Gravenche

Gravenche (Coregonus hiemalis )

The Gravenche (Coregonus hiemalis ), locally referred to as Small Fera or whitefish, is probably extinct freshwater fish from Lake Geneva. The name Kilch however, is not only used for this type, but for several congeneric taxa of the Alpine foothills lakes.

System

The taxonomic status of Gravenche is controversial, as there are no preserved specimens in museums. In 1959, he was seen by Emile Dottrens as a subspecies of Lavarets (Coregonus lavaretus ). However, other experts, including Maurice Kottelat and Jörg Freyhof, Coregonus hiemalis regarded as an endemic in the Lake Geneva, an independent art

Description

The Gravenche resembled the transitional fish. It reached a total length of 25 to 32 inches. The eye diameter was 18 to 22 percent of the head length. There were 25 to 33 gill rakers. The back was bent. The dorsal head profile and the muzzle was rounded. Her head was thick and the fins were relatively longer than in the FERA. Your caudal fin was cut less deep.

Way of life

The Gravenche had a benthopelagic mode of life, that is, that they mostly stayed near the ground. She felt at great depths and fed on zooplankton. The spawning season was mid-December.

Dissemination

The Gravenche is or was endemic in the deep water areas of Lake Geneva. Older literature call for Coregonus hiemalis the Ammersee, Chiemsee and Lake Constance. However, these are more related to the Ammersee whitefish (Coregonus bavaricus ), the Chiemsee whitefish (Coregonus sp.) And the Lake Constance whitefish (Coregonus gutturosus )

Extinction

Together with the also considered to be extinct Fera (Coregonus fera ) was one of the Gravenche of the most caught food fish of Lake Geneva. Around the year 1890 the quota of these two types accounted for 68% of all fish caught in the Lake Geneva. Overfishing made ​​sure that she was already extremely rare in the 1920s and has not been detected since 1950.