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Historic Caribbean sea turtle population falls 99%

Historic Caribbean sea turtle population falls 99%

Historic Caribbean sea turtle population falls 99%
Plunge has significant ecological consequences
August 1, 2006

Current conservation assessments of endangered Caribbean sea turtles are too optimistic due declines of populations on historically important nesting beaches, according to new research from the Scripps Institution of Oceanography.

The study, published in the August issue of Frontiers in Ecology and the Environment, says that while “conservation efforts since the 1970’s have dramatically helped increase green and hawksbill turtle populations that nest on protected beaches… 20 percent of historic nesting sites have been lost entirely due to land development and turtle exploitation, and another 50 percent of the remaining sites have been reduced to dangerously low populations.”

Hatchling sea turtle. Photo by N. Butler

Sex sells sea turtle conservation in Mexico Mexican authorities announced they will use posters of scantily dressed young women to promote the protection of endangered sea turtles. The promotion comes just weeks after some 80 protected Olive Ridley sea turtles were found chopped to pieces on Escobilla beach in Oaxaca, Mexico.

Sea turtles protected in Costa Rica are killed in Nicaragua Sea turtles that receive the highest protection in Costa Rica and other neighboring countries are dying by the thousands at the hands of unregulated – and unsustainable – commercial fishing in Nicaragua, according to a study by the Bronx Zoo based Wildlife Conservation Society.

Sea turtles temporarily lose protection from trawlers in wake of Hurricane Katrina The National Marine Fisheries Service (NMFS) has granted shrimp trawlers a temporary 30-day exemption from federal Turtle Excluder Device requirements in certain state and federal waters off Alabama, Mississippi and Louisiana. Turtle Excluder Devices protect sea turtles and other large marine animals from being captured in trawl nets. The exemption from federal TED requirements will expire at 11:59 pm on October 22, 2005, unless otherwise extended by NMFS.

Red Tide Causes Sea Turtle Die-Off in El Salvador
A “Red Tide” event that occurred off the coast of El Salvador late last year directly caused the deaths of some 200 sea turtles, according to test results released today by the Wildlife Conservation Society (WCS) and other organizations.

“The loss of even a single nesting site makes a permanent, irreversible dent in the sea turtle population,” said Loren McClenachan, who conducted the research with Jeremy Jackson and Marah Newman of the Scripps Institution of Oceanography.

The researchers estimate that turtle populations have declined significantly since the 17th century, with the number of green turtles living throughout the Caribbean falling from 91 million to 300,000 today and the population of Hawksbill turtles plunging from 11 million to less than 30,000 during this same time period. The change represents a 99.7 percent drop in historic Caribbean sea turtle populations for the two species.

McClenachan and colleagues suggest that the loss of nesting sites and nesting populations due hunting contribute to the decline. They say that the reestablishment of lost nesting sites is “extremely unlikely” but that more protection is needed for existing sea turtle nesting sites.

Ecological impact

The decline in sea turtles has had consequences for other marine life in the Caribbean. The researchers say that sea turtles, as “ecosystem engineers”, shaped the environment around them by feeding on turtle grass (green turtles) and sponges (hawksbill turtles).

“The ecological extinction of green turtles transformed an ecosystem with diverse species of seagrass dominated by large herbivores into a detritus-based ecosystem dominated by overgrown monocultures of one species of grass,” said the researchers. “The decline in green turtles has led to a loss of productivity available to the animal food chain — including commercial reef fishes — reducing the protein-rich food available for the Caribbean people.”

The Scripps team says that hawksbill’s now eat less toxic sponges, a shift that could “ultimately affect the landscape of coral reefs” in the region.

This is a modified news release from WCS.