Ecological Risk Screening Summary - Wels Catfish (Silurus glanis) - High Risk

Species that are considered high risk have a well-documented history of invasiveness in at least one location globally and are of establishment concern for the contiguous United States based on a climate matching analysis.

Silurus glanis, Wels Catfish, is a freshwater fish that is native to Europe and Asia. It has been introduced outside of its native range in Europe with many established nonnative populations, as well as to Africa (not established) and Asia (some established populations). In its native habitat, this species is typically found in large rivers, lakes, and coastal areas of low salinity. S. glanis is well adapted to water with low visibility and feeds primarily at night. The largest individuals are the apex predators within the trophic system. S. glanis has not been reported as introduced or established in the wild in the United States, and it is listed under the Lacey Act as a federally banned species, prohibited from import and trade. S. glanis possession, transport, or trade is also regulated in several U.S. states. The History of Invasiveness for S. glanis is classified as High due to evidence from peer-reviewed studies that this species has led to the decline of native fish and waterbird populations through predation and competition, as well as abandonment of traditional fishing practices. The climate matching analysis for the contiguous United States indicates establishment concern for this species. The highest climate matches were found in the Great Basin, Great Lakes, Appalachian Mountains, and the Northeastern regions, although most of the country had a high climate match. The Certainty of Assessment for this ERSS is classified as High due to the existence of high-quality research on impacts and established non-native populations. The Overall Risk Assessment Category for Silurus glanis in the contiguous United States is High.