Melissa Vezard, California State University, Monterey Bay

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Abstract:

Northwest Atlantic leatherback turtles, (Dermochelys coriacea), have been in decline and are listed as critically endangered. They are particularly vulnerable to interactions with human activities such as vessel traffic during the internesting period (between nesting bouts), when females are concentrated in nearshore habitats. In our study we used spatial statistics, including a switching state-space model (SSM) and home-range estimates to determine the distribution of the internesting leatherback population off Limón Province, Costa Rica. To determine if there was any impact on the turtle behavior, we then analyzed vessel traffic exposure and speed and compared it to turtle movement characteristics; speed, turning angle, and absolute angle. We found that turtles were concentrated off the nesting beach and their turning angles were significantly associated with vessel exposure and speed. Our results can help to inform managers and future studies about the impact vessel traffic may have on this endangered species and encourage potential mitigation, such as regulations on vessel speed.