Volume 72, Issue 7 p. 1628-1633

Evaluation of Turtle Exclusion and Escapement Devices for Hoop-Nets

ZACHARY W. FRATTO

ZACHARY W. FRATTO

Missouri Department of Conservation, Open Rivers and Wetlands Field Station, 3815 E Jackson Boulevard, Jackson, MO 63755, USA

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VALERIE A. BARKO

Corresponding Author

VALERIE A. BARKO

Missouri Department of Conservation, Open Rivers and Wetlands Field Station, 3815 E Jackson Boulevard, Jackson, MO 63755, USA

John A. Logan College, 700 Logan College Road, Carterville, IL 62918, USA

[email protected]Search for more papers by this author
PHILLIP R. PITTS

PHILLIP R. PITTS

Missouri Department of Conservation, Central Region, 1907 Hillcrest Drive, Columbia, MO 65201, USA

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STEVEN L. SHERIFF

STEVEN L. SHERIFF

Missouri Department of Conservation, Resource Science Center, 1110 E College Drive, Columbia, MO 65201, USA

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JEFFREY T. BRIGGLER

JEFFREY T. BRIGGLER

Missouri Department of Conservation, Resource Science Division, P.O. Box 180, Jefferson City, MO 65102, USA

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KEVIN P. SULLIVAN

KEVIN P. SULLIVAN

Missouri Department of Conservation, Grassland Field Station, P.O. Box 368, Clinton, MO 64735, USA

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BRIAN L. MCKEAGE

BRIAN L. MCKEAGE

Missouri Department of Conservation, Central Region, 1907 Hillcrest Drive, Columbia, MO 65201, USA

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TOM R. JOHNSON

TOM R. JOHNSON

7078 Crisptown Road, Mountain Grove, MO 65711, USA

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First published: 13 December 2010
Citations: 9

Abstract

Abstract Baited and unbaited hoop-nets commonly are used to capture catfish in lotic and lentic systems. Turtle bycatch and post-capture mortality has been problematic during catfish surveys in Missouri, USA, most recently in the Gasconade River, Gasconade and Osage counties. We evaluated 3 modified hoop-net designs that would reduce turtle bycatch without reducing catfish capture in the Gasconade River during 15 May-15 July 2006 after pilot study evaluation of 5 hoop-net designs in April 2006. We deployed modified and control-nets in blocks for 48 hours to evaluate differences in turtle and catfish catch rate, as well as abundance, size, and mortality rate of turtle bycatch. The chimney design reduced turtle bycatch by 84% when compared to the control, without decreasing the number or average size of captured flathead catfish (Pylodictis olivaris). Environmental conditions that affected turtle mortality included Secchi disc transparency, temperature, dissolved oxygen, and stream river depth. This is the first known attempt to create turtle exclusion or escapement devices for hoop-nets deployed in freshwater systems. Biologists using hoop-nets to sample aquatic vertebrates in moderate to large river systems will benefit from our study. The application of this methodology will reduce turtle bycatch mortality, especially when sampling is conducted in high water temperatures.