Indonesian Manta Mapping Project Update

Since the start of this project, and with the invaluable help of dive operators and dive and snorkel tourists, we have been collecting manta ray identification photos at the three most well known manta locations in Indonesia; Raja Ampat, Komodo National park and Nusa Penida, Bali. These photos, along with key information about each manta sighting (such as time, date, location and weather and sea conditions) help us monitor and learn more about these populations and already we are starting to uncover important information about each populations ecology.

Indonesian Manta Mapping Project Update

In Raja Ampat both reef (Manta alfredi) and oceanic (Manta birostris) manta rays occur and at one particular cleaning station, both species can often be seen at the site at the same time. This is one of the only known places in the world where both species regularly overlap in this way and before Manta Trust researchers started monitoring this population local resorts did not realize just how unique this site was regarding its manta rays. Despite our growing databases of over 200 reef and 40 oceanic mantas in Raja Ampat, to date there has been no cross over between the Misool region (South) and the Dampier Strait region (central) of Raja Ampat. We originally thought that there would be one population of each species in Raja Ampat and that they migrate between the different regions, however our data suggests that there may be at least two distinct populations of both species in Raja Ampat, however continued monitoring is needed before we can confirm this.

In Nusa Penida, Bali, where mantas can be seen at a few key sites year round, the population is already larger than we suspected it would be and, recently, through photo matches we have confirmed that two individuals from our Nusa Penida population have been sighted off Gili Trawangan Island, Lombok. We had our suspicions that the manta rays occasionally sighted off Gili Trawangan are the same population as the Nusa Penida mantas but this is the first definite match. This is an exciting discovery in our research but also raises issues in regards to the conservation management of this population.

 

As well as learning more about the well-known manta populations we are also striving to fill in some of the gaps on the map. One of the main aims of the manta mapping project is to get an idea about the distribution of manta populations throughout Indonesia and how human pressures are impacting them. Very little is known about the presence of mantas away from tourist hotspots but it is likely that the remote populations may be the most threatened by fisheries. We have highlighted a few remote locations in Indonesia where there have been reports of regular manta sightings and throughout the next year we will be conducting trips to survey these areas and hopefully determine whether mantas actually exist in the area, which species and whether there is any significant pressure from fishing. In-fact we will be conducting our first remote survey in a few days, when we are off to Pulau Banyak, off the west coast of Sumatra, stay tuned for how we get on.

 

Finally I would like to take this opportunity to thank Project AWARE for supporting our work and also all of the divers, snorkelers, dive operators, liveaboards, resorts and other NGOs who have assisted our work and who have donated manta ray photos. Our Gili Trawangan manta match with a Nusa Penida manta is a great example of just how important your manta ID photos are towards our research. If you have manta photos from anywhere in Indonesia I would love to hear from you so please don’t hesitate to get in touch, you can email me at sarah@mantatrust.org or alternatively you can upload your photos directly, just follow this link: http://www.mantatrust.org/make-a-difference/id-the-manta/