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Loggerhead nesting on Florida beaches appears to be in serious, rapid decline, researchers have found—much to their own amazement.
“People are used to hearing that the Florida population is so big and everything is fine,” says Alan Bolten, a University of Florida biologist who studies loggerheads, the most common sea turtle species nesting in Florida. “But everything isn’t rosy.”
Data from the Archie Carr National Wildlife Refuge, a 20-mile stretch on Florida’s east coast from Melbourne Beach to Wabasso Beach, shows the number of loggerhead nests has dropped markedly since 2000—when almost 20,000 nests were dug in the refuge—to last year’s approximately 8,000.
Loggerhead nesting activity is inconsistent from year to year; and high and low cycles, lasting a few years each, are considered normal. The low nesting numbers were noted for several years without alarm. But then a few years became three. And four. By last year, the sixth consecutive year of rapid decline in the Carr Refuge and the fifth statewide, something seemed clearly amiss.
“Ups and downs don’t last five years,” said Bolten. “This could be indicative of a real decline.”
Trends at the Carr refuge “are generally mirrored statewide,” said Llewellyn Ehrhart, the University of Central Florida researcher who collected the nesting data and presented it at the 25th Annual International Sea Turtle Symposium, a conference that attracts about 1,000 biologists and conservationists from around the world who are working with marine turtles.
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The significance and consequences of the recent dips “are beyond the scope of this data,” Ehrhart told those in attendance.
But whatever the news means, few see it as good. Florida accounts for 90 percent of the loggerhead nesting in North America, and a statewide drop-off could have repercussions for the species as a whole. Loggerheads are listed as threatened under the federal Endangered Species Act.
The loggerhead nesting news “has generated some of the biggest buzz at the Symposium,” said Gary Appelson, Policy Coordinator for the Caribbean Conservation Corporation.
Attendees at the conference speculated about what was causing the decline in nesting numbers. Several years of severe cold water in the Atlantic, coastal development, and beach armoring were all discussed as potential culprits. While Florida had a very active hurricane season, this was dismissed as a reason for 2004’s low numbers since nesting activity was low before the storms.
Bolten, who studies juvenile loggerheads and their migrations, thought the cause might be farther flung. In his own presentation at the Symposium Bolten presented data on a potential link to longline fishing near the Azores islands off Portugal.
After hatching in Florida, loggerheads spend between seven and 12 years in the open ocean, often feeding near the Azores. When they reach their late teens, they head back to the Florida coast.
But longlining—a technique in which monofilament lines are set with hundreds of baited hooks—tends to catch young turtles as well as the target fish, hooking them fatally through their throats.
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According to Bolten, data collected from longline fishing boats near the Azores show that most of the turtles accidentally caught and killed on longlines are 7- to 12-year-olds.
“Because the longline fishery itself began fairly recently there would be a measurable lag between the first deaths of those juveniles and a dip in the number of mature loggerheads returning to Florida beaches,”he said. “We were expecting a decline to occur at the end of the 1990s.” The first year of the Florida drop-off was in 2001.
CCC will keep its members informed about this troublesome trend in future Velador articles.
Sea Turtle Conservancy
