Turtle comeback in Cuba at risk from climate change

A lone baby loggerhead heads to the ocean from a Broward Beach. Only out of about a thousand survive to adulthood.
A lone baby loggerhead heads to the ocean from a Broward Beach. Only out of about a thousand survive to adulthood.

Turtle conservation efforts in Cuba may be winning the battle only to lose the war.

A new study published this month in the journal Chelonia found that over the last 18 years, the number of loggerheads nesting in Cuba, a centrally located turtle nursery for the entire Caribbean, has increased. Scientists credit the jump to a local project to educate fisherman and nearby communities, where turtle meat is still consumed. Poaching fell by 80 percent.

At the same time, the number of eggs in clutches dropped and nesting seasons grew shorter, a troubling pattern likely linked to climate change.

“The hope is we’re seeing a conservation success story,” said Fernando Bretos, director of the Ocean Foundation’s Cuba Marine Research and Conservation Program, which has been monitoring the turtles with Cuban researchers.

loggerhead release
A loggerhead rescued by the Miami Sequarium was released from Key Biscayne in 2011. Walter Michot Miami Herald Staff

But with mounting evidence that changing temperatures and sea levels hurt turtles, Bretos worries more work needs to be done to get a better read on what the future holds for Cuba’s loggerheads. Temperature determines turtle sex and Florida researchers have found nests have been producing more and more female hatchlings. A foot-and-a-half rise in sea level expected to occur between 2060 and 2100 could also wipe out a third of the Caribbean’s nesting beaches.

There’s also the problem of enigmatic turtles.

Scientists get most of their information about loggerheads from their habits on beaches, or when they turn up in fishing nets, said Bretos, who is also ecology curator at Miami’s Frost Museum of Science. Hardly anything is known about where they feed. The island’s better tracked and larger population of green turtles regularly head to miles of seagrass pastures near shore “like cattle.” But loggerheads, he said, also venture into deeper water where they are hard to track. And Cuba scientists don’t have access to satellite tracking technology used by scientists in the U.S., he said.

loggerhead hatcchlings
Baby loggerheads scurry to the water from the beach on Key Biscayne near Crandon Park. The hatchlings were found at the bottom of a nest, unable to escape in 2011, and scooped out by turtle rescuers. ALLISON DIAZ FOR THE MIAMI HERALD

For the study, the scientists gathered data from 18 years of nesting along 10 beaches across the island’s west coast, focusing on the southernmost point of the Guanahacabibes Peninsula, which is protected by a national park.

Cuba is the only Caribbean country with several large nesting beaches, where the number of nests regularly tops 100, the study said. While the beaches along Guanahacabibes don’t have the highest number on the island, the study found the area did have the longest sustained increase in nesting. That lead them to conclude conservation was making a difference, although turtle meat is still consumed and, Bretos said, available in private restaurants.

In Florida and across the U.S., laws are much stricter. It is illegal to even touch protected sea turtles and since 1989, shrimp trawlers have been required to use nets with turtle escape hatches.

On Thursday, to demonstrate the effectiveness of the special nets, the National Oceanic and Atmospheric Administration and Florida wildlife officials released 215 captive-raised loggerheads into nets off Fort Pierce. After escaping the nets — the ongoing project is intended to improve the design — the turtles join local wild populations.

loggerhead beach hatch
Baby loggerhead sea turtles were released into from the beach near the Biscayne Nature Center at Crandon Park in 2012. ALLISON DIAZ FOR THE MIAMI HERALD

But increasingly, climate change may prove a bigger challenge. Since warmer temperatures produce more females, scientists worry the sex ratio of turtles could become lopsided. And if the narrow beaches along the U.S. disappear, turtles may head elsewhere. Cuba, which sits at the intersection between the Gulf of Mexico and U.S. east coast, is a possible destination. Already, Bretos said it’s likely turtles from Florida and south through the Caribbean end up in Cuba’s seagrass meadows, which remain among the healthiest.

“The big wild card is the feeding area” he said. “It’s a huge area...And so many areas are not getting research.”

Follow Jenny Staletovich on Twitter @jenstaletovich