Comparative food studies of yellowfin in tuna, Thunnus albacares, and blackfin tuna, Thunnus atlanticus, (Pisces: Scombridae) from the Southeastern and Gulf Coast of the United States

Abstract

Two hundred and six yellowfm tuna, Thunnus albacares,. and 98 blackfm tuna, T. atlanticus 1 were sampled from sport fisheries in the South Atlantic and the Gulf of Mexico from April 1980 to July 1982. Stomach contents were analyzed by frequency of occurrence, number of food items, and volume. Invertebrates and fish occurred in the diet of yellowfin relatively equally (85%­ and 77%). Major invertebrates by frequency of occurrence were cephalopods, 62% and crustaceans, 52%. Fishes were represented primarily by the families: Scombridae, 12.2%; Balistidae, 11.2%; and Syngnathidae, 8.2%. In addition, yellowfm ingested floating materials such as plastics, feathers, seagrasses, and balls of tar. Invertebrates occurred in 82% of the blackfin stomachs with food, and represented 75% and 31% of the foods by number and volume, respectively. Fish were found in 67% of the stomachs and constituted 26% and 68% of the food number and volume, respectively. The most frequently occurring invertebrates were crustaceans, 67.4% and cephalopods, 36.0%. Fishes were represented primarily by the families: Balistidae, 10.1 %; Trichiuridae 5.6%; and Carangidae, 4.5%. In addition, blackfm consumed floating materials, such as plastic and seagrasses. 26 Charles S. Manooch, Diane L. Mason