PROJECTS

This project aims to tag 75 green and 75 Kemp’s ridley turtles over 3 years, in multiple seasons and locations along the east coast, in order to robustly sample these species’ seasonal and year-round habitats with the end goal of producing spatial models of availability bias for both species at a seasonal or lower spatial resolution. Wild caught animals will be tagged at the Archie Carr National Wildlife Refuge and St. Lucie Nuclear Power Plant, located on the east coast of Florida. Additional rehabilitated and wild caught animals will be tagged and released in partnership with several aquarium and rehabilitation centers in and north of Florida, the exact mix to be determined based on seasonal turtle availability. In addition to the availability bias data products, the tracking and dive data collected as a part of this project will provide a valuable ecological baseline for other studies, as these species are underrepresented in the tagging record in the region.

The tags being utilized are new, lower profile models of Wildlife Computers SPLASH10 tags. These tags are appropriate for tagging juvenile through adult specimens of both species, allowing maximum flexibility for tagging permits and available animals, as well as a range of turtle sizes to best represent size-based physiological differences in behavior. No animals smaller than 30 cm straight carapace length (SCL) will be tagged as this is the smallest size generally considered to be visible from aerial survey platforms. The Wildlife computer dive data products are appropriate for calculating the dive statistics required for availability bias surface modeling, such as percentage time below a dive threshold and dive and surface intervals. Tags will not exceed 2-5% of the turtle's weight in air, and transmitter designs and attachment methods will be selected to minimize drag per federal and state tagging requirements for sea turtles. No turtles that are injured/ill or fibropapillomatosis positive will be selected for this telemetry study.

Tags will be deployed over the course of the year, as animals are acquired, with the bulk deployed between spring and fall each year. Some tags may be reserved for deployments as late as March in the first two years of tagging to allow for maximum flexibility with the species and age classes tagged, and to sample southern overwintering habitat.

In spring, prior to tagging years 2 and 3, an evaluation of tag deployments and acquired telemetry data will be undertaken to ensure the data collected is robust and to assess whether any changes to tag attachment methodology, tag programming, or data collection is required. Additionally, the mix of species tagged, and the geographic coverage of tag data will be assessed, adjusting planned deployment locations and species mix as appropriate to tag roughly even numbers of both species across the three years of tagging, and sampling as many relevant environments as possible. Year 4 will be the capstone analysis, fitting a Generalized Additive Model (GAM), or other appropriate statistical framework, relating environmental covariates to dive behavior.  GAMs fit flexible relationships between a response variable (animal availability metrics) and explanatory covariates including remotely sensed environmental conditions, temporal covariates, and categorial considerations such as sex or size class. This allows for complex relationships to be modeled both spatially and temporally, as we would expect animal behavior to change as conditions and habitats change. Selected environmental covariates will plausibly influence animal dive behavior and hence, availability. Example candidate covariates include temperature, habitat structure, prey fields, and productivity metrics.