Meeting Abstract

61.4  Saturday, Jan. 5  Feeding behavior of a generalist and a specialist shark GERRY, S.P.**; WILGA, C.D.; University of Rhode Island; University of Rhode Island sgerry@mail.uri.edu

Feeding specialization in fishes can be categorized based on diet, behavior, function or morphology. Prey selection and temporal variables describing foraging behavior were investigated in a trophic specialist (Mustelus canis) and generalist (Squalus acanthias) shark in order to characterize their behaviors. Five dead natural prey items were offered to each individual for each species while selection and foraging behaviors were recorded. Manly�s alpha was calculated to determine the level of selection for each prey item. Both species selected all five prey items and showed a preference for herring and squid. The specialist did not favor the preferred prey item cited by other diet studies. Temporal variables of feeding behavior were investigated including pre-capture search, prey capture and processing during feeding on two prey types. Prey capture had the shortest duration of the behaviors while prey processing took the longest time for both species. The duration of searching and prey capture did not differ by prey type for S. acanthias; however, smaller prey items were processed more rapidly. Modulation based on prey type, such as during processing, is characteristic of a generalist. Temporal variables of foraging behavior are stereotyped for M. canis regardless of prey type. Both species chose prey items indicative of a generalist diet, likely because both are known to scavenge on a variety of dead prey. However, M. canis shows specialist feeding behavior whereas S. acanthias shows versatility.