Analysis of stomach contents of the porbeagle shark (Lamna nasus Bonnaterre) in the northwest Atlantic

Stomachs of 1022 porbeagle sharks (Lamna nasus) ranging in size from 85-264 cm were examined from the Canadian porbeagle shark fishery and a scientific cruise in the northwest Atlantic between February 1999 and January 2001. Teleosts occurred in the majority of stomachs and constituted 91% of the diet by weight. Cephalopods occurred in 12% and were the second most important food category consumed. Pelagic fish and cephalopods comprised the largest portion of the diet in the spring while groundfish dominated the diet in the fall. Diet did not differ significantly between the sexes. Stomach fullness differed slightly but significantly across months and declined slightly with fork length. The porbeagle is primarily an opportunistic piscivore with a diet characterized by a wide range of species. Diet composition changed seasonally following a migration from deep to shallow water. Crown