New Zealand Journal of Marine and Freshwater Research abstracts

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Population viability analysis for Hector’s dolphin (Cephalorhynchus hectori): a stochastic population model for local populations

Stephanie M. Burkhart*
Elisabeth Slooten

Environmental Science
University of Otago
P.O. Box 56, Dunedin
New Zealand
email: Liz.Slooten@stonebow.otago.ac.nz

*Present address: Coast Guard Pacific Area, Coast Guard Island,
Bldg 51-5, Alameda, CA 94501- 5100, United States.
email: sburkhart@d11.uscg.mil

Abstract  Mortality of Hector’s dolphin (Cephalorhynchus hectori) in gill-net fisheries is a threat to local populations throughout its range. This population viability analysis extends previous work by exploring a wider range of fishing levels and population growth rates, by incorporating year-to-year and environmental variability and by reporting results for smaller population units. Ten of the 16 populations are likely to continue to decline, five are indefinite, and one is likely to increase. All populations subjected to high fishing effort are declining. The only population predicted to increase is partly protected by a marine mammal sanctuary (created in 1988) which reduces the amount of gill-net fishing. Conservation measures are most urgently needed for the highly threatened North Island population, in particular the dolphins at the northern and southern end of this range.

Keywords  Hector’s dolphin; population viability analysis; PVA; extinction risk; gill-net entanglement; bycatch; environmental impacts of fishing

M02041 Received 7 June 2002; accepted 30 January 2003; Published 5 August 2003
New Zealand Journal of Marine and Freshwater Research, 2003, Vol. 37: 553-566
0028-8330/03/3702-0553 $7.00 © The Royal Society of New Zealand 2003

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