Deepwater cisco

The deepwater cisco, Coregonus johannae, was one of the largest ciscoes in the Great Lakes, averaging about 30 centimeters in length and 1.0 kilogram in weight. It was found only in Lakes Huron and Michigan at depths of 50 to 150 meters, was silvery with a green or blue back, and was difficult to distinguish from other ciscoes, possibly representing the same species as the shortjaw cisco. It had fewer than 33 gill rakers, relatively long pectoral fins, and unpigmented jaws, spawned in August and September, and fed on the opossum shrimp Mysis relicta, fingernail clams, and aquatic insects. The species declined due to competition from invasive alewives, predation by sea lampreys, and commercial fishing, with the last recorded specimens taken from Lake Michigan in 1951 and Lake Huron in 1952; it is now considered extinct. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/