JOURNAL OF AQUATIC SCIENCES 24(1): 40 – 45 APRIL (2009)
A TROUSER BAG EXPERIMENT THAT QUANTIFY BY-CATCH SPECIES ESCAPING FROM A MODIFIED SHRIMP BEAM TRAWL CODEND WITH EXCLUDER DEVICE
AMBROSE, E.E., ENINI, U.I. and LEBO, P.E.1
Fisheries Resources Division, Nigerian Institute for Oceanography and Marine Research,
Victoria Island, PMB 12729 Lagos.
1Institute of Oceanography, University of Calabar, Cross River State, Nigeria.
Sea fishing trials were conducted to quantify by-catch species escaping from a modified shrimp trawl codend and retained in a trouser bag. Modification was by inserting a rectangular aluminum frame excluder device with bar spacing of 20mm at the anterior bunt. Thirty replicate landings showed that; Drepane africana have the highest escape rate of 50.76% followed by Pseudotolithus elongatus (46.83%), while flat fishes like Dasyatis margarita and shell fishes like Callinectes amnicola have low escape rates of zero and 17.62% respectively. Among the five fish groups of pelagic, semi-pelagic, demersal, shell and target shrimps, pelagic have the highest escape rate of 39.8% and target shrimps Nematopolaemon hastatus the least, 2.3%. The influence of water flow speed in the codend on t he escape rates of five fish groupings is discussed.
Keywords: Trouser bag, by-catch, Codend, Excluder device