Tiger shark population faces decline: Study
Kochi: Even as India urges researchers to identify and establish its biodiversity information, several species are either on the brink of extinction or entering the near-threatened categories.
Recent studies by fisheries scientists of the
Kerala University of Fisheries and Ocean Studies
(Kufos) raised concerns about the dwindling populations of shark species in the Indian Ocean. The studies, which looked at the iconic tiger sharks (
Galeocerdo cuvier
), flagged concerns about global decline and called for
shark conservation
zones.The population of the tiger shark is in a state of global decline, with the species assessed as 'Near Threatened' on the
IUCN Red List
. Despite this, there is a lack of fundamental information required for regional management, such as those on life history and ecology."We
looked at the population dynamics of G. cuvier in the Arabian Sea, which is one of the world's most important shark fishing regions. Length-frequency data of G. cuvier landed at Cochin over 16 months in 2023–2024 revealed the dominance of the 180–240cm length class, with the largest individual measuring 405cm long.
Almost 95% of younger adults are caught and they are coming in as bycatch, contributing to 23% of the shark landings," said Rajeev Raghavan, aquatic biologist and faculty at the Kufos department of fisheries resource management.A total of 264 species of sharks and rays are known from the Western Indian Ocean (WIO), of which 43% are threatened. Some parts of the WIO are more significant for shark fisheries, such as the Arabian Sea, which harbours 15% of the described chondrichthyan species of the world, more than half of which are threatened. Close to 98% of the tiger sharks that landed at Cochin during the study period were the targets of commercial fishery using baited longline, while the remaining 2% were bycatch originating from gillnet and trawl fisheries."We need to bring in the tiger shark conservation zones. Unlike the Indian Ocean Tuna Commission, which looks at the entire tuna catches across the world, shark conservation does not have such a body. Some countries have banned tiger shark catches. Since it is not banned in India, our fishermen go to far-off deep-sea waters to catch them. The fact that they must go far to catch these species is an indication of dwindling numbers," Raghavan said.
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