Indonesia · Global Manta Ray Program · Since 2012

Indonesia Manta Ray Project

We have followed Indonesia's reef manta rays since 2012, and the data helped protect the species nationwide.

2,000+reef manta rays identified at our Indonesian sites

170 → 447estimated reef mantas at Nusa Penida, 2012 to 2022

1,300+reef manta rays identified in Komodo

80%of Nusa Penida's mantas seen more than once

Indonesia holds some of the largest reef manta ray aggregations on Earth. We have followed them since 2012 at three sites, Nusa Penida, Komodo, and Sangalaki, identifying more than 2,000 individual manta rays and producing the data that helped protect the species nationwide.

Since 2012, MMF has studied reef manta rays (Mobula alfredi) in Indonesia, starting with a citizen science partnership with dive centers at Nusa Penida and Komodo. Divers photographed the unique spot pattern on each manta’s underside, which works like a fingerprint. When researchers compared the two photo catalogs, they found the same individuals at both sites, 450 kilometers (280 miles) apart. This showed that mantas can’t be protected one site at a time, and the finding helped bring about Indonesia’s 2014 national ban on manta ray fishing, which protects the species across the country’s entire exclusive economic zone.

Today, the program is run by MMF’s Indonesian affiliate, Yayasan Megafauna Laut, from its base on Nusa Lembongan. It is supported by a network of more than 40 partner dive centers across Bali, Komodo, West Nusa Tenggara, and the Derawan Islands. Each study site plays a different role: Nusa Penida is our longest-running site, where we have now measured the population growing. Komodo hosts one of the largest documented reef manta ray populations in Indonesia. Our carrying-capacity research there has helped shape how the park manages manta tourism. West Nusa Tenggara, between Bali and Komodo, is visited by the same mantas seen at both ends, yet we still know very little about what they do there or which habitats they use. Sangalaki, in the Derawan Islands of East Kalimantan, is our newest site. It has almost no baseline data and faces a tourism surge as Indonesia’s new capital is built nearby.

In 2026, the program expanded from photographing mantas to tracking them with the launch of the Lesser Sunda Seascape Tracking Network. Using acoustic receivers on loan from the Ocean Tracking Network, we began tagging reef manta rays at Nusa Penida. This is the first step toward a receiver network stretching from Bali to Komodo. Alongside it, we are surveying the coasts of Lombok and Sumbawa to find critical manta habitats that lie outside existing protected areas.

Objectives

Keep the long-term photo-identification catalogs at Nusa Penida, Komodo, and Sangalaki growing, and share them across Indonesia so movements between sites are detected.
Map how reef manta rays move between Bali, Lombok, Sumbawa, and Komodo with an acoustic telemetry network, and locate the nursery areas that lie outside protected areas.
Turn the evidence into management: site-specific limits on boat and diver numbers, codes of conduct in the water, and protection for the places the animals actually use.
Build the population baseline at Sangalaki before East Kalimantan’s tourism grows, so that management gets ahead of the pressure rather than following it.
Train Indonesian scientists to lead this work.

What we've done

Began acoustic tagging of reef manta rays at Nusa Penida, with a workshop for Indonesian partners and funders, as the first stage of a Bali-to-Komodo receiver network.
Published the first population estimates for Nusa Penida in 2025, built from eleven years of photo-identification: numbers rose from about 170 manta rays in 2012 to about 447 in 2022, with high annual survival, and nearly 80% of individuals were seen more than once, the highest resighting rate documented for any manta ray aggregation in the Indo-Pacific. The most likely explanation is that the 2014 protections are working.
Relaunched field research in the Derawan Islands, after a six-year gap.
Led three successful proposals, through the IUCN Shark Specialist Group, to recognize Nusa Penida, Komodo, and the Derawan Islands as Important Shark and Ray Areas in 2024.
Published the Komodo population study in 2022: 1,085 individual manta rays identified between 2004 and 2018, strong loyalty to particular sites even 5 kilometers (3 miles) apart, courtship confined to three core sites, and a northern site used mainly by immature animals that meets several of the criteria for a nursery.
Completed a carrying-capacity study at Komodo in 2019 that led directly to limits on boat and diver numbers at Karang Makassar, the park’s busiest manta ray site.
Identified more than 900 individual manta rays at Nusa Penida and more than 1,300 at Komodo, with eleven individuals recorded at both.

What's next

Extend the acoustic receiver network through the Lesser Sunda Seascape.
Expand manta ray surveys beyond the Derawan Islands MPA.
Publish several studies: the impacts of tourism on manta ray behavior, the environmental factors influencing manta ray presence, and the reproductive productivity of reef manta rays, all at Nusa Penida; and the environmental factors influencing manta ray presence and behavior in Komodo National Park.

Support manta ray research in Indonesia

Your gift funds survey days at Nusa Penida, Komodo, and Sangalaki, the acoustic tags and receivers that will show how Indonesia's manta rays move, and the training of the Indonesian scientists who will run this work for decades.

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Our work on manta rays in Indonesia

Nusa Penida: where Indonesia’s protections have been shown to work

The Nusa Penida MPA, off the southeast coast of Bali, hosts two critical reef manta ray habitats: Manta Bay is a feeding ground and may function as a nursery; Manta Point is a cleaning station used mainly by adults, and the only place where we regularly observe courtship. Both sites are among Bali’s busiest dive and snorkel destinations. That tourism gives living manta rays enormous local value, but it concentrates on exactly the places where the animals feed, are cleaned, and court. We present our findings to dive centers in Bali and snorkel operators on Nusa Penida and Nusa Lembongan, and we are working with the community and the MPA authority on the evidence needed to set defensible limits.

A reef manta ray swims along the steep reef of Manta Bay, Nusa Penida

Komodo National Park: several populations in one park

Komodo National Park, in East Nusa Tenggara, is a UNESCO World Heritage site best known for the lizard that gives it its name. Underwater, it is one of the most important places in Indonesia for reef manta rays. Diving with manta rays is central to Komodo’s tourism economy, and that revenue helps fund the park. Between 2014 and 2017 the number of dive boats per survey at the central sites rose by 34%, and visitor numbers have kept climbing. Because each site is used for a specific purpose, crowding interrupts a different essential behavior at each place. Our carrying-capacity study produced the boat and diver limits now in force at Karang Makassar, and our current work with park management focuses on enforcing them, on codes of conduct in the water, and on finding the critical habitats that lie beyond the park’s boundaries.

A reef manta ray swims over a diver in Komodo National Park

Sangalaki and the Derawan Islands: a baseline before the boom

Sangalaki Island, in the Derawan Islands of East Kalimantan, hosts the only documented reef manta ray aggregation in the region. We ran seasonal monitoring there from 2017 to 2019, but the pandemic halted the work before it was complete, leaving one of the region’s most important manta sites with almost no one watching. Since then, the stakes have risen. In 2024, the Derawan Islands MPA was recognized as an Important Shark and Ray Area, confirming its significance at a global level. At the same time, Indonesia is building its new capital city in East Kalimantan, and a surge in tourism and boat traffic is expected to follow. Sangalaki is about to become much busier, and without a baseline there will be no way to measure what that pressure does to its mantas. Re-establishing that baseline now, before the boom arrives, is the focus of our work in the Derawan Islands.

Sangalaki Island in the Derawan Islands, ringed by white sand and shallow reef, seen from the air

A tracking network across the Lesser Sundas

Photographs tell us who is where; they cannot tell us how the animals get there. Recently, we began fitting reef manta rays at Nusa Penida with acoustic transmitters, small tags that are detected whenever the animal passes a receiver moored on the seabed. The receiver network, built with equipment on loan from the Ocean Tracking Network and in collaboration with Elasmobranch Institute Indonesia, will run across the islands between Bali and Komodo.

The project on film

Searching for Rays, a film made by Mantahari Oceancare and MMF Indonesia.

Tracking manta rays across the Lesser Sundas

Tracking Manta Rays Across Indonesia introduces the Lesser Sunda Seascape Tracking Network that follows these manta rays between Bali and Komodo National Park.