Surging cormorant population takes toll on catfish farms

Cormorants, once endangered, are now increasing at a rate of 29 percent every year

July 14, 2000
Web posted at: 5:00 p.m. EDT (2100 GMT)

From CNN Earth Matters Correspondent David George

(CNN) -- An increase in the double-crested cormorant population is taking a bite out of once-thriving catfish farms.

The birds that once faced extinction now increase at a rate of 29 percent every year in North America.

"The farm has literally been brought to its knees by the birds," said Albert "Rusty" Gaude, a Louisiana catfish and crawfish farmer.

From Mississippi to Maine, farmers face the population growth of various fish-eating birds. Cormorants, egrets, white pelicans and herons, once decimated by agricultural chemicals such as DDT, are taking a chunk out of farm-raised and wild fish stocks.

VIDEO CNN's David George says cormorants and other seabirds are eating profits at fish farms in the eastern United States. Real 28K 80K Windows Media 28K 80K     ALSO Scaring off seabirds is a way of life for some. Meet the tern-inators     FACTOIDS A typical 10 acre pond can be invaded by as many as 500-1,500 birds at a time Each catfish is worth .10 - .35 cents to farmers Cormorants can consume up to1 1/2 pounds of fish per day   POP QUIZ Why do cormorants often perch with their wings spread? A. To show dominance B. To get the attention of the opposite sex C. To dry themselves off

"Our primary problem here in the southern United States is double-crested cormorant impacts to catfish," said Scott Werner, a wildlife biologist at the USDA National Wildlife Research Center. "We also work with American white pelicans, herons and egrets, which impact catfish production, bait fish production and crawfish production."

Cormorants gained protection under the Migratory Bird Treaty Act in 1972 -- the same year that DDT was banned. Now farmers try everything to keep the proliferating birds from eating their profits.

Using scarecrows and noisemakers, even shooting some birds with permission from the Fish and Wildlife Service, farmers have resorted to diverting some workers from their regular duties to chase away birds. But these methods are merely a temporary and costly deterrent.

"My bird-control budget right now is running about thirty to fifty thousand a year," Gaude said.

And 200 to 300 pelicans herded in a small area for two or three nights can easily cost $20,000 to $30,000 worth of fish, Gaude said.

Now biologists from the U.S. Department of Agriculture are using technology to learn more about these birds.

Scientists put 25 to 30 satellite transmitters on cormorants last winter, and they plan to add 25 more this winter. The battery-powered backpacks transmit information to orbiting satellites.

"We're looking at regional movements of the birds," said Tommy King, of the USDA National Wildlife Research Center. "Like when they're down here in the wintering grounds, where they go when they're not in this immediate area, their migration corridors, the timing of migration, and where they breed. (We'll) hopefully track them back down here when they come next winter."

Pelicans and other fish-eating birds are making a dent in fish farmers' profits

Farmers and researchers are eagerly awaiting the results of this USDA study. And with more than 1 million cormorants born each year, scientists are in a race against time. In some areas, the cormorants have begun to degrade the natural environment.

"They like to congregate with one another and they're social animals," Werner said. "While they're congregated in those very dense breeding colonies, the accumulation of their excrement, in some cases, at least in the northern United States, has negative consequences on the growth of the trees in those colonies, as well as the water."

With the cormorant problem looming over several farms and many natural areas under siege, scientists hope the new knowledge will bring the birds under control.

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