Electrosensory avoidance of metal obstacles by the paddlefish

Authors

  • C. Gurgens,

    1. Center for Neurodynamics, Department of Biology, University of Missouri-St Louis, 8001 Natural Bridge Road, St Louis, MO 63121-4499, U.S.A.
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      508 Blythe, Liberty, MO 64068, U.S.A.

  • D. F. Russell,

    1. Center for Neurodynamics, Department of Biology, University of Missouri-St Louis, 8001 Natural Bridge Road, St Louis, MO 63121-4499, U.S.A.
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  • L. A. Wlikens

    Corresponding author
    1. Center for Neurodynamics, Department of Biology, University of Missouri-St Louis, 8001 Natural Bridge Road, St Louis, MO 63121-4499, U.S.A.
      Author to whom correspondence should be addressed. Tel.: 314 516 6222; fax: 314 516 6233; email: lon_wilkens@umsl.edu
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Author to whom correspondence should be addressed. Tel.: 314 516 6222; fax: 314 516 6233; email: lon_wilkens@umsl.edu

Abstract

Paddlefish Polyodon spathula detected and avoided obstacles with an exposed metallic surface but not plastic objects. An aluminium obstacle was avoided from significantly greater minimum approach distances than were any of the other obstacles. No significant difference was detected between the plastic and plastic-covered aluminium obstacles, while control values were significantly less than for all obstacle types. Avoidance distances measured at different water conductivities were not significantly different. Fish collided frequently with the plastic and plastic-covered aluminium obstacles, and with the control site, suggesting that these obstacles were not detected by the electrosensory apparatus. The aluminium obstacle was avoided successfully in all test runs. The unambiguous avoidance behaviour elicited by the aluminium obstacle suggests that large metallic structures, such as locks and dams, have the potential to interfere with paddlefish migrations. ©2000 The Fisheries Society of the British Isles

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