Ordination plots of sample distribution after principal component analysis (PCA) of functional traits as response variables (A) and redundancy analysis (RDA) (B) of functional traits as response variables and weight of sheatfish, Silurus glanis as explanatory variable. N+skin = nitrogen concentration in fillet with skin, N-skin = nitrogen concentration in fillet without skin, Fat+skin = fat percentage in fillet with skin, Fat-skin = fat percentage in fillet without skin, Weight = body weight of individual fish; abbreviations used in legend: S = spring sampling, A = autumn sampling). The length of the arrow reflects the power of the variable to differentiate the samples.