Research Document - 2013/020
Information in support of a Recovery Potential Assessment of Silver Chub (Macrhybopsis storeriana) in Ontario
By B.R. McCulloch, L.D. Bouvier, and N.E. Mandrak
Abstract
In April 1985, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessed Silver Chub (Macrhybopsis storeriana) as Special Concern. The species was re-examined and the status confirmed in May 2001. In 2012, COSEWIC separated the populations into two separate designatable units: 1) the Saskatchewan - Nelson River populations; and 2) the Great Lakes - Upper St. Lawrence populations. The Saskatchewan - Nelson River populations were not considered to be at risk, while the Great Lakes-Upper St. Lawrence population was reassessed from Special Concern to Endangered in May 2012. The reason given for this designation was “This is a small bodied fish species native to the middle Great Lakes that has declined substantially in abundance over the previous three generations. The species is assessed as at a high risk of extinction from several threats including habitat degradation, exotic species interactions and climate change”. No schedule or status has yet been assigned to the Great Lakes – Upper St. Lawrence designatable unit of Silver Chub under the federal Species at Risk Act. The distribution of the Great Lakes-Upper St. Lawrence populations is restricted to Ontario, where it is known only from lakes Erie and St. Clair, and the extreme southern portion of Lake Huron. The Recovery Potential Assessment (RPA) provides information and scientific advice needed to fulfill various requirements of SARA including permitting activities that would otherwise violate SARA prohibitions and the development of recovery strategies. This Research Document describes the current state of knowledge of the biology, ecology, distribution, population trends, habitat requirements, and threats of Silver Chub in the Great Lakes-Upper St. Lawrence designatable unit (DU). Mitigation measures and alternative activities related to the identified threats, that can be used to protect the species, are also presented. This information may be used to inform the development of recovery documents and for assessing SARA Section 73 permits.
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