Mote Marine Laboratory

Turtle Tales

By: Susannah Costello

It’s a long journey from hatchling to nesting adult for endangered and threatened sea turtles

When she first left the beach, she was only 2 inches long and weighed less than an ounce.

Traveling the loop current, she moved around the Florida Keys and into the Gulf stream, which carried her north, then toward Europe and Western Africa. Some 30 to 40 years later, the currents carried her south toward the Florida straits and back to the Gulf.

Home.

She’s a survivor.

“Probably one of a thousand sea turtle hatchlings will live long enough to mature and reproduce,” says Dr. Tony Tucker, staff scientist with Mote’s Sea Turtle Conservation and Research Program. “For a loggerhead turtle in the Atlantic, that equates to surviving 30 to 40 years before returning to nest the first time.”

In 2003, there were 1,239 sea turtle nests on the 30 miles of Sarasota beaches monitored by Mote. Based on average nest size, that represents about 127,617 eggs. In an average year, 73 percent of those eggs will actually hatch with about 68 percent of the hatchlings making it to the water.

Their numbers drop drastically as the survivors travel the world’s oceans and encounter hungry mouths. Ghost crabs, birds and fish feast on the hatchlings; sharks attack older turtles.

Any turtle that makes it back to the beach where it was born — its natal beach — to lay eggs has overcome the odds.

The survivor is a little lean from her journey. As she approaches the shore, she raises her head to find the dark shape of land. At the surf line, she pauses, watching for signs of movement or light and listening for noise that might signal danger. As she labors ashore, she pauses often.

She raises her head to breathe, as if still in the water. Her vision on land is more limited than at sea. She moves cautiously. At the dark front of the sand dune, she begins to dig a pit. Her front flippers scrape away the dry surface sand; it soon dusts her back.

Then she uses her rear flippers to dig down and shape the hole.

Though the survivor’s body is still, her rear flippers move gracefully, scooping up sand and setting it aside, like flexible shovels.

“Genetic research confirms that turtles have natal site fidelity,” says Tucker. “So turtles born in Southwest Florida will generally return to lay eggs in the same region, provided that suitable beaches remain there in the future.”

If it takes sea turtles 30 to 40 years to reproduce, the hatchlings leaving Florida beaches today won’t become Florida’s turtle parents until sometime after 2035. Because loggerheads can breed for several decades, those same turtles will be parents long past the midpoint of the century.

For turtle researchers and volunteers, the lesson is simple: What happens on beaches today will affect the turtles that their grandchildren will see as adults.

Fighting the odds

Turtles lay large clutches of eggs multiple times in a breeding season to ensure that at least a few of those hatchlings live long enough to reproduce.

When her pit is deep enough, the nesting female becomes still. She places her rear flippers just to the side of the hole and they begin to flex. Eggs drop softly into the moist sand, a few at a time. Five, 10, 50, 100; sometimes, there are more than 150 eggs before the mother’s job is done.

“But if only one in 1,000 hatchlings survives to reproduce, saving one hatchling doesn’t do it,” says Tucker. “And if half the hatchlings in a nest are female, that’s a multiplier of two for a female to attain adulthood. In other words, the chances become one in 2,000 for an egg to yield an adult female.”

The numbers are challenging.

And so are the costs.

An economic analysis of the 2002 nesting season shows that it would cost $5.46 to safeguard one egg if only paid staff were used to protect turtle nests. That’s $562 per nest.

The cost drops to $1.28 per egg and $132 per nest thanks to the help of Mote’s many volunteers who patrol beaches, mark turtle nests and help turtle hatchlings.

“Mote’s success story in beach coverage really relies on these volunteer efforts,” says Paula Clark who, along with Jim Grimes and Sarah Condran, coordinates a coalition of volunteers, interns and students who help sea turtles.

Last year, volunteers spent 18,000 hours patrolling beaches. Staff and interns spent 5,800 hours coordinating those efforts. “That’s what it took to walk 30 miles of Sarasota beaches every morning from May through October to record the season’s turtle activities,” Clark says.

After about 20 minutes, the survivor’s eggs are all dropped. She moves her rear flippers over the sand, scooping it in and pressing.

Scooping and pressing.

A mound builds, which she compacts with the weight of her shell. Then she crawls down to the water, stopping to rest along the way.

At the edge, she stops, breathes and slowly moves in and sinks. Moments later, the turtle pops up her head for a breath. Then she submerges and disappears from sight.

Off the beach

Historically, turtle research focused on the beach and not on turtles in the water because of the logistical challenges.

But recent advances in technology are enabling scientists to focus on in-water research using tools like acoustic and satellite telemetry to better understand use of local habitats and migratory movements.

“If you look at a hospital’s maternity ward, it’s a small but important slice of the larger population,” says Tucker. “That’s analogous to studies of female turtles, eggs and hatchlings on a beach. But the other 99 percent of turtle life is in the water as teens and adults. That reality has generated a re-emphasis for studies of turtles in-water.”

The survivor uses her rear flippers like rudders, with front flippers stroking through the water. At speeds as great as 10 miles per hour, she uses currents and the earth’s magnetic fields to travel the sea. Her journey is not a new one; previous generations have been making similar trips for 200 million years.

Long-term commitment

Sea turtle science is a relatively young science with its roots in the late 1950s.

At most, there have been about two academic generations of sea turtle biologists studying what is possibly still the same generation of turtles.

“There are turtles nesting today that were already laying eggs when Mote began its turtle efforts in 1982 and probably for many years before Mote began tagging them,” says Jerris Foote, program manager for the conservation and research program’s beach efforts.

If it takes more than one generation of sea turtle biologists to study a single turtle from hatchling to a natural death from age, how do you study an animal that lives longer than your career? An animal that takes 30 to 40 years to mature and decades to breed?

Studying a long-lived species requires a long-term commitment.

“Unless you’re committed to more than a decade of work, you have no business tagging turtles,” says Tucker. “After a decade or more, the information begins to increase in value. Since Mote has historical data going back to 1982, that long-term commitment begins to pay dividends.”

Beaches, bays and bootstraps

Mote’s turtle research focuses on beaches, bays and bootstraps, developing studies that can better inform and advise local coastal management and conservation efforts.

“In studies of the nesting stages, we focus attention to what happens on the index beaches around the state (including Siesta Key) so we can understand issues that affect the future turtles returning to these shores,” Tucker says.

That’s beaches.

“We need to study the in-water stage to identify critical habitats that young turtles use as they survive and journey on their breeding migrations,” he says.

That’s bays.

And the bootstraps?

“We need desperately to pull together funding support for the research so that Mote’s studies address the tough questions that are measured across large scales of time and space,” Tucker says, “time measured in decades of turtle generations and space as vast as the Atlantic Ocean.”

Learn more about: Turtle Research

Help pull Mote up by the bootstraps. Even with the generous time of our volunteers, we still need money to help the sea turtle survivors that nest on our beaches. Don't hide in your shell.