Evaluating techniques for sampling stream crayfish (Paranephrops planifrons) |
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Authors: | Charles F Rabeni Kevin J Collier Stephanie M Parkyn Brendan J Hicks |
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Institution: | 1. Missouri Cooperative Fish and Wildlife Research Unit, Biological Resources Division, U.S. Geological Survey , University of Missouri , 112 Stephens Hall, Columbia, Missouri, 65211, United States;2. National Institute of Water &3. Atmospheric Research Ltd , P.O. Box 11 115, Hamilton, New Zealand;4. Department of Biological Sciences , University of Waikato , Private Bag 3105, Hamilton, New Zealand |
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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. |
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Keywords: | crayfish population structure depletion mark‐recapture electrofishing New Zealand |
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