Tony Candela gently lowered the juvenile leatherback into the Atlantic off the coast of Gabon, its tiny satellite tag glinting in the morning sun before it vanished into the deep blue. For decades, what happened next—where these young turtles went, how they lived, how deep they dove—was a mystery scientists called the 'lost years.' Now, thanks to miniaturized tracking technology, those hidden chapters are beginning to unfold. A groundbreaking study published in Scientific Reports in April 2026 has revealed, for the first time, the detailed diving behavior of juvenile leatherback and loggerhead sea turtles, drawing from over 2,400 daily records across multiple ocean basins. This research, led by Candela—a Ph.D. student at the University of Toulouse and oceanographer with Upwell, Mercator Ocean International, and the Centre d'Etude et de Soin des Tortues Marines—marks a turning point in marine conservation science.
For years, the small size of juvenile turtles made satellite tracking impossible. They’d hatch, scramble into the sea, and disappear—drifting into vast oceanic zones where no human could follow. This knowledge gap left conservationists blind to a critical phase of their life cycle, one where they’re most vulnerable to threats like fisheries bycatch and plastic pollution. But with tags now small enough to attach safely to juveniles weighing less than a kilogram, researchers can finally map not just where they go, but how they move through the water column.
The findings are striking: as turtles grow, their diving behavior changes dramatically. Larger juveniles dive deeper and spend more time below 60 meters, with structured patterns that suggest increasing reliance on deeper prey and thermal regulation. The data shows a clear ontogenetic shift—growth directly linked to deeper, longer dives. This three-dimensional understanding of their habitat use is revolutionary. It means conservation strategies can now be tailored not just to surface locations, but to the vertical zones these animals actually inhabit.
The implications are immediate. Knowing how deep young turtles dive allows fisheries managers to adjust longline depths or time closures to reduce bycatch. Marine protected areas can be designed to encompass not just surface waters but critical subsurface layers. "We aim to see these findings applied to management and conservation outcomes that work to protect sea turtles throughout their life histories," says Dr. George Shillinger, Executive Director of Upwell, which leads the international Lost Years’ Initiative behind this research.
As ocean temperatures rise and marine ecosystems shift, understanding the behavior of young turtles may be key to their survival. This study doesn’t just illuminate the lost years—it lights a path forward for smarter, more effective conservation. And as Tony Candela puts it, this is where science and purpose meet: "This study was the perfect way to align my background with my values."