The control stations register fish that come up the rivers to spawn, e.g. salmon and sea trout, but also local migratory fish species like nase and barbel.
The work done at the control stations makes it possible to come to definite conclusions on the success of current measures for the protection and development of the waterways. The more fish return and succeed in spawning, the closer we come to the goal of intact and natural water bodies in NRW.
At present there are three control stations operating: