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environment general science genetics health and medicine space technology May 20, 2003 
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Gone Fishing (video)
June 14, 2001

Also on ScienCentral News

Tipping the Scales - Eating fish may be healthy for you, but eating some kinds of fish may not be healthy for the environment. Some species are so depleted they’re in danger of disappearing from markets and restaurants. (11/9/00)

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National Coalition for Marine Conservation

S.O. Conte Anadromous Fish Research Center (CAFRC)

Status of the Fishery Resources off the Northeastern US

Biologists angling for ways to restore fish populations to their old abundance are turning to an old technology.

As this ScienCentral News video report shows, they’re using a device that was once part of the problem.

Fishwheels keep on turning

When fishwheels were introduced in the Nineteenth Century, they captured large amounts of fish and marked the beginning of overfishing in America. Today, fishwheels are returning as a tool to study rebounding fish stocks.

Researchers are using fishwheels, which catch fish in their large baskets, in North Carolina’s Roanoke River, British Columbia, and Alaska, to monitor the migrations of fish. In these projects, the fish, often salmon or striped bass, are tagged, counted, and then returned to the water unharmed.

However, overfishing is not the only obstacle facing the return of migratory fish. "The usual reason suggested for the declines we’ve seen in some of these migrating fishes, like American shad, is overfishing—that they’ve been fished too hard," says Joe Hightower, a fisheries biologist with the United States Geological Survey. But Hightower also notes that loss of habitat can also come about through the construction of dams and changes in the water quality. "So we’re trying to address all those different factors that have caused these populations to decline," he says.

Many of the dams that were built in the last 50 or 60 years blocked the migration of fish. In an attempt to circumvent the problem, "fishways" were built to aid migration—but they were usually in the wrong place. Now new fish passages or ladders are being built to enable fish to reach their spawning habitats.

On the water quality front, treatment plants and changes in industrial practices have improved the situation. Better water quality may counter the reproductive and developmental problems that fish experience.

Hightower says his fishwheel on the Roanoke has caught more than 4,000 blueback herring and 1,100 striped bass, but only 12 American shad. "We’re very encouraged about the high catches of blueback herring this year because it might be a signal that that population is rebounding, but the catch of American shad is very low and disconcerting," he says. "We’re making a big push to restore American shad populations to their historical levels of abundance, and if we can do that it’ll once again support substantial commercial fisheries, and also recreational fisheries."

by Sara Kuzmarov

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