PENN YAN — Sea lampreys are an invasive, parasitic fish in Seneca Lake that attach themselves to native species. They feed on and damage lake trout, rainbow trout, brown trout and landlocked salmon.

In an effort to curb the lamprey population, the state Department of Environmental Conservation will apply a chemical called TFM in Yates, Schuyler and Chemung county tributaries. Those applications begin next week.

TFM is a selective pesticide used extensively for lamprey control in the Great Lakes for decades. It’s been used in Seneca Lake since 1982.

DEC Region 8 Director Paul D’Amato said the dosage levels of TFM that are lethal to larval sea lampreys can be processed harmlessly by most other aquatic organisms. Following an environmental impact study and a public hearing conducted prior to deciding on the lampricide program, DEC officials concluded that the lamprey control program offers an effective and immediate measure for protecting the native fish populations in Seneca Lake.

DEC further concluded the project will not have any significant impacts to the environment or non-target organisms exposed to the lampricide. Some minor fish and aquatic invertebrate mortality is expected and may be visible.

D’Amato said the stream treatments do not pose any significant harm to human health. However, as a precautionary measure, the state Department of Health has advised that no streamwater consumption, fishing, swimming, livestock watering or irrigation occur in the treatment zone in the period immediately following applications.

Signs will be posted along the treated streams.

“Since 1982, Catharine Creek and Keuka Outlet have been treated 10 and six times, respectively, without any significant environmental or human health problems or impacts,” D’Amato noted.

The DEC will treat waters inhabited by juvenile sea lampreys in Catharine Creek and tributaries from the Chemung and Schuyler county lines to Montour Falls, and Keuka Outlet from Cascade Mills downstream.

Lampricide applications are scheduled to start Tuesday in Catharine Creek and Thursday in Keuka Outlet. Weather conditions may result in postponement to later in the week or the following week.