Ecosystems

, Volume 5, Issue 2, pp 202–216

The Role of Sharks and Longline Fisheries in a Pelagic Ecosystem of the Central Pacific

  • James F. Kitchell
  • Timothy E. Essington
  • Christofer H. Boggs
  • Daniel E. Schindler
  • Carl J. Walters

DOI: 10.1007/s10021-001-0065-5

Cite this article as:
Kitchell, J., Essington, T., Boggs, C. et al. Ecosystems (2002) 5: 202. doi:10.1007/s10021-001-0065-5

Abstract

The increased exploitation of pelagic sharks by longline fisheries raised questions about changes in the food webs that include sharks as apex predators. We used a version of Ecopath/Ecosim models to evaluate changes in trophic interactions due to shark exploitation in the Central North Pacific. Fisheries targeted on blue sharks tend to produce compensatory responses that favor other shark species and billfishes, but they have only modest effects on the majority of food web components. Modest levels of intraguild predation (adult sharks that eat juvenile sharks) produce strong, nonlinear responses in shark populations. In general, analysis of the Central North Pacific model reveals that sharks are not keystone predators, but that increases in longline fisheries can have profound effects on the food webs that support sharks.

Key words: sharks; blue shark; food web; models; ecosystem; pelagic ecosystem; fisheries; predation; predator–prey interactions; conservation; Pacific Ocean. 

Copyright information

© Springer-Verlag New York Inc. 2002

Authors and Affiliations

  • James F. Kitchell
    • 1
  • Timothy E. Essington
    • 1
  • Christofer H. Boggs
    • 2
  • Daniel E. Schindler
    • 3
  • Carl J. Walters
    • 4
  1. 1.Center for Limnology, University of Wisconsin, 680 North Park Street, Madison, Wisconsin 53706, USAUS
  2. 2.National Marine Fisheries Service, Southwest Fishery Center, Honolulu Laboratory, Honolulu, Hawaii, USA 96822US
  3. 3.Department of Zoology, University of Washington, Seattle, Washington, USA 98195US
  4. 4.Fisheries Centre, University of British Columbia, Vancouver, British Columbia, Canada BCV6T 124CA

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