Extensive asynchrony of sexual maturation is characteristic of salmonid females, and, for various reasons, the spawning season can be extended for 4 months, although it generally extends over a 3 week to 2 month period, as in brook trout and northern whitefish. In aquaculture, to ensure high fertilization and egg survival rates, it is recommended that identification of ovulating females be undertaken at least twice weekly. This is time-consuming when keeping large numbers of broodstock with an extended spawning season, and risk of stress damage to fish increases. Ensuring sufficient Arctic grayling broodstock relies on capture of wild animals from natural waters before onset of the spawning season. Capture and long-term holding of wild stocks is associated with high pre-spawning mortality. Due to the high ovulation synchronizing effect, GnRHa is practical for induction of ovulation 1?1.5 months prior to the natural spawning season. This work focused on optimization of methods of hormone-controlled reproduction using GnRHa in brook trout, northern whitefish, and Arctic grayling from Siberia. Because this is the first report of use of GnRHa in these species, emphasis was on optimization of the hormone dose and delivery method along with assessment of effects of GnRHa treatment on postspawning broodstock mortality, egg size, and egg viability. As in other salmonids, GnRHa treatment effectively synchronizes the onset of ovulation in brook trout and northern whitefish. This gives accurate information about ovulatory status of the broodstock and enables planning of the stripping schedule. The most convenient methods were the double acute injection at 25 ?g.kg-1 ?-Arg6,Pro9-NHEt-sGnRHa administered 3 days apart and injection of 25 ?g.kg-1 of emulsified ?-Arg6,Pro9-NHEt-sGnRHa in Freund´s incomplete adjuvant, which prolongs and more effectively stimulates LH secretion and requires only a single injection. Double acute injection at 10 ?g.kg-1 of ?-Tle6,Pro9-NHEt-mGnRHa (Supergestran) was sufficient to induce ovulation in Arctic grayling 1?1.5 months prior to natural spawning, and enabled accelerated stripping and return of wild broodstock to their natural habitat. Single acute injection proved to be ineffective or unreliable in most cases and therefore cannot be recommended. No negative effect of GnRHa or GnRHa-FIA treatments on post-spawning mortality of broodstock was observed. It has to be noted that that to the extent of law Nr. 166/1999 statute book (Czech veterinary law)injective procedures can be carried out just by the veterinarian or by a verinarian-authorized person in veterinarian presence. GnRHa treatment has side-effects and alters egg quality. Apart from in brook trout, egg survival was significantly lower (5?20%) in treated females. Increased hormone dose did not influence egg survival at the levels tested. Egg and hatchling size was lower in treated females compared to untreated specimens irrespective of dose or hormone delivery method. Reduced egg size is, however, not the likely source of reduced viability. In general, our results corroborate results of studies dealing with assessment of effects of hormone treatment on egg quality. Based on current experimental designs it is impossible to identify the cause of the side-effects with certainty. Solving this problem should be priority for future research.

Morphological properties, species specific differences, development, and function of egg envelopes are of importance for a better understanding of fertilization strategies as well as for captive reproduction. We reviewed morphology and the developmental stages of egg envelopes, mechanism of polyspermy block, and also the role of micropyle and cortical granules in polyspermy block for acipenserid eggs. The structure of the egg envelope is similar among the acipenserids, comprising an external envelope (thecal cells, basal lamina, and follicular epithelium), a five-layered oocyte envelope (adhesive layer, alveolar layer, epilayer, and zona radiata externa and interna) and a layer of oocyte matrix and cortical granules. The development of acipenserid egg envelope within the ovary comprises five stages, with further changes following fertilization. Moreover, we standardized the terminology used to describe the egg membranes which can minimize the confusions and be helpful for future work on acipenserids eggs as well as for other fish species. The sperm to egg ratio (required to fertilize eggs) and effects of pre-incubation of eggs in freshwater before fertilization were studied to standardized fertilization protocols for sterlet Acipenser ruthenus. Pre-incubation time had no effect on fertilization success at 430,000:1 and 43,000:1 sperm to egg ratios, while it was significant at the 4300:1 and 430:1 ratios. The use of adequate experimental suboptimal sperm to egg ratio revealed a positive effect of pre-incubation time, such that at the 430:1 ratio, 0.5 min pre-incubation increased the fertilization rate than 10 min. Transmission electron microscopy showed that pre-incubation of eggs in water for <10 min did not trigger a cortical reaction, suggesting that a low sperm to egg ratio 0.5 to 1 min pre-incubation of eggs in freshwater prior to fertilization can enhance fertilization rate of sterlet (minimally do not change fertilization). The effects of pre-incubation in seawater and the duration of egg receptivity were determined for fresh and over-ripe sea bass eggs. Our results revealed a significant effect of pre-incubation time for both the fresh (P < 0.01) and over-ripe eggs (P < 0.01). The fresh eggs had a higher fertilization success than over-ripe eggs. Fertilization success of eggs significantly declined for both of these treatments after 3 min of pre-incubation clearly indicated that sea bass eggs are able to be fertilized by sperm for up to 3 min after release into seawater. Effects of pre-incubation of eggs and activation medium on the percentage of eyed embryos for Ide Leuciscus idus were examined. At the eyed-egg stage, pre-incubation time was significant for the freshwater activation medium (P < 0.001), such that the percentage of eyed embryos declined across the pre-incubation time gradient. Activating medium had a significant effect on the percentage of eyed embryos for each pre-incubation time (P < 0.05). More precisely, freshwater produced the lowest percentage of eyed embryos at all pre-incubation times, whereas saline water and Woynarovich solution produced the highest percentage of eyed embryos at 0 s and 30 s before incubation. Examination of sperm traits showed no impact of activating medium on computer assisted sperm analysis parameters. Our results suggested that saline water or Woynarovich solution improve fertilization rate in Ide during fertilization. In conclusion, this thesis provides basic knowledge on gamete biology, role of egg receptivity period, effects of pre-incubation of eggs and different activating medium which can be useful to understand the fertilization strategies of different externally fertilizing fishes as well as standardize their fertilization protocol for captive reproduction.

Pond and intensive aquaculture of percids relies mainly on juveniles supplied by semi-artificial and artificial reproduction. Fish hatcheries do not always provide optimal conditions for percid reproduction. This project was undertaken to optimize reproduction methods of Eurasian perch (Perca fluviatilis L.) and pikeperch (Sander lucioperca L.). Reproduction parameters were compared in farmed and pond-reared perch broodstock without hormone treatment. Spawning was successful without hormone induction at 92.3% and 76.9% in farmed and pond-reared perch, respectively. Significant differences in morphological characteristics (gonadosomatic, hepatosomatic and viscerosomatic indices), fecundity, hatching, and post-spawning mortality were detected. All results, with the exception of spawning success and post-spawning mortality, were superior in pond reared broodstock. Further studies are required to optimize protocols for using better artificial food in farmed perch and decreased stress and post-spawning mortalities in pond reared perch broodstock. The possibilities of using clove oil, Propiscin, or 2-phenoxyethanol as an alternative to tricaine methane sulphonate (MS222) as anaesthetic, particularly with respect to reducing fish stress, were investigated. The haematological and biochemical profiles of pikeperch anaesthetized with clove oil (33 mg l?1), Propiscin (1.5 ml l?1), 2-phenoxyethanol (0.3 ml l?1), and MS222 (150 mg l?1) were determined. Each tested group was divided into two subgroups; the first subgroup was sampled 10 min after application and the second 24 h post-application. Clove oil was shown to be associated with the lowest effects in pikeperch, and therefore could be recommended as an alternative to MS222, while Propiscin and 2-phenoxyethanol were shown to be unsuitable for use with pikeperch. In Eurasian perch the use of semi-artificial reproduction for mass production of embryos was shown to be simpler and more effective. With mass incubation, 1 134 000 embryos (59% of total production) were obtained with a semi-artificial spawning regime and 796 000 embryos (41% of total production) with artificial spawning. Based on these results, we can recommend the semi-artificial spawning for production of perch embryos. Differing doses of two commonly used hormone preparations: human chorionic gonadotropin (hCG) and mammalian GnRHa (Supergestran) were tested for induction of ovulation in pikeperch. A broad range of effective doses is used in aquaculture of pikeperch. The minimal effective dose based on ovulation success is still missing. Hormone therapy applied to excess can result a detrimental impacts on broodstock fecundity and quality of eggs. Results indicated that a single injection of hCG or Supergestran could be used for successful ovulation, while no spawning was observed in a control group treated by saline solution. Among hormone treated groups, the best results were observed in groups treated with hCG at 500 and 750 IU kg-1 BW and in groups treated with mGnRHa at 25 ?g kg-1 BW. The sperm of pikeperch and Eurasian perch show similar morphology and fine structure, with the exception of differences in arrangement of midpiece and centrioles and the presence of a fin-like structure on the flagellum in pikeperch. Our results suggest use of an activation medium containing Ca2+ for activation of short-term stored sperm. Efficacy of five concentrations of Alcalase enzyme for elimination of egg stickiness compared to a milk/talc suspension was determined. Results indicated that 0.5-2.0 ml l-1 of Alcalase for 2 min may increase pikeperch egg hatching success (80-85%) compared to the milk-talc suspension. The highest hatching rate (85.4%) was observed with 1.5 ml l-1 of Alcalase. The application of Alcalase successfully eliminated pikeperch egg stickiness in 2 min compared to 60 min with traditional milk/clay/talc methods.

When hormonally induced artificial spawning of african catfish (Clarias gariepinus), was several female injected intraperitoneally in one dose preparation Ovopel at doses of 1.5 pellet × kg-1. Females were kept separately in the tanks at a temperature of 21.5 °C. All females were spawned at the same time latency 19.2 hours. Eggs from three spawned females were mixed and divided into 6 doses. Each batch was placed into thermoboxes at temperature 5 °C, 10 °C, 15 °C, 20 °C, 25 °C and 30 °C. These eggs were stored in thermoboxes and after times of storage 0.5 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 6 h, 8 h, 10h, part of the eggs (approximately 50 to 100 pieces) were taken out from each thermoboxes in three replications and was placed into individuals cups and fertilized by adding 5 drops of sperm and 20 ml of water. In these samples were subsequently observed fertilization, hatching rate and survival rate. When watching fertilization was in individual temperature the highest values and also statistically non-significant difference ( = 0.05) achieved: at 5 °C in times of fertilization 0.5 2 hrs. (61.6 +- 5.81 % - 47.7 +- 1.48 %), at 10 °C in times 0.5 - 1.5 hrs. (70 +- 6.7 % - 62.1 +- 8.9 %), at 15 °C in times 0.5 - 3 hrs. (59.6 +- 9.4 % - 59.6 +- 2.9 %), at 20 °C in times 0.5 - 3 hrs. (61.4 +- 3.6 % - 56.1 +- 2.5 %), at 25 °C in times 0.5 - 4 hrs. (55.5 +- 7.2 % - 49.7 +- 9.3 %) and at 30 °C in times 0,5 - 3 hrs. (61.6 +- 10.3 % - 51.8 +- 17.8 %). When watching hatching rate was in individual temperature the highest values and also statistically non-significant difference ( = 0.05) achieved: at 5 °C in times of fertilization 0.5 - 1 hrs. (28.4 +- 2.9 % - 21.1 +- 9.5 %), at 10 °C in times 0.5 - 1 hrs. (36.6 +- 17.3 % - 22.1 +- 7 %), at 15 °C in times 0.5 - 2 hrs. (34.1 +- 5.5 % - 26.9 +- 5.1 %), at 20 °C in times 0.5 - 2 hrs. (33 +- 8.2 % - 28.8 +- 1.6 %), at 25 °C in times 0.5 - 4 hrs. (31.4 +- 6.2 % - 15.3 +- 13.5 %) and at 30 °C in times 0.5 - 2 hrs. (33.1 +- 9.2 % - 21.2 +- 8 %). When watching survival rate was in individual temperature the highest values and also statistically non-significant difference ( = 0.05) achieved: at 5 °C in times of fertilization 0.5 - 1 hrs. (20.1 +- 6 % - 13 +- 3.3 %), at 10 °C in times 0.5 - 3 hrs. (19.8 +- 15.31 % - 3.1 +- 3 %), at 15 °C in times 0.5 - 6 hrs. (23.3 +- 9 % - 5 +- 2.8 %), at 20 °C in times 0.5 - 2 hrs. (22.4 +- 1.9 % - 15.1 +- 5.2 %), at 25 °C in times 0.5 - 4 hrs. (18.7 +- 4.4 % - 4.1 +- 1.9 %) and at 30 °C in times 0.5 - 1.5 hrs. (26.2 +- 5.5 % - 21.4 +- 6.8 %). Suitable temperatures for the storage of unfertilized eggs after spawning are two hours before fertilization at temperatures from 15 to 30 °C. Other suitable temperatures which are useful for storage are temperatures 15 to 25 °C, for preservation after 3 hrs. and longer after fertilization.

The optimalization way of hormonal induction ovulation females barbels (Barbus barbus) hunted from river is the aim of work with the help of hormonal preparate on the base functional of the analogue GnRH.

Objectives of thesis: 1.To evaluate the effect of pH and total hardness of water on the development of eggs in aquarium fish Corydoras paleatus, Corydoras paleatus albin, Tanichthys albonubes, Tanichthys albonubes gold, Aphyosemion gardneri, Aphyosemion gardneri gold. 2.Recommendation of optimal values of total hardness of water and pH for successful development of eggs for each monitored aquarium fish. Based on published data in available literature sources and on own experiments, it was evaluated how total water hardness (CM) and pH influences development of aquarium fish eggs of Aphyosemion gardneri, Aphyosemion gardneri gold, Tanichthys albonubes, Tanichthys albonubes gold, Corydoras paleatus, Corydoras paleatus albin.

The aim of this diploma thesis is to compare quality of northern pike sperm collected by different methods. First method is collection of stripped sperm by abdominal massage of the belly. Second method is collection of stripped sperm with special catheter to eliminate sperm contamination by urine. The last method is collection of testicular sperm. Differently collected sperm was evaluated and compared its quality. The main observed parameters were sperm volume, spermatozoa concentration, spermatozoa motility and velocity and osmolality of seminal fluid. Sperm samples were used for eggs fertilization. In fertilized eggs, the fertility of eggs and larvae hatching rate were observed.