Reducing Ecosystem Effects of Commercial Fish Trap Fishing

Fisheries can have unintended effects, particularly in highly integrated coral reef ecosystems.  Bottom tending gears can affect benthic habitat characteristics, and the removal of non-target species can disturb ecosystem processes.  To examine effects, this multifaceted research used observer trips, port samples, and trip tickets over a six-year period to document the species composition and quantities of bycatch by gear from St. Thomas commercial fisheries (U.S. Virgin Islands).  High catches of ecologically important species, particularly herbivorous fishes known to assist corals in their competition for space, encouraged further study of ways to reduce bycatch in fish traps. Cooperative research examined vent size, placement, and number per trap.  Well-designed escape vents proved an effective means to increase size selection for key target species (Epinephelus guttatus – increased mean catch length by 5 cm TL) and reduce bycatch and bycatch mortality of herbivorous species (from 20-90%).  Habitat science provided the foundation for judging the importance of reductions in removals.  Expanded use of escape vents throughout the commercial trap fisheries of the USVI is underway with the potential to benefit corals and the integrity of the coral reef ecosystems.