Identifying nursery habitats and determining life history of Guitarfish in Sri Lanka
Gobiraj is the lead researcher for the Blue Resources Trust’s “Sri Lanka Elasmobranch Project” for the north and east coasts. To understand the composition of Sri Lanka’s shark and ray fisheries, with a particular focus on Critically Endangered sharpnose guitarfish, he collects identification photos and a host of other measurements, as well as gathering tissue samples for genetic and stable isotope analysis. Gobiraj also speaks to local fishers to understand fishing gear and catch locations. He aims to use his project’s insights to help shape policy and better protect sharks and rays – and the sharpnose guitarfish – across the region.
Gobiraj Ramajeyam
I am a young researcher in the field of fisheries science and I have a passion for marine biology and ecology, conservation and fisheries management in Sri Lanka. Unfortunately, I had no interaction with the marine environment until I was 20, although in those days I enjoyed seafood very much. I first got an opportunity to study marine biology and fisheries science when I embarked on my Bachelor’s degree in 2012. I became fascinated by the marine environment and the organisms that live in it. At the same time, I learned that ocean resources are not infinite but are being...
Identifying potential nursery habitats and determining life history of the Critically Endangered guitarfish
By collecting data at fish landing sites and making detailed biological studies, this project aims to discover more about the life history of the sharpnose guitarfish. It will also identify potential nursery habitats for the species around Mathagal in northern Sri Lanka.
The sharpnose guitarfish is a Critically Endangered benthic and coastal species with a limited distribution in the northern Indian Ocean. It is heavily impacted by coastal fisheries, but the fact that so little is known about it makes it challenging to manage the species effectively. This study addresses these issues and provides the first comprehensive baseline data to help conserve the sharpnose guitarfish and allow it to recover sufficiently to fulfil its functional role in the ecosystem.
The global IUCN Red List of threatened species reveals that sawfish, wedgefish and guitarfish are among the most threatened marine fishes. More than 70% of guitarfish species are either threatened or data deficient, including the sharpnose guitarfish, whose geographical distribution is restricted to the northern Indian Ocean region. It is estimated that its population here has decreased by more than 80%. Urgent action is needed to conserve the sharpnose guitarfish and other rhino rays and their habitats, but the lack of species-specific information makes effective management action challenging. Since August 2017, Blue Resources Trust (BRT) has conducted more than 900 survey days and distributed 300 fisheries-dependent questionnaires on Rhinopristiformes around Sri Lanka. These revealed that Mathagal is the only place where the sharpnose guitarfish is frequently recorded (80% of survey days). More importantly, 25% of landed specimens were juveniles, suggesting that there may be nursery habitats in this area. Results also showed that more than 50% (24 species) of the species recorded in the north are present at Mathagal and that it is a key site for some priority species, including the sharpnose guitarfish and the Endangered longheaded eagle ray. Since elasmobranch nurseries are where females lay eggs or give birth to their young and where juveniles spend their early stages of life, the conservation of such habitats is essential to provide nutrition and protection and reduce early mortality in young individuals. This project will provide comprehensive life history data for sharpnose guitarfish and identify potential nursery habitats so that effective management interventions can be developed.
The aim of the study will be to collect landing site data on an ongoing basis to learn more about Sri Lankan shark and ray fisheries, with a special focus on the sharpnose guitarfish, and to support the management and conservation of sharks, rays and shark-like rays. The project will also make a detailed study of the life history of the sharpnose guitarfish and identify potential nursery habitats for it around Mathagal in northern Sri Lanka with the help of selected fishers. The results will be published and used to inform management recommendations and support stock assessments.