Float-way restoration in northern Scandinavia, effects on juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta)

Anthropogenic activities that causes degradation of freshwater habitats is one of the main factors causing worldwide population reductions of stream dwelling salmonids. In Scandinavia, the construction of float-ways during the timber-floating era, 1850-1970, caused large physical alterations of fresh water habitats. At the end of the timber floating era, 1980's, the issue about stream ecology, production of salmonids and the need for restoration of float-ways was raised, which resulted in numerous restoration attempts. The main goal was to enhance the abundance of Atlantic salmon and brown trout. The major restoration actions applied were restoration of migration routes, and of spawning, nursery and rearing habitats. Restoration of float-ways and biological recovery of stream dwelling salmonids have received little scientific attention and hence, the effect of restoration remains largely unclear. Due to lack of proper sampling methods for stream dwelling fish, evaluations of restoration efforts on the whole fish community have been hard to conduct. However, according to our present knowledge about freshwater habitat requirements restoration of float-ways should benefit salmonid populations. Due to lack of historic information about natural fish abundance exact goals of restoration has been difficult to define