But why are these gentle giants being fished for a small, seemingly inedible piece of feathery cartilage?

Historically, mantas have not been targeted to any great extent and they had never demanded a high price due to the poor quality of their meat, but in the last decade a commercial fishery for manta and mobula rays has begun in order to support a new demand for their gill plates for use in the Chinese Medicinal Trade. It is claimed that the plates can treat health issues ranging from asthma, to skin rashes, chicken pox and even cancer. Some of the practitioners also maintain that the gill plates reduce toxins, boost the immune system and aid in the detoxification of the bloodstream. However, there is no scientific evidence to support any of these claims, and some Traditional Chinese Medicine practitioners have even admitted that gill plates are not effective and that many other alternatives are available. As demand from this senseless and unnecessary new market is increasing manta rays are becoming extremely vulnerable in a number of locations around the world, in-particular Indonesia.

Manta rays are slow growing, live a long time and reproduce very slowly, giving birth to only a single offspring after a year long pregnancy every 2 to 5 years. These factors make mantas extremely vulnerable to exploitation, as they are not able to quickly replace individuals removed from the population. Fishing these animals can fast lead to population collapses.

There is, however, a ray of hope on the horizon for mantas. The next CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) convention is coming up in March 2013 and a proposal to have the genus Manta listed on Appendix II at the next convention has been accepted. Now it is up to member nations to vote upon this and a two thirds majority vote will secure this crucial international protection for mantas.

Manta ray researchers, conservationists and enthusiasts are all currently pulling together to try and urge for this protection. The UK registered charity, The Manta Trust, who I work with, have recently started a petition directed at the delegates of CITES to help highlight the importance of voting to protect manta rays.

By signing the petition you’ll be letting your CITES delegate know that as your representative you would like them to vote in favour of the proposal to protect manta rays. They are at the meeting to represent the view of their country, so with a high number of signatures from their own country on the petition we’re hoping they will listen! Every single signature counts, but with Indonesia’s manta populations being some of the most threatened of anywhere in the world we are hoping we will gain the support of many Indonesian nationals.

If you would like to sign the petition you can find it here: http://www.avaaz.org/en/petition/Protect_Manta_Rays/

Thank you for signing and please don’t forget to share the petition with everyone you know.

Over the last few months we have conducted a number of presentations and workshops with dive operators, live-aboard boats and dive resorts at our study sites across Indonesia.

As well as raising awareness, these workshops act as a practical lesson on our manta photo-ID research techniques. Dive operators and their customers are encouraged to get involved with our research by using this simple (but very useful) data collection method during their dives with manta rays. Through this collaboration, we have already built up a network of enthusiastic ‘manta spotters’….ID images are flooding in!

For Coral Triangle Day in June we were also invited to give a presentation at an educational day run by The Coral Triangle Center and The Nature Conservancy in Sanur, Bali. Present at the talk were senior members from several NGO’s along with local and international schools. The event was filmed by the WWF and was a great success. There were many challenging questions from the younger participants. My favorite question being: “if the world ends, would manta rays survive?”

Since our preliminary data collection trips, Misool Eco Resort, who’s generous support has made it logistically possible for us to reach the remote study site in Southern Raja Ampat, have established the Misool Manta Project to assist with data collection in the region.

Understanding movement patterns and habitat use is crucial in order for conservation initiatives and management plans to be implemented effectively, and acoustic tags are valuable tools that help us depict these aspects of a manta rays life. Each acoustic tag transmits an individualized code and when the tagged manta swims within range of a receiver station the code is detected and logged along with the time and date. After a year or so the receivers will be bought up and all the stored data is downloaded onto a computer, revealing exactly when the tagged mantas were visiting specific sites.

So, with a mission to tag up to 10 mantas and deploy 6 receivers strategically around the area, and only 8 whole days to do it we didn’t waste any time getting all the equipment set up and ready to go. By day three we were all set; tags were prepared, receivers deployed and research boat prepped with everything we would need to photograph, collect DNA samples and tag, now all we needed were the mantas to show up so we could fit them with their new accessory.

Worryingly, very few mantas had been seen in the area for the couple of months prior to our visit, but with enthusiasm and hope we spent each day waiting patiently at the cleaning station. However, as the days slipped slowly by with no sign of any mantas, the chances of deploying the tags were getting slim, and our hope was diminishing.

Unfortunately, luck, and the mantas were not on our side this time, and we didn’t see a single manta ray during our time in Southern Raja Ampat. Leaving the equipment in the capable hands of Calvin and Becky, founders of the Misool Manta Project, Guy and myself left Misool Eco Resort feeling a little frustrated but hopeful that the mantas would be back soon so Calvin and Becky could start tagging.

Sure enough, a couple of days after leaving we get reports that the mantas are back…typical! Relieved that our beloved mantas had returned but a little frustrated with the unfortunate timing of our trip, we are now left pondering over the reason for the mantas disappearance. Data from this time last year, and reports from previous years, had revealed relatively abundant manta sightings during this time of year. So what factors had changed this year that had altered the mantas movements and site use? And where are they when they are not in this area? Initially it was thought that the presence of a large school of false killer whales, one of mantas few natural predators, were keeping them away, however, it seems unlikely that this factor would keep them away for so long. Changes in environmental conditions affecting their planktonic food source are also possible explanations that we are exploring.

Ironically, if we could deploy some tags it could help us to answer these questions. However, this is the nature of studying a wild animal, especially one that lives and roams the depths of the ocean, an element that is largely inaccessible to us, and no matter how well we think we understand and can predict their movements and behaviours it is never black and white.

So once again the mysterious mantas have left us asking more questions and are yet to reveal their secret lives. But piece-by-piece we are starting to paint a picture of this population, and so far we have identified over 200 individual reef manta rays (Manta alfredi) and over 50 giant manta rays (Manta birostris) from Raja Ampat.

Cilacap is one of the largest fishing ports in Java where more than 160 drift gillnet fishing boats operate from. The drift gillnet fisheries are primarily targeting tuna species, however due to the destructive nature of the fishing techniques a large proportion of by-catch is caught.
Drifting gillnets are large-meshed nets that are designed to hang vertical in the water column not far from the surface. Once deployed the nets form an invisible, drifting wall that entangle anything that comes into contact with it, including marine mammals, sea birds, turtles, sharks and rays. Each piece of gillnet used by Cilacap fishers is approximately 40m wide and 20m high, and each fishing boat uses about 60 pieces of gillnet, forming a wall of net several kilometers long. It has been reported that approximately 35% of the total catch by Cilacap gillnet fishing boats is non-target “other” species.

Day 1 at the fishing port was surprisingly quiet considering the number of boats operating from here. We arrived at 7am and the only action was one fishing boat unloading frozen tuna, we visited the port every hour until 5pm however no more landings came in.

Day 2 couldn’t have been more different from the previous day. When we arrived in the morning there were already a large quantity of fish laid out ready to be weighed and sorted, including a number of juvenile and mature sharks. Soon after we arrived a pile of 10 mobula rays (all Mobula japanica) were unloaded off a boat along with a number of sharks, stingrays, marlin and many other large pelagic fish species.

By interviewing fishermen and a local port operator it was determined that mobula and manta rays are caught most frequently between May and September, and approximately 1 ton of these rays are landed each day between these months. Although we did not see any manta, they are reportedly landed in Cilacap but not as regularly as mobula. The meat is sold locally as food and the gill rakers are removed and dried. One kilo of dried gill rakers reportedly sells for 500,000 IDR (US$ 50).

There is not a target fishery for manta and mobula rays in Cilacap, however, the relatively large amount taken as by-catch is extremely worrying. The slow growth and reproductive rates of these rays suggests that such high fishing pressure is not sustainable.
Manta and mobula rays are caught as by-catch throughout Indonesia and in order to prevent irreversible population declines these destructive fishing techniques need to be managed far more efficiently, and increased protected areas need to be created to provide protection for these graceful rays.

If you or anyone you know has been to Indonesia and taken photos of manta rays in Sangalaki (or any other part of the country) or have any information regarding manta fishing we would love to hear from you, any information is greatly appreciated .....you can send me email at sarah@mantatrust.org.

In depth fish market surveys are set to begin soon…...so stay tuned as more on this to come.

Manta Point is a small, relatively shallow (3-24m) site lined by limestone cliffs and mantas come here regularly to feed, which they do mostly at the surface of the water. Understandably, this attracts a huge number of tourists hoping to get the chance to snorkel and dive with these incredible rays. But, unregulated this results in a scary mix of boat propellers (and lots of them), people and mantas. All added up this equals an accident waiting to happen and also potential habitat disturbances that may impact the manta’s feeding behaviour.

Thankfully, Nusa Penida is currently being established as a Marine Protected Area and I have teamed up with the Coral Triangle Center (CTC) to assist their efforts to create effective zoning and management policies for the MPA. It is likely that Manta Point will be designated as a Marine Tourism Zone, meaning fishing practices will be banned and tourism management will be implemented. Manta rays are an icon of Nusa Penida, but unlike other iconic marine species found around the island (such as the Mola mola) no research has been conducted on this population of rays, which is surprising given their popularity among dive tourists. My research, which aims to better understand the population ecology, habitat use and movements of these rays, will be making a significant contribution to the conservation of this ecologically and economically important population of reef manta rays.
As well as conducting research we are also working with CTC to set up workshops to educate local dive operators and communities about manta rays and the importance of ecotourism management.

There’s still a lot of work to be done, but the future of Nusa Penida’s manta rays is looking bright.