A freshwater fish belonging to the salmon and trout family, the fish (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).
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 fish 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).
The Lake Bourget population of the fish 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).
Diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans (whales, dolphins and porpoises).
Of the stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Etheridge, E.C. (2009) Aspects of the conservation biology of Coregonus lavaretus in Britain. Ph.D. Thesis, University of Glasgow, Scotland.
Kottelat, M. and Freyhof, J. (2007) Handbook of European Freshwater Fishes. Publications Kottelat, Cornol, Switzerland.
Stich, H. and Maier, G. (2006) Enumeration of prey items in stomachs of European whitefish which contain digested fragments. Limnologica - Ecology and Management of Inland Waters, 36: 138-142.
Aronsuu, K. and Huhmarniemi, A. (2004) Changes in the European whitefish population of the Kalajoki - potential consequences of the alterations of fishing patterns in the Gulf of Bothnia. Annales Zoologici Fennici, 41: 195-204.
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