Deepwater cisco
Encyclopedia
The deepwater cisco was one of the largest ciscoes
in the Great Lakes
. Its average length was 30cm (12 inches) and it was about 1.0 kilogram (2.2 pounds) in weight. Occurring only in Lakes Huron
and Michigan
, and inhabited 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
(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 and, because of its large size, the deepwater Cisco was heavily fished commercially.
The last specimens of deepwater ciscoes were recorded in Lake Huron in 1952 and Lake Michigan in 1951. The main reasons for its extinction were competition from the invasive alewife
and predation by the introduced sea lamprey
.
Cisco (fish)
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...
in the Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
. Its average length was 30cm (12 inches) and it was about 1.0 kilogram (2.2 pounds) in weight. Occurring only in Lakes Huron
Lake Huron
Lake Huron is one of the five Great Lakes of North America. Hydrologically, it comprises the larger portion of Lake Michigan-Huron. It is bounded on the east by the Canadian province of Ontario and on the west by the state of Michigan in the United States...
and Michigan
Lake Michigan
Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...
, and inhabited 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
Shortjaw cisco
The shortjaw cisco is a deepwater cisco or chub . It 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...
(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 and, because of its large size, the deepwater Cisco was heavily fished commercially.
The last specimens of deepwater ciscoes were recorded in Lake Huron in 1952 and Lake Michigan in 1951. The main reasons for its extinction were competition from the invasive alewife
Alewife
The alewife is a species of herring. There are anadromous and landlocked forms. The landlocked form is also called a sawbelly or mooneye...
and predation by the introduced 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...
.