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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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The optimization of transfer Northern whitefish larvae (Coregonus peled) on complete feed mixture.
PITHARDT, Tomáš
In this work was tested optimal rearing protocol for Northern whitefish larvae in two experiments. Both experiments lasted for 34 days. In the first experiment the effect of feed particle size on the survival and growth were tested in Northern whitefish larvae with initial body weight of 3.01 +- 0.48 mg. Larvae were weaned from live feed 10th, 15th, 20th, 25th and 30th day after hatching when co-feeding was took for 3 days before the weaning. In the first experiment were tested particle size of 100 micrometers and 300 micrometers. Groups weaned 20th, 25th and 30th with 100 micrometers feed and groups weaned 25th and 30th with 300 micrometers feed had similar final survival (without significant differences). The best growth (final weight 39 +- 12 mg) had group weaned 30th day after hatching using particle size of 300 micrometers. In the second experiment the effect of length of combined feeding (co-feeding) on the survival and growth were tested in Northern whitefish larvae on a unit weight 3.01 +- 0.48 mg. Co-feeding lasted for 1, 3 or 6 days before the weaning. Larvae were weaned from live feed 10th, 15th, 20th, 25th and 30th days after hatching. Groups weaned 10th, 15th, 20th, 25th and 30th had similar final survival (without significant differences). But the best growth (final weight 37 +- 15 mg) reached group weaned 30th day after hatching with combined feeding for one day. Groups weaned 20th, 25th and 30th had similar final body weight (without significant differences). There was no observed effect of co-feeding duration on survival and growth.
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