Manta and devil rays, collectively known as mobulids, are fascinating creatures closely related to sharks and rays. They inhabit the warm waters of the tropics and sub-tropics with Manta rays growing up to seven meters wide and having the largest brains of all fish species. Devil rays are smaller and more elusive, making their behaviour in the wild less understood.
Threats Facing Mobulids
Despite being some of the oceans’ most captivating species, mobulids are under significant threat due to climate change and human activities. Rising ocean temperatures directly impact manta and devil rays and indirectly affect them by reducing food availability and causing habitat loss at cleaning stations.
Although not traditionally targeted by commercial fisheries, the demand for mobulid gill plates in Asian medicine has led to a drastic decline in their populations. Additionally, they are often caught as bycatch in fisheries targeting other species and face other threats such as unsustainable tourism, injuries from boat strikes, and entanglement in mooring lines.
The Manta Trust: Protecting Mobulid Rays
Formed in 2011, the Manta Trust is a UK charity dedicated to protecting mobulid ray populations and their habitats through research, education, and collaboration.
The Manta Trust conducts scientific studies to gather robust data that can inform governments, NGOs, and conservation groups about marine management. A key area of their research is acoustic tracking. They use telemetry studies to understand the behaviour and migratory paths of tagged manta and devil rays.
Precision Tracking for Protection
For several years, the Manta Trust has used Innovasea’s passive acoustic fish tags and receivers to gather information about the species. These tags emit a unique coded ID every 90 seconds, which is detected by receivers within range, revealing behaviour patterns and movement activities of the rays.
Leveraging public interest in manta and devil rays, the Manta Trust is on a mission to educate people about marine conservation. Public education is crucial for the long-term survival of mobulids and the ecosystems they depend on and the charity collaborates with over 25 global projects to advance conservation efforts – Launching the Global Mobulid Conservation Programme in 2014.
“The Manta Trust uses acoustic transmitter tags supplied by RS Aqua to monitor the movements of reef manta rays in the Indian Ocean. These tags have helped to identify fine-scale movement patterns, which will assist in developing effective protection strategies throughout the species range. Publications include ‘Fine-scale oceanographic drivers of reef manta ray (Mobula alfredi) visitation patterns at a feeding aggregation site’ and ‘Environmental drivers of reef manta ray (Mobula alfredi) visitation patterns to key aggregation habitats in the Maldives’.
Our research is ongoing and currently includes V16-4x Innovasea acoustic transmitter tags deployed onto 51 reef manta rays and an acoustic array of Innovasea VR2W and VR2AR receivers. These receivers are ideal for monitoring specific areas of interest in both coastal and deep-sea environments.”
For more information about the Manta Trust and their research, visit their website. To explore aquatic animal monitoring equipment, please speak to one of our advisors today.