THE MALDIVES’

MANTA RAYS

The Maldives supports the largest known population of reef manta rays (Mobula alfredi) anywhere in the world and these charismatic creatures have become an iconic species for the island nation. Often described as gentle giants, manta rays are completely harmless, eating only zooplankton and possessing no harmful defense mechanisms such as a barb in their tail. Reef manta rays can grow up to 4.5 meters in diameter (wingtip to wingtip) while oceanic manta rays (Mobula birostris) can grow to up to 6.8 meters. The size of these animals and their social nature makes them magical to interact with and many tourists visit the Maldives with a keen desire to encounter manta rays.

For divers and snorkelers, the Maldives is one of the most world-renowned destinations for manta ray encounters. Manta rays are therefore an incredibly important economic resource for the Maldives, bringing tens of thousands of people to the country each year to dive and snorkel with them, and generating millions of USD for the economy annually. In the Maldives, manta rays are protected from targeted fisheries following bans initiated between 1995-1996. Although manta rays are not fished in the Maldives they are still highly vulnerable to the increasing pressures of tourism development - habitat degradation and increases in unsustainable tourism activities.

MANTA RAY

POPULATION STUDIES

Like how humans are identifiable by fingerprints, manta rays can be identified by their unique ventral spot patterns. The Manta Trust team conducts research dives to record photos of different individuals for their growing database which currently includes 150 Manta Rays as of January 2025. 

MANTA RAY

GESTATION RESEARCH

Through a collaboration of Six Senses Laamu, The Manta Trust, IMV Imaging, Vetsonic (UK) ltd and the University of Cambridge Veterinary School, the very first underwater contactless ultrasound scanner was developed. This innovative unit aims to assist monitoring of the internal maturity and reproductive status of manta rays in the wild, without requiring any physical contact. So far, the team at the Manta Trust have successfully scanned 15 Manta Rays, with 5 pregnancies recorded, helping further our understanding of the little-known reproduction of these animals. 

MANTA RAY

GROWTH RATES

The team is also recording valuable data on the growth rates of the individuals in Laamu using a stereo-video camera system to obtain accurate data on growth and body size. The Manta Trust team at Laamu Atoll have successfully recorded more than 100 measurements of mantas using the stereo video system. This work combined with ultrasound examinations, aims to provide accurate data on manta rays’ size at maturity in both males and females.

REMOTE UNDERWATER

PHOTO AND VIDEO CAMERAS

SCUBA diving offers only short glimpses of manta ray activity at nearby cleaning sites each day, greatly limiting data collection abilities. The deployment of remote underwater cameras has allowed the Manta Trust team to run uninterrupted, long-term monitoring of cleaning stations for the first time. In addition, the team can collect comparative data on manta behavior when divers are present and absent, to assess the impact of tourism practices.

Since 2021, the team have been collecting long-term surveillance data of 4 manta ray cleaning stations in Laamu, recording data using remote underwater videos (RUVs) and time-lapse cameras called the “Eyes on the Reef” (EOTR). The EOTR systems photograph the cleaning station every 60 seconds, from sunrise until sunset.Using these remote sensing systems, the team are better able to understand the environmental variables that influence manta habitat use at these sites. 

A Marine Environmental Management MSc student from the University of Exeter analyzed one full year’s worth of data (approximately 156,472 photos!), of which the published report is available here

ACOUSTIC SOUNDSCAPES OF

CLEANING STATIONS

The Manta Trust is studying the sounds of manta cleaning stations to better understand these important marine habitats. By analyzing sound recordings collected throughout 2024 using hydromoths, the research is uncovering how different cleaning stations have unique "sound signatures" influenced by their environment.

Early findings show that the sounds in these areas change throughout the day, with fish vocalizations being more complex in the morning and evening, and quieter at midday. This pattern may reflect the behavior of different species, including those that rest or dive deeper during the day.

The research is now expanding to other locations, including areas with more human activity, to see how factors like time of day, lunar cycles, and human presence affect the health of these vital ecosystems.

3D MODELLING

CLEANING STATIONS

The Manta Trust is using 3D modeling to study manta cleaning stations in Laamu Atoll. In 2024, the team created detailed maps of these important habitats to track changes in reef health over time.

One key achievement was mapping Shallow Block, the largest cleaning station, which will serve as a baseline for future monitoring. The research also showed that larger cleaning stations attract more manta rays, providing valuable insights into what influences their behavior.

This ongoing work helps improve our understanding of reef health and supports efforts to protect these crucial marine ecosystems.

FISHER

INTERVIEWS

During 2019, the Manta Trust began conducting fisher interviews with the local community in hopes of learning more about manta sightings and community perceptions of manta rays in Laamu. In 2022, the Manta Trust developed this project further, in collaboration with the University of Exeter, in which another Marine Environmental Management MSc student is visiting every inhabited island of Laamu to interview fishers, boat captains, and seafarers to understand their local ecological knowledge of manta rays. The published report is available for reading here

MANTA RAYS

IN VIRTUAL REALITY

Manta rays are rarely seen surface feeding in this atoll and since the majority of encounters are whilst diving, manta rays are not often seen by members of the community. To allow more people to encounter Laamu’s gentle giants, the MUI team recorded a manta dive in virtual reality.  We’ve been sharing this video in the community and with guests and the response has been overwhelmingly positive! We’re looking forward to continuing manta education sessions in the community and will be visiting community members for additional interviews in the upcoming year.