Preliminary results of a study of the commercial trawl fisheries in Lingayen Gulf

Abstract

This paper presents preliminary results of an ongoing survey of the commercial trawl fisheries of Lingayen Gulf covering the period June 1987 to April 1988. A total of 102 hauls from 24 trawl-trips were sampled during the 11-month period. Mean catch rate was 31.8 kg/hour for medium trawlers (10-20 GT) and the catch consisted of 158 species/groups distributed among 58 families/groups. Mean stock density (D) and biomass (B) were estimated (via the swept area method) to be 0.570 t/km2 and 1,190 t, respectively. Landings (Y) by the trawl fleet averaged 280 t/month, or an aggre- gate of 3,070 t for the 11-month period. These imply considerable fishing pressure from the trawl fleet comprising 24 medium and 2 large (20-40 GT) trawlers, representing fishing mortalities (F = Y/B) of 0.23 per month and 2.58 for the 11-month period. The faunal composition of trawl catches indicates that the optimum mesh size for trawlers in the area is 3.5-4.0 cm, and that the current mesh size of 2.0 cm being used results into considerable losses in aggregate yield from the multispecies mix. The length composition data generated thus far indicate that more accurate species-specific assessments are plausible after the data collection phase is completed.