Department Fish Ecology and Evolution

During the last century, Switzerland has drastically modified its rivers for electricity production and flood prevention. This has led to habitat fragmentation and disruption of fish migration. Consequently, species such as salmon and sturgeon that migrate between freshwaters and the ocean have gone extinct. Barriers in the rivers are also a major challenge to species moving between different freshwater habitats during their lives. Cold-water species are further facing severe negative effects by rising temperatures. To balance energy production and fish movement under a changing climate, knowledge about timing, routes and accessibility to cold-water refugia of different riverine fish species is needed.

In this project, we build an acoustic receiver network in the Rhine-Aare River network. We tag and track several of the most important and vulnerable fish species for several years under changing environmental conditions like rising temperatures. This project will thereby create needed knowledge on large-scale migration patterns to aid the decision-making regarding hydropower mitigation. More, this project will identify species-specific ultimate barriers and accessibility to cold-water refugia during heat waves.

The hydrophone network will remain open to different stakeholders. The telemetry network will further be part of the European & the Ocean Tracking Network enabling tracking across borders.

• Jan Reubens, Flanders Marine Institute, VLIZ, Belgium:
• Henrik Baktoft, Danish Technical University, DTU-Aqua Denmark
• Karl Øystein Gjelland, Norwegian Institute of Nature Research, NINA, Norway
• Luiz Gustavo Martins da Silva, Department Bau, Umwelt & Geomatik, ETH Zürich