News-Journal • January 21, 2005 SAVANNAH, Ga. -- Loggerhead nesting on Florida beaches appears to be in serious, rapid decline, scientists at an international sea turtle meeting have found -- much to their own amazement.
"People are used to hearing that the Florida population is so big and everything is fine," said Alan Bolten, a University of Florida biologist who studies loggerheads, the species most commonly found 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 have dropped steadily since 1998, when almost 18,000 nests were dug in the refuge, to last year's approximate 8,000.
Loggerhead experts have noted this trend for years without sounding alarms. Loggerhead nesting activity is inconsistent from year to year, and high and low cycles, lasting a few years each, are considered normal. But then a few years became four. And five. By last year, something seemed clearly amiss.
"Ups and downs don't last six years," said Bolten. "This could be indicative of a real decline."
Trends at the Carr refuge "are always mirrored statewide," said Llewellyn Ehrhart, the University of Central Florida researcher who collected the data and presented it Wednesday to the 25th annual Sea Turtle Symposium, a conference that attracts about 1,000 biologists and conservationists working with marine turtles.
The significance and consequences of the six-year dip "are beyond the scope of this data," Ehrhart told the conferees Wednesday.
But whatever the news means, few see it as good. Florida provides 90 percent of the loggerhead's North American nesting grounds, 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 news "has generated some of the biggest buzz here," said Gary Appelson of the Caribbean Conservation Corp. in Gainesville, Fla.
Attendees at the conference, which ends today, speculated about what was causing the low nest numbers. Recent cold-water upwellings, coastal development, and beach armoring were all bandied about as potential culprits. (Hurricanes were dismissed as a reason for this year's low numbers; 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 Wednesday he brought up 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 teens, they head back to the Florida coast to mate and nest.
But longlining -- a technique in which monofilament lines are set with hundreds of baited hooks -- tends to catch young turtles as well, hooking them fatally through their throats.
Data collected from longline fishing boats near the Azores, Bolten said, 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, Bolten said, 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.
"We were expecting a decline to occur at the end of the 1990s," he said. The first year of the Florida drop-off was 1999.
Reprinted from © 2005 News-Journal Corporation.
Scientists startled by loggerhead turtle decline
VIRGINIA SMITH