ON THE OPTIMUM BUOYANCY WEIGHT RELATION FOR A BOTTOM TRAWL.

Abstract

Comparative fishing operations were carried out with 0.55;
0.75 and 1.00 buoyancy-weight relations of bottom trawl in order
to find out the optimum relation. Two nets Viz, 18.26 m. (60')
two seam nylon and 16.16 m. (23') two seam cotton trawls were
used for the experiment. The results showed that the total catch
per trawling hour with 0.75 B-W relation was 16.5% and 32.08%
more than that with 0.55 and 1.00 B-W relation for nylon net
used. A similar trend was noticed with cotton trawl also as the
catch rate with 0.75 B-W relation was 13.89% and 25.78% more
than that with 0.55 and 1.00 B-W relation. However, the analysis
of catch composition indicated that the off bottom fishes like lactarius,
upenoides sp., synagris sp. etc., were of more percentage
with 1.00 B-W relation, near bottom fish like saurida, sciaenids
etc., were more with 0.75 B-W relation, while the bottom fishes
like soles, prawns, skate3 and rays etc., were more with 0.55 B-W
relation.