Statistical analysis of the somatic growth rate of 0+ fish in relation to temperature under natural conditions

The somatic growth rate of 0+ fish of the six major species in Dutch shallow eutrophic lakes, bream (Abramis brama), roach (Rutilus rutilus), pikeperch (Stizostedion lucioperca) (planktivorous and piscivorous), perch (Perca fluviatilis), ruffe (Gymnocephalus cernuus), and smelt (Osmerus eperlanus), was analysed by using a differential equation. This equation models the instantaneous growth rate of a fish as a temperature-dependent power function of body weight. Two of the model parameters were calibrated by optimising the prediction of the growth rate of the fish. Using a new method, which included a parametric bootstrap procedure, confidence limits were estimated for these two calibrated parameters and were used to test the significance of differences between species in growth performance under natural conditions. These tests revealed four groups of species: (A) smelt, (B) roach and bream, (C) ruffe and perch, and (D) piscivorous pikeperch. Growth performance of planktivorous pikeperch mainly overlapped with roach and bream (B) but showed some overlap with ruffe and perch (C). Differences and similarities are explained from the food type (D Versus A, B, and C) and the phylogenetic constraints (A versus B versus C) of each species. [KEYWORDS: Shallow eutrophic lake; rutilus-rutilus; salmo-trutta; brown trout; body-size; tjeukemeer; patterns; bream; roach; life]