Mote Marine Laboratory

Seeing Turtles In a New Light

By: Kristin Harrison

A female loggerhead sea turtle is hatched on a beach in a nest with 100 or so siblings. Measuring about 2 inches long, she breaks out of her egg, crawls across the sand and into the ocean. Over her decades-long life, growing to about 250 pounds, she spends 99 percent of her time at sea.

Unlike males, female loggerheads make brief onshore appearances. Some 30 years after birth, a female is guided by the earth’s magnetic field back to the beach where she hatched to lay new clutches of eggs. She will return to the beach for nesting every two-to-three years. Mote scientists, marking their 25th year of nesting turtle studies, are now using this species’ short land visits to answer a crucial, but little-studied question: Where do turtles go once they leave the beach?

Since 2005, Dr. Tony Tucker, manager of Mote’s Sea Turtle Conservation and Research Program, and his team of scientists, interns and volunteers has worked to answer that question by attaching cell phone-sized satellite tags to the shells of loggerhead sea turtles. The strong-jawed behemoths nest on Florida beaches and are listed as threatened by the U.S. Fish and Wildlife Service.

To attach a tag to a turtle, Tucker and his group patrol the beaches of Casey and Manasota keys in Sarasota County during nesting season, May through October. They battle bugs and tar-black nights as they wait for a turtle to emerge from the Gulf, lay her eggs, then begin her slow crawl back to the water. Before she reaches the water, the team moves in with a wooden corral to delay her return.

Then, Tucker cleans the turtle’s shell and uses an epoxy to affix the tag. Once the glue-like substance is dry, the turtle is released to swim away. Turtle tagging can take many sleepless nights but the information is worth it, Tucker says.

Watching from afar 

In the water, a turtle surfaces to breathe as often as a few times an hour. That’s when the tag’s antenna transmits data — location, water temperature — to NOAA satellites that  relay it to scientists for analysis. “Before we started using satellites to track sea turtle movements, we had very limited information about where and how they lived,” says Dr. Michael Coyne, a Duke University research scientist who collaborates with Tucker. Coyne is also executive director of seaturtle.org, the Web site that Mote and many other organizations use to track satellite-tagged animals and share the data with the public.

“Not knowing where turtles are makes it extremely difficult to protect them,” says Coyne. “Satellite tracking has, for the first time, provided us a glimpse into their daily lives.”

In the last two years, Tucker has tagged 17 loggerhead turtles: 13 nesting females and four males cared for and released by Mote’s Sea Turtle Rehabilitation Hospital. He has also tagged one rehabilitated green sea turtle.

The rehabilitated loggerheads, treated for red tide toxicosis, were released in November 2006 and March 2007 and are the first males Tucker has tracked, providing important information about the success of the hospital’s efforts and male migratory patterns. The data collected so far have more than answered the initial question of where turtles go.

Tucker has discovered that loggerheads are serious travelers.

Take Redlow, a large female more than 3.5 feet long, for example. Tagged on Manasota Key on May 25, 2006, she traveled more than 2,600 miles in nine months, up the Florida coast and out into the deep waters of the Gulf of Mexico.

Other turtles have proven to be international migrants. Squirt, tracked in 2005, left Casey Key and headed around the Florida Keys to the Bahamas; Yertle made a beeline for Mexico’s Yucatan Peninsula; Raphael wintered just north of Cuba.

Tucker has found that each of the 13 tagged female loggerheads migrated from Southwest Florida to a home foraging ground, with six heading to international locations. And all the turtles exhibited exceptional navigational abilities, fighting currents, tropical storms or hurricanes, to get to these home ranges.

Despite the wealth of information, satellite tags pose a variety of research challenges. “Under good circumstances, a tag will last for a year,” Tucker says. “But its functionality is really a combination of luck and where the turtle happens to go.” Numerous factors — a dead battery, antenna damage, algae growing on its switch — can interfere with a tag’s ability to transmit data. One of the challenges the Mote tagging project faces is finding sponsors or grants to fund each $3,000 satellite tag.

Supporting the science

Virginia Miller, a Mote volunteer for more than 10 years, has sponsored two tags since 2005. She donates because she believes the research is important. “It’s an investment that keeps on giving because of the contribution you’re helping make to science, and the education and entertainment you get by following ‘your’ turtle on the Internet,” Miller says.  One of her sponsored turtles was named Tuttle for Tuttle Elementary School of Sarasota, whose mascot is a turtle.

More than 200 students at New Canaan Country School in Connecticut are also fascinated by Mote’s tagging program. In 2003, Chris Lener, head of the school’s science department for first-through fourth-graders, worked with Tucker in Charlotte Harbor during an Earthwatch Institute trip. Earthwatch supports scientific research by offering volunteers the opportunity to join research teams around the world. During her trip, Lener became fascinated with sea turtles.

Thanks to a grant from the Jeniam Foundation and Lener’s own persistence, the school has since funded five satellite turtle tags. Every week, Lener holds “Turtle Thursdays” in her classroom and students track “their” turtles’ movements online, learning about biology, ecology and turtle behavior in the process. “The kids are getting a first-hand look at real, ongoing scientific research,” she says. “And they’re learning they can be scientists too. They’re also discovering they can make a direct impact on sea turtle conservation, which is really important.”

Tucker says one of the great benefits of the satellite tracking program is that it’s accessible to everyone through seaturtle.org. “The public can see for themselves where turtles are,” says Tucker. “It’s hard to grasp the challenges they face until you can follow them at sea.” Besides, he says, “it’s neat and fun to get an e-mail each day about a turtle’s whereabouts, and it’s also intellectually stimulating. This is state-of-the-art marine science.”

Supporting the species

Perhaps even more important, the satellite tagging program has helped Tucker and other scientists identify dangers a decreasing population of loggerheads confront in the ocean: red tide outbreaks, boat traffic, commercial fishing and dredging operations. The work also highlights — in real-time — that sea turtles are international travelers, and their protection and conservation require cooperation among many countries.

“By learning more about sea turtles’ movement and behavior, we can optimize our management activities to conserve and protect them,” says Coyne.

Tucker agreed: “Given the state of the world’s oceans and global warming, we must do everything we can to monitor and protect them.”

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Since 2005, Dr. Tony Tucker and his team have satellite tagged and tracked 13 female loggerhead sea turtles. Here are a few fun findings:

• Turtles seem to prefer water temperatures of at least 62 degrees and water depths of less than 120 feet.

• They migrate alone and in very divergent directions.

• At press time, Virginia was tracked for the longest period of time. Her tag transmitted       for 354 days. Ariel had the shortest tracking period of 95 days.

• Six turtles migrated internationally, with Yertle swimming the farthest: 767 miles in 45 days to the Gulf of Campeche in Mexico.

• Turtles swim 1 to 1.5 miles per hour during migration and .5 miles per hour once they arrive home.

• They spend less time at the surface after nesting and during migration than upon arrival at their home range. They spend less time at the surface as the water temperature drops.

• Seven of 13 turtles that nested on Casey Key returned within two weeks to nest again, demonstrating site fidelity to the rookery. 

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About the photos

Because sea turtles are sensitive to certain light wavelengths, photographer Greg Nelson of Nokomis (www.gregnelson.com) shot these nighttime images using an infrared emitting flash, giving the photos that red, otherworldly look. Using infrared lights kept turtles from being disoriented. Greg first started photographing Florida beaches professionally 35 years ago. His work has been published by major newspapers, magazines and the Associated Press.

To learn more

To view maps of where the turtles tagged in Southwest Florida have visited, go to www.seaturtle.org/tracking or www.mote.org/environmentalupdates and page down to “Sea Turtle Nesting Updates.” Also, check out Mote's Sea Turtle Conservation and Reseach Program page.

To help

To help defer the cost of satellite tags for turtles, Mote seeks individuals and organizations to sponsor tags. “Citizen Scientists” can also adopt a turtle online for $25, $50 or $100 at www.seaturtle.org, or donate directly to the Sea Turtle Conservation and Research Program. For more information, contact Dr. Tony Tucker at 941-388-4441, ext. 470 or tucker@mote.org.

Residents and visitors can also help by keeping lights from shining on beaches during the May to October nesting season.