In the run up to CITES CoP 16 in Bangkok, Dr. Andrea Marshall returned to Thailand for a third consecutive year on another Ray of Hope Expedition conducting giant manta ray (Manta Birostris) research in the Andaman Sea. Dr. Marshall was accompanied by Janneman Conradie, Director of Conservation at the Marine Megafauna Foundation and myself, co-owner of Thailand Dive & Sail, on a nine day trip hosted aboard the luxurious SY Diva Andaman.
The SY Diva Andaman’s schedule included diving at Burma and Thailand’s best dive sites including the Burma Banks, the legendary Black Rock in Burma’s Mergui Archipelago and other important manta ray sites, and Koh Tachai and Koh Bon in Thailand.
SY Diva Andaman at Black Rock, Mergui Archipelago ©Janneman Conradie, Marine Megafauna Foundation
The previous two trips had seen Dr. Marshall successfully satellite tag three giant manta rays as part of a six year global tagging project at the world’s main manta aggregation sites. This year’s expedition was to collect skin samples and I.D. photographs. Dr. Marshall is currently analysing samples to determine the main diet of Manta rays and where exactly they are feeding. Until recently, most scientists thought that mantas feed on plankton in the water column, however Andrea’s recent studies may lead to more complex conclusions about their feeding habits.
This latest expedition could prove to be the most successful to date. Over four dives at Black Rock on 20th February 2013 Dr. Marshall identified 28 individual Manta rays using both her own and Janneman’s I.D. shots and also some taken by guests on the trip. This is a staggering number considering the size of the site and it’s remote location. Each sighting was unique to it’s particular dive with no repeat sightings on consecutive dives.
Andrea’s preliminary comparisons of I.D. shots taken over the last three years are already yielding some revealing insights in giant manta ray behaviour. One female manta was positively identified at Black Rock in both 2012 and 2013, while one male manta was positively identified at Black Rock in 2011 and 2013.
After a few unsuccessful visits to Thailand’s Manta ray hotspot Koh Bon, Dr. Marshall’s luck finally changed with a positive I.D. shot, a Manta she named ‘Turtle Dove’.
This was my first manta ray sighting at Thailand’s famed Koh Bon ridge and it did not disappoint. Although my experience was shared with quite a few other divers unlike in many parts of the world where I have encountered these giants, the water was warm and clear the conditions were calm and the manta ray was friendly and approachable, Dr. Marshall explains.
The highlight of the expedition for me came when Andrea excitedly announced that a manta I had photographed at Koh Tachai on 12th December 2012 was one of the 28 identified at Black Rock. Since my sighting of ‘Diamond’, the name I chose for the Manta, she had travelled 260 kilometres north over 70 days to Black Rock. A long migration in only a short amount of time considering the manta would have meandered along the way. I was extremely pleased with myself feeling like a shining example of the importance of citizen science.
‘Diamond’ Giant Manta Ray. Photo left ©Ric Parker from Koh Tachai, Thailand. Photo right ©Andrea Marshall from Black Rock, Burma
This data, along with the data compiled from past satellite tagging and the ever growing database of I.D. photographs, is providing a more detailed view of giant manta ray behaviour in the Andaman Sea. Results like this highlight the importance of sites such as Black Rock, Koh Tachai and Koh Bon to the region. A steady decline in manta ray sightings over the past decade also calls for better conservation efforts to be made on an international level, especially due to the long migrations these magnificent rays make. It is not enough for one country to propagate protection of these magnificant creatures, everyone has to commit to the continued safeguarding of the species.
Dr. Andrea Marshall, Director of the Marine Megafauna Foundation and the Foundation’s principal Manta ray scientist and Janneman Conradie are scheduled to attend the CITES CoP in Bangkok as part of the Ecuadorian delegation, Ecuador being the country proposing to get Manta rays listed on CITES.