Nursing of Pike-Perch (Sander lucioperca) in Recirculating Aquaculture System (RAS) Provides Growth Advantage in Juvenile Growth Phase

Abstract

This study aimed to estimate the efficacy of two pike-perch juvenile production technologies: exclusive Recirculating Aquaculture System (RAS) culture (the RAS group) and pond larviculture with a transfer to the RAS at the 42nd day post-hatch (DPH). Both direct weaning on dry feed (the Pond-D group) and 10-day gradual weaning using bloodworms (the Pond-B group) after transfer to the RAS were evaluated in pond-nursed fry. Their survival and morphometric indices were monitored after the RAS habituation period (first 10 days), after the 18-day post-habituation period and after an additional 30 days of on-grow. Our results indicate a negative allometric growth of the pond-nursed fish during the nursing period, which was slower (p < 0.0001) in comparison to the RAS-nursed fry (16.3 ± 0.4 vs. 17.8 ± 0.7%/day). After transfer, these fish grew faster than the RAS-nursed fry (7.7 ± 0.1, 4.9 ± 0.5 and 6.1 ± 0.6 during habituation, 8.5 ± 0.6, 9.3 ± 0.5 and 6.7 ± 0.1%/day during post-habituation period, in the Pond-B, Pond-D and RAS groups, respectively). However, four weeks afterwards, the RAS-nursed fry were again superior in terms of growth (4.0 ± 0.1, 3.6 ± 0.2 and 4.6 ± 0.2%/day, for the Pond-B, Pond-D and RAS groups, respectively), and this was accompanied by a significantly lower feed conversion ratio in this group. Although the survival of the RAS-nursed fry during the nursing period was lower in comparison to the pond-reared fry (11.3 vs. 67.3%), the RAS seems to provide a long-term growth advantage.

Dynamics of Fatty Acids in Pikeperch (Sander lucioperca) Larvae and Juveniles during Early Rearing and Weaning in a Commercial RAS—Implications for Dietary Refinement

“…The present study analyzed the growth and fatty acid composition of conventionally reared pikeperch larvae during their first 56 days post hatch. The observed growth was comparable to growth rates described in the literature, such as Colchen et al (2020) [22], who described SGRs of 16.9 ± 1.7%•d −1 , or Péter et al (2023) [23], who described 17.8 ± 0.7%•d −1 , but exceeding other studies where SGRs were ranging between 0.8 and 3.0%•d −1 (Ballesteros et al, 2023) [24] and 0.9 and 4.1%•d −1 (Bischoff and Kubitz et al, 2022) [25]. Consequently, the sampled pikeperch larvae performed according to other studies, also mainly based on Artemia as first life feed.…”

“…However, this data comparison should be considered carefully and together with the survival rates as well as other parameters, such as the condition index, which shows already a strong variation for the first 13 days of larval development, which indicates a possible lack of nutrients very early post hatch. The survival rates of 7.9 ± 3.5% per tank described by Colchen et al (2020) [22] and 11.3% by Péter et al (2023) [23] were rather low survival rates compared to the survival rates ranging from 64.0 to 93.7% by Ballesteros et al (2023) [24] and up to 94.0% by Bischoff and Kubitz et al (2022) [25]. Therefore, we hypothesize that a low survival rate might lead to growth rates that do not represent the whole population but rather the small group of survivors, which are strong and fast-growing.…”

Evaluation of Post-Larval Diets for Indoor Weaned Largemouth Bass (Micropterus salmoides)

“…of the average values of three tanks (n = 3, one tank = the average value of the representative sample of 18 fish). Calculations of Specific Growth Rates (SGR), allometric coefficient (b), relative condition factor (Kn), and FCR were carried out as explained previously [6]. Survival and skeletal deformity rates were calculated as the percent of surviving and deformed fish out of the initial 60 fish per tank.…”

“…This MUFA/PUFA balance additionally affects fish survival, which is also influenced by feed fat content and protein quality (4), as well as the carbohydrate content of the diet (5). Skeletal development is negatively affected by the amount of dietary fiber (6), and it positively affects fish survival (7). On the other side, feed moisture percent improves fish growth rate (8), while the addition of probiotics to the diet improves FCR (9).…”

“…This raises several issues in terms of economic viability: first, the vast space occupied, and second, the shortened grow-out and fattening phases. In addition, a recent study has shown that indoor larviculture of pike-perch may bring significant benefits for its growth in later life stages [6]. Thus, the establishment of indoor LMB larviculture can be deemed critical for the introduction of LMB farming in Europe.…”