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Vliv teploty na schopnost oplození a líhnivosti při krátkodobém skladování neoplozených jiker síha peledě (Coregonus peled)
RYTÍŘ, Jan
The northern whitefish Coregonus peled (Gmelin, 1788), originally from Russia, was introduced to the Czech Republic in 1970 for its tasty meat and good growth ability. Breeding of this species has been very popular in the past. Currently, thanks to the fish-eating predators, traditional breeding of this species is on decline. The aim of this M. Sc. Thesis was to sumarize the avaible information in the field of peled biology, artificial propagation and also information about effect of temperature on the ability of fertilization and hatching for short-term of unfertilized eggs in other salmonid species. In the practical part, the influence of temperature and length of storage of stripped, unfertilized eggs of peled on fertilization, survival to eyed eggs and hatching were observed. Unfertilized eggs were divided into five bowls and deposited in thermo boxes, which were tempered to 2.5, 5, 7.5, 10 and 12.5 °C. After time intervals of 1, 4, 12, 24, 36, 48, 60 and 72 hours, approximately 100 - 200 eggs were taken from each thermobox, which were fertilized with fresh sperm (collected from several males) and water from the hatchery. The fertilized and purified eggs were moved to the incubators with continuously inflow of fresh water. Dead eggs were removed and recorded. Subsequently, fertilization, eyed eggs and hatching eggs were determined. The resulting values of these parameters were expressed as a percentage of the total number of used eggs. High levels of fertilization and survival to eyed eggs were achieved when stored within 1 day from eggs stripping at all temperatures except the highest temperature of 12.5 ° C. As the interval gradually lengthened, the fertilization and survival parameters also decreased, most notably at 7.5 and 10 ° C. To obtain the largest possible amount of fry in fishing practice, it is recommended to store eggs at 2.5 and 5 ° C, up to 48 hours after ova stripping. At higher temperatures, the effective storage time is reduced to 12 hours. Storing eggs for longer than 48 hours, in practical terms has no meaning. At the same time, it was found that at the above-mentioned optimal temperatures for storing eggs (2.5 and 5 ° C), the best hatching results were obtained when storing stripped eggs for 12 hours. Not only for longer, but also for shorter storage lengths, the values of this parameter were lower.
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Vliv teploty na oplozenost a líhnivost po krátkodobém skladování neoplozených jiker sumce velkého (Silurus glanis)
PŘIBYL, Tadeáš
The experiment validated the impact of storage of artificially spawned unfertilised eggs of European catfish on fertilization, hatching and the beginning of exogenous food intake throughout the transition from the embryonic to larval life period. The eggs from artificially spawned individuals have been used for this experiment using the induction of ovulation by the carp pituitary system. Sperm from each individual was collected by stripping using a hypodermic needle, that were partially filled with immobilising solution for sperm before artificial spawning of female individuals. Artificial stripping of fish was carried out under anaesthesia (by clove oil). Immediately after artificial hatching, samples of eggs (approximately 50 g) were put into six plastic bowls. Covered with wet cloth, bowls with eggs were placed into tempered, isolating thermo boxes with temperatures of 5, 10, 15, 20, 25 and 30 °C. Subsequently, in time intervals of 0,5, 1, 2, 3, 4, 6, 8 and 10 hours (after spawning) a small amount of eggs (approximately 50 pieces) was taken away from each temperature and put into glass beakers (with three repetitions), then the sperm was added and finally activated by adding water. In beakers with incubated non-sticking eggs and during the consequent storage of hatching embryos through temperature between 19,5-20 °C, water was changed two times a day. Approximately 4 hours after incubation, the exact number of used and fertilised eggs, was calculated. Unfertilised eggs (of white colour) and dead embryos were removed. Hatchery was assessed approximately 100 hours after fertilisation, when all living embryos had been hatched. After another 115 hours, throughout the transition from the embryonic to larval life development, live food (nauplia Artemia) was put into each bowl. Three hours after, individuals that began the food intake were calculated. The highest level of fertilisation was found in eggs stored between 0,5 and 2 hours (95,0?2,2 % - 100,0?0,0 %). The decrease in fertilisation is noticeable in all tested groups after 3 hours from stripping. Statistically significant decrease in fertilization was detected in eggs stored for 6 hours, the storage temperature did not affect the fertilization. Similar results have been maintained also in hatchery, where hatchery decreases as storage time increases. The highest level of hatchery was found in eggs stored in 25 °C (for 0,5 h 61,4?5,5 %), or more precisely 1 h 42,8?12,9 %). Hatching significantly decreases in all storage temperatures when storage time is longer than half an hour. The last parameter concerned how many percent of the individuals began the food intake. The highest level was recorded in eggs stored for half an hour (after spawning) in 25 °C (60,1?5,3 %), 30 °C (54,5?17,7 %) and 20 °C (39,0?12,7 %). On the contrary, storage temperatures 5 °C, 10 °C and 15 °C had results between 8,9?2,8 % and 35,0?18,8 %. Total mortality was detected when the storage time was more than 8 hours. It is necessary to fertilize the eggs as soon as possible (max. up to half an hour) after spawning, and to avoid storage of eggs at low temperatures (below 15 °C), to obtain viable individuals.
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Vliv teploty na udržení schopnosti oplození a líhnivosti při přechovávání neoplozených jiker u keříčkovce červenolemého
BORŮVKA, Vít
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.
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