EVALUATION OF SHRIMP TRAWLS EQUIPPED WITH BYCATCH REDUCTION DEVICES IN INSHORE WATERS OF LOUISIANA

Trawling was conducted in three areas of coastal Louisiana during both 1993 shrimp seasons to evaluate the effectiveness of bycatch reductio n devices (BRD's). Two industry-designed devices (Authement-Ledet 2 an d CJ Kiffe) and two National Marine Fisheries Service designs (Extende d Funnel and Skirted Extended Funnel) were evaluated during the spring . Based on the results from the spring season and diver evaluations, t hese device nets were modified before the fall season in an attempt to improve effectiveness. Additional tows compared a polyethylene net wi th the nylon control net. The Authement-Ledet 2, Extended Funnel, and Skirted Extended Funnel nets caught fewer fish (-40, -46, and -25%) an d shrimp (-22, -16, and -21%) than the control nets. Biomass catch dif ferences were -37, -30, and -35% for fish and -19, -18, and -21% for s hrimp. Compared with the corresponding control nets, the modified nets caught fewer fish (-22, -44, and -38%) and shrimp (-16, -5, and -19%) . Biomass catch differences were -27, -50, and -40% for fish and -9, - 5, and -18% for shrimp. The CJ Kiffe net caught 55% fewer fish numeric ally, 62% less fish biomass, and fewer shrimp (-39% numbers, -35% biom ass). The CJ Kiffe 2 net caught 4% more fish (-50% biomass) than the c ontrol net and 18% fewer shrimp (-22% biomass). The CJ Kiffe 2 device and codend were constructed with polyethylene webbing and collected 30 3% more bay anchovy than the control net. The polyethylene net caught 239% more bay anchovy and 480% more striped anchovy than the nylon con trol net, indicating that polyethylene webbing may retain these specie s. The modified Extended Funnel design had the best combination of hig h fish reduction and low shrimp loss of the devices tested. However, t he effectiveness of some of the modifications suggests that devices co uld be further fine-tuned to improve performance. (C) 1997 Elsevier Sc ience B.V.