of the prey found in the stomachs 

 of silver hake caught in the Northwest Atlantic during the years 

 1973-76. Data are expressed as a percentage weight. (+ indicates 

 <0.1%). 



phausiids (3.4%) and decapods (2.6%) account for 

 most of the Crustacea. 



The Cephalopoda was the only other prey group 

 recognized as an important food of silver hake. Fish 

 in Southern New England eat the largest quantities of 

 squid (13.7%). Silver hake sampled on Georges Bank 

 and in the Middle Atlantic also take fairly large 

 amounts of squid as prey (6.7% and 4.3%, 

 respectively). 



A comparison between the quantities of food in the 

 stomachs of fish from each area revealed that Middle 

 Atlantic silver hake have about two to three times 

 more food in their stomachs (on the average) than fish 

 from Southern New England or Georges Bank. 

 Stomach content data for fish 24-35 cm FL from each 

 area were adjusted for fish length; the adjusted mean 

 stomach content weights were Middle Atlantic, 

 1.328 g; Southern New England, 0.593 g; and Georges 

 Bank, 0.707 g. The quantity of food in the stomachs 

 of Middle Atlantic silver hake is significantly 

 different (with 95% confidence) from the quantity 

 in the stomachs of fish from Southern New England 

 (F = 6.862 exceeds F 005 lj21 = 4.32). The adjusted 

 mean stomach content weights of small (4-15 cm FL) 

 silver hake from each area were Middle Atlantic, 

 0.149 g; Southern New England, 0.198 g; and 

 Georges Bank, 0.214 g. 



Yearly and Seasonal Differences 



the majority of the identified fish prey. The stomachs 

 of silver hake caught in Southern New England con- 

 tain fairly high percentages of silver hake (7.97o), 

 Atlantic mackerel (6.0%), and scup (4.1%). Silver 

 hake caught on Georges Bank eat mostly Atlantic 

 mackerel (21.1%), butterfish (8.97o), Atlantic saury 

 (6.1%), herring (Clupeidae, 5.0%), and American 

 sand lance (4.8%). Evidence of the cannibalistic na- 

 ture of silver hake is seen in all three areas. In addi- 

 tion, silver hake taken as prey comprise the highest 

 percentage of identified fish in both the Middle 

 Atlantic and Southern New England (Table 7). 



Crustaceans are most important in the diet of silver 

 hake collected from Georges Bank (16.4%). Eu- 

 phausiids (7.9%), decapods (mostly pandalid 

 shrimp, 4.4%, and crangonid shrimp, 1.3%), and 

 mysids (1.2%) account for the majority of crustacean 

 prey consumed on Georges Bank. In the Middle 

 Atlantic and Southern New England, Crustacea is of 

 equal importance (7.3%) as a food. For Middle Atlan- 

 tic fish, decapods (4.9%) and euphausiids (1.2%) 

 make up the majority of crustacean prey identified in 

 the stomachs. In Southern New England, eu- 



Percentages of various prey categories in the silver 

 hake diet between years, seasons, and geographic 

 areas indicate the stomach contents are quite vari- 

 able (Table 8). For example, in the Middle Atlantic, 

 the Crustacea portion of the diet of silver hake varies 

 from 3.1% (spring 1973) to 70.0% (fall 1976). Similar 

 variability can be seen in the percentages listed for 

 most of the prey categories. Much of the observed 

 variation is probably due to differences in predator 

 lengths (note mean fish FL's given at the bottom of 

 Table 8). Only one prey, the American sand lance, 

 was noted as being unique in the diet of silver hake. 

 American sand lance was only found in the stomachs 

 of silver hake collected in the spring during 1975 and 

 1976. The largest percentage weights of American 

 sand lance were derived from samples collected only 

 during the spring of 1976 in all three areas. Another 

 observation is that fish sampled in the spring tend to 

 be larger (see mean lengths at bottom of Table 8) 

 than those collected in the autumn. 



The adjusted stomach content data for large and 

 small silver hake from all areas and years combined 

 indicate that about twice as much food is found in the 

 stomachs during spring than in autumn. The adjust- 



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