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News | Sept. 18, 2017

Tagging Project to Aid in Successful Management of Guam's Endangered Sea Turtles

By Frank Whitman Naval Facilities Engineering Command Marianas

Hawaii researchers are preparing to publish information, sometime this year, based on three years of fieldwork and data collection which assessed juvenile sea turtle behavior in Guam's waters. 

Since 2014, scientists from the National Oceanic and Atmospheric Administration (NOAA) Pacific Islands Fisheries Science Center (PIFSC) in Honolulu have visited Guam to tag and collect data from green and hawksbill sea turtles. This data will help to inform policy designed to protect these endangered species on Navy submerged lands.

"With every tag we put out, we're learning something we didn't know before about the waters around Guam," said Tammy Summers, natural resources marine specialist, Naval Facilities Engineering Command (NAVFAC) Marianas. "This research will help determine how we may further protect these animals."

The research is the result of a long-term project funded by the Navy and carried out by Honolulu-based NOAA PIFSC scientists with the assistance of the Guam Department of Agriculture Division of Aquatic and Wildlife Resources (DAWR), environmental personnel from Naval Base Guam, Andersen Air Force Base, U.S. Fish and Wildlife Service Office of Law Enforcement (OLE), the Guam NOAA office, and the University of Guam (UOG) Marine Lab. 

Earlier this summer, this multi-agency team completed a six-day mission of tagging turtles that was considered the most successful since the project began. The team carefully caught and gathered data on 29 turtles, and attached transmitter tags to 23 of them before releasing them back into the water. 

Over the three-year period, a total of 57 turtles were caught, 43 of which were tagged to be tracked by satellite. Data gathered from the tracking devices not only tracks their movements around Guam, but is used to determine where sea turtles live, and what depths and water temperatures they seem to prefer.

"Basically, we're just trying to figure out sea turtle behavior and distribution in Guam," Summers said. "The information will help us figure out where these turtles are foraging and what times of year we need to try to avoid these areas."

In addition to the satellite tags, team members attach metal Inconel tags to the turtles' fore flippers. While the metal tags do not provide the same real-time information as the satellite tags, they are relatively inexpensive, their identifying number is easily read by the naked eye and they last much longer than the several-month life expectancy of the satellite tags. They will likely provide more long-term information, provided they are found by, or returned to, the researchers.

Previous turtle research in Guam and the Northern Mariana Islands focused on adult females and their nesting behavior. The current project is the first to focus on juvenile and foraging turtles. 

Researchers are collecting biosamples before the turtles are released to determine, among other things, what impact climate change may have on them. 

The gender of sea turtles is influenced by their temperature while incubating in their nests - warmer nest sand yields more females. The gender of juvenile turtles cannot be determined by appearance, so the turtles' hormones are measured to ascertain the ratios of females to males within the population. 

Summers said the team is also using biosamples to monitor the turtles' possible exposure to any impurities.

"This is an important project for the Navy," Summers said. "We're receiving a lot of really good data out of it; data that will help us with planning and determining how we're going to manage the endangered sea turtle population on our island."