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Selected aspects of intensively cultured European whitefish (Coregonus maraena, Bloch) and peled (Coregonus peled, Gmelin)
ŠEBESTA, Roman
Maraena whitefish and peled are considered to be economically important fish species. This Ph.D. thesis deals with testing of selected aspects which show potential for improvement of quality and effectivity of larvae and juveniles of both fish species in recirculating aquaculture systems. The whole Ph.D. thesis includes 9 chapters described in 125 pages. In chapters 2-8, there are described the individual factors which can influence quality of intensive rearing of mentioned fish species. The effect of light intensity and tank wall colour on growth and survival of peled larvae is tested in chapter 2. The effect of different temperature on growth and survival of maraena whitefish larvae is presented in chapter 3. The effect of various stocking density on growth and survival of maraena whitefish larvae is given in chapter 4. The influence of different feeding strategy on survival, growth, and intestine and liver development of maraena whitefish larvae is being shown in chapter 5. The effect of various weaning time and co-feeding duration on growth and survival of peled larvae is described in chapter 6. The effect of variable water oxygen saturation on growth and haematological profile of peled juveniles is shown in chapter 7. The prevalence of deformities in intensively reared peled and comparative morphometry in intensively reared fish compared to pond-reared fish is described in chapter 8. Ph.D. thesis contains important advices which can be used in fishery practise and at the same time they can prevent from elevated fish mortality.
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Vliv délky světelného dne na příjem krmiva a růst síha peledě (Coregonus peled) v intenzivním chovu
KOS, Martin
The effect of the length of the daylight on growth of in peled (Coregonus peled) juveniles was tested in the intensive culture. Fish of mean body weight 1.82 +- 0.48 g and total length of 65 +- 7 mm were divided into four groups (the ratio of light and darkness 12k12, 16k8, 20k4, 24k0). The experiment lasted for sixty-three days. Every twenty-one days fishes were sampled for biometric measurements. Fish reached mean body weight of 15 +- 4.9 g (12k12); 15.6 +- 4.5 g (16k8); 16.7 +- 4.5 g (20k4); 16.8 +- 5 g (24k0) in experimental groups. The longest total body length was detected in both 20k4 and 24k0 groups (127 +- 11 mm). The lowest one was registered in the 16k8 (114 +- 11 mm). The highest condition coefficient had group 16k8 and lowest was found out in group 20k4. Specific growth rate during the course of the experiment was 3.33 %xday -1 (12k12); 3.28 %xday -1 (16k8); 3.49 %xday -1 (20k4) and 3.43 % xday -1 (24k0). The highest final survival (95.8 +- 1.4 %) was achieved in group 12k12. On the contrary, group 16k8 showed lowest survival of 90.0 +- 4.6 %. There were no significant differences in final survival rate.
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The effect of feeding frequency on feed intake and growth for Peled whitefish (Coregonus peled) in intensive aquaculture.
DOFEK, Jan
Frequency influence of animal feed has been tested (6×, 4×, 2× and 1× per day). Food income and new arrival experiment was repeat in three phases after every 21 days. Fish age after 124 - 187 days from the beginning till the end of the experiment. Average weight in all tanks was 1.86 + - 0.5 g in first experiment phase (0. 21. days). At the end of first experiment fishes with the biggest weight were the one with frequency influence of animal feed 6 times a day. Individual weight at the end of first fishing was 4.21 + - 1.31 g (6× a day), 3.74 + - 1.24 g (4× a day), 3.6 + - 0.46 g (2× a day), 2.89 + - 1.29 (1× a day). The best growth group become group with frequency influence (6× a day and 4× a day) and on the other hand group with the smallest growth was the group with frequency influence (1× a day). Fishes achieved weight of 15.9 + - 4.5 g (6× per day), 15.1 + - 4.9 g (4× per day), 12.19 + - 5.4 g (2× per day), 5.54 + - 4.05 g (1× per day). Chance of survival (96 %) was the best in group with frequency influence of animal feed (4× a day) and the last (89 %) was the group with frequency influence (6× a day). The highest rate of heterogeneity (74 + - 9 %) was in third phase of experiment in fish group with frequency influence (1× a day) as compared to group (28 + - 2 %) with frequency influence of animal feed (6× a day).
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