Assessment of Juveniles in Trash Fish Landing from Trawlers of Mangalore
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Date
2014-10-15
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Karnataka Veterinary, Animal and Fisheries Sciences University, Bidar
Abstract
Trawling is one of the most efficient methods of catching fish world over and is
also the most important human intervention causing physical disturbance to the
continental shelves, and consequently, the physical destruction of ecosystems. Trawl
fishery is generally a mixed fishery targeting a number of species and sizes,
simultaneously. By-catch not only includes non-commercial species, but also
commercial species that are below minimum legal size (MLS) or less profitable species
owing to market conditions. Since the demand for fish meal is on the rise, more
advanced technologies in fishing and vessel infrastructure are being introduced and
practiced. These developments have resulted in heavy exploitation of juveniles of
commercially important fishes and other ecologically important biota.
At Mangalore Fisheries Harbour, it was estimated that in 2012-14, trawlers landed
on an average 1.68 lakh t of fishes per year, of which 1.33 lakh t (79%) was retained for
edible purpose and 0.35 lakh t (21%) was marked as “low value by-catch” (LVB)
mainly for fish meal production. For assessing the sustainability of marine fisheries
production it is imperative to understand the species composition and the juvenile
composition of the fishes in the LVB. From the LVB, 121 species of finfishes were
recorded in MDT. Juveniles of commercially important finfish species formed 47.53 %
of the finfish LVB by weight (56.1% by number). An estimated 4,693.4 t (272.4 million
in number) of Decapterus russelli juveniles, 1,395.7 t (144.9 million in nuamber) of
Saurida tumbil and 1,671.4 t (142.9 million in number) of Rastrelliger kanagurta were
landed as LVB per year by multiday trawlers. From the results it is evident that the
trawlers equipped with advanced technologies in fishing and high storage capacity are
intensively trawling to catch as much as possible without any concern over the size or
the species of fish or the sustainability of the fishery. Since trawl fishery is the backbone
of Indian marine fisheries bycatch is unavoidable in multi-species scenario. Bycatch
problem to a large extent can be reasonably addressed by allowing trawling with nets
with bigger mesh sizes, banning of trawling in certain seasons, effort reduction in
critical fishing grounds and adoption of BRDs such as Juvenile Fish Excluder cum
Shrimp Sorting Device (JFE-SSD) can bring down the damages to the ecosystems by
reducing juveniles in by-catch considerably.
Description
Ph.D. Thesis
Keywords
land resources, yields, fruits, fungi, niger, imports