Experiments with By-Catch Reduction Devices to Exclude Diamondback Terrapins and Retain Blue Crabs
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Experiments were completed in SE Virginia during June–July 2014 and 2015 to examine the responses of blue crabs (Callinectes sapidus) and diamondback terrapins (Malaclemys terrapin) to commercial-style crab pots modified in visual and other ways that might attract and retain crabs while excluding terrapins as by-catch. In a seawater tank, far fewer crabs entered crab pots fitted with red plastic by-catch reduction devices (BRDs), relative to pots without BRDs. Crab retention times, however, were significantly longer in pots fitted with red BRDs. In a second experiment, fewer terrapins entered crab pots with funnels painted red relative to black. From a field pilot study, the legal crab catch from pots with red BRDs was similar to pots without BRDs, and terrapin by-catch was reduced. Relative to those treatments, fewer crabs and more terrapins were captured in pots with orange BRDs and blue BRDs, and in pots with a magnetic field directed into the funnel openings. Based on these results, a final field trial yielded comparable crab catch from 15 pots without BRDs and 15 pots fitted with red plastic BRDs. Of a by-catch of 68 terrapins, 58 were from pots without BRDs. The structure and color of BRDs can exclude most terrapins; because crab retention rates are high, the net effect of BRDs on crab catch is relatively minor, even though fewer crabs may enter pots fitted with BRDs.
KeywordsBlue crab Diamondback terrapin By-catch reduction device Crab pot Fisheries management
This research was supported by a National Fish and Wildlife Foundation Grant 718361-712685 to VIMS, by the William & Mary Committee on Sustainability, and by the W&M Environmental Science and Policy Program. Thanks to S. Belfit for volunteer support and to the Yorktown Naval Weapons Station for logistical support and access to field sites. This study benefitted from discussions with J. Baldwin and A. Dominy and was permitted by VA DGIF and W&M IACUC.
- Chambers, R.M., and J.C. Maerz. 2017. Terrapin bycatch in blue crab fisheries. In Ecology and conservation of the diamond-backed terrapin (Malaclemys terrapin), ed. W.M. Roosenburg and V.S. Kennedy, Chapter 16 ed. Baltimore: Johns Hopkins University Press.Google Scholar
- Coleman, A.T., T. Wibbels, K. Marion, D. Nelson, and J. Dindo. 2011. Effect of bycatch reduction devices (BRDs) on the capture of diamondback terrapins (Malaclemys terrapin) in crab pots in an Alabama salt marsh. Journal of the Alabama Academy of Science 82: 145–157.Google Scholar
- Dominy, A.E. 2015. Modeling underwater visual ability and varied color expression in the diamondback terrapin (Malaclemys terrapin) in relation to potential mate preference by females. PhD dissertation, Drexel University, Philadelphia, PAGoogle Scholar
- Guillory, V., and P. Prejean. 1998. Effect of a terrapin excluder device on blue crab, Callinectes sapidus, trap catches. Marine Fisheries Review 60: 38–40.Google Scholar
- Hoyle, M.E., and J.W. Gibbons. 2000. Use of a marked population of diamondback terrapins (Malaclemys terrapin) to determine impacts of recreational crab pots. Chelonian Conservation and Biology 3: 735–737.Google Scholar
- McKee, R.K., K.K. Cecala, and M.E. Dorcas. 2015. Behavioural interactions of diamondback terrapins with crab pots demonstrate that bycatch reduction devices reduce entrapment. Aquatic Conservation: Marine and Freshwater Ecosystems. doi: 10.1002/aqc.2587.
- Miller, T.J., M.J. Wilbert, A.R. Colton, G.R. Davis, A. Sharov, R.N. Lipcius, G.M. Ralph, E.G. Johnson, and A.G. Kaufman. 2011. Stock assessment of the blue crab in Chesapeake Bay. Final report to NOAA Chesapeake Bay Office, Annapolis, MDGoogle Scholar
- Rook, M.A., R.N. Lipcius, B.M. Bronner, and R.M. Chambers, R. M. 2010. Bycatch reduction device conserves diamondback terrapin without affecting catch of blue crab. Marine Ecology Progress Series 409: 171–179.Google Scholar
- Roosenburg, W.M. 2004. The impact of crab pot fisheries on terrapin (Malaclemys terrapin) populations: Where are we and where do we need to go. In Conservation and ecology of turtles of the mid-Atlantic region: a symposium, 22–30. Salt Lake City, UT.Google Scholar
- Sturdivant, S.K., and K.L. Clark. 2011. An evaluation of the effects of blue crab (Callinectes sapidus) behavior on the efficacy of crab pots as a tool for estimating population abundance. Fishery Bulletin 109: 48–55.Google Scholar
- Wood, R.C. 1997. The impact of commercial crab traps on northern diamondback terrapins, Malaclemys terrapin terrapin. In Proceedings: conservation, restoration, and management of tortoises and turtles-an international conference, 21–27. New York: New York Turtle and Tortoise Society.Google Scholar