The shortjaw cisco (''Coregonus zenithicus'') is a North-American

freshwater whitefish The freshwater whitefish are fishes of the subfamily Coregoninae, which contains whitefishes (both freshwater and anadromous) and ciscoes, and is one of three subfamilies in the salmon family Salmonidae. Apart from the subfamily Coregoninae, ...

in the salmon family. Adult fish range to about in length and are silver, tinged with green above and paler below. One of the members of the broader ''Coregonus artedi'' complex of

ciscoes The ciscoes (or ''ciscos'') are salmonid fish that differ from other members of the genus in having upper and lower jaws of approximately equal length and high gill raker counts. These species have been the focus of much study recently, as resea ...

, it is distributed widely in the deeper lakes of

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...

, but populations in the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five la ...

have been declining and it is no longer present in Lakes

Michigan Michigan () is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the List of U.S. states and ...

Huron Huron may refer to: People * Wyandot people (or Wendat), indigenous to North America * Wyandot language, spoken by them * Huron-Wendat Nation, a Huron-Wendat First Nation with a community in Wendake, Quebec * Nottawaseppi Huron Band of Potawatomi ...

, and

Erie Erie (; ) is a city on the south shore of Lake Erie and the county seat of Erie County, Pennsylvania, United States. Erie is the fifth largest city in Pennsylvania and the largest city in Northwestern Pennsylvania with a population of 94,831 at ...

. It feeds mainly on crustaceans and insect larvae and spawns in the autumn on the lake bed. It is part of the important cisco (chub) fishery in the Great Lakes. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natur ...

has rated its conservation status as "

vulnerable Vulnerable may refer to: General * Vulnerability * Vulnerability (computing) * Vulnerable adult * Vulnerable species Music Albums * ''Vulnerable'' (Marvin Gaye album), 1997 * ''Vulnerable'' (Tricky album), 2003 * ''Vulnerable'' (The Used album) ...

". Shortjaw cisco have however evolved from the cisco ''

Coregonus artedi ''Coregonus artedi'', commonly known as the cisco, is a North American species of freshwater whitefish in the family Salmonidae. The number of species and definition of species limits in North American ciscoes is a matter of debate. Accordingl ...

'' independently in different lakes and different parts of the range, and conservation assessments therefore should be made on a lake-wise rather than range-wide basis.Julie Turgeon, Scott M. Reid, Audrey Bourret, Thomas C. Pratt, James D. Reist, Andrew M. Muir, Kimberly L. Howland (2016
Morphological and genetic variation in Cisco (''Coregonus artedi'') and Shortjaw Cisco (''C. zenithicus''): multiple origins of Shortjaw Cisco in inland lakes require a lake-specific conservation approach
''Conservation Genetics'' 17(1):45-56

Description

The shortjaw cisco has large, smooth scales and is iridescent silver, with a greenish back and white belly. The mouth is small and toothless, and the lower jaw is shorter than or equal in length to the upper jaw. It typically weighs approximately , and ranges from 150 to greater than 300 mm (6 to 12 inches)

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

. Very difficult to differentiate from other cisco species by superficial appearance, this species typically has fewer

gillrakers Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch (gill arch) and are involved with suspension feeding tiny prey. They are not to be confused with the gill filaments that compose the fleshy part of the ...

than other ciscoes.

Distribution

Once common throughout the upper Laurentian Great Lakes it is no longer found in

Lake Michigan Lake Michigan is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume () and the third-largest by surface area (), after Lake Superior and Lake Huron. To the east, its basin is conjoined with that ...

and populations are much lower in

Lake Huron Lake Huron ( ) is one of the five Great Lakes of North America. Hydrologically, it comprises the easterly portion of Lake Michigan–Huron, having the same surface elevation as Lake Michigan, to which it is connected by the , Straits of Ma ...

than in the past. The population in

Lake Superior Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh w ...

is known to be lower than historically, based on commercial catch statistics. Its status in

Lake Nipigon Lake Nipigon (; french: lac Nipigon; oj, Animbiigoo-zaaga'igan) is part of the Great Lakes drainage basin. It is the largest lake entirely within the boundaries of the Canadian province of Ontario. Etymology In the Jesuit Relations the lake is ...

is uncertain. It has been reported in at least 22 other lakes outside of the Great Lakes, from the Canadian provinces of

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central C ...

Manitoba , image_map = Manitoba in Canada 2.svg , map_alt = Map showing Manitoba's location in the centre of Southern Canada , Label_map = yes , coordinates = , capital = Win ...

Saskatchewan Saskatchewan ( ; ) is a province in western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the U.S. states of Montana and North ...

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

, and the

Northwest Territories The Northwest Territories (abbreviated ''NT'' or ''NWT''; french: Territoires du Nord-Ouest, formerly ''North-Western Territory'' and ''North-West Territories'' and namely shortened as ''Northwest Territory'') is a federal territory of Canada. ...

. It is not known whether the remaining Great Lakes populations are increasing, decreasing or stable. Population trends in other lakes are unknown.

Habitat

The shortjaw cisco is most commonly found in the deeper waters of large lakes. It has been found at depths of between in Lakes Superior, Michigan, and Huron, and is known to exhibit seasonal changes in depth distribution in Lake Superior.

Reproduction

Spawning occurs in the autumn. Eggs are deposited over the lake bottom in deep water and develop over three to four months, depending on water temperature. This fish reaches sexual maturity at five years of age.

Ecology

Crustaceans and insect larvae are important food items.

Lake trout The lake trout (''Salvelinus namaycush'') is a freshwater char living mainly in lakes in northern North America. Other names for it include mackinaw, namaycush, lake char (or charr), touladi, togue, and grey trout. In Lake Superior, it can als ...

(''Salvelinus namaycush'') and

burbot The burbot (''Lota lota'') is the only gadiformes, gadiform (cod-like) freshwater fish. It is also known as bubbot, mariah, loche, cusk, freshwater cod, freshwater ling, freshwater cusk, the lawyer, coney-fish, lingcod, and eelpout. The species ...

(''Lota lota'') are known to feed on shortjaw cisco. Shortjaw cisco are believed to be vulnerable to the invasive

sea lamprey The sea lamprey (''Petromyzon marinus'') is a parasitic lamprey native to the Northern Hemisphere. It is sometimes referred to as the "vampire fish". Description The sea lamprey has an eel-like body without paired fins. Its mouth is jawless, ...

(''Petromyzon marinus'',) which has presumably played a role in its decline in the Great Lakes, where expansion in the range of sea lamprey has overlapped the decline in shortjaw cisco numbers.

Fisheries

This species was an important component of the cisco (chub) fishery in the Great Lakes. Competition and predation from

rainbow smelt The rainbow smelt (''Osmerus mordax'') is a North American species of fish of the family Osmeridae. Walleye, trout, and other larger fish prey on these smelt. The rainbow smelt prefer juvenile ciscoes, zooplankton such as calanoid copepods ('' ...

(''Osmerus mordax'') and alewife (''Alosa pseudoharengus''), two introduced exotic fish species, have had a negative impact on shortjaw cisco populations. The cumulative effect of these factors, sea lamprey predation and habitat changes associated with urban, agricultural, and industrial activities in the

Great Lakes Basin The Great Lakes Basin consists of the Great Lakes and the surrounding lands of the states of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin in the United States, and the province of Ontario in Canada, whose dir ...

undoubtedly combined to make this species vulnerable to

over-exploitation Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term ap ...

, even at exploitation rates that had once been sustainable. In lake Superior, the shortjaw cisco has been part of deepwater cisco fisheries. The deepwater ciscoes there also comprise ''

Coregonus hoyi ''Coregonus hoyi'', also known as the bloater, is a species or form 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, and inhabits und ...

'' and ''

Coregonus kiyi The kiyi (''Coregonus 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 ...

''.

Systematics

The systematics of the group of fishes called "

" is complicated. The shortjaw cisco is part of the ''

'' complex (which also comprises ''C. hoyi'' and ''C. kiyi''). Particularly it was thought to be conspecific with the (presumably now extinct)

longjaw cisco The longjaw cisco (''Coregonus alpenae'') 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. Silver colored and growi ...

(''Coregonus alpenae''). Genetic data show that the shortjaw cisco is not a unique and coherent taxon, but has evolved from the sympatric ''Coregonus artedi'' s.str. independently in different lakes. Particularly there is a major distinction between the eastern and western parts of the range, and the differences between sympatric ''C. artedi'' and ''C. zenithicus'' are smaller than differences among lakes.

References

* *
The Shortjaw Cisco... ''a Species at Risk''
Fisheries and Oceans Canada *Hoff MH, Todd TN (2004
Status of the shortjaw cisco (''Coregonus zenithicus'') in Lake Superior
''Annales Zoologici Fennici'' 41:147-154. {{Taxonbar, from=Q306293 Coregonus Fish of the Great Lakes Freshwater fish of the United States Fish of Canada Fish described in 1909