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There is still so much left to learn about the ocean. I am constantly reminded of this as I travel to new places and see new things. As a marine biologist I find this both comforting, in terms of job security, and exhilarating. One of my favorite new places to explore is Southeast Asia. At the moment, this region is offering up some of the most exciting opportunities for manta ray research in the world. So much that after a three-month stint in Southeast Asia I am still radiating this glow of satisfaction having completed several very successful Ray of Hope Expeditions in Thailand, Myanmar and Indonesia.

Giant Manta tourism Thailand copyright Andrea Marshall

One of the many majestic giant manta rays spotted during our Ray of Hope expedition in Thailand

MMF has been working in these three countries for years now on a hunch that they harbor very important manta ray populations and our exploratory work is paying off in spades. In fact, Thailand now has the largest identified population of giant manta rays in the Indian Ocean and Indonesia is threatening to dethrone the Maldives in terms of their number of reef manta rays.

Major Cleaning Station Indo Copyright Andrea Marshall

Indonesia is home to an abundance of manta rays

The biggest challenge with Southeast Asia is often the remote locations of manta ray aggregation sites. Places like the Mergui Archipelago in Myanmar and Misool in Raja Ampat are NOT easy places to get to and present many logistical challenges that slow research efforts and make operations complicated and costly. However, the upsides far outweigh the consequences - with extraordinary aggregation sites like Black Rock (Myanmar) and Karang Makassar (Komodo, Indonesia) where upwards of 50 mantas can be seen in a single day of diving.

One of the most exciting things about this region for me is the fact that many of the areas have suitable habitat for both species of Manta meaning that they can occur in mosaic sympatry, or patchwork-like distributions, where giant mantas and reef mantas use different reefs in close proximity to one another. Most of the time they do not mix but there are a few special locations in Southeast Asia where they occur together. It is indeed a special dive when both species of Manta can be seen side by side.

Manta alfredi trashed feeding site Raja Ampat copyright Andrea Marshall

Manta ray feeding grounds are becoming more and more choked with plastic garbage

Our researchers are still trying to get a sense of what is going on with the various populations in this region, and indeed are still finding new ones. Many of the populations appear stable and thriving but others are face severe anthropogenic pressures including entanglement, habitat degradation, and even overly intense tourism pressure. Prime feeding grounds are choked with plastic garbage, mantas are still being poached to supply illegal international trade to China and animals are often injured or killed at the surface from increasing boat traffic in the region.

Our team is on it and we have students investigating many of these issues in detail, in particular our ‘Microplastics and Megafauna’ study which aims to learn more about the impacts of marine microplastic pollution on manta rays - something that has never been examined before. My recent trip was a huge motivator as I documented manta rays feeding in plastic polluted areas in more places than ever before. I intend to return later this year to continue this important work.

Rubbish in Kawe Raja Ampat copyright Debbie Arriaga

We are already investigating the impacts of marine microplastic pollution on manta rays

Despite all of this, there is a ray of hope on the horizon. Manta sanctuaries are being created. Countries like Indonesia, once one of the top offenders for directed manta fishing, have committed to protecting these gentle giants, and tourism for these iconic rays is on the rise in Southeast Asia, providing an economic incentive for their protection. There is also a flurry of research beginning on populations in this part of the world that will ensure that sound science-based management plans and conservation strategies are created for these animals in the near future. One thing is for sure, MMF’s manta team will be spending a LOT of time in this region. Watch this space for updates!