Magazine article Science News

Gill Net Changes Can Prevent Bird Drownings

Magazine article Science News

Gill Net Changes Can Prevent Bird Drownings

Article excerpt

A test of modified fishing nets has revealed ways to make gill nets friendlier to seabirds, reducing the number that get entangled underwater and drown, according to Washington scientists.

These efforts represent the first fix for protecting birds from gill nets without closing a fishery, says Ed Melvin of the Washington Sea Grant Program in Seattle.

Other gear, such as trawls, have devices to protect wildlife, but technology has lagged for the gill net, Melvin points out. In the December CONSERVATION BIOLOGY, he and his colleagues describe modifying gill nets used to catch sockeye salmon in Puget Sound.

Full-size gill nets stretch 1,800 feet in length and dangle 60 ft deep. Their monofilament line, hard to see underwater, snags birds when they dive.

Previous bird-saving experiments haven't worked out well, Melvin notes. Some Japanese boats fishing for flying squid sank nets about 2 yards below the water's surface. Fewer birds died, but the squid catch shrank to as little as 5 percent.

In Washington State, concern about bird entanglement rose in 1992 after the marbled murrelet, a bird that forages at sea, was listed by the federal goverment as a threatened species, explains Jon Anderson of the Washington Department of Fish and Wildlife in Olympia. Observers on salmon boats in 1994 saw only one murrelet entangled but recorded 3,500 other birds snared, mostly common murres and rhinoceros auklets.

"Some by-catch problems can be solved if you sit down and listen to people," Melvin says. Talks with fishing crews led to the tests reported this week. Two boats replaced the top 7 ft of their nets with white, multistrand mesh. Two other boats replaced the top 15 ft.

Both white-topped nets reduced murre entanglement by about 40 percent. …

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