Young giant manta rays remain close to coastlines during their early years, using shallow waters as refuges before venturing into the open ocean as adults, according to a new study published in Frontiers in Fish Science. The research provides the first detailed investigation of giant manta ray movements in Central America, revealing a striking difference between the habitats used by juveniles and mature individuals.
Giant manta rays can grow up to nine metres long, with a disc width of seven metres and a weight of up to 2,000 kilograms. Once they reach adulthood at around eight to ten years old, their enormous size leaves them with few natural predators. Their young, known as pups, are more vulnerable to predators in the open ocean, including several shark species and orcas.
Researchers found that juvenile manta rays remain in shallow coastal areas where food is available and reefs provide shelter and essential cleaning services. As the rays mature, their movements change considerably, with adults undertaking long-distance migrations along the continental shelf break across Central America.
“We show that manta rays’ lifestyle isn’t a one-size-fits-all behavior. Giant manta rays in Central America undergo a dramatic shift in space use as they mature,” said lead author Jeffry Madrigal-Mesén, a researcher and project leader of Mantas Costa Rica. “Juveniles remained strictly within shallow nearshore waters that serve as coastal refuges, but most of the tracked adults executed long-distance transboundary migrations along the continental shelf break into Central America.”
Tracking Reveals Different Habitats for Young and Adult Rays
The research team used three complementary methods to track and identify manta rays at five locations between 2018 and 2025.
Acoustic telemetry, which uses underwater sound pulses, enabled researchers to monitor the fine-scale movements of 59 individuals around coastal aggregation sites, including cleaning stations. Satellite telemetry was used to track the broader movements of 12 individuals, while photo identification helped researchers distinguish individual manta rays.
Together, these methods generated a dataset containing more than 12,000 detections, providing insights into how the rays use coastal and offshore habitats.
“If we hadn’t used all three technologies together, we simply wouldn’t have been able to piece this puzzle together,” explained Madrigal-Mesén. “Combining these tools turned fragmented data into a unified, undeniable story.”
The findings showed that young manta rays, with disc widths of approximately three metres or less, remained in shallow coastal refuges. These areas offer access to food, hiding places and reef-based cleaning services while keeping the juveniles away from the hunting grounds of some open-ocean predators.
Madrigal-Mesén said mature rays have advantages that juveniles lack, including their large body size and ability to dive deeply to evade threats. The researchers also observed that young individuals repeatedly returned to the same coastal locations, sometimes being sighted at their original tagging sites more than a year later.
“Mature adults can rely on their massive body size and their ability to dive deep to evade threats. But juveniles don’t have that luxury,” said Madrigal-Mesén. “What is truly amazing is seeing how strictly young manta rays stick to coastal waters as long-term refuges. We see the same individuals more often than once a year. In fact, just recently, they were sighted again at the exact same tagging location,” continued Madrigal-Mesén. “It is always a joy to see them again – they have truly become a part of the family.”
In contrast, nine mature manta rays undertook extensive migrations along the continental shelf break. Their movements indicated that adults also retain strong attachments to particular locations, despite travelling over much larger distances.
One individual, nicknamed Mickey Mouse because of the distinctive spot pattern on his belly, was particularly valuable to the research. His unusual approachability allowed scientists to tag him multiple times over several years, creating a continuous record of his movements.
In 2020, Mickey Mouse registered 462 acoustic detections at El Secreto, a coastal hub. Three years later, he returned to the same shelf area and remained there for 38 days.
“Nearshore cleaning stations transcend basic hygienic function; they act as primary social hubs where courtship and reproductive interactions take place,” explained Madrigal-Mesén. “Returning to a predictable coastal depot allows mature rays to prioritize social and cleaning needs before undertaking large-scale regional migrations.”
Researchers Call for Protected Migration Routes
Although adult manta rays benefit from their size and diving abilities, their long-distance movements expose them to different threats. Coastal habitats are often covered by marine protected areas, but protection may not extend to the international waters and offshore corridors that adults cross during migration.
“As soon as these rays move beyond isolated marine reserves, their legal protection drops to zero. This exposes them to unselective industrial fisheries and vessel strikes as they navigate unprotected international corridors,” said Madrigal-Mesén.
The researchers argue that marine protected areas alone cannot adequately protect a highly mobile species whose habitat requirements change with age and whose migrations cross national boundaries.
They propose establishing multinational conservation swimways that connect coastal refuges used by juveniles with the migratory corridors travelled by adults. Such networks could help provide more continuous protection as manta rays move between national waters and unprotected offshore areas.
The study highlights the importance of understanding how marine species use different habitats throughout their lives. Protecting the shallow coastal environments where young manta rays grow is important, but conservation measures must also account for the extensive movements of adults.
“This study opens a new chapter for manta ray research in Central America,” Madrigal-Mesén concluded. “We hope it sparks fresh enthusiasm and encourages future collaborators to join us in executing the new ideas and research projects we have planned for the conservation of this species.”
Read More :