Ecological Risk Screening Summary - Alewife (Alosa pseudoharengus) - 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.

Alewife, Alosa pseudoharengus, is an anadromous marine and freshwater fish native to the Atlantic Coast of North America and associated streams and rivers. Landlocked populations also exist. This species generally consumes plankton and is a prey species in both the native and introduced ranges. There is some human consumption, however it is more commonly used as bait and for pet food. The History of Invasiveness is High. A. pseudoharengus has spread to the Great Lakes most likely through man-made channels, such as the Erie and Welland canals. It was also intentionally stocked or was a possible contaminant of other stocked species elsewhere. It has become established in much of the eastern contiguous United States. A. pseudoharengus is an efficient zooplanktivore and causes changes in the zooplankton community. Those changes and direct competition have caused declines in native fishes, especially planktivorous coregonids. Salmonids that consume A. pseudoharengus are at risk of a thiamine deficiency, resulting in Early Mortality Syndrome in their offspring which has severely impacted populations. A. pseudoharengus is prone to mass die-offs, which are a nuisance for lakeshore property owners and have a negative economic impact on the recreation industry. There may be some beneficial impacts through a reduction in biomagnification of contaminants in Walleye as A. pseudoharengus are on a lower trophic level than the Walleye’s native prey. A. pseudoharengus is regulated in 11 States. The climate matching analysis for the contiguous United States indicates establishment concern outside its native range. Almost the entire eastern two-thirds of the contiguous United States (including the native range of the species) had a high climate match. Low climate matches were found along the Pacific Coast and the Desert Southwest. The climate match is valid for freshwater and brackish water areas only. The Certainty of Assessment is High. The biology of the species, distribution, and history of invasiveness is well documented. The Overall Risk Assessment Category for Alosa pseudoharengus is High.