Study On the By Catch Loss in Two Coastal Districts of West Bengal, India

Abstract

By catch is now a worldwide concern among Scientists, policy makers and other discrete bodies concerned with aquatic biodiversity. The term by catch means the incidental catch (retained catch) of non-target species plus discarded catch, while 'discards' or 'discarded catch' denotes the portion of the catch returned to sea. The problem of discarding and by catch has attracted substantial attention among researchers in the last three decades due to their deleterious effects on marine biodiversity with particular reference to egg bearing adult and young ones of commercially valuable and endangered species. In West Bengal, India two coastal districts, Namkhana and Digha are famous for production of a huge amount by catch and discards in the range of 3000-8500 kg/month depending on the season. Constituent groups include Bhola, Clupidae, catfish, flat fish, ribbon fish and Carangidae and a number of important groups of fishes. Trawl net is the major contributors of by catch, particularly during shrimp harvest, when discard/ catch ration ranged somewhat from 3:1 to 15:1. Considering the importance this study was initiated covering period of nine month, for documentation of the groups and species caught unintentionally during the capture of target species in two coastal districts of West Bengal, India. A comparative data was created to assess the by catch / discards in terms of weight, percentage, groups and also in terms of seasons and region. The study revealed that large groups important fishes are caught (6 or even more) in targeting one or two species.