Blackfin cisco
| Blackfin cisco | |
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C. nigripinnis
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| Coregonus nigripinnis (Milner, 1874)
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The blackfin cisco (Coregonus nigripinnis) was a North American salmonid fish in the freshwater whitefish sub-family Coregoninae. This silvery, deep-bodied fish with black fins, large eyes, a blunt snout and a terminal mouth, is one of the largest forms of ciscoes. The blackfin cisco used to inhabit the Great Lakes of North America until recently, but has been reported to have gone extinct.
Description
It was a dark silvery color, with a dark green to black back, and pink or purple on the sides; the outer half of the fins was black. Blackfin ciscoes measured up to 510 mm (21 inches in length). Its preferred habitat was cold lakes at depths of up to 180 metres.
There is great doubt whether the Coregonus nigripinnis was an independent species separate from Coregonus artedi (lake herring) or just an ecomorphotype, as has also been argued for other cisco forms in the Great Lakes area.
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.[citation needed] 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.
References
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- Froese, Rainer and Pauly, Daniel, eds. (2005). "Coregonus nigripinnis" in FishBase. 10 2005 version.
- COSEWIC (2007). COSEWIC assessment and update status report of the blackfin cisco Coregonus nigripinnis in Canada Committee on the Status of Endangered Wildlife in Canada. vi + 23 pp
