Fishery changes during re-oligotrophication in 11 peri-alpine Swiss and French lakes over the past 30 years

Peri-alpine lakes in Switzerland and France exhibit a spectrum of intensities of eutrophication and re-oligotrophication over the past 30 years. Phosphorus inputs have been decreasing since the 1970s. TP has altered from 135 to 50 μg l−1 in the more eutrophicated lakes, and 25–2 μg l−1 in the others. Fish communities were dominated by cyprinids and perch in eutrophic lakes. During re-oligotrophication, the total yield remains nearly the same while coregonids become dominant. In oligotrophic lakes, when the TP was below 5 μg l−1, the total yield decreased rapidly, and fish production was low.