Document Type

Article

Publication Date

2002

Abstract

Dolphins and sharks feed at times on the same food; however, the influence of these interactions on the feeding success of either predator has not been measured. I employed underwater video to record bottlenose dolphinsTursiops truncatus and silky sharks Carcharhinus falciformis feeding on the same school of fish, and for the first time measured food intake of free-ranging dolphins. Regression analyses showed that dolphin food intake diminished as the number of feeding sharks increased, but was unrelated to the number of dolphins feeding, size of the prey clump or duration of feeding events. The number of dolphins increased at the beginning of a feeding event in the presence of sharks but not in their absence. This increase apparently provided a benefit to dolphins since the number of sharks feeding was negatively related to the number of dolphins feeding. Other studies have indicated that risk of shark predation influences dolphin group size and habitat use. This study indicates that interspecific contests over food influence dolphin food intake and perhaps also dolphin group size.

Publication Title

Marine Ecology Progress Series

Volume

240

First Page

267

Last Page

271

Comments

© 2002, Inter-Research

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