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Lampreys Take Toll On Fish In Lake Champlain

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By Matt Crawford

Burlington Free Press

Fisheries biologists on Lake Champlain spent time this spring looking for landlocked Atlantic salmon, rainbow trout and brown trout.

They didn't find many.

Staff from the U.S. Fish and Wildlife Service office in Essex Junction and the New York Department of Environmental Conservation sampled four tributaries on the New York side of the lake to obtain information on salmonid populations and sea lamprey wounding rates, and to evaluate differences among three strains of landlocked salmon being stocked.

The survey crews turned up just 93 salmon, one brown and no rainbows; and the fish they found showed a high level of lamprey-wounding rates.

Of those 93 salmon, biologists determined that only four had spent more than a year in the lake and found a sea lamprey-wounding rate of 42 wounds per 100 salmonids.

"The reason we didn't find many big fish in the sample seems pretty clear," said David Nettles of the U.S. Fish and Wildlife Service office in Ray Brook, N.Y. "The lamprey have hit them all."

Nettles and Craig Martin of the U.S. Fish and Wildlife Service Lake Champlain project in Vermont, found a high number of smaller fish with lamprey wounds. Lamprey prefer to prey on larger fish, but appear to now be hitting smaller fish in Champlain and at a very high rate.

"In my opinion," said Nettles, "lamprey have attacked and killed the majority of the larger fish and no have no choice but to start feeding on the smaller ones -- and we're talking fish just 17 inches long. We didn't use to see that."

Nettles said the ratio of young-to-adult fish in the sample this year was the worst he's seen.

Martin said lamprey wounding of salmon and trout has been on the increase since an eight-year experimental sea lamprey control program ended in 1997, and the fishery is showing the effects of a growing lamprey population.

"Research shows that fish with one sea lamprey wound have about a 60 percent mortality rate," said Martin. "Some of the fish we found have multiple wounds. We have to draw the conclusion the mortality rate is pretty high in the lake."

Vermont wildlife officials are preparing to begin chemical lamprey treatment of the Winooski River in the fall. Officials from the Vermont Fish and Wildlife Department are lining up needed permits for the treatment program.

"We're jumping over the hurdles to get through the permit process," said Fish and Wildlife Commissioner Wayne Laroche. "Everything seems to be going well. There are some concerns we are addressing."

Nettles and Martin said the spring survey drove home the need for lamprey control on the lake.

"We're sort of at a point where we have two choices," said Nettles. "We control lamprey and have a robust fishery, or we don't control them and we have no fish."

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Here's some pictures of lampreys:

Close-up of head:

lamprey.jpg

Poor trout!:

lamprey.jpg

Lamprey-induced injuries:

post-1466-1155427967_thumb.jpg

We've got "pouched lampreys" in Australia - Geotria australis

Flattieman.

Edited by Flattieman

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