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Following the Mantas: 1,384 Nautical Miles from New Zealand to Fiji

10 hours ago
6 min read

An ambitious sailing expedition brought marine researchers into the Southwest Pacific's industrial tuna fishing grounds, supporting efforts to understand the extraordinary migration of New Zealand's endangered oceanic manta rays.


In June 2026, a team of marine researchers, conservation storytellers and sailors completed a 12-day, 1,384-nautical-mile voyage from Aotearoa New Zealand to Fiji aboard the sailing vessel FREERANGER.



The Bluewater Pathways expedition was hosted by Free Range Ocean in collaboration with Manta Watch Aotearoa New Zealand, Citizens of the Sea and The International SeaKeepers Society, the expedition set out to investigate one of the ocean's remarkable and little-understood migrations, while demonstrating the valuable contribution sailing communities can make to marine science.


The voyage took the crew across challenging offshore waters, into the remote North Minerva Reef and through areas of concentrated industrial tuna fishing activity south of Fiji, where researchers suspect migrating manta rays may be dying as a result of accidental fisheries bycatch.


Along the way, the team collected 30 environmental DNA (eDNA) samples for marine biodiversity research and established new connections between manta researchers working across the Southwest Pacific.


A remarkable migration, and a troubling mystery


Only a few years ago, remarkably little was known about New Zealand's oceanic manta rays.


Through six years of citizen science sightings, photographic identification and dedicated research, Manta Watch Aotearoa New Zealand has now identified more than 235 individual oceanic mantas in the country's waters.


Satellite tagging has since revealed something extraordinary: these animals undertake biannual migrations between New Zealand and the tropical Southwest Pacific, travelling further and diving deeper than any other known manta population.


But the tracking has also raised serious conservation concerns.


Four of the 40 satellite-tagged mantas are believed to have died during their migration, with tags ceasing transmission after the animals moved north of New Zealand. Two were pregnant females in the final stages of gestation.


Manta Watch researchers believe the evidence points towards accidental capture in industrial tuna fisheries as a likely cause, although further research is needed to establish exactly what is happening.


Oceanic manta rays are vulnerable to entanglement in pelagic longlines and accidental capture in tuna purse seine fisheries. Unlike many marine animals, mantas must swim continuously to breathe and cannot reverse to free themselves when entangled.


Understanding the scale and location of these losses is critical to informing future conservation measures.


Following the migration into the fishing grounds


The expedition originally planned to sail from New Zealand towards Tonga, passing through high seas areas associated with previous satellite-tag losses.


Once underway, the team adapted its route towards Fiji, where industrial tuna fishing activity was concentrated at the time and where another tagged manta had been lost.


After departing Opua, the crew sailed north through demanding offshore conditions, spending three nights inside the remote North Minerva Reef before continuing towards Savusavu.


The decision brought the expedition directly into areas of active industrial fishing.


During the passage, nearby were fishing vessels deploying longlines up to 50 kilometres in length, carrying thousands of hooks. Reports from other passing sailing vessels who shared screenshots of the gauntlet the crews were running described similar encounters across the region.


For Duncan Copeland, FREERANGER's skipper and Free Range Ocean co-founder, who has spent more than two decades working internationally on fisheries monitoring, intelligence and enforcement, the experience reinforced the importance of the research.

"We were repeatedly sent reports by fellow sailing vessels who were having the same experience, all of us running the same gauntlet of fishing activity that the manta rays face on their migration each year."

The observations did not establish that the fisheries were responsible for the satellite-tag losses, but they helped the team better understand the fishing activity occurring along the migration route and the importance of further investigation.


Collecting ocean biodiversity data along the way


While the manta migration was the expedition's central research focus, FREERANGER also contributed to another collaborative ocean science project.


Working with New Zealand-based nonprofit Citizens of the Sea, the crew completed 30 environmental DNA sampling tows during the 1,384-nautical-mile passage.

Environmental DNA, or eDNA, is genetic material shed by organisms into their surroundings. By collecting samples from seawater, researchers can investigate the biodiversity present in an area without needing to directly observe or capture individual species.


The samples contribute to research across parts of the Pacific that remain difficult and expensive to survey using conventional scientific expeditions.


Citizens of the Sea equips sailors with sampling technology and training, enabling cruising and racing vessels to contribute biodiversity observations as they travel.


For Free Range Ocean, the collaboration demonstrates how existing sailing journeys can help expand the geographic reach of marine research, particularly across the vast, under-sampled open ocean.


Connecting manta research across the Pacific


The expedition's contribution continued after FREERANGER reached Fiji.

Manta Watch Aotearoa New Zealand founder and marine ecologist Lydia Green connected with Fiji-based marine biologist Luke Gordon, who leads Manta Project Fiji, an affiliate of the global Manta Trust.


Together, they shared knowledge about their respective manta populations, discussed the voyage's early observations and collaborated on manta ray surveys in the Suva region.

Strengthening these relationships is particularly important for highly migratory species whose movements cross national boundaries and international waters.


The research is still at an early stage, but the longer-term ambition is significant.

"Our hope is that, one day, the evidence gathered through efforts like this could help support a protected seasonal migratory corridor linking New Zealand, Tonga and Fiji for oceanic manta rays and other highly migratory marine species."Lydia Green, Manta Watch Aotearoa New Zealand

Achieving that ambition would require extensive further research and collaboration between governments, fisheries, scientists, conservation organisations and communities throughout the region.


What the expedition demonstrated


Beyond the scientific observations and samples, the voyage provided an opportunity to bring together organisations with complementary skills, experience and ambitions.

Marine ecologist Lydia Green and filmmaker Samantha Campbell joined Free Range Ocean founders Larissa Clark and Duncan Copeland, alongside their children Eden and Skye-Elizabeth, aboard the independently owned 49ft (14.9m) sailing vessel FREERANGER.


For Lydia and Sam, it was their first offshore sailing passage. The demanding conditions, close encounters with industrial fishing activity and experience of crossing the same ocean areas used by migrating mantas provided a powerful perspective on the challenges facing these animals.


Sam documented the voyage to help communicate the research and conservation issues to wider audiences and a shoft film and coffee table photobook are soon to be published!


The expedition also built on FREERANGER's participation in The International SeaKeepers Society's DISCOVERY Yacht Programme, which connects private vessels with scientific research and conservation opportunities.


For Free Range Ocean, the experience reinforced a central belief: that people already travelling across or spending time around the ocean have opportunities to make meaningful contributions to science.


Sailors can collect biodiversity samples, report wildlife sightings, document environmental conditions and provide researchers with access to locations that might otherwise be prohibitively expensive to reach.


"We hope this expedition inspires more sailors to see that the journeys they're already making can also become opportunities to support research, conservation and the remarkable people working to better understand our ocean."Larissa Clark, Free Range Ocean co-founder

The voyage is over. The research continues.


The expedition was one contribution to a much longer programme of research and conservation.


Important questions remain about the number of manta rays lost during their migration, where these losses occur and how fisheries interactions may be affecting the population.

Answering them will require sustained, international cooperation and better information from across the Southwest Pacific.


There are ways for ocean users to contribute now.


Manta sightings and photographs can be reported to Manta Watch Aotearoa New Zealand, Manta Project Fiji and regional research partners, helping build knowledge of individual animals, populations and movements.


Sailors can also contribute directly to marine biodiversity research through Citizens of the Sea, while SeaKeepers continues to connect private vessels with scientists seeking access to remote research locations.


Through our free, open-access Ocean Citizen Science Directory, Free Range Ocean helps people discover credible marine research projects they can participate in, wherever their ocean adventures take them.


The more people who take part, the more we can learn about our ocean and the remarkable species that depend on it.


Explore the projects and partners

 
 
 

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