Study finds unsustainable and alarming rates of tiger shark capture

A fisher with tiger shark, Galeocerdo cuvier, at Cochin Fisheries Harbour in Thoppumpady
| Photo Credit: SURESHKUMAR C

While populations of the tiger shark, Galeocerdo cuvier, are in a state of global decline, a study by researchers at the Kerala University of Fisheries and Ocean Studies (KUFOS), Kochi, and the Shiv Nadar Institution of Eminence, New Delhi, has revealed that the species is being heavily and unsustainably fished in the Laccadive and Arabian Seas. The 16-month study undertaken at the Cochin Fisheries Harbour, and published in the international journal – Biological Conservation, points to alarming levels of indiscriminate exploitation as close to 95% of the landings were immature tiger sharks preventing population replenishment. Furthermore, roughly 25% consisted of ‘young of the year’ (animals born within the same year), largely caught unintentionally as bycatch.

The study spanning from March 2023 to September 2024 also documents a shocking 7% mortality rate of newborn tiger sharks (neonates) within the catches. The annual exploitation rate in this region surpasses those in the Pacific Ocean, indicating a dangerously unsustainable fishery in the Western Indian Ocean comprising the Laccadive and Arabian Seas. This shows the critical need for developing and implementing immediate management strategies to prevent further population collapse,” said Rajeev Raghavan, Assistant Professor at KUFOS, and the senior author of the scientific paper.

Assessed as ‘near threatened’ on the IUCN Red List, tiger shark holds a special place in evolutionary history as the only species within its family, Galeocerdonidae. These large, apex predators, found in diverse ocean climates, face pressure from commercial, recreational, and artisanal fishing. They also possess the remarkable ability to undertake long-distance, transoceanic migrations. “Despite their iconic status, tiger shark fisheries have been largely overlooked, resulting in a critical lack of data on stock assessments, population structures, and overall trends across their range. This study is therefore ground breaking, as it represents the first comprehensive effort in the Arabian Sea to evaluate the fishery and exploitation dynamics of these sharks,” said K. Ranjeet, Professor at the KUFOS, and co-author of the study. Muralikrishna Gurugubelli, C. Abisha, T.A. Arundhathy and Neelesh Dahanukar are the other researchers who were part of the study.

The study points out that effective tiger shark conservation in India demands a collaborative approach involving fishers, traders, researchers, and policymakers. Another key hurdle is ensuring local fisher compliance. The study calls for targeted education and awareness programmes for fostering a shift towards sustainable practices and proposes several management strategies, including establishing protected zones for key habitats such as pupping and nursery grounds, implementing size restrictions including minimum legal size to prevent overfishing, and promoting participatory research for long-term sustainability.