Food and gastrointestinal parasites of dolphin Coryphaena hippurus collected along the southeastern and gulf coasts of the United States.

Abstract

A total of 2, 632 dolphin Coryphaena hippurus, 250 to 1, 530 millimeters fork length (FL), were captured by hook and line off the southeastern United States and from the Gulf of Mexico in 1980 and 1981. Eighty-four percent (2, 219) of the stomachs contained ingested materials consisting of 13, 383 individual items, displacing 57, 648 milliliters, and representing 248 different categories. Fishes occurred in 77.6% of the stomachs, invertebrates in 27.5% and miscellaneous items (Sargassum, tar balls, plastics, etc.) in 50.6%. Much of the material indicated that dolphin frequently feed at the surface and ingest fishes, crustaceans, insects, plants, and inorganic items that are associated with floating Sargassum. Index of relative importance (IRI) revealed unidentified fish, balistids, crustaceans. carangids, exocoetids, teuthidiEs (squids), syngnathids, coryphaenids, stomatopods, and diodontids as the 10 most important foods in the diet. Sargassum, which occurred in 48.6% of the stomachs, was considered to be consumed incidental to normal foods. The diets differed with size of dolphin (8 size classes), area of collection (10 areas), and season (4 seasons). The ascaridoid nematode Hysterothylacium pelagicum sp. n. and an unidentified digenetic trematode were found in the digestive tracs. Nematodes were far more numerous and occurred more frequently than did trematodes. Infestation rate seemed to be more associated with size of dolphim than with season or area of collection.