By Daniel Fernando and Gobiraj Ramajeyam
Sharks and rays (elasmobranchs) are a unique group of fishes with skeletons made of cartilage. They play an important role in the marine food web, with many found in the higher trophic levels helping to maintain natural balance. Most elasmobranchs are extremely vulnerable to external pressures, such as fishing, due to their long lives, slow growth rates, late maturity, and low reproductive potential.
Unfortunately, overfishing, and other anthropogenic activities (such as destruction of their critical habitats like coral reefs and mangroves) have increased the extinction risk of most shark and ray species across their global ranges. They are captured in both target and bycatch (incidental capture) fisheries driven by growing international demand for shark and ray fins, meat, gill plates (from manta and mobula rays), liver oil, and other derivates. Many of the fisheries resulting in their overexploitation are mismanaged and unregulated. Given that living organisms are interconnected, their presence is important for ecosystem equilibrium. And the removal of even one species, and particularly keystone species like sharks, can have devastating impacts on the ecosystem and associated habitats.
In recent years, sharks and rays have received a lot of conservation attention around the world. However, there is still a lot more to be done. To effectively protect them, we have to study their life history, population status, their habitats and movements, and also their definitive role within marine ecosystems. Armed with this information, we will be better placed to provide scientific recommendations to halt population declines and enable recovery of depleted stocks, while supporting sustainable fisheries for the more productive species.
Sri Lanka, being an island nation relies heavily upon fisheries – and sharks and rays – as affordable sources of protein and as a means of employment. Supporting fisher livelihoods is essential, however for long-term sustainability, we also must consider the survival of the species. If a species goes extinct or is depleted to the extent that commercial fisheries for that species are no longer viable, the associated fisher livelihoods would also collapse.
Since 2017, Blue Resources Trust (BRT) have been conducting a systematic shark and ray research project across Sri Lanka. This includes surveys of landing sites to determine the magnitude and composition of Sri Lanka’s shark and ray fisheries and expand available knowledge on their biology and ecology. This dataset also provides a baseline with which we can assess future population trends to determine the effectiveness of fisheries management.
BRT data have shown that nearly half of the Sri Lankan shark and ray species diversity is present around the Jaffna peninsula. In this region, small-scale artisanal fisheries are prevalent, and their fishing is mostly restricted to the coastal areas. This area also appears to be key sites for some priority species, such as the sharpnose guitarfish (Glaucostegus granulatus, an IUCN Red List Critically Endangered species).
Subsequently, BRT have initiated a project, with support from the Tokyo Cement Group, focusing on identifying the critical habitats of sharks and rays in northern Sri Lanka and to improve understanding of this fishery and associated fisher communities. With this scientific data, it will become possible to recommend effective, sustainable management measures to prevent overfishing of sharks and rays and enable their recovery.
About the authors:
Daniel Fernando
Daniel is a marine biologist and the co-founder of Blue Resources Trust; a Sri Lankan marine research and conservation organisation, where he leads the Sri Lanka Elasmobranch Project. Since 2013 he has been providing technical support for elasmobranch management policy at conventions such as CITES, CMS, and the Indian Ocean Tuna Commission, thereby helping bridge the gap between science and policy and encouraging a shift towards sustainable fisheries. He has served as a ministerial advisor, is currently the Regional Co-Vice Chair of the IUCN Shark Specialist Group for the Indian Ocean, an MCAF Fellow, and the Vice Chair to the Sessional Committee of the CMS Scientific Council.
Gobiraj Ramajeyam
Gobiraj is a marine biologist currently working on the Sri Lankan Elasmobranch Project with Blue Resources Trust. He completed his undergraduate in 2017 at the University of Jaffna and is now pursuing his MPhil degree studying the biology of the Critically Endangered Sharpnose guitarfish in and around the Jaffna Peninsula.
