Figure 2. Development of perch populations in the littoral zone of study lakes from year 1990 to year 2020. a) Proprtion of perch in the study lakes, the black line shows the overall trend given by the Linear-mixed-effect model (Appendix Table S11). b) Relative density (ln-CPUE, no. of fish per 100m2 per 12h) of perch in the littoral zone of Lake Vaggatem (green) and Lake Skrukkebukta (blue) from year 1990 to year 2020. c) Relative density (ln-CPUE) of perch dependent on annual mean water-temperature (Weighted-Moving-Average, WMA, over the last two years) in Lake Skrukkebukta (blue) and Lake Vaggatem (green) in the Pasvik watercourse.