- Determine Habitat Utilization
- Population Size and Structure
- Define Migration Patterns
Project Start Date:
The main focus of the work in the Seychelles will be to investigate in detail how the reef manta ray (Manta alfredi) moves within its reef habitat and how these movements are driven by environmental variables such as lunar and tidal cycles. We will achieve this by using acoustic tagging, including active tracking, and a large established network of receivers. Through regular boat surveys and the collection of identification photographs, we will also build knowledge of the size of the population and the number of mature, breeding females. Furthermore, the project will collect biopsy samples from a number of individuals, geographically broadening the genetic work already being carried out in Sri Lanka and India.
Why this is important:
It is no secret that manta ray populations are in decline globally due to pressures from humans. By understanding when and why manta rays use different habitats we will have an enhanced capacity to effectively conserve the species. For example, knowledge of movements of individual rays and the environmental variables which restrict their range can be used to model effective marine protected area (MPA) boundaries. It is also important to build knowledge of population size in this previously non-researched population, so that global population estimates and conservation statuses can be made with more reliability, allowing effective conservation measures to be put into place.
Located in the Indian Ocean, northeast of the island of Madagascar, the Republic of the Seychelles is an archipelago of 115 islands. Tourism has been a major part of the economy in the Seychelles since the 1970s which was joined by fishing during the 1990s. Shark fishing by local operators is not illegal and does happen through out the archipelago. Fortunately, however, the Republic has not developed a targeted manta fishery to supply the Asian demand for gill rakers.
For this reason, the Seychelles offers a rare opportunity to study healthy populations of reef manta rays. Furthermore, the field base for the Seychelles Manta Ray Project is located on the Save Our Seas Foundation’s (SOSF) research island far from the main economic centre of the republic. This allows for the fantastic novel opportunity of carrying out field research and tagging activities away from tourism pressures.
A variety of marine research is already being carried out on the reefs around the SOSF island and as a result there is an established network of 51 receivers in place, with the Manta Trust adding a further 9. The Manta Trust will tag reef manta rays around the island with acoustic tags, which will add to the important data already being picked up by the receiver network. This data will allow us greater insight and understanding into the movements of manta rays. For example, do they venture between reef systems and if so, how do they move between them? Is there a pattern to their movements, and how is this affected by environmental variables? Do juvenile rays inhabit different areas to mature rays?
1: Develop a photographic identification database of the Seychelles reef manta population
2: Tag a selection of mantas with acoustic tags to determine their broad-scale movements
3: Collect tissue samples from the mantas for use in a global population genetics study
4. Increase education and awareness within the Seychelles of the conservation status and needs of this species.
Partners & Sponsors:
Without the generous support and sponsorship we receive we would not be able to achieve our work in the Seychelles. We are very grateful to these organisations for their support.
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