Department Fish Ecology and Evolution

Projet Lac

An assessment of the Swiss fish fauna

Almost two-thirds of the native fish species of Switzerland are threatened by extinction. To preserve or specifically enhance aquatic biodiversity and habitats, a representative assessment of the existing species in lakes is necessary. Eawag and its partners, the Federal Office for the Environment (FOEN), cantonal fisheries authorities and the Office National des eaux et des milieux aquatiques (ONEMA), Fédération de pêche Doubs et du Jura in France, perform through Projet Lac for the first time a standardized assessment of the fish fauna of Alpine lakes with a special focus on deep and large lakes.


Projet Lac is an important research project, but it also provides important data for management. The objectives of Projet Lac are defined as follows

  • Assessment of biodiversity and intraspecific diversity of fish in Alpine lakes
  • To analyze and evaluate current and historical environmental data to identify key factors that influence the development of biodiversity
  • Contributions to a national strategy for fish monitoring in lakes
  • Establishment of a reference collection at the Natural History Museum of Bern as a basis for future research
  • Publication of scientific discoveries in ecology and evolutionary research
  • Convergence of research and management in the field of biodiversity conservation and management of fish stocks
  • Providing data on the current ecological status of the lakes studied with special emphasis on fish stocks

Synthesis report

You will find the synthese report here 


Spatially randomized fishing efforts

Vertical and horizontal multi-mesh nets (= nets with different normalized mesh sizes) are set in accordance with the EU Water Framework Directive in all depths. Thus, the results from the "Projet Lac" are comparable to those of EU member countries.


All fish caught are measured, weighed and photographed for morphological measurements. In addition, special features are described and tissue samples are taken for genetic and ecological analyses. All data are stored in a database, which is coordinated with the Swiss Centre for Cartography of Fauna. Upon completion of the "Projet Lac", all data will be freely accessible.

Reference collection

At least 30 individuals per species per lake are prepared for long-term storage at the Natural History Museum of Bern. These specimens will thereby be available for future research projects.


Hydroacoustic surveys are performed both during day and night. These investigations are performed in regular transects. This makes it possible to estimate the fish biomass without catching fish.


One goal of Projet Lac is to publish the results in the form of publications in scientific journals, and in reports to cantonal authorities. In addition, the main findings will be presented to the public.

Jardim de Queiroz, L.; Doenz, C. J.; Altermatt, F.; Alther, R.; Borko, Š.; Brodersen, J.; Gossner, M. M.; Graham, C.; Matthews, B.; McFadden, I. R.; Pellissier, L.; Schmitt, T.; Selz, O. M.; Villalba, S.; Rüber, L.; Zimmermann, N. E.; Seehausen, O. (2022) Climate, immigration and speciation shape terrestrial and aquatic biodiversity in the European Alps, Proceedings of the Royal Society B: Biological Sciences, 289(1980), 20221020 (10 pp.), doi:10.1098/rspb.2022.1020, Institutional Repository
Alexander, T.; Seehausen, O. (2021) Diversity, distribution and community composition of fish in perialpine lakes. "Projet Lac" synthesis report, 284 p, doi:10.55408/eawag:24051, Institutional Repository
Doenz, C. J.; Bittner, D.; Vonlanthen, P.; Wagner, C. E.; Seehausen, O. (2018) Rapid buildup of sympatric species diversity in Alpine whitefish, Ecology and Evolution, 8(18), 9398-9412, doi:10.1002/ece3.4375, Institutional Repository
Alexander, T. J.; Vonlanthen, P.; Seehausen, O. (2017) Does eutrophication-driven evolution change aquatic ecosystems?, Philosophical Transactions of the Royal Society B: Biological Sciences, 372(1712), 20160041 (10 pp.), doi:10.1098/rstb.2016.0041, Institutional Repository
Alexander, T. J.; Vonlanthen, P.; Périat, G.; Degiorgi, F.; Raymond, J. C.; Seehausen, O. (2015) Estimating whole-lake fish catch per unit effort, Fisheries Research, 172, 287-303, doi:10.1016/j.fishres.2015.07.024, Institutional Repository
Alexander, T. J.; Vonlanthen, P.; Périat, G.; Degiorgi, F.; Raymond, J.-C.; Seehausen, O. (2015) Evaluating gillnetting protocols to characterize lacustrine fish communities, Fisheries Research, 161, 320-329, doi:10.1016/j.fishres.2014.08.009, Institutional Repository