The tragic news of another manta death due to mooring entanglement has highlighted the need for proper protocols and mitigation measures throughout the Maldives.
Tambourine (MV-MA-2801) had been sighted 11 times since 2011 and already had injuries to both cephalic fins.
In early January we learned of the sad demise of Tambourine (MV-MA-2801), a reef manta ray (Mobula alfredi) of Lhaviyani Atoll that was found entangled in a mooring line that had not yet been fitted with mitigation measures to prevent such an incident from occurring. Tambourine (MV-MA-2801) was an adult male manta that was first identified in February 2011 and had a total of 11 confirmed sightings all of which were recorded within Lhaviyani Atoll. Tambourine (MV-MA-2801) was last seen alive on the 27th of December 2020 and was noted to be gulping down mouthfuls of plankton at the time of this sighting.
Manta rays are obligate ram ventilators, meaning that they need to swim constantly to “breathe”. Therefore, entanglement in a mooring line rapidly leads to asphyxiation and death. Unfortunately, manta rays cannot swim backwards, and they often cannot see a thin mooring line directly in front of them as they swim forward. This incident has set a harsh reminder of this reality and how easily and quickly it can occur. This is now one of half a dozen manta ray deaths resulting from mooring line entanglements that the Manta Trust is aware of throughout the Maldives in the last few years, and we are concerned the true number is likely to be much higher as many incidents likely go unreported. Entanglements appear to be an increasing threat to these endangered rays as more and more lines are deployed throughout the country to facilitate the operations of new resorts, guest houses, dive centres and water sport businesses. It is increasingly evident that mitigation measures are urgently required throughout the country to address this growing threat.
Tambourine (MV-MA-2801) entangled in a mooring line.
Tambourine (MV-MA-2801) entangled in a mooring line.
Incidental capture (mostly through fisheries bycatch) is one of the greatest threats to manta rays worldwide, including the Maldives. Indeed, approximately 10% of the Maldives reef manta ray population (n= ~5000) suffer from sub-lethal injuries resulting from fishing line entanglements. The conservative life history traits of manta rays mean that populations are ill-equipped to recover from anthropogenic pressures. Reef manta rays (Mobula alfredi) are classified as Vulnerable to extinction, and oceanic manta rays (Mobula birostris) are now listed as Endangered on the IUCN’s Red List of Threatened Species. Therefore, to safeguard these vulnerable and nationally protected species, it is important that all mooring and buoy lines in the Maldives are modified to reduce the risk of manta ray entanglements. To aid these efforts, the Manta Trust has developed a few simple actions which can be taken to help prevent manta ray entanglements.
The Manta Trust have advised all the operators we work with to carry out mitigation actions, but this is an urgent call-to-action for all operators to be aware of this growing threat and make concerted efforts to follow prevention measures to diminish the chances of this happening again. We can be contacted for any such advice or assistance in addressing this nationwide issue. Further to this we also urge all individuals and operators to please inform us and the government of any entanglements which have occurred in the past. It is crucial that we not only mitigate against future entanglements, but that we also learn from previous accounts. This information may identify possible trends in the incidence of entanglements and could be used to advise against certain practices related to depths, locations and types of mooring lines.
Finally, it is important to highlight that manta rays remain largely enigmatic with little known about their biology, ecology, migration patterns and population dynamics. The Manta Trust have released some preliminary guidelines for protocols to follow should you encounter a deceased manta ray and encourage all operators and individuals to acknowledge the significance of data collection at this time. Collecting identification photos, disc width measures, and tissues samples for genetic analysis is paramount to research efforts for the conservation of these animals.
For more information or to report an incident, please contact info@mantatrust.org.