Abstract
This study investigated the impacts of ghost fishing on collapsible crab traps targeting the blue swimming
crab, Portunus pelagicus. The impacts were examined by a simulated lost-gear experiment to
compare conventional and vented traps, with long-term diving monitoring from 6 January 2013 to 15
January 2014, at a depth of 4e6 m in Si Racha Bay, Gulf of Thailand. Twelve pairs of box-shaped traps
36 54 19 cm were compared using the conventional design and a vented trap with escape vents of
35 45 mm. Throughout the 374 d experiment, 520 individuals from 25 different species were
entrapped in the conventional traps, with 19 were classified as target, and 501 individuals as by-catch
species. In the vented traps, 222 individuals of 24 species were entrapped in total, of which 17 were
classified as target and 205 as by-catch. The catch-per-unit-effort of all animals entrapped in conventional
traps was significantly higher than in the vented traps at each time observation. Furthermore, the
vented traps showed lower entrapment and mortality numbers than the conventional traps. These results
demonstrate the positive functions of escape vents in reducing the negative impacts of ghost
fishing, not only on the number of entrapped individuals but also on mortality rates.
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