Dead fish are found on banks of Potomac River

June 05, 2002|by LAURA ERNDE

People enjoying the Potomac River in recent weeks might have noticed an unusual number of dead fish floating to the surface or laying on the river bank.

But a fisheries expert said thousands of red horse suckers died this spring due to a naturally occurring phenomenon that poses no threat to human health.

Ed Enamait, freshwater fisheries manager for the Maryland Department of Natural Resources, fielded a number of calls about the dead fish. Most of the reports came from the section of the Potomac that flows through Washington County he said.


Every year after spawning, a small percentage of suckers die off. Weakened by their preoccupation with procreation and the loss of a protective coating of mucus on their gills, the suckers aren't able to fight off the naturally occurring bacteria in the water, he said.

"What we've experienced is kind of a Mother Nature die-off of these suckers," he said.

But this year's fish kill seemed to be more pronounced than it has been in the last 15 to 20 years, Enamait said.

The reason, he speculates, could be an aftereffect of 1996 flooding. A large hatch following the flood might have further stressed the population.

As the weather turned warmer around Memorial Day, boaters and anglers headed for the river and took notice of the dead fish.

Biologists knew right away that the kill was not caused by pollution because it affected only one species, but Enamait said he still appreciates the calls.

"That's what we want, people looking over the environment," he said.

Enamait said the fish kill probably has peaked for the spring with an estimated 10 percent of the sucker population lost.

Although this year's sucker fish kill was unusually high, it was not as large as it was in the 1970s when you would find a dead fish every 10 paces along the river bank.

The state introduced walleyes into the Potomac, which have acted as a natural predator to the suckers and kept the population in check, he said.

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