Grant: 22-013R
Project Title: Understanding fine scale behavioral response of sea turtles to vessels to infer non-lethal impacts from vessel interactions
Project Manager: Mariana Fuentes
Organization: Florida State University (Research and Educational Institute)
Grant Amount: $30,775.00
Completion Date: 2024-09-20
Summary: Sea turtles and boating activities often occur in shared waters. Vessel presence and traffic can affect the fitness of individual turtles, impact their energy expenditure, cause changes in foraging activities, and displacement and disturbance. However, limited information exists on how these parameters are impacted by vessel interactions. This is of particular concern, especially in areas heavily used by boats and that provide important foraging and developmental habitat for sea turtles. This is the case within the Big Bend Region of north-western Florida, which serves as important developmental habitat for green (Chelonia mydas), Kemp's ridley (Lepidochelys kempii), and loggerhead turtles (Caretta caretta) and also supports Florida's largest recreational bay scallop (Argopecten irradians) harvest. The scallop fishery occurs annually from late June to late September and attracts thousands of boaters to the region, which overlap with turtles in space and time. Recent advances in bio-logging devices, which include fine-scale movement measurements (e.g., accelerometer, gyroscope and time-depth recorder) as well as recordings of an animals surrounding, have allowed fine-scale behaviors of sea turtles to be determined and have provided fine scale information on behavioral response to disturbances. Thus, this project will leverage on recent advances in biologging devices, with the aim to quantify the fine scale response of sea turtles to vessel interactions. This will provide a better understanding of the energetic implications of sea turtle responses to vessel interactions and help inform management strategies.
Results: One animal-borne camera was purchased from Customized Animal Tracking Solutions (CATS; Queensland, Australia) in July 2022. Because of delays with purchasing and delivery, and the temporal restriction of our research question, we had to postpone the start of the project by a year. The purchased device has an HD camera for recording videos of animal behavior, tri-axial accelerometers, gyroscopes, and magnetometers for analyses of fine-scale movement, pressure sensors for recording depth and dive information, and a hydrophone for recording sound.
To date, August 2024, we have conducted thirteen field expeditions where we have deployed the purchased CATScam, some of these trips were conducted as part of two other projects "Foraging ecology and diet selection of sympatric marine turtles in the Gulf of Mexico (24-047R)" and Using Passive Acoustic Monitoring to Determine Exposure Levels of Marine Turtles to Vessels in North-Western, Florida (23-002R). During these trips we conducted 18 deployments on loggerhead turtles for a total of 352 hours of data, which includes 14 24-hour deployments. As a first step to analyzing this data we explored whether handling and capture of turtles had an effect on the behavior of turtles. For this we quantified changes in diving behavior, activity (dynamic body acceleration), and behavior for 6 h following release. Sea turtles spent more time swimming and surfacing for air immediately following release, corresponding with shorter more frequent dives and increased activity/energy expenditure (greater dynamic body acceleration). Over time, dives became longer, and sea turtles were more likely to rest and forage. However, the time scale over which behavior returned to 'normal' was strongly dependent upon the variable considered, suggesting that consideration of the effects of capture, handling, and tagging will depend upon the question of interest. Read full publication.