Introduction
Pikeperch is a well-appreciated freshwater fish, due to its nutritional value and palatability (Péter et al, 2023). The rearing of these species in Recirculating Aquaculture System (RAS) is not optimized due to the maintenance of high-water quality and high fish stress levels, which causes an overall decrease in production (Thomas et al., 2020). It has been reported that pikeperch is susceptible to changing conditions, given its high basal cortisol levels, and the duration of its recovery period (Baekelandt et al., 2019; Pourhosein-Sarameh et al., 2013; Pourhosein-Sarameh & Falahatkar, 2024).
The transfer from one tank to another is a source of stress and a necessary step duringthe rearing of this species. To minimize the stress caused by this process, assessing the shortest acclimatation time is key. Therefore, the aim of this study was to test the effect of transferring two sizes of juvenile pikeperch into different tanks on length of acclimatation period, survival, growth, oxidative stress, blood biochemistry to identify the optimal juvenile size to perform the transfer.
Materials and methods
In total, 2700 juveniles for each group as: on-growing with total length (TL) = 161.4 ± 10.4 mm and body weight (BW) 27.2 ± 7.2 g, and early grown-out with TL = 242.1 ± 18.87 mm, BW = 104.1 ± 14.7 g were cultured 3 months before the transfer in three 1.5 m3 tanks connected to an experimental 30 m3 RAS. Three fish per tank were sacrificed and sampled one day before transfer. Fish were transferred manually using nets from three tanks to seven tanks connected with the same RAS.
Three samples per tank were collected immediately after the transfer (T), one day post transfer (1DPT), 7 days post transfer (7DPT), 21 days post transfer (21DPT), 35 days post transfer (35DPT) and 49 days post transfer (49DPT). Samples of blood, brain, gill, liver and kidney were taken for evaluation of blood profile and biochemisry oxidative stress and antioxidant enzymes. The required time for acclimation of each category was assessed by the comparison of founded values with optimal values of each parameter for pikeperch which were mainly published by Kolářová and Velíšek (2012). This procedure was repeated twice for each experimental group.
Results
Cortisol, glucose, lactate and ammonia presented significantly higher concentrations until 35DPT for on-growing and until 7DPT for grown-out. On-growing individuals required 35 days to eliminate oxidative stress in brain, gill, liver and kidney, in contrast to grown-out group, which took 7 days.
Larger individuals exhibit equivalent levels of stress sensitivity yet demonstrate a more abbreviated acclimatization phase. This suggests that the optimal timing of the transfer process can be determined through strategic selection.
Discussion
Previous results (Baekelandt et al., 2019; Ende et al., 2021; Malinovskyi et al., 2020), aligns with the fact that pikeperch is a highly sensitive species. (Kozłowski & Piotrowska, 2024; Pourhosein-Sarameh & Falahatkar, 2024). Size seems to be a factor that infuences in the acclimatization period. Recent research has further established differences in stress response between wild and pond-reared pikeprch juvenile (W = 16g) during transfer (Péter et al., 2023). Other parameters such as domestication process of the broodstock, life cycle and individual physiology influences acclimatization period (Falahatkar et al., 2025).
Acknowledgements
The study was supported by the Ministry of Agriculture of the Czech Republic, project NAZV QL25020009.
References
Baekelandt, S., Mandiki, S. N. M., & Kestemont, P. (2019). Are cortisol and melatonin involved in the immune modulation by the light environment in pike perch Sander lucioperca? Journal of Pineal Research, 67(1). https://doi.org/10.1111/jpi.12573
Ende, S. S. W., Larceva, E., Bögner, M., Lugert, V., Slater, M. J., & Henjes, J. (2021). Low turbidity in recirculating aquaculture systems (RAS) reduces feeding behavior and increases stress-related physiological parameters in pikeperch (Sander lucioperca) during grow-out. Translational Animal Science, 5(4). https://doi.org/10.1093/tas/txab223
Kozłowski, M., & Piotrowska, I. (2024). Effect of stocking density on growth, survival and cannibalism of juvenile pikeperch, Sander lucioperca (L.), in a recirculating aquaculture system. Aquaculture International, 32(3), 3587–3595. https://doi.org/10.1007/s10499-023-01339-6
Malinovskyi, O., Blecha, M., Křišťan, J., & Policar, T. (2020). Feeding activity of pikeperch (Sander lucioperca) under winter and spring photothermal conditions of pre-spawning period. Aquaculture Research, 51(2), 852–857. https://doi.org/10.1111/are.14401
Péter, G., Lukić, J., Brlás-Molnár, Z., Ardó, L., Horváth, Z., Rónyai, A., Bársony, P., & Ljubobratović, U. (2023). Effect of single-generation domestication of pikeperch on the performance of the offspring in conventional and pond recirculation aquaculture system. Aquaculture Reports, 32. https://doi.org/10.1016/j.aqrep.2023.101702
Pourhosein Sarameh, S., Falahatkar, B., Azari Takami, G., & Efatpanah, I. (2013). Physiological changes in male and female pikeperch Sander lucioperca (Linnaeus, 1758) subjected to different photoperiods and handling stress during the reproductive season. Fish Physiology and Biochemistry, 39(5), 1253–1266. https://doi.org/10.1007/s10695-013-9780-z
Pourhosein-Sarameh, S., & Falahatkar, B. (2024). Pikeperch (Sander lucioperca) adaptive or maladaptive reactions to environmental stressors؟ a review. In Aquaculture International (Vol. 32, Issue 5, pp. 6539–6573). Springer Science and Business Media Deutschland GmbH. https://doi.org/10.1007/s10499-024-01478-4
Thomas, M., Lecocq, T., Abregal, C., Nahon, S., Aubin, J., Jaeger, C., Wilfart, A., Schaeffer, L., Ledoré, Y., Puillet, L., & Pasquet, A. (2020). The effects of polyculture on behaviour and production of pikeperch in recirculation systems. Aquaculture Reports, 17. https://doi.org/10.1016/j.aqrep.2020.100333