MEPS 320:239-251 (2006)  -  doi:10.3354/meps320239

Distribution and diet of four species of carcharhinid shark in the Hawaiian Islands: evidence for resource partitioning and competitive exclusion

Yannis P. Papastamatiou1,*, Bradley M. Wetherbee2, Christopher G. Lowe3, Gerald L. Crow4

1Department of Zoology, Hawaii Institute of Marine Biology, University of Hawaii at Manoa, 46-007 Lilipuna Rd, Kaneohe, Hawaii 96744, USA
2Department of Biological Sciences, University of Rhode Island, Kingston, Rhode Island 02881, USA
3Department of Biological Sciences, California State University Long Beach, Long Beach, California 90840, USA
4Waikiki Aquarium, 2777 Kalakaua Ave, Honolulu, Hawaii 96815, USA

ABSTRACT: Competition and predation are both important in structuring the distribution of marine organisms; however, little is known about how competition and predation influence the distribution of elasmobranch fishes. We used data collected from shark control programs conducted between 1967 and 1980, throughout the Hawaiian island chain, to examine the distribution and dietary overlap of the 4 most abundant carcharhinid sharks. Tiger sharks Galeorcerdo cuvier and Galapagos sharks Carcharhinus galapagensis were caught at all islands, but were more abundant in the northwestern Hawaiian Islands (NWHI) than in the main Hawaiian Islands (MHI). Gray reef sharks Carcharhinus amblyrhynchos and sandbar sharks Carcharhinus plumbeus showed an inverse relationship in distribution, with sandbar sharks abundant in the MHI, but virtually absent throughout the NWHI, and gray reef sharks only sporadically found throughout the MHI, but abundant in the NWHI. Dietary overlap was high between gray reef and sandbar sharks, and between sandbar and Galapagos sharks. Tiger sharks had low dietary overlap with all other species, except for large Galapagos sharks. The data analyzed in our study support the hypothesis that interspecific competition influences the distribution of carcharhinid sharks throughout the Hawaiian Archipelago.


KEY WORDS: Diet · Competition · Tiger shark · Galapagos shark · Gray reef shark · Sandbar shark


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