Lake Champlain Alewife Die-off Update

WATERBURY, VT - Small fish called alewives are washing up on the shores of Lake Champlain in large numbers. State fisheries biologists from the Vermont Fish & Wildlife Department say it is an example of the kind of problems a non-native invasive species can cause.

First documented in Lake Champlain in 2005, alewives have since been found throughout most of the lake. Large numbers of young alewives were first observed in the Inland Sea in 2007.

Vermont Fish & Wildlife biologists responded to numerous calls from concerned anglers reporting dead fish washing up on shores of the Inland Sea during the January thaw of 2008.

Fisheries Biologist Bernie Pientka and Fish Health Biologist Tom Jones investigated and found tens of thousands of dead and dying alewives, most about three inches long and one year old. Adult alewives as large as eight inches were also documented. Results of testing showed that these alewives were negative for viral hemorrhagic septicemia (VHS), a disease that is killing fish in the Great Lakes.

"This type of winter kill of alewives was not unexpected," said Shawn Good, chair of Fish & Wildlife's Aquatic Nuisance Species Team. "Alewives are an exotic fish species native to the Atlantic Ocean, and they are not well adapted to winters in freshwater lakes such as Lake Champlain. Alewives are easily killed by rapid changes in water temperature that occur in the winter."

The story did not end in January. Throughout the winter additional reports of dead and dying fish were received from anglers as far south as Westport, NY and Basin Harbor, VT. In many cases, anglers were reporting that dying alewives were observed swimming up into recently drilled holes in the ice.

Dead fish tend to stay preserved for long periods of time in cold water. As spring temperatures melt the ice, the dead alewives trapped under the ice float to the surface and wash up on shore.

Lakefront property owners in certain areas of Lake Champlain are likely to see large numbers of dead alewives on their shorelines.

"There is a lesson to be learned here," said Good. "This is exactly why it is illegal to move fish from one water to another or introduce new species to Vermont lakes. While some anglers think alewives are a good food source for game fish, the reality is alewives provide an unstable and uncertain forage base -- a here today, gone tomorrow type of scenario. One month our game fish have an over-abundance of alewives to feed on, and the next month they are starving. Such alewife collapses in the Great Lakes historically have had huge negative impacts to the sport fishing there."

Good says anglers should be aware of the risks involved with introducing new species to new waters.
"The great fishing we enjoy today could be gone tomorrow if aquatic nuisance fish species are allowed to spread," he cautioned. We all need to work together to slow or prevent the spread of exotic species and protect Vermont's native fish and the fishing opportunities they provide.

With the growing concern of fish diseases like VHS, the Vermont Fish & Wildlife Department is very interested in fish kills statewide and what people are observing. Accurate disease testing requires recently dead or dying fish, so if you observe dying fish on any of Vermont waters, be sure to contact your local warden, regional Fish & Wildlife office or the main office in Waterbury.

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