Effect of single-generation domestication of pikeperch on the performance of the offspring in conventional and pond recirculation aquaculture system

Pikeperch aquaculture technologies have significantly improved, yet knowledge regarding the adaptation of pikeperch to captivity is very scarce. This study aimed to evaluate the survival, growth, stress response, and immune system function of the F2 generation of pikeperch subjected to pond nursing - Recirculating Aquaculture System (RAS) dry feed adaptation, with either RAS or pond grow-out. F2 generation in this research originated from the broodstock reared in the pond system during grow-out, while F1 originated from wild breeders. Critical points in fish growth were analyzed, including transport of pond-nursed juveniles to RAS at 42 DPH, dry feed habituation (42-52 DPH) and post-habituation (52-64 DPH) phase, as well as the on-grow/grow-out (64-154 DPH) phase. Our results showed better growth and survival of the F2 generation in comparison to F1 in pond grow-out. However, the F1 generation was superior in conventional RAS grow-out. Nevertheless, during RAS dry feed habituation, F1 fish were inferior, both in terms of growth and survival, in comparison to F2 fish. Stress and immunological marker analysis revealed higher stress sensitivity, accompanied by stronger immune system activation, in F2 generation in comparison to F1. This was manifested as higher cortisol and immunoglobulin response after moving fish from one system to another. Hypothetically, stronger stress and immune response might have induced better dry feed adaptation during the habituation phase in RAS, and better control of microbial growth in the grow-out environment with a higher microbial load, such as pond. On the other hand, according to the same hypothesis, in a cleaner grow-out environment such as RAS, fish with a weaker cortisol and immunological response would be at an advantage, since these fish are expected to have a richer intestinal microbiota that would eventually support better food digestion and growth. Assumed selection points shaping pikeperch response to farming have been discussed.