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Trapping Bias in Sampling Crayfish with Baited Funnel Traps
Author(s) -
Stuecheli Ken
Publication year - 1991
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1991)011<0236:tbiscw>2.3.co;2
Subject(s) - crayfish , carapace , funnel , minnow , trapping , biology , zoology , sampling (signal processing) , fishery , ecology , environmental science , crustacean , physics , fish <actinopterygii> , environmental engineering , detector , optics
Virile crayfish Orconectes virilis were sampled during 3 years (1981–1983) with baited Gee minnow traps with modified funnel openings. The mean (± SE) carapace lengths (mm) of crayfish captured in traps with 2‐, 3‐, or 4‐cm funnel openings (33.1 ± 0.2, 39.9 ± 0.1, and 44.3 ± 0.1, respectively) differed significantly ( F = 990.7, P < 0.001). The catch obtained with each trap opening size was dominated by a narrow size range of crayfish. Sex ratios also varied significantly ( X 2 = 217.06, P < 0.001). Male‐to‐female sex ratios were 62: 38, 80:20, and 89:11 for the 2‐, 3‐, and 4‐cm traps, respectively. Size constraint by the trap opening alone could not explain these discrepancies. Given these results, it is recommended that several trap opening diameters be used for sampling crayfish.