Students Research Presentations: Determining the spatial distribution pattern for Northwest Atlantic leatherback turtles in Costa Rica and potential vessel traffic impacts on their movement characteristics

Year:

2022

Source:

Ocean Sciences Meeting, Virtual

Abstract:

Northwest Atlantic leatherback turtles (Dermochelys coriacea) are in decline and listed as endangered. They are particularly vulnerable to interactions with human activities, such as fishing and vessel traffic during the interesting period (between nesting bouts) when turtles are concentrated in nearshore habitats. For our study, female leatherbacks (n=6) were tracked using satellite tags. We used spatial statistics, a switching state-space model (SSSM) and home-range estimates to determine the distribution of the interesting leatherbacks off Limón Province, Costa Rica at 6-hour intervals. We then analyzed vessel traffic in the region using their automatic identification system (AIS) and determined if it had an impact on the turtles’ behavior. We analyzed vessel traffic exposure and speed and compared it to the turtle movement characteristics; speed, turning angle, and absolute angle. We found that the turtles were mostly concentrated directly off the nesting beach, and their turning angles were significantly associated with vessel exposure and speed (Cochran-Mantel-Haenszel test, p<0.01). Our results can help to inform managers and future studies about potential vessel traffic impacts on this endangered species and encourage practical mitigation if necessary, such as regulations on vessel speed. 

Mentors:

Dong Liang, Ph.D.

Students:

Melissa Vezard, California State University, Monterey Bay