Seasonal and size-related differences in diet of the Atlantic angel shark Squatina dumeril in the northeastern Gulf of Mexico

摘要

Atlantic angel sharks Squatina dumeril were collected for stomach contents (n = 437) from November 2002 through April 2005 from a butterfish Peprilus burti bottom trawl fishery in the northeastern Gulf of Mexico. Teleost fishes, especially Atlantic croaker Micropogonias undulatus, butterfish, and goatfishes (Mullidae), dominated the diet of Atlantic angel sharks and were the most important prey items for sharks of all sizes (305 to 1160 mm total length). Squid (Loligo sp.) were also important prey for all shark sizes, though they became less important with increasing shark size. Crustaceans like mantis shrimp Lysosquilla sp., brown rock shrimp Sicyonia brevirostris, and portunid crabs (Portunidae) were also eaten by angel sharks of all sizes in all seasons sampled. Seasonal differences in diet were detected with niche breadth, which was narrowest in winter and broadest in fall. Niche breadth was also size related and narrowed with increasing shark size. Size of prey was also related to shark size, with sharks mostly consuming prey <30% of their total length and prey with body depths <60% of their gape width.