Mote biologists found the nesting leatherback, a rarity in the Gulf, and applied a tag and microchip, but were unable to apply a satellite tag.

SARASOTA — The feverish excitement over the discovery of the area's second-ever group of leatherback sea turtle nests is over. The eggs did not hatch, according to the Mote Marine Laboratory Sea Turtle Conservation & Research Program.

Melissa Bernhard and Kristen Mazzarella, Mote senior biologists who studied the nests, said recent excavations found some water damage and about 100-120 eggs per nest, including about 20 "spacers" without yolks, that were not fertilized. The female turtle, rarely found in the Gulf of Mexico, likely never met a mate.

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She is believed to be responsible for four massive nests found from Siesta Key to Venice Beach between April and May, and three false crawls (when a turtle crawls onto the beach at night but does not lay eggs).

"We knew from the get-go there was something crazy going on when we saw the first crawl," said Bernhard. "Then we got a few more nests and a couple false crawls. We were sure from the interval between nests that they were from the same individual."

Mote used data from the first two nests to place a team in the field and had two brushes with the turtle. Tags were put on her rear flippers, and a microchip was placed in her shoulder. This will allow scientists from around the world to identify her if she visits other beaches. Genetic samples (DNA) were also taken that will allow researchers to verify future nests.

But researchers were unable to deploy satellite tracking to trace her journey. Scientists do not know what leads leatherbacks, typically found in the Atlantic, to the Gulf.

Protective cages were placed over the nests to keep out predators, such as coyotes and raccoons, but the sea turtle eggs are sensitive to temperature, water content and vegetation that could grow through the eggs and suck nutrients out of the eggs around them.

Bernhard said that the female leatherback, an opportunistic mater, was probably alone in the Gulf.

"If they encounter a male, they mate and then go on their merry way," she said. "Other turtles have multiple paternities in single clutches. They could have mated with multiple males to produce a single nest."

The last leatherback nest found in Sarasota County, in 2001, also did not hatch. In 2015, Mote staffers rescued a juvenile leatherback that was caught in a crab pot line off Lido Key.

A successful hatch could have meant the potential expansion of the range for leatherbacks, whose numbers have declined in the last several years, Bernhard said. The turtles are deep-diving animals that spend most of their time in the open ocean. They feed primarily on jellyfish.

Leatherbacks are distinguished by their soft, streamlined shells and firm, rubbery skin.

Since this female turtle was not satellite-tagged, it did not get a name. Sea turtles are known to return to the regions where they were born to nest, however, leatherbacks are less loyal to their birthplace.

Sea turtle hatchlings can take anywhere from 16 to 30 years to reach sexual maturity depending on the species.

"There are leatherbacks in the Gulf, but we don’t know much about them," Mazzarella said. "We don't have many leatherbacks nesting on the Gulf Coast of Florida or any of the Gulf Coast of the U.S. very often. It's likely there aren't very many, so running into them would be difficult."

In early July, the Panama City News Herald reported that a Panama City Beach Turtle Watch volunteer using an infrared camera captured a photo of a leatherback on the white sand beaches. It presumably laid eggs and returned to the sea. The Panhandle turtle was not the Sarasota County leatherback, Mazzarella said.

Mazzarella and Lauren Kabat, a Mote tagging supervisor, correctly guessed where and when the turtle would emerge. They spotted her around 3 a.m. one morning making the third nest.

"We were pretty excited," Mazzarella said. "We were pretty shocked ourselves. We didn’t think we'd find her. We measured her shell — that doesn't include rear flipper or head — and she was 62 inches long. They can be bigger, but she's pretty average."

The Florida Fish and Wildlife Conservation Commission gave Mote permission to apply a satellite tag, but Mote did not have anyone trained, and a team from the East Coast of Florida was unable to find the turtle, who has not returned after its fourth nest.

The interval between the first four nests was about 10 days.

This summer has been nothing less than an extraordinary season for sea turtle nesting. Mote reported a 38-year record number of nests, including a count of green turtle nests more than double the previous record.

As of Aug. 4, Mote had documented 5,063 nests across all sea turtle species — 4,888 loggerhead nests, 170 green turtle nests and five other nests.

"We have broken almost every record we have set with very few exceptions on specific keys (barrier islands) for specific species," Bernhard said. "The uniqueness of the records is due to the green nesting numbers. We have broken loggerhead numbers, but they were close to old records. The green records are blown out of the water. ... It's the first time ever we’ve had a green nest on every island we patrolled in a season. They are taking charge of this season."

The green and loggerhead nesting season runs from May 1 to Oct. 31.

Mote's turtle program has tagged hundreds of loggerheads and about 39 green turtles this year — both record-breaking tagging numbers. Satellite-tagged sea turtles can be tracked on Mote's website.