Credit: Jeffry Madrigal.
Baby manta rays escape predators by avoiding them until they grow large enough for a face-off, a new study has found. Tracking data shows that young giant manta rays in Central America strictly stick to comparatively safe coastal areas for the first few years of their life. When they’re large enough that natural enemies are a lesser concern, they leave these sanctuaries and embark on journeys spanning hundreds of kilometers. This shift in space use allows mantas to grow in safety before facing another type of danger in the open oceans: industrial fisheries and vessel strikes in unprotected waters. The authors say underwater corridors are needed to protect adult mantas on their treks.
Giant manta rays can grow up to nine meters long with a disc size of seven meters across and weigh up to 2,000kg. This size leaves them with very few natural enemies once they reach adulthood at around eight to ten years old. But giant manta ray babies, called pups, cannot rely on their size to protect them from predators that live in the open ocean, including several species of shark and orcas. Instead, the first study to focus on giant manta ray movement in Central America has shown that pups stay in safe coastal areas where food is available until they’ve grown large enough to face the dangers of the high seas.
“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 of the Frontiers in Fish Science study, 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.”
Coast to sea
The team used a variety of methods for tracking and identifying mantas at five locations between 2018 and 2025. Acoustic telemetry, which uses underwater sound pulses, let them monitor fine-scale movement of 59 individuals across coastal aggregation spots like cleaning stations. Satellite telemetry, where transmitters track movement and behavior from a distance, was used to track large-scale movements of 12 individuals. Photo ID was used to identify individual manta rays.
Immature manta ray equipped with satellite tag. Credit: Jeffry Madrigal.
“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 combined dataset of more than 12,000 detections showed that young mantas – those with disc widths of around three meters or less – stick to shallow coastal refuges. These coastal waters provide pups with a safe place that doesn’t overlap with predators’ hunting grounds. There they can also find plenty of food and hiding spots, and rely on essential services provided by reefs, such as cleaning.
“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.”
Puntitos, one of the immature mantas followed in the study. Credit: Jeffry Madrigal.
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In contrast to the coast-loving pups, nine mature mantas went on expansive migrations along the continental shelf break. The movement of one manta ray, nicknamed Mickey Mouse because of a spot pattern on his belly, also suggested that mantas continue to display high site-fidelity once grown-up. Unusually approachable, Mickey Mouse allowed scientists to perform tagging multiple times over several years, which provided a continuous dataset. In 2020, he logged 462 acoustic detections at the coastal hub El Secreto. Three years later he returned to the same shelf and stayed 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.”
Protected manta highways
Adults, however, face different dangers when they leave coastal regions — which are often protected marine reserves — for the open ocean.
“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.
This shows that marine protected areas alone are not enough to protect highly mobile species moving across Central America, the authors say. What is needed are multi-national ‘conservation swimways’ that link domestic juvenile coastal refuges with adult migratory corridors.
“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.”
Credit: Jeffry Madrigal.
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