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Date of Issue: February 16, 2006

Dredgers required to protect turtles

The recent death of a green sea turtle in the intake of the Longboat Key beach renourishment dredge has highlighted the extraordinary measures in place for turtle protection.

Given those measures, required by state and federal regulators, catching the green up in the dredging mechanism was a highly unusual happenstance, its cause still not fully known.

Robin Trindell of the Florida Fish and Wildlife Conservation Commission staff said very stringent measures keep turtles out of dredges - almost always.

Only one kind of dredge causes such problems, she said. For that type of machine, special gear has been developed for the end of the dredge pipe, "Sort of like cowcatchers on railroad locomotives," she said. It pushes turtles away from the suction as the dredge pumps sand from the borrow area to the beach.

One problem that remains is that turtles sometimes burrow into the sand and mud of the bottom, where the "cowcatcher" can't reach.

Another possible problem, one that rarely occurs because of requirements imposed by the state and federal regulations as well as by Manatee County, is that the dredge moves from section to section of the borrow site to get the desired grade of sand.

That means the intake pipe has to be moved too, and though it's done with care, it sometimes lifts the intake opening and the turtle protector off the bottom. The suction at that point can catch the turtle.

Another turtle safety measure is trawlers employed to net turtles in the area and relocate them away from harm. They operate under special permits that include an exception to the turtle-exclusion devices required on the big nets for normal trawling for other marine life.

Such a trawler is operating at the Longboat Key dredge operation. It is fully permitted by FWC and the U.S Army Corps of Engineers, Trindell said, and has been quite successful.

Nevertheless, one green turtle slipped past the trawler's net and the special exclusion gear on the dredge intake, and ended up the victim of modern machinery. Its death, or "take" in dredgers' parlance, shut down dredging for the better part of a week at the end of January. 

The Longboat Key Public Works Department said that since November, when the project and the trawler started, the fishing boat has netted and relocated 45 marine turtles: 22 loggerheads, 15 Kemp's ridleys, seven greens and one hawksbill.

Anna Maria's beach renourishment has been shut down for weeks, and no one in authority seems to know when it will resume. Best guess seems to be about the first of April, which would have the dredge pumping sand onto the beach through the Easter holiday and well into the turtle nesting season which begins May 1.