A refuge amidst peril: Giant Guitarfish in the Andaman Islands, India

Region Update: Indian Ocean

Written by Evan Nazareth

Nature Conservation Foundation, Mysore

Many of the islands shallow coastal waters where Giant Guitarfish (Glaucostegus typus) pups were observed are in close proximity to human settlements. As a result, their habitats are threatened by anthropogenic activities such as waste disposal, boating and fishing activities.

India supports one of the world’s major shark and ray fisheries, the effects of which were largely undocumented until recently. While a growing field of shark and ray fisheries research expanded our knowledge on the sheer species diversity in our waters, it also uncovered their drastic population declines. Close relatives of the more familiar stingrays, giant guitarfishes (family Glaucostegidae), are one such example. Five of the seven species of Giant Guitarfishes are found in the heavily fished waters surrounding the Indian peninsula. As a result, their populations have declined significantly, making them one of the most threatened marine species.

After years of conducting fisheries surveys and seeing Giant Guitarfishes at fish markets and auction sites across India, it was not until a walk along the shore of the Andaman Islands that I saw my first live Giant Guitarfish, which was soon followed by a second, and then a third. New-born pups, merely 30 cm long, these odd little creatures seemed to be aggregating in ankle-deep water along the coast of India’s remote archipelago. This led me to wonder if they were using these habitats as nursery grounds, which, if true, could have major conservation implications for these Critically Endangered and poorly known species.

So began The Giant Guitarfish Project. With funding from the Rufford Foundation, we started by understanding the extent to which Giant Guitarfish were distributed across the Andaman Islands and identifying locations where the juveniles were aggregating. We did this by utilising Local Ecological Knowledge (LEK), which has proved to be a rich source of baseline information on elusive and data-poor species. Between September 2019 and June 2020, we conducted 175 interviews with members of local communities who lived and worked along the island’s vast coastline.

The extensive interview survey helped identify 70 locations across the islands where Giant Guitarfishes were observed, with a majority of these observations being of juvenile animals in shallow nearshore waters. However, our data also suggest that their populations have declined significantly over the last two decades. While at present we have only confirmed the occurrence of the Giant Guitarfish (Glaucostegus typus) in the islands, this may not have always been the case, but rather, a result of other Giant Guitarfish species succumbing to severe population declines.

Nevertheless, this survey has helped identify several potential nursery areas across the islands. This in itself is a significant finding, showing that a species on the verge of extinction across most of its range is still relatively abundant in these islands. As research focusing on these elusive species progresses in India, it is essential to see the data generated through these projects also translate to conserving the species in our waters. Moving forward, The Giant Guitarfish Project aims to understand better the role that shallow coastal habitats play in the species’ life, highlighting the importance of these habitats to this globally significant population and using these findings to designate areas that require focused conservation initiatives.

Further reading: Nazareth, E., D’Souza, E., Arthur, R., Jabado, R.W., 2022. Distribution of the Critically Endangered Giant Guitarfish (Glaucostegus typus) based on Local Ecological Knowledge in the Andaman Islands, India. Ocean Coast. Manag. 220. doi.org/10.1016/j.ocecoaman.2022.106075

A Shovelnose Guitarfish (Glaucostegus granulatus) at a fish landing site in south Maharashtra, India. Giant Guitarfishes are a frequent sight at fish markets and landing sites that obtain their fish from nearshore fisheries.

Respondents were shown pictures of Giant Guitarfish and Wedgefish to evaluate their ability to distinguish between these two morphologically similar species groups.