- The Sea Turtle Conservancy’s Tour de Turtles kicked off last month, tagging and tracking 17 sea turtles during a marathon migration.
- Turtles wear small transmitters during the annual event as they travel thousands of miles to from their nesting beaches to feeding grounds.
- Data collected from satellite telemetry help scientists gain a clearer understanding of how four species of turtles behave at sea, furthering efforts to protect endangered species.
Last year, a loggerhead named Eliza Ann took the crown. This year, Lucaya, the speedy leatherback, has pulled ahead to take an early lead. Every summer, a handful of sea turtles take to the water to compete in the Sea Turtle Conservancy’s, Tour de Turtles – an underwater marathon that blends competition with conservation.
This year, 17 sea turtles entered the Tour de Turtles, and the line-up is diverse, encompassing leatherbacks, loggerheads, green sea turtles and hawksbills. Organizers released the competitors from nesting grounds in Costa Rica, Panama, Nevis and Florida. The winner will be the turtle that swims the farthest during its three-month long migration.
Small tags tracking over large areas
Tagged and monitored remotely, these turtles aren’t just racing towards the finish line, they’re also providing scientists with key data collected via satellite telemetry.
Sea turtles spend the majority of their lives in the water – feeding, mating and roaming huge distances – but in the vast ocean it’s difficult for scientists to observe their behavior, leading them to turn to technology for answers.
Every turtle participating in the Tour de Turtles is fitted with a small, low-wattage Platform Terminal Transmitter (PTT) tag, which is controlled by a micro-processor.
These devices, which are designed to safely fall off the turtle after about a year and a half, send signals to Argos tracking instruments attached to orbiting satellites every time the turtle comes up for air. The satellite then relays this information back to earth where it can be accessed via computer.
Turtles must surface for at least three minutes to be detected, and once it detects a PTT, a satellite takes three to five minutes to record the location.
This tags provides the Tour de Turtles’ research partners, the University of Central Florida and the Nevis Turtle Group, with up-to-date location information so they can keep a watchful eye on the competitors through every stage of the race.
The researchers plot turtles’ routes on an online map so sponsors, donors and supporters can follow along in near-real time.
Turtles swim several thousands of miles in a typical Tour, but there’s more to the event than just distance travelled. The PTT data collected from each turtle delivers a goldmine of useful information, including an estimate of the number of dives the turtle has taken in the preceding 24 hours, duration of its most recent dive and the water temperature.
“We can estimate turtle behavior based on the information from the transmitters, and from that we can also look at the environmental characteristics, such as water depth and temperature,” said Dan Evans, Research Biologist with the Sea Turtle Conservancy. “There are definitely patterns and pathways we are learning about, but we are also learning their behavior.”
“We get confirmation of things we know, but every now and then we get something really interesting. There’s a lot of variation, even within species. It seems like every year one turtle does something different.”
This year, researchers are watching Lucaya, a leatherback who is hugging the East Coast of the United States rather than heading into the deep Atlantic as expected. Through his work with the Tour, Evans has discovered that leatherbacks move between a primary and a secondary foraging area, rather than sticking to a single feeding ground. He has also noted that leatherbacks spend more time in the Gulf of Mexico than previously thought and that hawksbills, a species that tends to stay local, are actually travelling all the way across the Caribbean in some instances.
“That was really cool to see,” he said. “It is a pretty incredible migration.”
Tagging turtles is not a new science, but as technology evolves, the research has become more efficient, more streamlined and more effective. When the Tour de Turtles first launched in 2008, transmitters were bulkier and more vulnerable to the elements than the modern-day version.
“They started out as bricks with antennae sticking out of the top,” Evans said. “We had to build a barrier to protect them in the water, but now they have built-in barriers. The transmitters have become smaller, more compact and more hydrodynamic.”
They also have a longer battery life that allows them to function for up to five years.
“That means we are able to track turtles for longer than we used to and can find out about their full migration, from their nesting beaches to the foraging areas,” Evans said.
Scientists still have a lot to learn, however, and Evans hopes that as the technology expands, it will paint a more complete picture of what sea turtles are up to in the deep ocean.
“I think the accuracy of the transmitters will improve over time. My dream transmitter would include a camera that would allow us to really see what kind of interactions the turtles are having with their environment and each other.”
He would also like to make better use of GIS mapping technology, creating a program that can superimpose layers of variables on the turtles’ route such as water temperatures and chlorophyll levels.
Six out of seven sea turtle species are listed as endangered or critically endangered. Human hunting , fishing lines, and plastic debris all kill adult turtles. Natural predators and various human threats to sea turtle hatchlings and nesting beaches result in very low nestling survival rates. The Sea Turtle Conservancy estimates that as few as one in a 1,000 survive to adulthood.
The data amassed through the Tour de Turtles focus on promoting sea turtle conservation and education. In 2010, findings from the Tour were used to educate stakeholders on the need to protect sea turtles from the Deepwater Horizon oil spill.
“Leatherbacks from Costa Rica and Panama are utilizing the Gulf of Mexico much more than anybody thought, [but] leatherbacks had not been in the discussions until we shared the tracking information that we had,” Evans said. “That provided support for including them in discussions about what species need to be protected.”
Raising awareness is a key part of the Tour’s message. Turtles are sponsored and/or adopted by donors, and each swims for a specific cause. This year’s turtles are swimming to highlight the threats of commercial trawl fisheries, water quality, pollution, beach erosion, and adult and egg harvesting.
The Tour’s tracking efforts have made one thing very apparent: turtles do not respect boundaries, making their survival an international issue.
“Turtles are international travelers, they do not have borders or passports. They go where they need to go, so cooperation among nations is really important,” Evans said. “With our data, we can identify foraging areas and be able to see whether they are in protected areas. If they are in protected areas, we can then look at whether the protections are good enough for sea turtles.”
Follow this year’s Tour de Turtles, which ends November 2, 2018.
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