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Intenzivní chov okounka pstruhového (Micropterus salmoides) v RAS s různým světelným režimem
BOŇKO, Dominik
Largemouth bass (Micropterus salmoides) is one of the species of fish that don´t have a significant position among the species of fish breeded in Czech Republic. However the trend of building aquaculture recirculation systems with warm water comes to the fore. Breeding in these conditions opens up the possibility of introducing new kinds of thermophilic fish species. Largemouth bass definitely belongs to this group. The general factors of successful breeding of largemouth bass are the temperature and purity of the water, the suitable-composed diet and the correct stocking density. This work studies another factor that not only participates in the success of the breeding, but also has influence on the energy expenses of the aquaculture system. It is the effect of photoperiod during breeding. Five experimental groups with three repetitions were created according to the time of lighting (8, 12, 16, 20 and 24 hours of light a day). The experiment lasted 16 weeks. The average water temperature was 24,6 °C. The initial stocking density for all tanks was 20.6 kg . m-3. Fish had an initial average weight of 32.6 +- 2.1 grams. The feed ration was set up at 1% of biomass per day. As a diet were used a floating dry pellets Skretting R-2 Europa 15 F of 2 mm. The feed contained 55 % of protein and 16 % of fat. Fish were fed manually by hand. All groups showed high survival during the experiment (99.4 - 100 %). The best results were achieved by a group of 8 hours with the highest feed conversion (FCR = 0.94 +- 0.06) and the highest growth rate (SWGR = 0.6 +- 0.04 % . day-1). The average individual fish weight of the 8 hour group at the end of the experiment was 64.07 +- 2.82 g. On the other hand, group of 12 hours was the worst with the lowest average individual weight (W= 57.51 +- 1.51 g), growth rate (SWGR = 0.49 +- 0.04 % . day-1) and the lowest feed conversion (FCR = 1.16 +- 0.08). These two groups were significantly different in most production indicators. The pervisceral fat index grew with biomass. The longer the photoperiod, the higher the plasma and ammonia content of lactate. In contrast, glucose content decreased. A longer photoperiod also influenced the higher production of antioxidants.
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ADAPTACE A INTENZIVNÍ CHOV OKOUNKA PSTRUHOVÉHO (Micropterus salmoides) V POROVNÁNÍ S INTENZIVNÍM CHOVEM CANDÁTA OBECNÉHO (Sander lucioperca)
HANZLÍK, Petr
The object of this thesis is to verify Largemouth bass (Micropterus salmoides) as an alternative species to Pikeperch (Sander lucioperca) for fish farming in RAS (Recirculating Aquaculture Systems). Largemouth bass with its good meat quality is comparable to Pikeperch and with its lower sensitivity to stress related to RAS conditions could expand the number of species used in intensive aquaculture. This experiment was split to two parts. In the first part was documented adaptation of Largemouth fingerlings to RAS conditions and artificial feed. After successful adaptation, the second part was started the main experiment. Only 9-16g form pieces were picked from the fish from the first experiment.) The Fish were divided into four groups: Candát 100%, Okounek pstruhový 100%, Candát mix, Okounek mix in three repetitions to nine tanks with capacity of 600 l. Dimensions of these tanks are 101x100x59,5 cm. Each tank was settled by 700 fish. In mixed groups were 350 of Pikeperch to 350 of Largemouth bass in each tank. Second part of experiment lasted 60 days. During that time different parameters of water quality were monitored. Twice a day oxygen, water temperature and once a day pH, NO2- , NH4- were monitored. Every day feeding dosage and mortality were counted. At the end of the experiment all fish were weighed piece by piece to find out the percentage frequency of each weight category in 1 g step. From each tank after every part of the experiment 33 pc of fish were selected and the biometrics were made. Monitored parameters were TL,SL,W and FC, FCR, SGR were counted. Evaluation of outcome and comparison of researched groups pointed to next findings. Largemouth bass showed a slightly smaller growing ability than Pikeperch in RAS. We have to consider a lower water temperature to the end value 21,5°C in system which was set because of Pikeperch sensitivity to bacterial infection and the optimum water temperature for Largemouth bass to 26°C. The experiment proved a high survival of Largemouth bass in groups Okounek 100% 99,86% survival, Okounek mix 99,81% survival. Pikeperch in groups Candát 100% and Candát mix did not exceed 97% in survival. An interesting finding of this thesis proved a positive influence of Largemouth bass to the growth of pikeperch. The group Candát mix had the best results in all monitored parameters TL,SL,W and FC, FCR, SGR.
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