Pioneering insights into the diving behavior of early-stage sea turtles revealed by novel marine miniaturized satellite tags.

Understanding how sea turtles interact with their environment during their early oceanic life stages—the time often termed “Lost Years”—is critical for informing conservation strategies. This study provides the most comprehensive analysis to date of vertical diving behavior in early life stages of two sea turtles species: leatherback (Dermochelys coriacea) and loggerhead (Caretta caretta) sea turtles. Using over 2400 daily records from 71 individuals equipped with miniaturized satellite tags across multiple ocean basins, analyses revealed a clear ontogenetic progression. As a turtle’s size increases, they dive deeper and longer, with increasingly structured use of the water column. Some individuals also exhibited brief acclimatization phases after release, gradually adopting deeper and more consistent diving patterns. Environmental analyses highlight qualitative associations between vertical behavior in larger turtles and the structure of the water column, including thermal gradients and subsurface layers potentially associated with prey availability. These findings offer novel insights into the development, acclimatization, and ecological drivers of vertical movement in “Lost Years” sea turtles, helping to bridge knowledge gaps during this critical life stage.