Recent surveys by the PFBC and partner organizations have detected New Zealand mudsnails, roughly the size of a match head, in several popular cold-water trout fisheries in central and eastern Pennsylvania. In some infested waters, New Zealand Mudsnails have the potential to reach densities of hundreds or even thousands of snails per square foot. These snails are not harmful to humans but can compete with and negatively impact native freshwater invertebrate species, such as other snails and aquatic insects.
Until recently, New Zealand Mudsnails were known to occur only in Lake Erie, Erie County; Spring Creek and Bald Eagle Creek, Centre County; and the Little Lehigh Creek in Lehigh and Berks counties. Surveys during 2020 revealed populations of snails in Trindle Spring Run, Cumberland County; Codorus Creek, York County; and Valley Creek, Chester County; prompting expanded surveys. Members of the public who observe suspected New Zealand Mudsnails or other aquatic invasive species may report their sightings to the Commission.