Biotelemetry

Despite decades of conservation efforts, population recovery remains elusive for the loggerhead sea turtles (Caretta caretta) nesting in Florida, the largest aggregation globally. Limited studies exist regarding reproductive strategies and in-water habitat use of loggerheads in southeastern Florida. I used satellite telemetry to track the movements of 17 nesting loggerheads on Juno and Jupiter Beaches during the 2020 and 2021 nesting seasons. The majority of females displayed high nest-site fidelity. Inter-nesting intervals ranged from 10–19 days and were negatively correlated with water temperatures. Core inter-nesting areas ranged from 3.7–805.8 km2 and were located a mean 1.6 km from land. Mean clutch frequency was 5.9 nests/female, the highest reported for any loggerhead population worldwide. These findings suggest the number of females in the southeastern Florida population may be over-estimated due to an underestimated clutch frequency. Protective measures should target high-use coastal areas to maximize conservation benefits.

Shellfish aquaculture “grow-out” sites for Northern Quahog (Mercenaria mercenaria) clams have substantially higher densities than the surrounding ambient environment and thus can attract local molluscivores to these areas. I used acoustic telemetry to examine potential interactions of two highly mobile ray species (cownose ray, whitespotted eagle ray) with two clam grow-out sites in the Indian River Lagoon near Sebastian, FL, where clammers have reported damaged grow-out gear. Visitation patterns of telemetered rays to these sites were compared to other reference sites in the region and modeled using local environmental data. While both species spent greater time elsewhere, I found many instances in which rays remained within range of clam grow-out sites for extended periods (>60 minutes). Mesocosm experiments with whitespotted eagle rays confirmed they were capable of interacting with and damaging clams housed within antipredator materials, although mortality was significantly reduced compared to controls and in particular by multi-layer netting.

Elasmobranchs play ecologically important roles in coastal environments.
Unfortunately, the basic distribution and movement patterns of these species, particularly
rays, remain relatively unknown. This is especially true for the Whitespotted Eagle Ray
(Aetobatus narinari), a protected species in Florida with poorly described migratory and
habitat use patterns. I employed a combination of acoustic telemetry techniques to reveal
multi-scale spatial patterns of A. narinari around Florida. Movement patterns between the
east and west coast individuals were distinct; a majority of west coast tagged A. narinari
exhibited migratory or transient behavior while most east coast tagged individuals
remained resident in the Indian River Lagoon. Fine-scale tracking of A. narinari revealed
individuals spent a large percentage of time in the inlets and channels and frequently
reused habitats parallel to the shore. This study fills a knowledge gap on the species
ecology which may be used for adaptive management strategies throughout A. narinari’s
range.