The effect of escape vents on the capture of black sea bass, Centropristis striata, in fish traps

Black sea bass fisheries in the Middle Atlantic have traditionally used fish traps without escape vents that required sorting the catch by size after hauling the trap. The need to reduce discard mortality and increase the yield per recruit in sea bass fisheries prompted an investigation into the effectiveness of escape vents in the traps. An array of experimental traps using one of four escape vents openings (sizes of 2.86 cm x 14.6 cm, 3.18 cm x 14.6 cm, 3.49, cm x 14.6 cm, or 3.81 cm x 14.6 cm) was fished from May to November 1994. Use of escape vents significantly (p < 0.001) reduced catch of black sea bass in traps with the primary impact on sub-legal size fish. The optimal vent size was 2.86 cm x 14.6 em, which produced the highest ratio of legal- to sub-legal-sized sea bass. The catch of legal size sea bass was reduced in number by 3% whereas the catch of sub-legal fish was reduced to 72%. Seasonal changes in catch occurred among all vent sizes, which followed the traditional pattern of highest landings in the fall prior to the fishes migration to the outer continental shelf. The use of escape vents should result in relatively small short-term economic losses to fishermen while increasing the efficiency of fishing practices and increasing long-term yields from the fisheries. Published by Elsevier Science B.V.