Size Preference of Live Fish Prey in the Pellet-Consuming Pikeperch

Abstract

The production of pikeperch in a recirculation aquaculture system (RAS) is of growing importance. However, the use of combined technologies may also be justified, especially in countries with larger pond areas. However, this requires the most effective adaptation of pellet-consuming individuals to pond conditions. Foraging training, a form of environmental enrichment to compensate for the poor environment in hatchery rearing, can play a major role in this. The aim of our study was to investigate the prey size preference already observed in wild pikeperch, during prey capture by intensively reared naive individuals. We investigated predation success, latency, number of attempts during the process, and size distribution, in a total of 152 foraging trials of 38 pikeperch fingerlings (mean TL = 90.65 mm) at three different prey sizes (predator–prey length ratio (PPR): 0.11, 0.22, 0.33). Although predation on medium–large prey was more successful overall, it was achieved in more attempts and with greater latency. Small prey was captured with the fewest attempts. These results suggest that when calculating prey size in the foraging training of pikeperch, it is recommended to use a 0.11–0.22 PPR less than the optimal PPR described for wild individuals.

Reproduction of Hatchery-Reared Pike-Perch (Sander lucioperca) Fed Diet with Low-Marine-Ingredients: Role of Dietary Fatty Acids

“…However, in a study performed in 2017, the reproductive potential of wild and hatchery pike-perch broodstock fed forage fish high in ARA [10] was assessed. Although this study can have substantial implications in evaluating the role of fish physiology and/or feeding history in reproductive efficiency, it does not account for the lower feeding efficacy of F1 broodstock in comparison to F0 fish, due to different cognition and preying capacities between the two fish populations [11,12] Anyway, it indicated the potentially lower intrinsic capacity of F1 fish to accumulate ARA in oocytes. This finding was further confirmed when hatchery fish were fed with feed enriched with ARA at the same percentage as was present in live feed [13].…”