The starting point
Due to the increasing pollution of the waters and the displacement of the brown trout, two species were "on the brink" in Rhineland-Palatinate in the early 1990s.
The brown trout (lat. Salmo trutta fario) prefers the fast and turbulent flowing, as well as oxygen-rich and summer-cold upper reaches of rivers. It is a district builder and the leading fish species of the "trout region" named after it.
The brown trout hunts its prey, predominantly insects, insect larvae living in the water, but also small fish such as minnows, gudgeons or paddocks from the cover of tree roots that protrude into the water or washed-down bank areas.
During the spawning season, which extends from late autumn to the winter months, the brown trout migrate upstream to spawn in gravelly areas, sometimes in the smaller side streams. It was found that the brown trout rises to the smallest brooks.
In the last century, the brown trout was widespread in all running waters in the trout and grayling region. Spawning areas have been lost or silted up due to water pollution and the technical expansion of small streams, as well as the entry of washed-off arable crumbs in agricultural areas, which has had a negative impact on the breeding success of brown trout and unfortunately still does. So it was no wonder that the brown trout in Rhineland-Palatinate was often found only in smaller stocks and in 1987 on the Red List
"endangered species" was recorded.
On the other hand, a decrease in the population and habitat loss was observed in the river pearl mussel as early as 1800. It was not until the end of the 1960s that intensive studies on the pearl mussel and its rapid decline in population began at several locations. In the years 1985-1987 a comprehensive inventory check of the pearl mussel stocks in the FRG was carried out. It was found that the stocks on the right bank of the Rhine had already expired and the stocks on the left bank of the Rhine only existed at 5 locations, four of which were in the Eifel and one in the Hohen Venn. In 1985 it was decided to take measures to safeguard existence.