Classic loggerhead turtle (Caretta caretta) early ocean dispersal models focus solely on the northern Atlantic and the North Atlantic Subtropical Gyres. Little is known about hatchling and oceanic stage sea turtle dispersal in the southern Atlantic where the offshore ocean circulation changes from south to north over the course of each hatching season. This differs from the western North Atlantic where the Gulf Stream dominates the oceanographic ‘landscape’. This study uses neonate loggerhead tracking data from the north Atlantic to compare with tracking data from tracked oceanic-stage turtles in the southern Atlantic. The researchers aim to determine if a similar gyre-based dispersal pattern occurs within the South Atlantic Subtropical Gyre, and to determine the likelihood of genetic connectivity with northern sea turtle Distinct Population Segments.
Yonat Swimmer (NMFS PIFSC-FRMD) along with Co-PIs, Dr. Kate Mansfield (NMFS, Southeast Fisheries Science Center), Dr. Nathan Putman (Oregon State University), Gustave Lopez, Neca Marcovaldi and Milagros Lopez (TAMAR, Brazilian sea turtle research and conservation organization) placed solar-powered satellite transmitters to track the horizontal movements of neonate loggerhead sea turtles (Caretta caretta) released off of the eastern Atlantic coast of Brazil. The project uses ocean circulation models and passive drifters released at the same time as the turtles to model turtle distribution and habitat use in the South Atlantic Ocean. To date the project has supported three trips deploying about seven neonate turtles and two passive drifters per trip since January 2013. Images above depict the size of turtle released and transmitter images.