Impact of a bycatch reduction device on diamondback terrapin and blue crab capture in crab pots

Published source details Roosenburg W.M. & Green J.P. (2000) Impact of a bycatch reduction device on diamondback terrapin and blue crab capture in crab pots. Ecological Applications, 10, 882-889.
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This study is summarised as evidence for the following.

	Action	Category
	Install exclusion devices on fishing gear: Tortoises, terrapins, side-necked & softshell turtles Action Link

Install exclusion devices on fishing gear: Tortoises, terrapins, side-necked & softshell turtles

A replicated, controlled study in 1996–1997 in an estuarine river in Maryland, USA (Roosenburg & Green 2000) found that after fitting rectangular exclusion devices (‘bycatch reduction device’) to crab pots, unwanted catch of diamondback terrapins Malaclemys terrapin tended to be lower. In 1996, no terrapins were caught in crab pots modified with a 4 × 10 cm exclusion device, compared to 21 terrapins in unmodified pots. In 1997, fourteen terrapins were caught in pots with a 4.5 × 12 cm exclusion device and 56 in pots with a 5 × 10 cm exclusion device, compared to 105 in unmodified pots (results were not statistically tested). Blue crab Callinectes sapidus catch was 2 crabs/pot/day lower when 4 x 10 cm devices were used compared to unmodified pots. Neither the 4.5 x 12 cm nor the 5 x 10 cm excluder device affected crab catch. Three sizes of 11-gauge galvanised wire exclusion devices were tested on modified and unmodified crab pots (standard: 60 cm square, tall: 60 x 60 x 180 cm). In 1996, fourteen unmodified and 14 pots modified with a 4 × 10 cm exclusion device were used (50 days total fishing). In 1997, ten unmodified and 20 pots modified with either 4.5 x 12 cm or 5 x 10 cm exclusion devices were used (10 pots/excluder type, 42 total fishing days). Traps were checked and baited daily.

(Summarised by: Maggie Watson, Katie Sainsbury)