Jon NORDHEIMER,
Biologists Try to Follow Well-Traveled Turtles.

- With a brain.barely as big as a human thumb - and hard-wired in the Mesozoic era - 
an immense marine turtle fonctions within a narrow band of 
cognition, guided more by instinct than by strategy.

Still, waves of sea turtles have been slipping out of the 
surf line to take up positions on beaches along the Florida coast 
and the Caribbean. 

Green turtles, loggerheads, leatherbacks, hawksbills, ridleys - all are 
playing out the egg-laying segment of a life cycle that is as old 
as the dinosaurs and nearly as mysterious.

Within weeks, hatchlings will dash on flippers to the surf. And 
there, at the water's edge, is where most knowledge of their 
journey to adulthood ends.

"They disappear for many years into the ocean before the 
females weighing hundreds of pounds return to nest on land," 
said Dr. Llewellyn M. Ehrhart, a biologist at the University of 
Central Florida. 

"Where they go from here has not been fully understood."

But now, with the help of improved satellite technology, researchers 
like Dr. Ehrhart are tracking adult females through 
ocean migrations of thousands of miles, and they are learning 
about behavior patterns that have helped the turtles survive 
millennia.

For the past three years Dr. Ehrhart and Dr. Scott Eckert, a 
senior research biologist at Hubbs-Sea World Research Institute 
in San Diego, have focused on leatherback turtles, 
the largest living turtle, which can grow to a half-ton or more.

Chief among their concerns is the fear that more leatherbacks 
than previously suspected are being trapped and killed in commercial 
shrimping nets off the coasts of Georgia and northern Florida. 

Though their tracking data are far from conclusive, 
they were surprised to learn that some of the leatherbacks 
seemed to prefer foraging close to the coast, in prime shrimping 
waters, instead of swimming far out into the Atlantic, as did 
most of the others followed in the program.

The team's project began two years ago in May with a leatherback 
named China Girl. In spring 2001, the team outfitted 
five more leatherbacks with transmitters.

Swimming independently of each other, two leatherbacks 
went to Nova Scotia and began a long southward movement far 
out in the Atlantic, with one approaching South America by January. 

A third got all the way to the African coast by this 
March before transmissions ended. 

The other two, like China Girl the previous year, surprised 
their observers by hugging the Florida coast to feed in the rich 
shrimping zone until their signals ended somewhat abruptly.

The research team had looked forward to the return of the
six leatherbacks by the end of the nesting season in July. 

They were prepared to refit them with new transmitters.

But by mid-June none had appeared at the refuge's beaches.