Lavaret  (Coregonus lavaretus)

Classified as Vulnerable (VU) on the IUCN Red List (1).

A freshwater fish belonging to the salmon and trout family, the lavaret (Coregonus lavaretus) has a typical salmon-like appearance and is distinguished from other species by its distinctive, protruding upper jaw (1). The lavaret varies from olive-green to light brownish-grey, with silver sides and a white underside. The species has a distinctive sail-like caudal fin containing 19 soft rays. The body of the lavaret is elongated, with a linear scale pattern visible on the flank of the fish running from the gills to the dorsal fin (2).

Interestingly the classification of this species is controversial. The name Coregonus lavaretus has been used for nearly all Eurasian members of the genus at some point in history and its current classification is under review (3) (4).

The lavaret is native to the Swiss-French border, where it was originally found in Lake Bourget and Lake Aiguebelette in France, and Lake Geneva in Switzerland. Unfortunately the population in Lake Geneva is now extinct (1) (2). The lavaret has also been introduced into many pre-alpine lakes and much of Eastern Europe and Russia due to the commercial value of the species (4) (5) (6).

Most commonly, the lavaret occurs in permanent, deep, freshwater lakes over eight hectares in size (2). A shallow gravel area, preferably near shore, is necessary for the fish to spawn (2).

The species has also been known to inhabit brackish water in river estuaries but is rarely found in full salt-water (1).

When found in freshwater lakes, the lavaret is a social species and is usually found in open water shoals (3). It feeds almost exclusively on insect larvae and crustaceans (2). Populations inhabiting brackish water, feed on larger crustaceans that inhabit the riverbed (1).

For most of the year, the lavaret lives near the bottom of the lake. However, when spawning occurs in December, individuals migrate to gravelly shallows near shore, on which the female deposits its eggs. This process normally occurs at night. The eggs are fertilised externally and are left to develop at the bottom of the lake, with the larval stage lasting 19 days (2).

The Lake Bourget population of the lavaret has no known threats, and the reasons for extinction of this species in Lake Geneva are unknown. However, the introduction of non-native invasive fish species is a potential threat (1). There is also the threat of overfishing as the lavaret is fished commercially as a food source (6).

The lavaret is abundant in Lake Bourget, and therefore there are no current conservation measures in place for this species (1).

Learn more about the lavaret:

• IUCN Red List - Lavaret:
  http://www.iucnredlist.org/apps/redlist/details/5369/0