Deepwater cisco

Coregonus johannae (English name: Deepwater cisco) is an extinct North American freshwater fish.

Description

Coregonus johannae was one of the largest whitefish in the Great Lakes. Their average length was 29 cm, weight about 680 grams. From other whitefish they differed by their relatively long pectoral fins and their unpigmented jaw. Furthermore, they had 27 to 32 short gill rakers on the first gill arch. The color of the shed was silvery with a delicate pink or purple tinge. The back was greenish or bluish. The belly was white.

Occurrence

Coregonus johannae came at depths from 50 to 160 m in front of Lake Huron and Lake Michigan.

Lifestyle and food

The spawning season was in late summer from mid-August to late September. The main diet consisted of small crabs and clams as Mysis, Pisidium and Pontoporeia.

Extinction

Overfishing of Coregonus johannae began in the mid-19th century and the beginning of the 1920s, the stocks were so seriously depleted that these whitefish was extinct in much of its former distribution area. 1951, the species was recently in Lake Michigan and Lake Huron 1952 last detected in. Other reasons for their extinction were the hybridization with Coregonus hoyi (English: bloater ) and parasitism by the invasive sea lamprey.