WESTPORT The sparkling reflection coming off Lake Champlain last week werent caused by the waves a closer look revealed thousands of dead fish washing up on the coasts. Thousands of dead fish appeared on the surface and shores of Lake Champlain, the New York State Department of Environmental Conservation reported last week. The dead fish were being sighted on both the New York and Vermont sides of the lake. The fish are alewives, a type of herring with a gray-green back and silvery iridescent sides. Alewives are an invasive species, first found in Lake Champlain in 2005. Their presence became more widely known earlier this year when tens of thousands of dead alewives turned up on the Vermont side of the lake. Vermont 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. Alewives are susceptible to rapid drops in water temperature that can occur at the onset of winter and when cold waters from melting ice mix with the somewhat warmer waters below. This is what caused the die off in Vermont earlier this year and is thought to be responsible for the recent die-off. The fish might have died over the winter, but were preserved in the cold waters under the ice. Now that the ice has thawed, these dead fish are surfacing. This type of winter kill of alewives was not unexpected, said Shawn Good, chair of Vermont 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. 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. 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. While large number of dead fish are unsightly, and possibly odorous, they do not present a wide spread health or environmental problem. Gulls, raccoons and other scavengers will consume many of the fish, the rest will decompose, following the cycle of the natural environment. Lakefront property owners in certain areas of Lake Champlain are likely to see large numbers of dead alewives on their shorelines. It is not certain if the alewives was entered the lake as a result of illegal stocking of the fish into waters in the Lake Champlain watershed or by migrating through connecting canal systems. Misguided anglers may have introduced the fish thinking they would provide a good food source for gamefish. Unfortunately, alewives in the Great Lakes, where they are also an invasive species, have a history of large crash and boom population cycles. 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 Vermonts native fish and the fishing opportunities they provide. The New York State DEC has regulations that anglers must follow to prevent the spread of non-native fish and ensure healthy populations of native and managed fish: Do not move fish from one water body to another; Do not release unused bait fish even where using them is allowed; Do not move fish overland unless they are certified as disease-free.