18: Restoration of biodiversity. the case of the migratory fish in the river Meuse

During the 19th century, amphibiotic anadromous migratory fish (Sea lamprey Petromyzon marinus, River lamprey Lampetra fuviatilis, Sturgeon Acipenser sturio, Atlantic salmon Salmo salar, sea trout Salmon trutta, Houting Coregonus oxyrhinchus, Allis shad Alosa alosa, Twaide shad Alosa falalx) were widespread in the entire River Meuse basin and fisheries were prosperous in France, Belgium and the Netherlands. From 1800 onwards, building of navigation weirs on the River Meuse, increase of industrial pollution and overexploitation of riverine fish stocks caused the regression and extinction of these migratory fish populations (Atlantic salmon became extinct in the 1930's). The capture of several individuals of sea trout in 1983 in the Meuse at the Belgian-Dutch border triggered the idea of attempting to restore an Atlantic salmon run in the river system. 

A 'Meuse Salmon 2000' project was started in 1987 as a contribution of Wallonia to the European Year of Environment. A first facet of this programme consisted in assessing the carrying capacity of nursery streams in the Belgian Ardennes by means of experimental reintroduction stockings (with fish from Scottish, Irish and French origin) into selected salmonid streams in order to demonstrate the good ecological quality of these habitats. The second, most difficult and expensive facet of the programme focused on the restoration of the fluvial continuity and the free circulation for upstream migrating adult fish. In 1998-2001, modern fish passes have been built at three navigation weirs on the Belgian Meuse between the Belgian-Dutch border and Liège, complementing a series of new fishways constructed since 1989 at five of the seven weirs obstructing the Dutch Meuse. Since 2000, the International Commission for the Protection of the Meuse has been coordinating actions towards restoring the free circulation (upstream and downstream) of Atlantic salmon and other amphibiotic species such as sea trout and European eel (Anguilla anguilla) in the River Meuse basin including the French upper course. 

This communication reports on the long genesis, wide partnership, first successful results (73 new Meuse salmon recorded in the Dutch Meuse since 1994; one salmon radio-tracked in Liège by the end of 1999), and great future ecological prospects (recovery of other anadromous migratory fish) of that historical operation which is on the way of restablishing the presence of S. salar in the Belgian Meuse about seventy years after it became extinct.