Winooski River Lamprey Control Is Successful

November 02, 2004

WATERBURY, VT - The Winooski River lamprey control effort conducted in October was a success, according to the Vermont Fish & Wildlife Department.

The Lake Champlain sea lamprey control team concluded a successful season of lampricide applications with the "TFM" treatment in the Winooski River on October 20. Biologists from the Vermont Fish & Wildlife Department, N.Y. State Department of Environmental Conservation, and the U.S. Fish and Wildlife Service applied about 1,200 gallons of the selective lamprey-killing chemical for 12 hours at the Winooski One Hydroelectric Dam in the City of Winooski.

The TFM formulation was applied at the minimum effective concentration to kill larval sea lampreys. This level was maintained through the application period by frequent monitoring of the river flow rate and TFM concentrations downstream of the application point.

The timing of the treatment and minimal level of TFM applied minimized potential harm to several threatened and endangered species, including five species of mussels, two species of small fish called darters, young lake sturgeon, and the non-parasitic American brook lamprey.

Follow-up assessments after the treatment showed a high level of success. Preliminary observations by biologists indicate that 100 percent of sea lamprey larvae held in cages throughout the river died during the treatment.

Non-target mortality was very light, as expected. Post-treatment assessment crews found low numbers of several common fish and amphibians that were affected over the 11 miles of treated river. Biologists found that 100 percent of juvenile lake sturgeon, channel darters, mudpuppies and mussels held in cages in the river survived the treatment.

Observations of American brook lampreys caged in the treatment area were also encouraging. Preliminary results show that from 14 to 41 percent of American brook lampreys caged in the area of the river they are known to inhabit survived the treatment, while none of the caged sea lampreys survived. This supports previous research findings that American brook lampreys are more resistant to TFM than their parasitic cousins.

Public water use advisories lasted four days in the upper portion of the treated river reach, while the lower river and surrounding lakeshore restrictions lasted seven days. The City of Burlington's public water system was not affected by the treatment. TFM was not detected in City intake water samples collected regularly throughout the treatment and water use advisory period. As an added precaution, a powdered activated carbon filtration system was installed at the Burlington water plant to remove TFM to cover the very remote chance that any would reach the intake.

"We could not have carried out this treatment without the generosity and cooperation from the Winooski One Partnership and Green Mountain Power Corp," said Brian Chipman a biologist with the Vermont Fish & Wildlife Department. "Winooski One allowed us to use their hydroelectric facility, which was the ideal place to apply the lampricide. Green Mountain Power operated their upstream dams to provide the stable river flow that we needed, which enabled us to precisely control the TFM application rate and have a safe and effective treatment."

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