Foods of Little Tunny Euthynnus alletteratus Collected along the Southeastern and Gulf Coasts of the United States

Abstract

A total of 2, 134 little tunny Euthynnus alletteratus were examined. Specimens ranged from 172 to 885mm fork length (FL) and were captured by hook and line and seines off the southeastern United States and from the Gulf of Mexico in 1980 and 1981. Approximately 57% (1, 212) of the stomachs contained ingested materials consisting of 20, 742 individual items, displacing 62, 961ml, and representing over 100 different categories. Fishes occurred in 66.9% of the stomachs with food, invertebrates in 30.5%, and miscellaneous items (Sargassum, seagrasses, inorganics, etc.) in 11.3%. Little tunny feed primarily in coastal waters on fishes, such as sardines, scads, and anchovies, and invertebrates. In decreasing order of importance clupeids, engraulids, unidentifiable fish, carangids, squid, stomatopods, penaeids, diogenids, stromateids, and synodontids were the most important foods in the diet, based on the index of relative importance (IRI). Diets differed with fish size (4 size classes), area of collection (8 areas) and season (4 seasons). Bray-Curtis similarity coefficients were used to compare the diet of little tunny with those of king mackerel Scomberomorus cavalla and Spanish mackerel S. maculatus collected from the same areas. Generally, the little tunny diet was more similar to that of king mackerel than to that of Spanish mackerel. All three coastal pelagic predators fed extensively on clupeids, carangids, and squids. Small crustaceans were more important to the diet of little tunny, and engraulids were more frequently eaten by Spanish mackerel.