Identifying patterns in foraging-area origins in breeding aggregations of migratory species: Loggerhead turtles in the Northwest Atlantic.

Population assessments conducted at reproductive sites of migratory species necessitate understanding the foraging-area origins of breeding individuals. Without this information, efforts to contextualize changes in breeding populations and develop effective management strategies are compromised. We used stable isotope analysis of tissue samples collected from loggerhead sea turtles (Caretta caretta) nesting at seven sites in the Northern Recovery Unit (NRU) of the eastern United States (North Carolina, South Carolina and Georgia) to assign females to three separate foraging areas in the Northwest Atlantic Ocean (NWA). We found that the majority of the females at NRU nesting sites (84.4%) use more northern foraging areas in the Mid-Atlantic Bight, while fewer females use more proximate foraging areas in the South Atlantic Bight (13.4%) and more southerly foraging areas in the Subtropical Northwest Atlantic (2.2%). We did not find significant latitudinal or temporal trends in the proportions of NRU females originating from different foraging areas. Combining these findings with previous data from stable isotope and satellite tracking studies across NWA nesting sites showed that variation in the proportion of adult loggerheads originating from different foraging areas is primarily related differences between recovery units: individuals in the NRU primarily use the Mid-Atlantic Bight foraging area, while individuals from the three Florida recovery units primarily use the Subtropical Northwest Atlantic and Eastern Gulf of Mexico foraging areas. Because each foraging area is associated with its own distinct ecological characteristics, environmental fluctuations and anthropogenic threats that affect the abundance and productivity of individuals at nesting sites, this information is critical for accurately evaluating population trends and developing effective region-specific management strategies.

Comparing quantity of marine debris to loggerhead sea turtle (Caretta caretta) nesting and non-nesting emergence activity on Jekyll Island, Georgia, USA.

Marine debris is defined as any manmade item, commonly plastics, which ends up in the ocean regardless of the source. Debris found along coastlines can cause harm or even death to nesting and hatchling sea turtles through ingestion, entrapment, or entanglement. Jekyll Island is a prominent nesting beach for loggerhead sea turtles with over 1700 emergences from 2012 to 2017. This study uses debris logged through NOAA's Marine Debris Tracker and loggerhead sea turtle nesting activity on Jekyll Island to generate density maps and evaluate possible interactions. These maps provide valuable information on portions of the coast most at risk for debris and sea turtle interactions. Using these maps help the GSTC Marine Debris Initiative focus citizen science efforts in high overlap areas of the beach. With marine debris being a global issue that impacts all sea turtle and beach nesting species, lessons learned can be applied across a wide range of taxa and management strategies.