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Ellimination of unwanted fish species from dam reservoirs - Possibilities, efficiency and economic evaluation.
Jůza, Tomáš ; Blabolil, Petr ; Čech, Martin ; Draštík, Vladislav ; Holubová, Michaela ; Hůda, J. ; Kočvara, Luboš ; Kolařík, Tomáš ; Muška, Milan ; Peterka, Jiří ; Prchalová, Marie ; Říha, Milan ; Sajdlová, Zuzana ; Tušer, Michal ; Vašek, Mojmír ; Vejřík, Lukáš ; Kubečka, Jan
spontaneous development of populations and the influence of human interventions. For situations where a certain part of the fish population needs to be caught, within the project 'Biomanipulation as a tool for improving the water quality of reservoirs', we tested the available approaches in terms of their effectiveness and difficulty. The target species of catches were mainly cyprinid fish (bream, bleak, roach, rudd, white bream), which feed mainly\non zooplankton and tend to form very large populations. Among the most effective methods of catch during spawning are catches using electrofishing boats and fyke nets. In the non-spawning period, it is possible to carry out mass catches using trawl nets. Catches are effective both before spawning (in April) and during the summer. However, with repeated catches in the same places, their effectiveness decreases as a result of the fish being spooked. The efficiency of the catches partially improves again if the catches are repeated with a break of approximately 1–2 weeks. Catches also vary according to the stocking density of a given water body. With effective catches, the cost of catching 1 kg of fish is in the range of CZK 15–50.
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Comparison of different ways of breeding, nutrition and controlled reproduction of Lota lota
ZÁVORKA, Milan
Based on the results reached after 216 days of experimentation with various breeding types, it can be said that the type of feed is not of paramount importance. This fact is based on the previous adaptation of submitted food, this is especially important for artificial feed. From our point of view, the more important factor is temperature, intensity and method of breeding. Prey selections choices involving 11 species of fish were performed on age groups of different burbot. All groups of burbot preferred the following species: grass carp, pikeperch, tench and stone moroko. The non-preferred species was ruffe. And different preferences were set for common carp, silver carp, burbot, sunfish and also for roach. The study evaluated reproductive parameters in burbot (Lota lota ) and focused on incubation time in two localities. Burbot spawning was observed from January to early February at an average temperature of 1.55 +- 0.9 °C in Borova Lada and 4.78 +- 0.11 °C in Mydlovary. For burbot at the age of 2+, at an average 1166 +- 100 were determined number of swollen eggs per gram. Relative fecundity was at 257260 +- 70678 eggs per kilogram of female. The absolute fecundity was at 24232 +- 6753 eggs.The last parameter evaluated was the incubation period. The average incubation period in the years 2020-2022 was 202 +- 24.55 °D in Mydlovary and 75.8 +- 16.67 °D in Borova Lada. In connection with artificial spawning, in this study, we further point out the possibility of peeling artificially spawn eggs with NaClO, in which we did not observe a negative effect.
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Posouzení možnosti reintrodukce lipana podhorního vysazením uměle odchovaných generačních ryb v předvýtěrovém období
PASTEJŘÍK, Jan
My bachelor s thesis deals with the possibility of reintroduction of the European grayling (Thymallus thymallus) into open waters by stocking artificially bred generation fish in their pre-spawning period. 3-4-year-old broodfish, bred in the pond Hulák in Prachatice, were used for the experiment. Then in the spring the fish were marked and stocked in the parts of FROV JU fishing ground, where fish were previously caught with electric aggregates and the local composition of fish stocks was examined. In the same way, a control catch was carried out also in the autumn - this time there was a main focus on the presence of the European grayling and juveniles. In addition, a follow-up section of the river (outside the experimental sections) was fished out and most fish were caught here. Based on the results of the monitoring, it can be said that in the section of the river where artificially bred generation fish were stocked at least partially successful natural spawning took place. Although the number of caught fish in the autumn was low (11 fish), this approach might be considered as promising in terms of the possibility of supporting the occurrence of the European grayling in open waters and suitable for further testing. Only 6 % of stocked generation fish were caught out 7 months after stocking. The size of these fish was practically the same as when stocked. In case of using this approach within the fishery management, it is necessary to stock generation fish no more than a few weeks before the expected spawning.
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Reproduction Burbot burbot (\kur{Lota lota}) and incubation of eggs at different temperatures in service
MIKEŠOVÁ, Lucie
The study evaluated the reproductive performance in Burbot burbot (Lota lota L.) and compared the incubation period at two locations. It was confirmed that the burbot wipes at the end of December and beginning of January with an average temperature of 1,93 ? 0,8 ° C. It was found that the content of the eggs in one gram is 3325 ? 248 pieces eggs and 1 ml is 1434 ? 24 pieces of eggs. Also, to evaluate the size of eggs before and after swelling. Size before swelling was 0,814 ? 8 mm and the swelling 0,838 ? 7,1 mm. Further, the absolute and relative fecundity and GSI, the absolute fecundity was 289,279 ? 204,759 pieces of eggs, the relative fertility of 763,523 ? 110,061 pieces of eggs per kilogram of body weight of fish and GSI was 23,15 ? 3.9%. The last parameter was rated incubation period. The incubation period was Vodňany 178,4 ° D and Borových Ladách 145,4 ° D.
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Optimization of artificial spawning of pikeperch (Sander lucioperca) using HCG and new ways of removing artificial stickiness of eggs before incubation.
BLECHA, Miroslav
The object of the thesis is to experimentally find the most suitable method of artificial spawning of pikeprech, using hormonal stimulation of ovulation in females hormonal medication containing HCG. After scraping of the broodstock and after artificial fertilization of eggs obtained experimentally test new methods of artificial stickiness removing of eggs and then evaluate the success of artificial incubation of stripped, fertilized and unstickeness eggs of pikeprech. Experiments that are part of the thesis have been divided into several sub-experiments. In the first experiment was observed effect of different doses of hormonal Chorulon, containing the active substance HCG, the basic indicators of reproductive females. Was evaluated as spawning synchronization, spawning success, the number of spontaneous spawnings, fertility of females and hatching rate of eggs. The used HCG doses were 250, 500, 700 and 1000 IU per kilogram of body weight. All eggs were deprived of stickiness using a mixture of talc and milk. In the second experiment was carried out comparing different types of removes stickiness solutions. Here was evaluated especially time and labor intensity and the influence of various solutions on fertilization and hatching rate of eggs. In this trial was all pikeperch females injected the same amount of HCG hormone 500 IU per kilogram of body weight. Tested solutions was a mixture of talc and milk, just eggs wash water and the solution of various concentrations alkalase. The amount alkalase was 0,5; 1; 1,5; 2 and 5 ml, which are mixed with distilled water, so that the total volume of the solution was 1000 ml. The third experiment was supposed to simulate the pilot plant mass propagation of pikeperch females. All females received the same amount of hormone 500 IU of HCG per kilogram of body weight. All eggs were deprived of stickiness using a mixture of talc and milk. In the last experiment was one of the methods tested, which could limit the number of spontaneous spawning during the artificial spawning of pikeperch. To prevent spontaneous spawning were selected females (all were injected with 500 IU of HCG per kilogram of body weight) sewing genitourinary papilla. The incubation of eggs collected during all the experiments were used Zugské bottle.
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Spawning of domesticated eurasian perches in controlled conditions of fish breed
TRNKA, Petr
The eurasian perch (Perca fluviatilis Linnaeus, 1758) is considered as very perspective species for breeding at intensive aquaculture, where was successful domesticated. Consumption of eurasian perch is increased at present. The greatest grow of consumption is mainly in countries of alpine region and in Scandinavian countries. The aim of experiment was monitor and character spawning of domesticated eurasian perch in controlled conditions of breed. It was determinated fertility and then fertilization of eggs. The next aim was make incubation of fertilization eggs and determinate hatching. After hatch was determinated total length of larvae and its quality by the help of osmotic shock. Domesticated eurasian perch is spawned without problems in controlled conditions of breed. The resulting data of domesticated perch are worse than date of non-domesticated perch in some spawning characteristic. This problem will resolve with gaining knowledge about spawning of eurasian perch. The greatest problem is hatching of eggs, which is very low during spawning of domesticated perch.
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