Vol. 11, Special Issue 11 (2022)

Bycatch is recognized as unavoidable in any kind of fishing but the quantity varies according to the gear operated. The changing perspective of bycatch itself offers the greatest challenge, as yesterday’s by-catch becomes today’s target catch. However, this study to ascertain the ichthyofaunal biodiversity loss due to trawling was conducted between August, 2010 to May, 2012 recorded a total 131 species of finfish and shellfish belonging to 62 families and 18 orders. Family Carangidae contributed 10.69 per cent of total number of species followed by Engraulidae (6.11%), Leiognathidae (6.11%), Synodontidae (3.82%), Tetraodontidae (3.82%), Nemipteridae (3.05%), Sciaenidae (3.05%) and Scombridae (3.05%) to the total number of fish species whereas, other families contributed less than 3 percent and a total of 52 commercial species were reported in by-catch in the year 2010-11 whereas, it reduced to 41 species during the year 2011-12 with increased species number of low value fishes. This trend showed that significant increase of low value fish species with decrease in commercial fish species in by-catch. The average bycatch contribution was 33.54% (2010-11) and 45.68% (2011-12) during the study period. The results of Shannon-Weiner index (H') showed variability in different capacity engines. This study also indicated that the Mangalore coast is one of the major fishing harbours having rich biodiversity. Hence, it is recommended to reduce the fishing pressure especially by trawling to conserve the resources and biodiversity of the marine fauna.