HUTCHINSON ISLAND Engineers for years have piled sand from the ocean onto eroded beaches to create what they considered a darn good approximation of a natural beach. Turtles weren't fooled. Mothers-to-be crawling up renourished beaches showed their displeasure by turning around and laying their eggs elsewhere.

"Typically, the first year after a beach is renourished, there are more false crawls," said Eric Martin, scientific director and vice president for Ecological Associates turtle-research consultants in Jensen Beach.

False crawls are turtles' movements onto a beach, but without egg-laying.

"It takes a lot of energy for a turtle to come ashore," said Robert Ernest, the firm's president. "If she has to do that repeatedly, she may lay fewer eggs."

To reduce false crawls, and enhance survival of endangered sea turtles, the Army Corps of Engineers this year is launching a pilot program along Martin County beaches on Hutchinson Island. Eight quarter-mile sections of the four-mile stretch of beach will be renourished in the usual style. That involves pumping sand from the ocean to create a broad, flat beach that drops off sharply near the water line. Between each conventional section will be a quarter mile section of "turtle friendly" beach. These sections also will be built from offshore sand, but with the continuous, gradual slope of a natural beach. The monthlong project is slated to start in March and end in April, just before the start of turtle-nesting season.

"Martin County is a great area to have this study because it has such a high nesting density," said Shelley Trulock, the Jacksonville-based project manager for the Army Corps.

Impetus for the pilot program stretches back to the 1990s, when researchers discovered turtle nesting success declined along renourished beaches.

"We think it has to do with what the turtle visualizes," Martin said. "The dune horizon seems to be very important. With a flat slope, the dune horizon is set back a considerable distance."

Martin and his colleagues shared their discovery with several stakeholders, including the Florida Department of Environmental Protection, which worked with Environmental Associates to develop the turtle-friendly pilot program. The National Fish and Wildlife Foundation provided a $600,000 grant to fund turtle-nesting studies along the renourished beaches over the next two years.

A key concern was whether the turtle-friendly beach profile would stand up to storms as well as the standard, renourished profile. Trulock put the question to computer models simulating storm impacts.

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Martin to be testing ground for turtle-friendly renourished beaches