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¹ Visakhapatnam Regional Centre of ICAR-Central Marine Fisheries Research Institute Visakhapatnam, Andhra Pradesh, India – 530003
² Mangalore Regional Centre of ICAR-Central Marine Fisheries Research Institute Mangalore, Karnataka, India – 575001
³ ICAR-Central Marine Fisheries Research Institute Kochi, Kerala, India – 682018 DOI : 10.4194/TRJFAS2454350 Viewed : 643 - Downloaded : 618 In light of the ecological concerns associated with bottom trawling in tropical multispecies fisheries, an attempt was undertaken to implement operational modifications in experimental trawling practices aimed at reducing bottom contact. This endeavour was pursued to investigate the resulting effects on bycatch biomass and diversity along the north-western Bay of Bengal. The average total catch rate and bycatch rate in 66 hauls from January 2017 to December 2019 were 35.46 kg/h and 9.70 kg/h respectively. Bycatch biomass was mainly contributed by Teleostei (77.90%), of which the dominant species was Equuilites lineolatus. Temporal variations in bycatch composition were recorded, and average seasonal dissimilarity ranged between 35.03% and 59.61%. Juvenile percentages varied among six commercial species from 1.42 to 28.0, and their occurrences were related to their peak spawning seasons. The trophic index of bycatch calculated was 3.65. Species diversity and richness in bycatch were higher during post-monsoon and summer seasons. Biomass and abundance plots indicated the bycatch fauna to be relatively unstressed during most seasons. Trawling marginally above the bottom had improved ecological outcomes; as evident from the decreased proportion of bycatch to total trawl catch, reduced growth overfishing from lower juvenile proportions and within optima for various diversity indicators. Keywords : Diversity, Experimental trawling, Juvenile fish, Target catch, Trophic level