Species that are considered uncertain risk need a more in-depth assessment beyond the Risk Summary to better define the species’ risk to U.S. environments.
Squalius cephalus is a freshwater and brackish water species with a broad native range in Europe and Asia Minor. This species is popular with anglers, which has facilitated its spread. Squalius cephalus has been introduced to Ireland (now eradicated), Italy, and possibly other locations. This species is known to hybridize with similar species, but congeners are not present in the United States. Other negative impacts of introduction have been speculated upon but not observed. Studies on the effects of introduced Squalius cephalus are lacking, which makes its history of invasiveness uncertain. This species has a high climate match with the contiguous United States. Most likely habitat is in California, Oregon, Washington, Idaho, and the Great Lakes. Due to a lack of information on impacts and uncertainty surrounding the established range of this species, the certainty of this assessment is low. The overall risk for this species is uncertain.
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Uncertain Risk
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