Shark and Ray Fisheries
Trisha Gupta, Chetan Rao, Muralidharan M., Naveen Namboothri and Kartik Shanker
Elasmobranchs (sharks and rays) represent some of the most endangered marine species across the globe. They are slow growing and produce relatively few young, which makes them very vulnerable to human activities such as fishing; millions of sharks and rays are captured by fishing vessels every year. India is among the top 3 elasmobranch fishing nations, and these species contribute to livelihood and food security of thousands in the country. However, catches in the country have been declining over the past few decades, indicating that elasmobranch populations are under serious threat.
Through an interdisciplinary approach, we studied the biology, ecology, fishery and conservation of sharks and rays in Malvan in southern Maharashtra on the west coast. We also conducted pilot surveys in Visakhapatnam, on the east coast. Our long-term goal is to align elasmobranch conservation with needs of the fishing community, by formulating management strategies for a more sustainable fishery.
Breeding and biology
We found at least 18 species of rays and 14 species of sharks in the Malvan region, including 3 Critically Endangered species. Most of the animals captured by fishing nets here were relatively small in size, as they were generally small-sized coastal species or juveniles of larger species.
We also found breeding individuals and neonates (i.e. newly born individuals) of vulnerable species such as scalloped hammerhead sharks, common blacktip sharks and eagle rays, in specific months of the year. These species are probably using the shallow productive waters around Malvan, interspersed with corals, mangroves and estuaries, as nursery grounds for their young.
Bycatch and conservation
Our work showed that while elasmobranchs are occasionally targeted by gillnetters and artisanal fisheries, they are incidentally caught as ‘bycatch’ in trawlers. However, even as bycatch, elasmobranchs are commercially sold and contribute to the earnings of fishers. Through a collaboration with Oxford University, we looked at measures to reduce this bycatch, especially of threatened species, while having a minimal impact on fisher livelihoods. We found that releasing live sharks and rays onboard trawlers may be the best option to conserve these species at present, as this measure had a minimal impact on the earnings of fishers.
Outreach and community engagement
We have developed an outreach book on sharks and rays of Malvan, in Marathi as well as English, which will be distributed among the fishing community.
Funding
Duleep Matthai Nature Conservation Trust
Mangrove Foundation of Maharashtra
Publications:
Mitigation of elasmobranch bycatch in trawlers: A case study in Indian fisheries
Avoid, minimise or remediate? Shark and ray conservation in an Indian trawl fishery