Fishways Enable Ecological Connectivity

Enabling the safe ascent and descent of fish at damming structures is vital for maintaining fish stocks at a sustainable level. Large rivers are not only used as waterways but are also important routes connecting different habitats, such as feeding or spawning grounds and winter habitats. Following the amendment of the German Federal Water Act in 2010, the federal government has therefore committed itself to preserving and restoring the ecological connectivity at the damming structures built or operated by the German Federal Waterways and Shipping Administration (WSV).

As initial analyses revealed, many barrages still lack sufficiently effective upstream and downstream fish passage facilities. The BAW and Federal Institute of Hydrology (BfG) are therefore conducting joint research and development projects on behalf of the WSV, often in cooperation with universities, to produce answers to unresolved questions relating to fishway design. What, specifically, are the shortcomings? Which aspects have to be considered when developing standardised design principles? How do flow velocity and water depth or the swimming capacity and behaviour of different fish species influence fishway dimensioning?

These questions are studied by the BAW and BfG by means of etho-hydraulic tests, field investigations on pilot facilities and physical and numerical modelling. One of the aims here is to develop new standards for upstream and downstream fishways that are adapted to the specific conditions on German federal waterways.