This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Florida State University researchers studying male green sea turtles off the coast of Brazil have discovered two distinct migration strategies, with some turtles traveling up to 1,000 kilometers (620 miles) after breeding while others remain in the same area year-round. The findings shed new light on the movements of male green sea turtles, which are much harder to study than females.
Female turtles regularly return to nesting beaches to lay their eggs, giving researchers predictable opportunities to tag and monitor them. Males, however, rarely return to land after entering the sea as hatchlings, leaving major gaps in scientists' understanding of where they travel and which marine areas are important to their survival. The FSU team, based in the Department of Earth, Ocean, and Atmospheric Science, tracked adult male green sea turtles at a remote breeding site off Brazil's coast during three breeding seasons.
The study provides new information about where the turtles travel during and after breeding season and could help guide conservation efforts in areas they use for migration and feeding. The research is published in Marine Ecology Progress Series. "Many turtles undertook long-distance migrations, with some migrating for almost a month," said Armando Barsante Santos, one of the study's co-authors and a postdoctoral researcher in the Marine Turtle Research, Ecology and Conservation Group at FSU.
"Their sense of navigation is impressive, and identifying paths they use during their oceanic migrations is essential for conservation management." The team studied the same group of adult male green sea turtles from late spring into early summer from 2019 to 2022 off the coast of Brazil to identify movement patterns and areas of high turtle density during and after the breeding season. Brazil's coastal waters are an important foraging ground for adult green sea turtles, the most abundant turtle species around Brazil, and the location also supports nesting and breeding areas. Researchers observed two distinct strategies: After breeding, about 80% of tagged turtles migrated 300 to 1,000 kilometers (190 to 620 miles) to different foraging grounds, while 20% stayed in the same breeding area year-round.
"Assessing the overlap between key habitats, such as migratory corridors and areas of high turtle density, and anthropogenic—human-made or human-connected—threats is crucial for redefining conservation strategies in the region and can minimize the mismatch between important areas for sea turtles and marine protected areas in Brazil," said Professor of Oceanography and Environmental Science Mariana Fuentes, another co-author and leader of the Marine Turtle Research, Ecology and Conservation Group. Satellite tags also collected data on turtles' vertical movement, such as dive frequency, depth and duration. Turtles that stayed in the breeding area made frequent, short daytime dives and long nighttime dives, while migrating turtles exhibited a variety of dives, likely to minimize the risk of detection by predators and reduce wave drag and the energy cost of migration.
"Understanding the three-dimensional use of the environment gives us more details about how susceptible turtles might be to certain fishing gear or vessel strikes, for example," Santos said. "With different fishing gear used at the water's surface, in midwater and at the bottom of the ocean, we need to know how turtles' use of the area overlaps with these layers. This can inform strategies that harmonize the use of the environment between humans and turtles, including enhancing the effectiveness of the marine protected areas that currently cover more than a quarter of Brazil's waters." Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. d research that matter—daily or weekly.
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