First Manta Ray Satellite Tagged in Japan!
November 2024
Manta rays in Japan!?
Japan’s oceans are home to the full range of mobulid rays found here, including oceanic and reef manta, spinetail, bentfin, and Chilean devil rays. The presence of manta rays in Japan has been reported for over 50 years and the longest photo identification in the world by Takashi Ito in the mid-1970s in the Yaeyama Islands. Despite this and the hugely successful manta exhibition in Okinawa Churaumi Aquarium, studies on mobulid rays, especially wild, remain largely limited to occurrence and observational studies. The lack of studies on their habitat use, distribution, and the presence of breeding or nursery grounds significantly limits conservation and management efforts. Since mobulid rays can migrate across vast distances and national borders, understanding how Japan's populations connect globally is essential.
The five mobulid species found in Japan
Tagging Expedition
In August, I, supported by Dr. Mark Erdmann from Conservation International, Lydia Green from Manta Watch Aotearoa New Zealand and Dive Gobies, successfully deployed the first-ever tag on an oceanic manta ray in Japan!
I’ve been working at the Okinawa Institute of Science and Technology, focusing on mobulid rays caught as bycatch. Recently, I heard from Simon about a newly discovered aggregation spot for oceanic manta rays in the Kerama Islands, and I decided to investigate further. The dive shop behind this discovery, Dive Gobies, is run by Masato and Yuko Kamotani on Aka-jima. Despite the challenges of typhoon season, cancelled ferries, and being early in the manta season, our expedition succeeded in tagging an oceanic manta ray—Japan’s first! The tagged manta was a male, measuring about 5.5 meters across from wingtip to wingtip. Reviewing the dive shop’s manta archives, we learned that this was the first time they had encountered this individual.
The tagged oceanic manta ray
This tagging is a critical first step for manta research in Japan. The GPS tag tracks location and environmental data, like water temperature and depth, transmitting this information whenever the manta surfaces. Our first transmission came in early October—an impressive 260 km away in Miyako Island! The manta’s most recent location is near the Yabiji reefs, just north of Miyako. According to Dive Gobies, this area is particularly notable because Yabiji, often called “Japan’s Great Barrier Reef,” is a national natural treasure with a rich coral ecosystem. The tag last pinged from this spot, and while we aren’t sure if the manta is still there or has moved on, we’ll continue to monitor its movements closely!
Watch the video to come along on the expedition with us!
Collaboration is the key
The Japanese population of mobulid rays remains a mystery, with little known about their interactions with global populations, especially those in the Philippines and Indonesia. Understanding where and when these rays move is key to assessing their status, and this tagging effort marks an important step in unravelling their story. However, conservation in Japan comes with its own set of unique challenges. These include regulations around boat ownership and the need to build strong relationships with fisheries cooperatives and dive operators. As well, Japan’s deep cultural connection to the ocean means that many stakeholders—scientists, conservationists, fishers, and dive operators—all have a role to play in protecting marine life. Understanding and working within these guidelines is crucial, which is why collaboration becomes so important. This expedition was only made possible by the collective efforts of Masato and Yuko from Dive Gobies, along with Dr. Mark Erdmann and Lydia Green.
The manta team
RIKA OZAKI
Manta Watch New Zealand - Outreach and Data Analyst