The reconstruction of an Atlantic salmon population in the Belgian River Meuse basin. First success and new threats.

A 'Meuse Salmon' project aiming at restoring an Atlantic salmon run in the River Meuse basin was put forward in 1983 (after the discovery of several 'sea trout' in the Meuse near Liège) and started officially in 1987 as a contribution of Wallonia to the European Year of Environment. In the course of this programme, most dams (3-8 m in height) obstructing the canalised River Meuse in Belgium and The Netherlands have been fitted with modern fish-ways in order to restore the free circulation of diadromous fish species. A second facet of the Salmon Meuse programme consisted in restocking salmonid streams in the Belgian Ardennes with hatchery reared salmon parr and smolt (maximum 200.000 fish per year) from foreign origins (Scotland, Ireland and France). Returning adult salmon have been scientifically recorded in the Meuse in The Netherlands (estuary and lower course) since 1994 but only since the year 2002 in Belgium: 13 (61-79 cm FL) fish in 2002 and 2 (71-76 cm FL) fish in 2003 caught mostly (13 fish) in a new big fish-pass at the Visé-Lixhe dam and (2 fish) in the River Berwinne, a small tributary of the Meuse known as the last spawning place for S. salar in Belgium in the 1920's. Female and male returning salmon in 2002 were successfully artificially reproduced in order to build a captive freshwater brood stock to be used for production of parrs and smolts of the new Meuse strain next autumn. The communication briefly reports on the progress of the program as concerns the salmon culture for stocking in Wallonia, the population dynamics of stocked parrs in nursery rivers, the patterns of upstream and downstream migration of salmon in the Belgian Meuse and its tributaries and the new challenges to meet (impact on salmon of rising water temperature, development of power generation, increasing predation on smolts by piscivorous birds).