Study

The effects of bycatch reduction devices on diamondback terrapin and blue crab catch in the North Carolina commercial crab fishery

  • Published source details Chavez S. & Williard A.S. (2017) The effects of bycatch reduction devices on diamondback terrapin and blue crab catch in the North Carolina commercial crab fishery. Fisheries Research, 186, 94-101.

Actions

This study is summarised as evidence for the following.

Action Category

Modify fishing gear to reduce reptile mortality in the event of unwanted catch

Action Link
Reptile Conservation

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

Action Link
Reptile Conservation
  1. Modify fishing gear to reduce reptile mortality in the event of unwanted catch

    A replicated study in 2012–2013 in five estuarine sites in North Carolina, USA (Chavez & Williard 2017) found that pots fitted with a wire mesh chimney led to low mortality of diamondback terrapins Malaclemys terrapin. One of 14 terrapins that were caught in pots modified with the chimney died. Standard commercial crab pots (61 cm × 61 cm × 61 cm) were fitted with a chicken wire chimney (122 × 30.5 cm diameter) to provide trapped terrapins with access to air. Pots were deployed June–July in 2012 (4 sites) and 2013 (2 sites). Pots were baited and submerged for 48 hours at a time.

    (Summarised by: Katie Sainsbury)

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

    A replicated, controlled, paired study in 2012–2013 in five estuarine sites in North Carolina, USA (Chavez & Williard 2017) found that crab pots fitted with one of two different sized wire rectangles (‘bycatch reduction devices’) limiting the size of the pot opening reduced the numbers of diamondback terrapins Malaclemys terrapin caught, compared to unmodified pots. No statistical analyses were carried out due to a small sample size. Pots modified to have small-sized openings and large-sized openings caught zero and one terrapin respectively, compared to 13 terrapins in unmodified pots. None of the terrapins caught were small enough to enter pots with the small-sized opening. One terrapin died in an unmodified pot. Standard commercial crab pots (61 × 61 × 61 cm) were modified with galvanized wire to create large-sized openings (5.1 × 15.2 cm, 10 pots), small-sized openings (3.8 × 15.2 cm, 10 pots) or were unmodified (20 pots). Pots were deployed June–July in pairs (one modified pot and one unmodified pot in 4 sites) in 2012 or in triplicate (1 of each size of modified pot with a single unmodified pot in 2 sites) in 2013. Pots were baited and submerged for 48 hours at a time.

    (Summarised by: Katie Sainsbury)

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