Cisco (fish)
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The ciscoes are salmonid fish of the genus Coregonus that differ from other members of the genus in having upper and lower jaws of approximately equal length and high gillraker counts. These species have been the focus of much study recently, as researchers have sought to determine the relationships among species that appear to have evolved very recently.
The five endemic cisco species of the Laurentian Great Lakes- kiyi, bloater, shortnose cisco, longjaw cisco and deepwater cisco are believed to be of very recent evolutionary origin and are said to represent an incipient species flock by some authors. The debate about which were true species and which were not has been rendered academic by the fact that some have disappeared from the system and are apparently extinct.
Several species belong to what various authors refer to as the "Coregonus artedi" complex, a group of closely related forms that appear to be derived from the northern cisco (C. artedi). The relationships among these forms remains unclear and have complicated discussion of the conservation status of some species.
Ciscoes have been exploited in commercial fisheries, particularly in the Laurentian Great Lakes where the deepwater forms were the basis of the so-called chub fishery. The chub fishery had nothing to do with the various Cyprinid fish species known as chubs but was exclusively based on the various species of ciscos. The fishery continued as cisco stocks fell and non-native species such as sea lamprey, rainbow smelt and alewife spread through the system and increased in abundance. Alewife, in particular, have been implicated as a predator of cisco eggs and larvae, and as a competitor with ciscos. The fishery shifted focus from species to species as cisco numbers declined and has been largely defunct for some years.
[edit] References
- "Coregonus". FishBase. Ed. Ranier Froese and Daniel Pauly. October 2004 version. N.p.: FishBase, 2004.
