Cisco (fish)
The ciscoes are salmonid fish of the genus Coregonus
Coregonus is a diverse genus of fish in the salmon family . The type species is the common whitefish . The Coregonus species are known as whitefishes...

that differ from other members of the genus in having upper and lower jaws of approximately equal length and high gillraker
Ichthyology terms
Ichthyology uses several terms that are unique to the science.Contents: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z- A :* Abdomen: belly* Abdominal: pertaining to the belly* Actinosts: a series of bones at the base of the pectoral rays....

 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
Saint Lawrence River
The Saint Lawrence is a large river flowing approximately from southwest to northeast in the middle latitudes of North America, connecting the Great Lakes with the Atlantic Ocean. It is the primary drainage conveyor of the Great Lakes Basin...

 Great Lakes, the kiyi
The kiyi is a species of freshwater whitefish, a deepwater cisco, endemic to the Great Lakes of North America. It previously inhabited Lake Superior, Lake Michigan, Lake Huron and Lake Ontario, but is now believed to persist only in Lake Superior where it is common...

, bloater
Coregonus hoyi
The bloater is a species of freshwater whitefish in the family Salmonidae. It is a silvery-coloured herring-like fish, long. It is found in most of the Great Lakes and in Lake Nipigon, where it inhabits underwater slopes....

, shortnose cisco
Shortnose cisco
The shortnose cisco is a species of freshwater fish in the salmon family . The species is native to the Nearctic ecozone, formerly occurring in Lakes Huron, Michigan, and Ontario in Canada and the United States...

, longjaw cisco
Longjaw cisco
The longjaw cisco was a deep water cisco or chub, usually caught at depths of 100 metres or more from Lakes Huron, Michigan, and Erie. Its Latin name was derived from Alpena, a city in Michigan...

 and deepwater cisco
Deepwater cisco
The deepwater cisco was one of the largest ciscoes in the Great Lakes. Its average length was 30cm and it was about 1.0 kilogram in weight...

, are believed to be of very recent evolutionary origin and are said to represent an incipient species flock
Species flock
In evolutionary biology, a species flock is a diverse, primarily monophyletic, group of closely related species in an isolated area.A species flock may arise when a species penetrates a new geographical area and diversifies to occupy a variety of ecological niches; this process is known as...

 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 lake herring or 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
The family Cyprinidae, from the Ancient Greek kyprînos , consists of the carps, the true minnows, and their relatives . Commonly called the carp family or the minnow family, its members are also known as cyprinids...

 fish species known as chubs but was exclusively based on the various species of ciscoes. The fishery continued as cisco stocks fell and non-native species such as sea lamprey
Sea lamprey
The sea lamprey is a parasitic lamprey found on the Atlantic coasts of Europe and North America, in the western Mediterranean Sea, and in the Great Lakes. It is brown, gray, or black on its back and white or gray on the underside and can grow up to 90 cm long. Sea lampreys prey on a wide...

, rainbow smelt
Rainbow smelt
The rainbow smelt, Osmerus mordax, is an anadromous species of fish of the family Osmeridae. The distribution of Osmerus mordax is circumpolar. The rainbow smelt was introduced to the Great Lakes, and from there has made its way to various other places. Walleye, trout, and other larger fish prey on...

 and alewife
The alewife is a species of herring. There are anadromous and landlocked forms. The landlocked form is also called a sawbelly or mooneye...

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 ciscoes. The fishery shifted focus from species to species as cisco numbers declined and has been largely defunct for some years.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.