New Zealand Journal of Marine and Freshwater Research abstracts

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Evaluating techniques for sampling stream crayfish (Paranephrops planifrons)

CHARLES F. RABENI

Missouri Cooperative Fish and Wildlife
Research Unit
Biological Resources Division
U.S. Geological Survey
112 Stephens Hall, University of Missouri
Columbia, Missouri 65211, United States

KEVIN J. COLLIER
STEPHANIE M. PARKYN

National Institute of Water & Atmospheric
Research Ltd
P. O. Box 11 115
Hamilton, New Zealand

BRENDAN J. HICKS

Department of Biological Sciences
University of Waikato
Private Bag 3105
Hamilton, New Zealand

Abstract  We evaluated several capture and analysis techniques for estimating abundance and size structure of freshwater crayfish (Paranephrops planifrons) (koura) from a forested North Island, New Zealand stream to provide a methodological basis for future population studies. Direct observation at night and collecting with baited traps were not considered useful. A quadrat sampler was highly biased toward collecting small individuals. Handnetting at night and estimating abundances using the depletion method were not as efficient as handnetting on different dates and analysing by a mark-recapture technique. Electrofishing was effective in collecting koura from different habitats and resulted in the highest abundance estimates, and mark-recapture estimates appeared to be more precise than depletion estimates, especially if multiple recaptures were made. Handnetting captured more large crayfish relative to electrofishing or the quadrat sampler.

Keywords   crayfish; population structure; depletion; mark-recapture; electrofishing; New Zealand

New Zealand Journal of Marine and Freshwater Research, 1997, Vol. 31: 693-700

0028-8330/97/3105-0693 $7.00/0 (c) The Royal Society of New Zealand 1997

PDF file of entire paper: medium quality (647K); (scanned from paper original: notes about this process)

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