Manta Rays and Us

Case in point, the reef manta ray (Manta alfredi). The Maldives has the highest documented population of reef manta rays in the world amounting at an estimated 5,000 individuals across the entire archipelago with 2,400 individuals identified by the Maldivian Manta Ray Project (MMRP) which was founded by Guy Stevens, a British marine biologist, in 2005.

The MMRP was established with the purpose of learning more about the life cycle, population dynamics and habitat usage of the Maldives manta population, while also working with the government, tourists, local communities and tour operators to create greater awareness and protection for these creatures.

The two key study sites of the project are Lankan Reef (Manta Point) in North Malé Atoll and Hanifaru Bay in Baa Atoll. Data is also gathered from dozens of other locations throughout the Maldives.

The project uses photographic identification images to identify individual manta rays from the distinctive black spots on the creatures’ belly. Each manta ray is born with these spots, which are unique to each individual much like the human fingerprint, which allows for easy identification. The mantas sex, size, maturity, injuries (natural or anthropogenic) pregnancies and mating scars can also be recorded using photographic identification.

Environmental and anthropogenic data; wind speed, direction, current, visibility, plankton levels, number of divers, snorkelers and dive operators is also collected by the project help identify trends in the manta rays abundance and movements, while tagging had also been carried out earlier in a bid to understand the manta rays more.

One particular finding by the project is that manta rays in the Maldives reproduce extremely slowly, giving birth on average to just one pup once every five years.  In fact, for the last two years in the Maldives not a single female manta ray has been recorded pregnant, despite thousands and thousands of sightings of mature females across the country.  The project also reports 2011 as the worst year for manta ray sightings since the project began operating in the Maldives.

It is likely this lack of reproductively is linked to the fluctuations in the Maldivian Monsoons.  For the last few years the SW Monsoon has been weaker than expected. 

Because the Monsoon winds, which drive the productivity of the planktonic food upon which the manta rays feed, have been weak in recent years it is likely that the manta rays have not had enough food to reproduce.  

Changes in the long-term patterns and stability of the Indian Ocean Monsoon could be linked to climate change events such as El Niño Southern Oscillation (ENSO); therefore the manta rays can be seen as an indicator species reflecting the overall health of the Maldivian ecosystem as well.

Manta rays, like any other creature have natural predators, such as Tiger Sharks, Greater Hammerheads and False Killer Whales, but the natural mortality rate of the creatures are very low.

One main and most important reason why the manta ray population of the Maldives is so massive is because these rays have never been fished in significant numbers.  Like all ray species, in the Maldives it is illegal to export these animals from the country, protecting them from commercial export fisheries, like the gill raker trade, which is devastating manta ray populations around the world as fishermen target manta rays for their gill rakers which are in high demand in the Chinese Medicinal Trade.

In the Maldives manta rays do occasionally become entangled in fishing nets, which drift into the Maldives from other areas, while entanglements in fishing line occur frequently often resulting in injuries to their cephalic fins and pectoral fins, which can occasionally be fatal.

In a bid to protect the biodiversity of the Maldives, in 2009 the Maldivian government declared two areas of Baa Atoll as Marine Protected Areas (MPAs), one of which was the world famous Hanifaru Bay.The year 2011 also saw Baa Atoll declared as the first UNESCO Biosphere Reserve in the Maldives, during the 23rd session of the Man And Boy Conference held in Dresden, Germany.

Manta rays in the Maldives generate over USD 8 per tourist to the economy each year through direct dive and snorkel excursions making it important to conserve these creatures, however manta rays are not yet specifically protected by Maldivian law.

For more information on the project and the work carried out visit www.mantatrust.org or Facebook page www.facebook.com/MantaTrust.