|
|
Optimalizace procesu triploidizace u candáta obecného (Sander lucioperca)
TRNKA, Kamil
This thesis was aimed on optimization of induction of triploidization of pikeperch (Sander lucioperca) using cold, hot and pressure shocks. To induce the triploid status of the larvae using cold shock fertilized eggs of pikeperch were dropped into the cold bath of temperature 0,5-1°C in 2, 4, 8, 12 and 16 minutes post fertilization with shock duration of 20, 40, 60, 90 and 120 minutes. Hot shock was induced by 30°C bath 2, 4, 8, 12 and 16 minutes post fertilization with duration of shock 5, 10, 20, 30 and 40 minutes. Pressure shock was also tested for induction of triploidization using pressure of 70 MPa 5, 10 and 20 minutes post fertilization with duration of shock 5 minutes. Ploidy level was then determineted using flow cytometry. As a result hatchability (%), share of malformed larvae (%), share of triploid individuals (%) and yield of triploids (%) were determined. None of the experiemental shocks have led to a 100% share of triploids concerning the samples examined by flow cytometry. Best result was reached via pressure shock with duration of 20minutes which resulted with share of triploid individuals of 95% and yield of triploids 12.2+-2.5%. It must be noticed that increasing duration of pressure shock resulted in decreased hatchability and increased share of malformed larvae. Second best result was achieved via cold shock. Worst results were obtained via hot shock.
|
|
|
Induction and potential use of monosex populations of pikeperch (Sander lucioperca) in intensive farming
ŠVEJDA, Pavel
The aim of this study was to induce monosex populations of pikeperch using the method of direct masculinization and direct feminization in order to change sex and evaluate the production parameters and body indices of the treated groups of pikeperch. For direct masculinization, 17 -methyltestosterone was used at a dose of 30 or 50 mg.kg-1 for 30 or 60 days. For direct feminization, 17 -estradiol was used at a dose of 30 mg.kg-1 feed for 30 days. Individuals of pikeperch with TL = 51.52 +- 4.19 mm and W = 1.23 +- 0.26 g, FC = 0.9 +- 0.3 were used for the experiment. In the experiment, direct feminization achieved a sex ratio 98.3 % of females and 1.7 % of males. This is the first record of an almost all-female population induced with 17 -estradiol. The highest level of masculinization of the tested individuals was achieved in the group exposed to 17 -methyltestosterone at a dose of 30 mg.kg-1 feed for 60 days. In this population, 75 % of individuals with male genital tissue were found, of which 21.7 % were individuals whose testicular sperm could be used to produce an all-female population. In groups treated with 17 -methyltestosterone for 60 days, the presence of "neomales" and intersex (hermaphrodite) individuals was observed. The experiment revealed that the use of the hormones 17 -methyltestosterone and 17 -estradiol can temporarily cause growth suppression, particularly during and shortly after exposure of individuals to these hormones. However, it does not have a lethal effect on individuals in the doses we applied. The higher growth rate of pikeperch females was not confirmed in the test. Females treated with 17 -estradiol did not show higher weight gains compared to the control group. A significant difference in the achieved final weight was not observed between both sexes in the control group at the end of the experiment.
|
|
| |
|
|
Influence of feeding management on intensive breeding of pikeperch (Sander lucoperca)
KUČERA, Václav
This thesis is aimed on problematics of intensive pikeperch aquaculture and the influence of the feeding by different types of pellets and also different frequencies of feeding during the day. Whole thesis consists of two separate experiments. In the first experiment I tried to evaluate the influence of sinking and floating type of pellets on the growth abilities and production markers of juvenile pikeperch. First experiment was stocked with 8000 pcs of juvenile pikeperch (average weight 21,38g). These fish were kept in controlled conditions for 16 weeks (average temperature of 21,37 ? 0,66 °C (7:00) and 20,77 ? 0,55 °C (15:00), average dissolved oxygen levels of 127,43 ? 2,37 % (7:00) and 117,03 ? 1,14% (15:00) °C, 120 % and initial biomass of 13,42 kg/m?). These fish were fed by belt feeders two types of pellets (floating Skretting Europa and sinking Biomar Effico Sigma) with the same nutrient composition. After 16 weeks all the production markers (SGR, FCR, WG, TL, CF and survival) were examined. Almost all the parameters showed the statistically significant difference in favor of the sinking pellets. Although growth heterogenity turned out to be lower in the group fed by floating pellets. In the second experiment 600 individuals of juvenile pikeperch with average weight of 37,49 g were stocked in tanks. These fish were kept in controlled conditions for 6 weeks (average temperature of 21,37 ? 0,66 °C (7:00) and 20,96 ? 0,66 °C (15:00), average dissolved oxygen levels of 127,43 ? 2,37 % (7:00) and 117,03 ? 1,14 % (15:00) with initial biomass of 13,35 kg/m?). These fish were fed by automatic feeder Imetronic Self Feeder in 3 different frequencies a day (3,6 or 12 batches). Pellets Skretting Europa- 15F were used in this experiment. After 6 weeks of rearing production markers were examined. Growth heterogenity, somatic indexes, and fin erosion were also examined. Also, blood samples were taken. After data analysis no statistically significant difference was found among the production markers in all three groups. Growth heterogenity was proven to be the lowest in the group fed 3x a day and highest in the group fed 12x a day. Organosomatic indexes showed statistically significant difference of HSI (hepatosomatic index). Highest index was observed in group fed 3x a day. During the analysis of the data from biochemical analysis increased levels of albumins and tryglicerids were observed especially in the group fed 12x a day. Simultaneously, statistically significant differences among the amonia levels (lowest concentration in the group fed 3x a day and highest in group fed 12x a day) and glucose (lowest concentration in the group fed 3x a day, two other groups had almost the same level of glucose) levels in plasma were found. As a group with the best results was determined a group fed 6x a day. This group reached satisfying results in production markers (better than group fed 3x a day but slightly worse than group fed 12x a day). Also, lower growth heterogenity than in group fed 12x a day was observed. Group fed 6x a day also displayed the best working lipid metabolism in contrary to the group fed 12x a day which displayed the disorder of the lipid metabolism. Also, the fin erosion was slightly lower than in a group fed 12x a day.
|
|
|
Rozvoj zooplanktonu v rybnících s produkcí rychlených stádií hospodářsky významných druhů ryb
PECHA, Oldřich
This master thesis was focused on zooplankton development in ponds with advanced fry rearing of economically important fish species. For the purpose of my study, we sampled pond cascade that is managed by Štičí líheň - ESOX, spol. s r.o. in the village Liderovice, near Tábor. In this particular pond cascade, the annual production of advanced fry of economically important fish species takes place, namely pike, pikeperch, carp, tench and grass carp. Importantly, pond cascade is used several times during one growing season, and zooplankton is the main food source of all early stages of rared fish. For the production of advanced fry of fish served 3 ponds, which were released and refilled 2-3 times a season. Fourth pond served as a control stocked with one year old carp throughout the whole season. The water from an upper pond in the cascade served as zooplankton inoculum to a lower pond after the pond harvesting. Statistical analyses showed that the fry of different fish species in ponds lying in the same cascade does not affect the composition of zooplankton after restocking and water refilling. The only difference we noticed was in the treatment with pikeperch, which partially does not share the food base of other monitored species.We also found out, that the occurrence of Cyclops vicinus, Daphnia magna, D. ambigua or D. pulicaria was positively correlated with increased P-PO4 concentrations. We also confirmed that pond ecosystem can effectively retain nutrients from basins and use them for its production. As was shown after a short rain when the measured concentration of total phosphorus in the inflow in our pond system was 0.50 mg/L, on the contrary in the last pond of our cascade we measured values below 0.08 mg/L. High transparency was maintained in the whole cascade throughout the monitoring period, and an adequate economic profit was generated. Such management can be applied to only a few ponds (systems).
|
|
|
Methodology of predatory fish quantification in reservoirs and lakes.
Blabolil, Petr ; Jůza, Tomáš ; Vašek, Mojmír ; Peterka, Jiří
The publication contains an evaluation of surveying 36 reservoirs and artificial lakes in the years 1985–2020 in different parts of the Czech Republic by four sampling methods, which are further divided according to the sampling environment, daily periods and targeted age groups of predatory fish. The methods are gillnets, seines, trawls and continuous boat electrofishing. The catchability, standardized and relative abundance of asp, pikeperch, pike and catfish are evaluated. Based on these data, the reader can decide which method to use to detect a particular predatory species and compare the results with the situation in other localities.
|
|
| |
|
|
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.
|
|
|
Indukce triploidie u candáta obecného (Sander lucioperca)
RŮŽEK, Martin
The aim of this study was to induce the triploidy in pikeperch (Sander lucioperca) with use of a cold shock. To induce the triploidy, fertilised egg were (spawning temperature 14,5 °C) submerged in a cold bath at the temperature of 2 °C. Time of initiation was 1; 3; 5; 7 and 10 minutes post activation. The exposure time was 20 and 40 minutes. Ploidy level of freshly hatched larvae was assessed with use of the flow cytometry. In both exposure times, the hatching rate was getting lower with later time of initiation (20 minutes exposure, hatching rate: 58,4-13,4 %; 40 minutes exposure, hatching rate: 28- 9,6 %). Number of malformed larvae increased with later time of initiation and longer exposure time (20 minutes exposure, malformed larvae 0-47,2 %; 40 minutes exposure, malformed larvae 0-58,8 %). None of the tested combination of exposure time and time of initiation led to a population containing 100 % triploid larvae. However, percentage of triploid larvae grew up with longer exposure time and later time of initiation. The best cold shock combination with highest yield of triploids were after 20 minutes long treatment initiated 10 minutes post activation (57,1 +- 14,2 %) and after 40 minutes long treatment initiated 10 minutes post activation (61,9 +- 8,2 %). The most important finding of this study is that cold shock treatment leads to triploidy in pikeperch. To obtain 100% triploid larvae, shorter exposure time and different shock temperature might be applied. It may also eliminate low hatching rate and high appearance of malformed larvae.
|
|
|
Optimalizace intenzivního chovu larev candáta obecného (Sander lucioperca L.)
MORAVA, Jakub
The aim of this master thesis was test, comapre and observe the best density of rotifers (Brachionus plicatilis) for growth and survival of zander (Sander lucioperca) larvae stage in the recirculation aquatic systém (RAS). The secondary experiment tests initial feeding of zander by dint of rotifers and consequently by mix of rotifers and artemia. Main experiment observe effect of different density of rotifers on survive and growth of zander. Other observe parameters such as Fulton´s coeficient, total lenght of fish, weight of fish, etc. Fish was divided into 4 groups with different density of feeding and the control group without feeding. Rotifers has been used in density of 2, 6, 10 and 20 pieces per larva. The best growth in "D" group has been compensate by lower surviving. On the other hand the best ratio of survive has been observe in "C" group, which showed lower growth. The optimal rate of growth and survive has been declared in "B" group, which were feed with dose of 6 pieces rotifers for larva. In the second experiment were observe body changes of zander after initial feeding by rotifers folowed with feeding mix of rotifers and artemia. There were observe successful fulfillment of gas bladder and deformation of fish body and spinal after 40 days of keeping larvae in RAS. In the end of experiment there were also observe defirmations body - for example missing lower jaw, upper jaw or both of them. Spinal deformities occured in the form of scoliosis, lordosis, kyphosis and zig zag distortion. The experiment has shown that unsuccessfully filled gas bladder is closely related to the formation of deformitiy in the zander. Another negative factor that affects the filling of the gas bladder is grease on the surface of the water level, so I recommend installing the grease trap in the fill phase of the gas bladder.
|
guest ::
