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Individual growth rates of pikeperch (Sander lucioperca) depending on water exchange rates in recirculating aquaculture systems

Steinberg, Kathrin, Zimmermann, Jan, Meyer, Stefan, Schulz, Carsten
Aquaculture international 2019 v.27 no.4 pp. 1025-1035
Sander lucioperca, body composition, equations, farmed fish, growth curves, growth models, lipid content, rearing, recirculating aquaculture systems, specific growth rate
The main focus of recirculating aquaculture systems (RAS) is to achieve the highest possible growth rates of the cultured fish at lowest possible cost implications. Growth rates of fish are species- and life stage–specific. Detailed knowledge on the growth rates of the reared species is thus indispensable. Commercial culture of pikeperch (Sander lucioperca) in RAS has been growing for the last decades, but knowledge on growth rates is still scarce. The aim of the study was to closely monitor the growth rates of pikeperch in RAS for a total of 98 feeding days. Three common water exchange rates (1000 L kg feed⁻¹, 500 L kg feed⁻¹ and 200 L kg feed⁻¹) were used to simulate different intensities of RAS and evaluate the effect on individual pikeperch from 250 g onwards. Pikeperch were tagged individually and weighted every 2 to 3 weeks. Whole body composition was analysed after 56 and 98 feeding days. The water exchange rate did not show a significant effect on the individual fish. Detailed information on individual pikeperch showed that 75% of pikeperch experienced low or even negative growth during at least one of the time periods. The body composition analysis showed similar results among all treatment groups with slight increases in lipid content at the end of the experiment. Growth of pikeperch in the monitored weight range (191.9–603.1 g) was neither linear nor exponential but indicates a sigmoidal shape. The equation for the average growth of pikeperch within this experiment was y = − 0.012 ± 0.004 x² + 3.21 ± 0.33 x + 249.76 ± 5.27 with an R² of 0.53. Based on this equation, pikeperch would experience positive growth in average until day 134 (ranging between day 90 and day 221) of the experiment. The average absolute growth rate among all fish over the whole experimental time period was 1.79 ± 1.00 g day⁻¹, and the average specific growth rate was 0.52 ± 0.26% day⁻¹. Further studies on a wider weight range need to be conducted in order to evaluate the shape of the overall growth curve and determine pikeperch-specific growth models for RAS.