Stillwell and Kohler: Food habits of Carcharhinus plumbeus off U.S. northeast coast 



143 



Elasmobranchs Elasmobranchs ranked second to te- 

 leosts as a major food group, accounting for 16.0% of 

 the food by frequency of occurrence (Fig. 2). Skates of 

 the family Rajidae were the principal representatives 

 in this food group, with Raja erinacea occurring most 

 frequently. Unspecified skate remains described as Raja 

 spp. in Table 2 most likely included R. erinacea and 

 possibly R. eglanteria, both which commonly occur in 

 the sampling area. Eleven skate egg cases were also 

 found in seven stomachs. These were generally torn 

 and old looking. However, a few contained yolk mate- 

 rial suggesting they were ingested as a food source 

 rather than by accident. Based on frequency of occur- 

 rence, spiny and smooth dogfish sharks are relatively 

 unimportant in the sandbar shark's diet when com- 

 pared with the importance of skates in the diet 

 (Table 2). Bigelow & Schroeder (1948), Bass et al. 

 ( 1973), and Lawler ( 1976) also report the occurrence of 



shark remains in sandbar shark stomachs. Springer 

 ( 1960), however, after examining several hundred sand- 

 bar sharks from the Florida coast, reported finding 

 very few stomachs with shark remains. The high fre- 

 quency of occurrence of skates in the sandbar shark's 

 diet can be attributed to their general abundance over 

 the continental shelf ( Waring 1986). 



Cephalopods From this study, cephalopods (squids 

 and octopus) appear to be generally unimportant in 

 the sandbar shark's diet by evidence of their low num- 

 ber, volume, and frequency of occurrence (Fig. 2). Ear- 

 lier studies by Springer (1960), Clark & von Schmidt 

 (1965), Lawler (1976), and Branstetter (1981) also 

 showed low occurrences of squid in the sandbar shark's 

 diet, but all were based on specimens obtained from 

 inshore areas of low squid abundance. Our findings, 

 however, suggest that predation on this food source is 



