The deepwater cisco (''Coregonus johannae'') was one of the largest

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 ...

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 lakes ...

. Its average length was 30 cm (12 inches) and it was about 1.0 kilogram (2.2 pounds) in weight. Occurring only in Lakes

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 Potawato ...

and

Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and t ...

, and inhabiting waters between 50 and 150 metres deep, it was difficult to distinguish from other ciscoes and was possibly the same species as the

shortjaw cisco The shortjaw cisco (''Coregonus zenithicus'') is a North-American freshwater whitefish 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 ''Core ...

(''Coregonus zenithicus''). The deepwater cisco was distinguished by usually having fewer than 33 gill rakers, relatively long pectoral fins, and unpigmented jaws. It was a silvery colour with a pink or purple lustre and a green or blue back. It spawned in August and September, earlier than most other ciscoes. Not much is known about its specific behaviors. Its diet consisted of

Mysis relicta ''Mysis relicta'' is a shrimp-like crustacean in the Mysida order, native to lakes of Northern Europe and to the brackish Baltic Sea. Appearance Mysis is a small, transparent shrimp-like crustacean, of less than 2.5 cm length. It has tw ...

, fingernail clams, and various aquatic insects. Because of its large size, the deepwater cisco was heavily fished commercially. The main reasons for its extinction was a combination of competition from the invasive alewife, predation by the introduced

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, ...

, and

commercial fishing Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must oft ...

on the Great Lakes.

Commercial Fishing in 1930s

Part of the reason for the lack of information on this species could be attributed to the commercial fishing during the early 1930s, before deep water species were properly analysed. The deepwater cisco was abundant before the 1900s as, before large-scale commercial fishing commenced in Lake Michigan, the larger ciscoes had no natural predators. It was not until the 1930s that the species was subject to commercial fishing exploitation. The deepwater cisco, also known as chubs in fishing terms, was prized for its larger-than-normal size. During this exploitation, the numbers of this species declined dramatically. The last deepwater cisco specimens were recorded in Lake Michigan in 1951 and Lake Huron in 1952. The species was declared extinct shortly after. When a re-evaluation was conducted in several states bordering Lake Michigan in the 1960s, there were no identifiable specimens of the deepwater cisco in any of the samplings. This served to confirm its extinction, caused by a combination of commercial fishing and invasive predators such as the sea lamprey.

References

* Smith S.H. 1964. Status of the Deepwater Cisco Population of Lake Michigan. Transactions of the American Fisheries Society 93:155–163. Available from Deepwater Cisco (accessed April 19, 2018). * Parker B.J. 1989. Status of the Deepwater Cisco, Coregonus johannae, in Canada. Canadian Field-Naturalist 103:168–170. Available from Deepwater Cisco (accessed February 15, 2018). * * {{Taxonbar, from=Q139371 Fish described in 1910 Coregonus Extinct animals of the United States Fish of North America becoming extinct since 1500