Effects of geographic origin on growth and food intake in Eurasian perch ( Perca fluviatilis L.) juveniles under intensive culture conditions

Abstract

Survival, growth, and food intake of Eurasian perch ( Perca fluviatilis) juveniles from different stocks originating from various geographic regions of Europe were compared under the same conditions of laboratory-scale intensive culture. In Experiment 1, four stocks originating from Italy (I), southwest (SF) and northwest (NF) France, and Belgium (B) were examined at larval and early juvenile (initial body weight, IBW=0.53 g) stages. In Experiment 2, B stock was compared to a Finnish (F) one in two trials, including small (IBW=1.26 g) and large (IBW=32 g) juveniles. In Experiment 3, small (IBW=1.29 g) and large (IBW=7.33 g) juveniles from Polish (P), F, and B stocks were examined. In Experiment 1, body weight means at hatching and survival at the end of the larval stage were significantly lower in the I and SF stocks than in the B and NF stocks. In the early juvenile stage, survival and growth rates were significantly lower in the I and SF stocks than in the B and NF ones. In Experiment 2, {early juvenile stage} survival in the F stock was significantly lower than in the B stock, partly due to a higher incidence of cannibalism. During this stage, growth rates and food intake or feed efficiency in the F and B stocks were comparable, but at the end of the juvenile stage, the F stock outperformed the B one. In Experiment 3, survival in all the three stocks was comparable both in small and large juveniles. In contrast to the higher performance of F juveniles in Experiment 2, growth rates were comparable between the B and F stocks, and fish from the P stock had the highest growth rates. The results indicate a high level of variation within and between hatchery stocks in survival rates, growth rates, and food intake. These variations depended on the geographic origin of the fish, with the lowest survival and growth potentials being in the stocks originating from the southern regions. These findings highlight the interest in evaluating growth and food consumption of different Eurasian perch stocks. Such evaluation is a necessary tool for genetic selection in improving performance in perch aquaculture.