Occurrence of Low Value Bycatch in Trawl Fisheries off Karnataka, India

Abstract

Bottom trawling in the most effective method of
shrimp capture but highly intensive trawling adversely
affects benthic ecology and biodiversity. The
present study is aimed to throw light on low value
bycatch (LVB) landings and catch composition of
trawl boats, at Mangaluru fisheries harbour. The
quantity of fish landings by single day trawlers
(SDT) during 2012-14 was 2 151.3 t y-1, of which
61.8% was considered as edible grade and 38.2%
was LVB. Multiday trawlers (MDT) landed an
estimated 165917.2 t of fishes/yr, out of which 79.6%
were marked for edible use and remaining 20.4%
was landed as LVB. LVB to target group ratio for
SDT and MDT landings was 1:1.66 and 1:3.93,
respectively. The LVB of MDT consisted of 121
finfishes belonging to 82 genera, 55 families and 13
orders. An estimated 47.53% of the finfish LVB
landing by weight (56.1% by number) was contributed
by juveniles of commercially important species
and the estimated resource loss was 14044 t by
weight and 11000 million in number. From the
fishery resource conservation and sustainability
point of view, the magnitude of resource damage
due to trawl bycatch is alarmingly increasing. The
study recommends using trawl nets with 35 mm
square mesh codend, effort reduction in critical
fishing grounds and adoption of Juvenile Fish
Excluder cum Shrimp Sorting Device (JFE-SSD)
which minimizes juvenile fish catch.