Agrology (Sep 2023)
Parameters of pikeperch (Sander lucioperca) produced by natural spawning with further growing in tanks
Abstract
Abstract. Pikeperch is a valuable object of fisheries around the world. Accordingly, the cultivation of this species under controlled conditions is a promising direction of aquaculture development. However, the technology of its cultivation needs improvement, as there are currently certain difficulties, especially at the early stages of ontogenesis, when a transition to artificial nutrition occurs and high mortality rates are observed. Therefore, we carried out a study the results of which suggest that natural spawning allows obtaining high-quality fish seeds. Weight of pikeperch during one growing season reaches 50 g that facilitates wintering and contributes to high rates of yield from it. The experiment was carried out on age-4–6 females and age-3–5 males, selected according to their outer appearance. The average individual body weight of the females was 2.4 kg and such of males was 2.0 kg. At the same time, females were characterized by a more slender body and a higher body weight than the males, but these differences were insignificant. According to the results of work with the brood fish, 810.7 kg of juvenile pikeperch were harvested from spawning ponds. They were characterized by the average body weight ranging 2.41 g to 2.50 g and the Fulton’s condition factor measuring 3.5. The industrial fecundity of females based on the output of 3-week-old fry amounted to the average of 43.5 thousand ind. per female. According to the test catches, the highest body weight was observed in young-of-the-years, grown at the stocking density of 2.5 thousand ind./m2 (second experimental group). They also had the highest rate of daily weight gain, exceeding such in the other experimental groups, 18.2% in the first and 2.7% in the second, with the stocking densities of 1.5 thousand ind./m2 and 2.0 thousand ind./m2, respectively. In general, the dynamics of daily weigh gain in all experimental groups was progressing, measuring 0.05‒0.10 g in the first 50 days of cultivation and 0.20–1.04 in the following days (from the middle to the end of the experiment). The absolute and relative weight gains confirm the obtained results. In particular, the minimum values of the absolute weight gain of pikeperch were recorded in the first half of the experiment. However, the relative increase did not have a clear trend in the experimental groups. In the first experimental group, a clear peak (32.5–39.0%) of the weigh gain was observed on days 67–85 of cultivation with a decline (29.1‒15.3%) starting from day 99 until the end of the growing season. At the same time, similar growth peaks were not recorded in the second and third experimental groups. By contrast, there was a decline on day 67, increasing to 30% on day 71, and further having a tendency to decrease until the end of the season. The highest individual weight and absolute weigh gain were recorded in the second and third experimental groups, where the maximum fish productivity was achieved from 1 m2, being 61.2 and 78.8 kg, respectively. At the same time, the survival rate, which is important for aquaculture conditions, was lower in these two groups than such in the first experimental group, 1.6% and 1.4%, respectively. Thus, the results of our study can help in ensuring the availability of high-quality pikeperch seeds, which in turn would be positive for both the consumer market of fish products and the state of native fish populations.
