....at migrationsobstacles is a very important instrument to proof the migrationactivities and chances for the waterorganism. Both upstream and downstream migration should be examined. Only examination leads to validation and thus proposals for improvements may be derived from the results.

.Functionscontrol on the maeanderfishway in Drakenburg/Weser in  (April 2002)
 

At the rivers Aller, Oker und Schunter ther have been done some function controls at  Hedwigsburg, Rueningen, Rothemuehle, Meinersen and Mueden. Furthermore there is a planning for a permanent controll- and informationstation in Meinersen at the river Oker .
 

In the sense of a real rivermanagement there should be scientific function controls from the estuary to the upper reaches of the rivers on upward and downward movements. The hope about riversections to be passed by the fishes should be replaced by the knowledge of examinations.  
Welldone function controls are good arguments for improvements on migration obstacles.

Devices behind downstream fishways and powerstations may deliver essential argumentationbase. And both functionanalysis and damage statements can be made by using such devices.