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Fishery Bulletin 94(2), 1996 



groups was not statistically different. The percent 

 occurrence of cephalopods (squid) was low for both 

 groups and differed insignificantly. 



Chi-square contingency analysis suggested that 

 geographic location did not significantly affect the 

 diet, although we did observe that cephalopods 

 (squid) were absent in the stomachs of all juveniles 

 («=6) collected west of the Mississippi River. The 

 stomachs of the 2 cobia collected in March (spring) 

 contained, collectively, the only specimens of sea bass 

 (Serranidae, n=3) and xanthid crab (n = l) encoun- 

 tered in the study. The only other prey found in the 

 stomachs of the juveniles collected in March were 

 anchovies which, notably, were the predominant fish 

 prey among the summer (July and September) co- 

 bia. A larger sample size is needed to assess accu- 

 rately any geographic or seasonal variations in diet. 



Discussion 



We found that juvenile cobia captured by trawl in 

 the northern Gulf of Mexico during fall 1993 and 

 early spring 1994 were carnivorous and fed exclu- 

 sively on small fish, crustaceans, and squid. Fish, 

 crustaceans, and cephalopods also comprised the diet 

 of adult cobia collected in the northcentral Gulf of 



Mexico (Meyer and Franks, 1996). On the basis of 

 the frequency occurrence of prey in the diet of cobia 

 caught near Aransas Bay, Texas, Knapp (1951) re- 

 ported the predominance of fishes (83^r ), followed by 

 stomatopods (589r), penaeid shrimps (46%), portunid 

 crabs (42^ ), and squid ( 177c ). Meyer and Franks ( 1996) 

 reported that the percent frequency of occurrence and 

 numeric percentage of crustaceans (79.17cF, 77.69WV) 

 dominated that of fishes (58.5%F, 20.3%N) and cepha- 

 lopods ( 13.2%F, 2.2%N). Our results showed that fish 

 and crustaceans were present in the diet in approxi- 

 mately equal volumes, and, as reported by Miles ( 1 949 1 

 and Christmas et al.) 1 for cobia taken off Texas and 

 Mississippi, respectively, occurred in nearly equal num- 

 bers; however, we found that fish occurred in the diet 

 with somewhat greater frequency than did crustaceans. 

 Based on IRI calculations, the relative importance of 

 fishes (7/?7=l,984.5) as prey items was approximately 

 three times that of shrimp (IRI=676.7) and three and 

 one-half times that of squid (7r?/=539.3). 



In our study, anchovies were the dominant prey 

 among the fish consumed and were major contribu- 

 tors to the diet. Unidentified fish remains, probably 

 anchovies, occurred in almost 75'; of the stomachs 



