The giant guitarfish project

Project timeline: 2019 - Present

Giant guitarfish, close relatives of sharks and stingrays, can reach lengths of three metres and live for at least 18 years. Like many sharks and rays, their populations drastically declined over the last few decades primarily due to over-fishing and other human disturbances.Efforts to conserve these large, mobile, and long-lived species are often challenged by the difficulty of implementing conservation measures across their extensive habitats.

Given that the Andaman Islands are situated in a heavily fished region with a rapidly developing coastline, this project seeks to identify sites where guitarfish are found and earmark them for conservation.

Although fully grown guitarfish inhabit deeper waters, their young (known as pups) spend much of their early life in shallow coastal regions. Incidentally, coastal waters are often the most exposed to fisheries, development, and pollution. Focused conservation and management strategies in near-shore ecosystems could be an effective way to protect pups and, in turn, the species.

Project objective: 

Identify locations that play an important role in the early life history of giant guitarfish in the Andaman Islands

To address our objective, we utilised local ecological knowledge of coastal communities in the Andamans to collect baseline data on giant guitarfish distribution and relative abundance across the islands and identify potential threats to the species. We conducted a total of 175 interviews at 33 locations across seven islands. 

Furthermore, we tested the effectiveness of different sampling methods to detect juvenile giant guitarfish, such as visual line transects and baited remote underwater video systems (BRUVS). We found that the visual transects were the most effective and used this method to confirm their presence and relative abundance at the sites identified through the interview surveys. 

Through this project, we found widespread distribution of juvenile giant guitarfish aggregating sites across the islands, highlighting the significant role these sites play in harbouring this species, especially during its crucial early life.

Based on our observation of juvenile stingrays using many of the same spaces as giant guitarfish pups, we expanded our focus to include stingrays. We documented the habitat characteristics, level of human disturbances, and the presence and abundance of guitarfish and stingray pups at the sites. Using this data, we are trying to identify the habitat requirements of juveniles and the influence that human disturbances have on them.

Project objectives:

• Improve our understanding of the habitat requirements for juvenile guitarfish and stingrays

• Identify the role of juvenile guitarfish and stingrays in their habitats

To understand what habitat characteristics lead to certain coastal areas supporting a higher abundance of guitarfish and stingrays, we conducted visual transects at a subset of sites identified in the previous project. 

Using the findings of this study, we will map out locations across the islands where guitarfish and stingray pups are found, along with the level of human disturbances at each site. These maps could enable conservationists and other governing bodies to prioritise areas and determine conservation strategies based on the level and types of threats these species are exposed to at each site.