Management generačních ryb candáta obecného (Sander lucioperca) a jeho vliv na produkci jiker a larev

This thesis provides an improve to existing reproduction technics through investigation of ecology and physiology features of pikeperch broodstock: (I) Spawning behavior and selectivity to different types of spawning substrates as an important part of the biology of pikeperch species. The main output of the study was revealing of strong selectivity to the spawning site with neither water temperature nor availability of spawning places haven't affected substrate preference of pikeperch broodstock. (II) Spawning in captivity is leads to decrease in physiological status of the pikeperch broodstock, especially in females. It was found that one of the reasons of the decrease was male protective behavior, that in limited space of the reproduction unit is forwarded to female. Separation of the sexes significantly reduces number injuries and improved physiological status of the broodstock. (Ill) The study investigated efficiency of different antifungal agents for pikeperch broodstock. The long term exposure to salt bath in concentration of 2.5, 5 and 10 g L-1 and formaldehyde in concentration 0.015 ml L-1 were found to be highly effective and significantly decreased mortality after spawning. In addition, treatment with salt bath are environmentally friendly and recommended for practical use as an effective way to prevent mortality of pond-cultured pikeperch broodstock. (lV) The provision of live feed is crucially important for proper gametes maturation, particularly in pond-cultured fishes not accepting pellets. The study investigated the effect of temperature on daily biomass of prey consumed by pikeperch broodstock. Significantly increased prey consumption was found after temperature reached 4.5 °C. Females exhibited significantly higher prey consumption rate in compare to male. Study revealed the tendency for pikeperch to consume largest available prey after water temperature reached 8.5 °C

Effects of Stocking Density and Pre-Slaughter Handling on the Fillet Quality of Largemouth Bass (<i>Micropterus salmoides</i>): Implications for Fish Welfare

There is currently insufficient acknowledgment of the relationship between fish welfare and ultimate fillet quality. The purpose of this study was to assess the impacts of pre-slaughter handling and stocking density as fish welfare markers on fillet quality of largemouth bass (Micropterus salmoides). Fish from three stocking densities of 35, 50, and 65 kg·m−3 were reared in a recirculating aquaculture system (RAS) for 12 weeks and received commercial feed. Ultimately, the fish were either stunned with percussion on the head (control group) or subjected to air exposure for 3 min (anoxia group) before stunning and subsequent collection of blood and fillet samples. Western blot analysis revealed the degradation of actin in both groups. Additionally, higher oxidation progress and lower hardness and pH were observed in anoxia compared to the control group. We observed higher hardness at 35 kg·m−3 in anoxia compared to 50 and 65 km−3. The initial hardness values at 35, 50, and 65 km−3 were 1073, 841, and 813 (g) respectively in the anoxia group. Furthermore, the anoxia and control groups had rigor mortis after 6 and 10 h, respectively. Cortisol and glucose levels, and oxidative enzymes activity were higher in anoxia than in the control group. In conclusion, oxidation induced by anoxia likely plays a crucial role as a promoter of the quality deterioration of largemouth bass fillets

Use of Lactic Acid Bacteria During Pikeperch (Sander lucioperca) Larval Rearing

This trial tested the use of lactic acid bacteria (LAB) on pikeperch (Sander lucioperca) larvae during their first feeding. The trial included the use of two probiotic treatments and one control (no probiotics). Pikeperch larvae were exposed to LAB as follows: (1) the live feed (Treatment 1, live feed) or (2) via the live feed and the larval rearing water (Treatment 2, probiotic). Significant differences were found between the treatments in terms of total length (TL), myomere height (MH), overall survival, and the tolerance to a high salinity challenge. Larvae exposed to LAB via both the live feed and the rearing water had a significantly higher overall survival rate (85%) than the other two treatments at 21 dph. When both treatments were subjected to high salinity rates (18 parts per thousand (ppt)), both treatments exposed to LAB demonstrated higher survival rates than the control treatment (28% and 40% survival rate at 180 min for the live feed and probiotic treatments, respectively, as compared with a 100% mortality rate at 150 min for the control). At the same time, larvae exposed to the probiotic treatment had a significantly higher TL as compared to the control after 12 and 21 days post hatch (dph) (probiotic 7.13 &plusmn; 0.21 and 11.71 &plusmn; 1.1 mm, control 5.86 and 10.79 mm at 12 and 21 dph, respectively). The results suggest that the use of LAB in both the live feed and the rearing water has a positive effect on pikeperch larval quality by strengthening their resilience to stress conditions, as well as improving the growth and survival rates

Bioenergetic Pathways in the Sperm of an Under-Ice Spawning Fish, Burbot (Lota lota): The Role of Mitochondrial Respiration in a Varying Thermal Environment

Regarding the sperm of cold-water fish, the contributions of different bioenergetic pathways, including mitochondrial respiration, to energy production at the spawning temperature and its adaptation at the maximum critical temperature (CTmax) are unclear. The roles of glycolysis, fatty acid oxidation, oxidative phosphorylation (OXPHOS) at 4 °C, and OXPHOS at 15 °C for energy production in burbot (Lota lota) spermatozoa were studied by motility and the oxygen consumption rate (OCR) (with and without pathway inhibitors and the OXPHOS uncoupler). At both temperatures, the effects of the inhibitors and the uncoupler on the motility duration, curvilinear velocity, and track linearity were insignificant; in addition, the OCRs in activation and non-activation media differed insignificantly and were not enhanced after uncoupler treatment. After inhibitor treatment in both media, OXPHOS was insignificantly different at the 2, 30, and 60 s time points at 4 °C but was reduced significantly at the 30 and 60 s time points after treatment with sodium azide at 15 °C. In conclusion, for burbot sperm at both the spawning temperature and the CTmax, the energy synthesized via OXPHOS during motility was insufficient. Therefore, the majority of the energy required to sustain motility was derived from pre-accumulated energy produced and stored during the quiescent state of the spermatozoa