Reducing bycatch in coral reef trap fisheries: escape gaps as a step towards sustainability

Alternative trap designs were tested to determine their ability to reduce bycatch of ecologically important herbivore species such as parrotfish and surgeonfish. Catches from traditional Antillean chevron traps were compared to catches from traps with 1) short escape gaps (20X2.5 cm), 2) traps with tall escape gaps (40X2.5 cm) and 3) traps with a panel of large aperture mesh. The mean number of fish caught in the various traps were: 11.84 (control), 4.88 (short gap trap), 4.43 (tall gap traps) and 0.34 (large mesh traps). Short gap traps caught 74% fewer bycatch fish species, 58% fewer key herbivores and 90% fewer butterflyfish. Large gap traps caught 80% fewer bycatch fish species, 50% fewer key herbivores and 98% fewer butterflyfish. Juveniles were able to escape via the gaps and so the mean length of captured fish was significantly higher in the gap traps compared to the control trap. Catches of high-value fish were not affected by the use of gap traps.