Decline
The decline of the species has been largely caused by overfishing and predation from the invading sea lamprey. The introduced alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) are also aggressive predators of juveniles. Blackfin ciscoes were commercially fished until the early 1900s when declining stocks made the fishery uneconomic. Current threats to the only remaining population include commercial fishing, predation by rainbow smelt and interbreeding with lake herring (Coregonus artedi).
The blackfin cisco was last seen in Lake Michigan in 1969 and in Lake Huron in 1960. The latest was seen in 2006 in Long Lake near Thunder Bay. Various sources state that the blackfin cisco is still occasionally sighted in Lake Nipigon in northern Ontario, and the status of the species in Canada and Ontario is still under review. However, the IUCN Red List lists it as extinct (1996). Canadian authorities listed it as threatened in 1988 and data deficient (DD) in 2007, due to the uncertainty of the taxonomic status.
Read more about this topic: Blackfin Cisco
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