Enormous recovery for green sea turtles

A turtle nesting in the Cayman Islands, where increasing numbers of turtle nests have been recorded in recent years. - Photo: Mark Orr

Green sea turtle nests have registered an enormous recovery on Florida’s Atlantic and Gulf coasts, as well as, according to Cayman’s Department of the Environment, on local beaches.

Turtle tracks, traditionally called Batabano in Cayman, left in the sand by a nesting female. – Photo: Gary Redfern
Turtle tracks, traditionally called Batabano in Cayman, left in the sand by a nesting female. – Photo: Gary Redfern

In the past year, nests have increased 20-fold in Cayman and 138-fold along Florida’s Atlantic and Gulf coasts. As numbers have grown, the U.S.-based National Oceanic and Atmospheric Administration has upgraded the Florida population from “endangered” to “threatened.”

Meanwhile, DoE volunteers last week found the breeding season’s first turtle nest as part of the annual survey of 60 miles of Cayman beaches. The nest was in the vicinity of Spotts, although officials declined to reveal more precise details, wishing to preserve the integrity of the location.

“The nest was on the south coast of Grand Cayman,” said Janice Blumenthal, DoE research officer with a Ph.D. in biological sciences.

“It was found by volunteers,” she said, “and organized beach monitoring starts May 1. It was a loggerhead nest, so not quite as big as a green turtle nest.”

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NOAA’s Dennis Klemm, sea turtle recovery coordinator for the Southeast region, said numbers for individual turtles remain inexact but can be extrapolated.

“We don’t have accurate estimates of numbers of individuals,” he said, adding that they can be generalized from “new record-high nest numbers.”

Fish and Wildlife surveys, he said, show that from 1989 to 2015 nest numbers grew from a low of 267 nests at regularly surveyed Florida beaches to a record 27,975 in 2015.

A Fish and Wildlife index of 27 Florida counties – including Palm Beach, Broward, Miami-Dade and Sarasota – shows an alternating annual pattern of highs and lows because, Mr. Klemm said, green turtles have alternating high and low years of nesting, but “the highs keep getting higher and the lows keep getting higher as well.”

“[Florida’s] 2015 statewide nest count for green turtles was 37,341,” he said, clarifying that NOAA surveys the same “index beaches” annually, while the statewide count draws on a less standardized canvass of more nesting areas.

Ms. Blumenthal said she was gratified by the increases: “It is extremely encouraging to see recovery trends from other green turtle populations, including Florida – where numbers from index beaches increased from a low of less than 300 nests in 1989 to a high of nearly 30,000 nests in 2015.

“In the Cayman Islands, we have also seen an encouraging increase in nesting numbers from less than 10 green turtle nests when DoE monitoring began in 1998 to more than 200 green turtle nests in 2015,” which she declared a “record year” for the Cayman Islands.

“During daytime nesting beach monitoring surveys, DoE staff and volunteers found and marked 437 nests … This was 242 nests in Grand Cayman, 34 nests in Cayman Brac, and 161 nests in Little Cayman.”

Still, Ms. Blumenthal cautioned that while the statistics point to improvements, “it is important to remember … absolute nesting numbers are still very low – and each turtle lays several nests per season.

“While the number of nesting female green turtles in the Cayman Islands is still critically low, the trend in Florida shows that with sufficient protection, green turtle populations such as ours can recover.”

Cayman Turtle Farm Chief Research Officer Walter Mustin said only about 100 turtles made up Cayman’s wild breeding numbers, “and that means about 50 females, and because of poaching, you probably have only 48, and that could even be down to 46 or 47, so it’s a pretty delicate population.”

Each release is tagged, and while it takes years before released turtles return to breed, Mr. Mustin said at least some have made their way back from Florida.

“Those that have returned were released 35 years, 40 years, ago,” he said. “Some have come from Florida. Others have come from as far away as Mexico, Honduras, Guatemala and Venezuela.”

New tagging systems based on genetics will enable a much closer tracking: “We can see what percentage of ‘our’ genes are showing up in the Florida populations,” he said.

Turtle Farm Managing Director and Chief Operating Officer Tim Adam said populations had also improved in Hawaii. The increases were a result of “good protection, continued monitoring and increasing scientific knowledge and attention. Given all that, they can come back.”

Mr. Klemm said the improvements not only to Florida’s previously endangered breeding populations, but also to the entire set of 11 distinct populations globally is “a result of past and current conservation efforts.”

Early bans on egg hunting and fishing expanded in 1991 to the creation of central Florida’s 900-acre, 20-mile-long Archie Carr National Wildlife Refuge, protecting green sea turtles and loggerhead turtles.

Later measures, Mr. Klemm said, have included “turtle excluder” devices in shrimp trawls, other fishery regulations such as gillnet prohibitions, better regulation of beach lighting and better management of beaches.

Ms. Blumenthal agreed, pointing to a 2014-2016 Darwin Initiative Study of turtle nesting in Cayman, “document[ing] that green turtles released from the Cayman Turtle Farm in the 1980s return to nest on our beaches and replenish our nesting population.

“Other factors contributing to the nesting increase include changes in fishery legislation to prevent adult turtles from being harvested and better protection of nesting turtles on the beach through enforcement efforts,” she said.

“As turtles are highly migratory, turtles in the Cayman Islands population are also affected by conservation efforts in other jurisdictions, such as reductions in harvesting and fishery bycatch.”

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  1. I think that why Florida turtle population is so high is because of LAWS AND ENFORCEMENT OF LAWS .
    I have been to many counties in Florida , you see signs posted in rental properties asking not to disturb , and to report nesting turtle to FLA Fish and Life department, then a marking of that nest is done and you dear not touch that nest , or you would be prosecuted and punished .

    I think that if Cayman take note from FLA Cayman Islands would see higher turtle population.