Article

Subsurface behavior of bottlenose dolphins (Tursiops truncatus) interacting with fish trawl nets in northwestern Australia: Implications for bycatch mitigation

  1. Vanessa F. Jaiteh1,*,
  2. Simon J. Allen1,
  3. Jessica J. Meeuwig2,
  4. Neil R. Loneragan1

Article first published online: 24 OCT 2012

DOI: 10.1111/j.1748-7692.2012.00620.x

Additional Information

How to Cite

Jaiteh, V. F., Allen, S. J., Meeuwig, J. J. and Loneragan, N. R. (2012), Subsurface behavior of bottlenose dolphins (Tursiops truncatus) interacting with fish trawl nets in northwestern Australia: Implications for bycatch mitigation. Marine Mammal Science. doi: 10.1111/j.1748-7692.2012.00620.x

Author Information

  1. 1

    Murdoch University Cetacean Research Unit, Centre for Fish, Fisheries and Aquatic Ecosystems Research, School of Biological Sciences and Biotechnology, Murdoch University, Murdoch, Western Australia, Australia

  2. 2

    Centre for Marine Futures and School of Animal Biology, Oceans Institute, University of Western Australia, Crawley, Western Australia, Australia

*Corresponding author (e-mail: v.jaiteh@murdoch.edu.au).

Publication History

  1. Article first published online: 24 OCT 2012
  2. Manuscript Accepted: 14 AUG 2012
  3. Manuscript Received: 27 JUN 2011

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Keywords:

  • bottlenose dolphin;
  • Tursiops truncatus ;
  • underwater video observation;
  • protected species;
  • bycatch reduction

Abstract

Most studies of delphinid-trawler interactions have documented the surface behavior of dolphins feeding on discarded bycatch, but not their subsurface behavior around demersal trawl gear. Using video cameras mounted inside trawl nets, we recorded the subsurface behavior of common bottlenose dolphins (Tursiops truncatus) in a demersal fish trawl fishery in northwestern Australia. Footage from 36 trawls across the fishery was analyzed to determine the extent of dolphin-gear interactions and the behavior of dolphins inside the nets. Interaction rates were high, with dolphins present inside and outside the nets during 29 and 34 trawls, respectively, and for up to 99% of the trawl duration. The proportion of foraging behaviors exhibited inside the nets was higher than the proportions of traveling and socializing behaviors. Twenty-nine individuals were identified inside the net, seven of which returned repeatedly within and between trawls and fishing trips, but were observed primarily in the same localized areas in which they were first recorded. Our results suggest that entering trawl nets may be a frequently occurring, yet specialized behavior exhibited by a small subset of trawler-associated dolphins. We propose that gear modifications, not spatial or temporal adjustments to fishing effort, have the greatest potential to reduce dolphin bycatch.

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