Dietary Habits of the Gafftopsail Catfish, Bagre marinus, in Tarpon Bay and Pine Island South, Florida (original) (raw)

2001, Gulf of Mexico Science

A total of 507 gafftopsail catfish, Bagre marinus, were captured by hook and line in Tarpon Bay and neighboring Pine Island Sound, Florida from June 3, 1999 to May 6, 2000 in order to identify foods of this understudied species. A total of 86 (17.0%) specimens contained only unidentifiable food, and 187 (36.9%) specimens were found with empty stomachs. Based on the index of relative importance, the pink shrimp, Farfmztepenaeus duorarum, was the most important food for specimens :5200 mm fork length (FL), amphipods the most important food for specimens 201-300 mm FL, and unidentifiable fish the most important food for specimens 2:301 mm FL. Diet of B. marinus was also compared among four seasons: June through August; September through November, December through February, and March through May. Unidentifiable fish was the most important food for June through August and September through November. Clupeid fishes were the most important food for December through February. The amphipod Ampelisca abdita was the most important food for March through May. The wide variety of foods consumed by B. marinus indicates an opportunistic feeding strategy. T he gafftopsail catfish, Bagre marinus, is an understudied species that inhabits coastal waters of Florida. It is eurythermal and euryhaline, and its morphological, reproductive, feeding and migratory patterns are linked to the heterogeneity of habitats encountered in estuaries (Yanez-Arancibia and Lara-Dominguez, 1 988). B. mminus ranges from Massachusetts to Panama and is reportedly common in bays and shallow areas of the northern Gulf of Mexico (Roese and Moore, 1998). In Florida, B. ma"linus is considered to be unexploited (Armstrong et al., 1996), with no recreational size limits or bag limits imposed. Literature suggests that B. mminus is an unselective feeder. Gudger (1910) found that the blue crab, Callinectes sapidus, is the staple food of B. mminusin North Carolina waters (quoted from Gunter, 1945) and also found C. sapidus in all five stomachs of B. mminus that he examined from Texas waters. Miles (1949) examined stomachs of 85 specimens from Texas and found 6 species of crabs, 11 species of fishes, and penaeid shrimp. Pew (1954) reported that, in Texas coastal waters, B. marinus usually fed near the bottom, consuming fishes, shrimps, and other small crustaceans. In Venezuela, Cervigon (1966) found that B. mminu.s fed on crabs, shrimp, and small fishes. Odum (1971) found in a sample of eight B. malinus (262-445 mm) taken from the North River, Florida, that three specimens had consumed C. sapidus, two had consumed unidentified fish, and three were empty. Yanez-Arancibia and