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Umělý výtěr karase obecného
VRBENSKÝ, Jakub
The thesis briefly summarizes the available information in the field of crucian carp biology. The experimental part includes, firstly, monitoring the effect of water temperature during the latency period in reproductive females affects the success of artificial spawning, the survival of eggs to the eyespot stage, the length of the latency interval in hours and in clock degrees, the relative fecundity of reproductive females and the pGSI. In the second part of the experiment, secondly, the effect of the method of unstickness eggs on the survival of eggs to the eyespot stage. To test the effect of temperature during the latency interval, the females (mean weight 329 +- 60 g) were divided into 7 groups (n = 5). The individual groups of reproductive females were placed in separate tanks with average water temperatures of 15.4, 17.2, 18.9, 21, 23.2, 25.2 and 27.2 °C. Females and males were injected with the hormone Ovopel (1 pellet per 1 kg of fish). Before injection and artificial spawning, the reproductive fish were anaesthetized with clove oil (0.03 ml.l-1). The each group of females were artificially spawned, the eggs were seeded with a mixture of sperm from three males, activated with hatchery water and unsticked with cow's milk diluted with water (1:9). Incubation of eggs was carried out in small experimental Zug bottles (0.45 l) at an average temperature of 21 °C. The highest number of ovulated and artificially spawned females was found at temperatures of 21 - 25 °C (80 %). At lower and higher temperatures the success of spawning was lower. A close positive linear dependence of the latency interval length (in hours) on water temperature was found in the monitored range of 15.5 - 27.2 °C (y =-1.5062 x + 50.663; R2 = 0.924). The length of the latency interval at 21 and 23 °C was 18,4 +- 0,9 and 12,4 +- 0,2 h, respectively 387 +- 18 and 289 +- 5 h°. The eggs have a yellow-brown to green-brown colouration, the average weight of one unswollen eggs is 1,10 +- 0,07 mg (corresponding to 911 +- 51 thousand eggs in 1 kg of eggs). In contact with water, the eggs are very sticky. The highest relative working fecundity was achieved at 21 and 23 °C (71,9 +- 10 and 75,9 +- 34 thousand eggs per 1 kg of female). The average survival rate of eggs to the eyespot, originating from artificially spawned females kept during the latency interval at temperatures between 18,9 - 23,2 °C, ranged from 92.9 +- 0.5 to 99.6 +- 2.2 %, and was lower at 17.2 and 27.2 °C (86.2 +- 0.6 respectively 74.2 +- 3 %), differences between groups were statistically significant. In evaluating the effect of unsticking preparations on the survival of eggs to the eyespots, the highest survival was achieved with milk (71.9 +- 7.3 %). Statistically conclusively lower survival was found with tannin (47.4 +- 0.4 %) and acetylcysteine (48.4 +- 8.6 %). The achieved results can be used in artificial spawning of crucian carp as part of rescue breeding.
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