February 2025
The First Dedicated Research Effort on Mobulid Rays in Madagascar Confirms Nosy Be as an Important Habitat and Suggests a Local Decline in Reef Manta Rays
© Stella Diamant
NOSY BE, Madagascar – The first dedicated research effort on mobulids (manta and devil rays) in Madagascar highlights the waters around Ampasindava Bay, in the northwest of the country, as an important mobulid habitat. The study also raises concerns that reef manta rays (Mobula alfredi) may be in decline in the area, as well as three other species of mobulids.
The study, published in Environmental Biology of Fishes, on February 5th 2025, documented 255 encounters with three Mobula species between 2016 and 2022. Spinetail devil rays (Mobula mobular) were the most commonly recorded (165 sightings) followed by oceanic manta rays (M. birostris, 60 sightings) and shorthorned pygmy devil rays (M. kuhlii, 30 sightings). All three species are categorised as endangered by the IUCN Red List. Reef manta rays have been identified in the area, but there were no confirmed records since 2015, suggesting a local decline.
© Stella Diamant
“It’s worrying that we haven’t recorded any reef mantas since 2015,” says lead author Stella Diamant, founder of the Madagascar Whale Shark Project. “Yet we have identified three other mobulid species, including oceanic manta rays. These amazing animals are listed as endangered, facing a very high risk of extinction, and face many threats including targeted fisheries, bycatch and boat strikes. This study highlights how important it is to protect the species from further decline.”
The study was based on sighting data in the Ampasindava Bay area. Sightings were collected during opportunistic tourism encounters as well as citizen science submissions, tourism operator reports, and social media records. Oceanic manta rays, shorthorned pygmy devil rays and spinetail devil rays were frequently observed and were regularly seen feeding and foraging. Oceanic manta rays and shorthorned pygmy devil rays were encountered in almost every survey year and courtship behaviours were also observed for these species.
© Stella Diamant
The islands of Nosy Be, Nosy Sakatia, Nosy Komba and the Ampasindava Peninsula of mainland Madagascar make up Ampasindava Bay. These waters are well-known for the occurrence of large planktivores, such as whale sharks (Rhincodon typus) and Omura’s whales (Balaenoptera omurai). This study now confirms that these waters provide a significant habitat for mobulid rays, which are commonly sighted in the region.
“We already knew that Nosy Be is a global hotspot for whale sharks, which are also endangered worldwide. This new study shows the region is also a haven for other threatened plankton-feeders,” says Dr Simon Pierce, a co-author and Executive Director of the Marine Megafauna Foundation. “More work is needed to protect these giant rays from harm – especially indiscriminate gillnet fishing.”
© Stella Diamant
Mobulids are caught regularly in nearby fisheries and experts are concerned by the potential impact of fishing on threatened sharks and rays. Bottom-set gillnets – fishing nets anchored to the seabed to catch fish that swim into them – are being used increasingly in the Nosy Be region and pose a direct threat to mobulids and other threatened species. Marine Protected Areas (MPAs), such as the existing Ankarea and Ankivonjy MPAs, and the proposed Tandavandriva “corridor” MPA that links these other MPAs, could provide spatial refuge for threatened species like mobulids, if they are well enforced with appropriate management measures for such species, says Dr Rhett Bennett, co-author on the study and Manager of the Wildlife Conservation Society’s Western Indian Ocean shark conservation programme.
With people from around the world travelling to this area to see these animals, many communities across Madagascar are reliant on eco-tourism for their livelihoods. “Marine tourism is estimated to bring in over one million dollars to the local economy each year so protecting these enigmatic species is vital for Malagasy communities as well as the environment” says lead author Stella Diamant.
© Stella Diamant
Press Release Credits
Corresponding author: Stella Diamant, stella@madawhalesharks.org
Images and footage are available here
For Manta Trust Media Enquiries
Contact: Jasmine Corbett
Manta Trust Media and Communications Manager
Email: jasmine.corbett@mantatrust.org
About the Madagascar Whale Shark Project
The Madagascar Whale Shark Project (MWSP) is a registered private foundation (# 0724.642.161). MWSP aims to study and protect whale sharks in Madagascar while raising awareness and empowering local communities.
MWSP is a collaborative research and conservation project working tirelessly for the protection of whale sharks and other marine life in Madagascar. Our conservation goal is to inform the management of marine megafauna habitat and species-specific regulations in northwest Madagascar by gathering scientific data on whale sharks.
https://www.madawhalesharks.org/
About the Manta Trust
The Manta Trust is a UK-registered marine conservation charity dedicated to the research and protection of manta and devil rays and their habitats. Through research, education, and collaboration, the Manta Trust works to ensure a sustainable future for these extraordinary creatures.