A juvenile loggerhead sea turtle with a micro-satellite tag on it’s carapace
Upwell Turtles, the Okinawa Churaumi Aquarium, and the Sea Turtle Ecology Lab (STEL) have launched a partnership to explore the migratory ecology of the early life stages of loggerhead sea turtles. On November 14, 2024, they released 11 turtles with micro-satellite tags off the West Coast of Ie Island, Okinawa, Japan. This is the first time that captive-reared juvenile loggerheads (~ 3 months old) of this early life stage have been tracked in the region. The collaboration is part of Upwell’s larger Lost Years Initiative that seeks to better understand the period of sea turtle life history between the departure from nesting beaches as hatchlings and the return as mature adults.
Each Lotek micro-satellite tag will collect position and movement data on the juvenile turtle’s movements. The tags are equipped with pressure sensors for the provision of dive data, including daily maximum dive depths and the proportion of time spent diving to different depths. Together, this information can be applied to understand early dispersal, habitat preferences, environmental influences on behavior, and utilization of the water column. The tags can transmit for approximately three months, depending on the solar-powered batteries’ longevity, and the attachment is designed to fall off the turtle's carapace as it grows.
The Okinawa Churaumi Aquarium, photo by George Shillinger
The Okinawa Churaumi Aquarium collected the loggerhead hatchlings from beaches in Okinawa with the approval of the Okinawa Prefectural Marine Fisheries Regulatory Commission (No. 6-k3) and with a special capture permit issued by Okinawa Prefecture (No. 6-35). The aquarium then reared the hatchlings for around 3 months until they could be tagged and released. Dr. Isao Kawazu, Manager of the Fish Section of the Okinawa Churaumi Aquarium, says, “We are so honored that the sea turtle husbandry techniques of Okinawa Churaumi Aquarium can contribute to this research project.”
The islands of Japan encompass the entire nesting range of North Pacific loggerhead turtles. A significant subset of the young turtles birthed in Japan transits the entire Pacific Basin using the powerful Kuroshio Current System as a dispersal and migration highway to the coasts of the United States and Mexico, whose waters host foraging aggregations of juvenile turtles.
Dr. George Shillinger, Upwell Executive Director remarked, “We are so excited to be part of this partnership that is providing a unique opportunity to gain insights into how this age group, which has never been tracked here before, is using this area. Juvenile loggerheads face many human threats at sea, all of which require concerted conservation and management efforts by individual governments and collaborative transboundary solutions by the many countries encompassed across the turtles’ range.”
Upwell Turtles, the Okinawa Churaumi Aquarium, and the Sea Turtle Ecology Lab (STEL)
Over the next few months, the tags will collect data that helps researchers and conservationists better understand juvenile turtle movements, behavior, and habitat use during this vulnerable life phase. The data can also be used to understand potential overlap with anthropogenic threats, including fisheries, plastic pollution, shipping, and energy development. Dr. Junichi Okuyama, Vice Director of STEL, says “In recent years, the number of nesting loggerhead sea turtles in Japan has drastically declined. We hope that the findings from our study, which are expected to shed light on the migration and behaviors of loggerhead sea turtles during their early life stages, will contribute to the conservation of this endangered species.”