DURHAM, N.C. -- More than 250,000 loggerhead and 60,000 leatherback turtles are estimated to be inadvertently snared each year by commercial longline fishing, with up to tens of thousands dying, according to the first global assessment of the problem. The researchers who conducted the assessment said that, although their numbers are estimates, they are firm enough to warrant the development of rules for fishing equipment and practices to reduce or avoid such losses.

The study, by researchers from Duke University's Nicholas School of the Environment and Earth Sciences, was published in the March 2004 online and print editions of the research journal Ecology Letters. First author was Rebecca Lewison, a research associate at the Duke University Marine Laboratory. Co-authors were Sloan Freeman, another Duke research associate, and Larry Crowder, who is the Stephen Toth Professor of Marine Biology at Duke. Their research was funded by the Pew Charitable Trusts.

Longlines are lengths of monofilament fishing lines that can stretch for 40 miles and dangle thousands of individually baited hooks. They are set at optimal depths and times to catch tuna and swordfish.

Because the environmentally protected loggerheads and leatherbacks frequent the same zones where these longlines are strung, many sea turtles are either hooked attempting to swallow the bait or are entangled in the fishing gear, the study noted. Such unintentional captures are classified as "bycatch."

"There have been few attempts to quantify the magnitude and extent of protected species bycatch even for fisheries in which bycatch is perceived as a pressing concern," Crowder and his colleagues wrote in their Ecology Letters research paper. "This is, in part, a consequence of limited data."

In the face of those shortcomings, the Duke team mined available turtle bycatch data from the 13 nations that collect such information. And they extrapolated estimates for areas like the I
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Contact: Monte Basgall
monte.basgall@duke.edu
919-681-8057
Duke University
8-Mar-2004

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