Usha, Bhagirathan; Dr.Meenakumari,B(Cochin University of Science and Technology, May , 2009)
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Abstract:
Bottom trawling is one among the most destructive human induced physical
disturbances inflicted to seabed and its living communities. The bottom trawls are
designed to tow along the sea floor, which on its operation indiscriminately smashes
everything on their way crushing, killing, burying and exposing to predators the
benthic fauna. Bottom trawling causes physical and biological damages that are
irreversible, extensive and long lasting. The commercial trawling fleet of India
consists of 29,241 small and medium-fishing boats. The northwest coast of India has
the largest fishing fleet consisting of 23,618 mechanized vessels, especially the
bottom trawlers. However, attempts were not made to study the impact of bottom
trawling along Northwest coast of India. The estimated optimum fleet size of
Gujarat is 1,473 mechanised trawlers while 7402 commercial trawlers are operated
from the coast of Gujarat. Veraval port was designed initially for 1,200 fishing
trawlers but 2793 trawlers are being operated from this port making it the largest
trawler port of Gujarat. The aim of this study was to investigate the effects of
bottom trawling on the substratum and the associated benthic communities of
commercial trawling grounds of Veraval coast. The study compared the differences
between the samples collected before and after experimental trawling to detect the
impacts of bottom trawling. Attempts were made to assess the possible impact of
bottom trawling on:(i) the sediment characteristics (ii)the sediment heavy metals (iii)
epifauna (iv) macrobenthos and (v) meiobenthos. This study is expected to generate
information on trawling impacts of the studied area that will help in better
management of the biological diversity and integrity of the benthic fauna off Veraval
coast. An exhaustive review on the studies conducted around the world and in India
on impact of bottom trawling on the benthic fauna is also detailed.In the present study, the bottom trawling induced variations on sediment
organic matter, epifauna, macrobenthos and meiobenthos were evident. It was also
observed that the seasonal/ natural variations were more prominent masking the
trawling effect on sediment texture and heavy metals.
Enforcement of control of excess bottom trawlers and popularization of semi
pelagic trawls designed to operate a little distance above the sea bottom for off
bottom resources will minimize disturbance on the sea bottom. Training and
creating awareness in responsible fishing should be made mandatory requirements, to
the coastal communities. They should be made wardens to protect the valuable
resources for the benefit of sustainability. To protect the biodiversity and ecosystem
health, the imminent need is to survey and make catalogue, identification of sensitive
areas or hot spots and to adopt management strategies for the conservation and
biodiversity protection of benthic fauna.
The present study is a pioneering work carried out along Veraval coast. This
thesis will provide a major fillip to the studies on impact of bottom trawling on the
benthic fauna along the coast of India.