Similar to the river lamprey, salmon is also an anadromous migratory fish, i.e. the reproduction occurs in the early autumn and early winter in fresh water in the upper reaches of rivers, whereas the food sources of adult fish are located in the sea. The eggs are laid in spawning pits, which are dug by females. Sufficient oxygen supply is of crucial importance for successful development. After they hatch, small salmons begin their search after the zones of fast-flowing water in the vicinity of the spawning pits, where they spend their first summer and autumn of their life. Each of the small salmons builds its own territory and defends it against its species-fellows. After 1-2 years in the fresh water, the salmons change: they form shoals and migrate downstream to the marine areas of North Atlantic. In this stage they are also called smolts. After 1-4 years spent in the sea, the salmons go back to their spawning waters as sexually mature animals with the considerable size of 60 to over 100 cm.

Atlantic salmon was widely spread earlier in the catchment area of Weser, Werra and Fulda. Until the beginning of the 20th century, up to 4000 ascending salmons were caught annually by the Hamelin dam. In Werra, Ulster and Schleuse the salmons have ascended up to the grayling regions.

With increasing anthropogenic river use, e.g. through the building of impoundments and dams, construction of navigation ways and pressures on water through pollutants, nutrients and, not least, high salt concentrations, salmon had died out during the 1920's in the Weser river catchment area. Due to the increasing improvement of the water quality, significant importance is attached also to the optimization of the water structure. Reestablishment of the migration routes continuity between the marine areas and original spawning and nursery waters represents a necessary prerequisite for salmon primarily in regard to its repopulation. Atlantic salmon was the fish of the year 2000.

Foto: Dr. Bernd Stemmer