Pelagic megafauna bycatch in the tuna longline fisheries off India

Pelagic megafauna bycatch in the tuna longline fisheries off India

Year of publication 2013

Product type Meeting

Edition 1

Synopsis (short abstract) To assess the diversity and abundance of pelagic megafau caught in the tu longline survey in the seas around India, data was collected and alysed from survey voyages of four research longliners of the Fishery Survey of India (FSI) during 2004-2010. Study was conducted by operating 11.99 million hooks in three regions of seas around India, i.e., eastern Arabian Sea, western Bay of Bengal and Andaman and Nicobar waters. Significant variations in the diversity and abundance of large pelagics were o bserved among the three regions of the study area. Besides the target species (yellowfin tu, Thunnus albacares), 60 species of large pelagics and sea turtles were incidentally caught. Indo-Pacific sailfish, Istiophorus platypterus, was the main bycatch species. In the order of abundance, pelagic stingray (Pteroplatytrygon violacea), common dolphinfish (Coryphae hippurus), pelagic thresher (Alopias pelagicus), skipjack tu (Katsuwonus pelamis), and long snouted lancetfish (Alepisaurus ferox), were the other important species recorded. Of the three species of sea turtles caught, olive ridley, Lepidochelys olivacea was prominent. Sea birds and cetaceans were not represented in the longline bycatch of seas around India. Length-weight relationship of 34 species and spatial distribution of seven species are presented and discussed. This study provides information on the relative abundance, size structure and sex ratio of the pelagic megafau of the seas around India which should be useful for identifying magement measures for these ecologically and economically important resources.

Statutory body / Meeting title Indian Ocean Tuna Commission (IOTC)

Meeting symbol IOTC-2013-WPEB09-36

Meeting Session Number 9

Language English

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This report was based on the data extracted from fishing logsheets by two Thai tu longliners mely, “Mook Andaman 018” and “Mook Andaman 028”, which declared to Department of Fisheries, Thailand. Data from their logsheets displayed important information of their fishing operation and effort. In 2012, fishing grounds were mainly in the Western coast of Indian Ocean. The total catches were 470.40 tons with 387 days of fishing effort. The average catch rate of total catch was 10.83 individual fish/1 ,000 hooks. The major catch species were bigeye tu (Thunnus obesus), yellowfin tu (T. albacares), swordfish and shark. Sharks are present as an important role in the ocean ecosystem. The fishing operation was reduced their population. Among the bycatch of tu longline fishery, The percentage of sharks to the total catch is 4.64% by weight and 3.94% by number. Numbers of shark were 544 individual fishes with 18,528 kg. The catch rate was 0.5 individual fish/1,000 hooks, 17.10 kg/1,000 hooks. Catch data of sharks are classed into a single group of “sharks”, due to species unidentification.

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