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1

Effects of the polyculture of juvenile stages of Northern pike [Esox lucius L.] and sturgeon in recirculating systems

100%
Szczepkowski M., Szczepkowska B.
Electronic Journal of Polish Agricultural Universities. Series Fisheries
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2006
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tom 09
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nr 1
The possibility of using sturgeon as a stock component during the rearing of pike (Esox lucius L.) fry in tanks was determined. The experiment was conducted in two stages. In the first, pike fry with a body weight of 0.1 g were reared in monoculture and polyculture with a sturgeon component comprising 40 and 80% of the pike biomass. In the second phase, pike fry weighing an average of 3 g were reared in monoculture and polyculture with a sturgeon component comprising 10 and 20% of the pike biomass. The introduction of the sturgeon improved feed utilization and lowered feed conversion ratios from 1.4 to 0.8 in the older pike group (statistically significant difference at P < 0.05). In experiment stage II, the pike fry reared in polyculture with sturgeon attained statistically significant (P < 0.05) higher body growth in comparison with the monoculture variant. Pike survival was the lowest in the monoculture at 72.1 and 91.4% in stages I and II of the experiment, respectively. With regard to the smaller fry, this was due primarily to cannibalism with such losses comprising over 50% of the total losses throughout rearing. Survival in the polycultures was as much as 12% higher. The authors believe that the possibility of rearing these two species together stems from their different behavior and feeding strategy. Another benefit was that the labor-intensive removal of feed not consumed by the pike fry was lowered which meant that there was minimal interference in the tank during rearing.
2

Oxygen consumption and ammonia excretion by Eurasian perch (Perca fluviatilis L.) reared under optimal thermal conditions

84%
Zakes Z., Demska-Zakes K.
Archives of Polish Fisheries
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2005
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tom 13
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nr 2
The aim of the study was to determine the oxygen consumption (OC, mg O₂ kg⁻¹h⁻¹) and ammonia production (AE, mg TAN kg⁻¹h⁻¹) of perch reared in a recirculating system at the optimal temperature for this species of 23°C. The studies were conducted when the fish were undergoing intense fattening on artificial feed. Measurements of metabolic rate were taken 24 hours per day in six size groups of fish (mean body weights (BW) in each group - 18.4, 30.7, 46.4, 56.5, 67.8, 82.3 g). Within the studied perch size range, OC decreased from 336.2 to 185.0 mg O₂ kg⁻¹h⁻¹, and AE from 22.0 to 5.6 mg TAN kg⁻¹h⁻¹. An increase in body weight by 1 g led to an average decrease in oxygen consumption by a mean of 2.53 mg O₂ kg⁻¹h⁻¹ and ammonia excretion by 0.28 mg TAN kg⁻¹ h⁻¹. During the analyzed period, the body weight of perch, the arithmetic dependence between OC-BW and AE-BW, was linear and the determination coefficients R² of the linear regression equations describing these relationships were highly statistically significant at a value exceeding 0.9.
3

The impact of water temperature on selected rearing indices of juvenile whitefish [Coregonus lavaretus [L.]] in a recirculating system

84%
Szczepkowski M., Szczepkowska B., Krzywosz T.
Archives of Polish Fisheries
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2006
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tom 14
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nr 1
This study investigated the impact of water temperature on the growth, feed uptake, and oxygen consumption of juvenile whitefish, Coregonus lavaretus (L.), reared in a recirculating system. The fish used in the study had a mean initial weight of 7.9 ± 0.2 g and a mean body length of 8.9 ±0.1 cm. The study was conducted at water temperatures of 20, 22, and 24°C (each group in replicates of four). The best weight gain and body length growth were obtained at the water temperature of 22°C. Increasing the temperature to 24°C caused a statistically significant decrease in fish growth rate (P < 0.05). The feed conversion ratios of the fish reared at water temperatures of 20 and 22°C were close at 0.89 and 0.90, respectively, while at the temperature of 24°C this ratio was statistically significantly higher at 1.17 (P < 0.05). Temperature was not found to have a statistically significant impact on fish survival or on the amount of feed consumed. Water temperature had an impact on oxygen consumption, and the mean value of this index at a temperature of 20°C (186.6 mg O₂ kg⁻¹ h⁻¹ ) was significantly statistically lower (P < 0.001) than in the water at temperatures of 22 and 24°C, at which the mean values were 349.3 and 409.9 mg O₂ kg⁻¹ h⁻¹, respectively. Based on the results obtained, it was confirmed that the upper thermal threshold during the rearing of whitefish juveniles is 22°C.
4

The influence of feeding frequency on the metabolic rate of perch Perca fluviatilis L.

84%
Zakes Z., Demska-Zakes K.
Archives of Polish Fisheries
|
2002
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tom 10
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nr 1
The aim of the study was to determine the impact of feeding frequency (one, two or three feeds and continuous feeding) on the magnitude of oxygen consumption (OC, mg O₂ kg ⁻¹ h ⁻¹) and ammonia excretion (AE, mg TAN kg ⁻¹ h ⁻¹) by juvenile perch. The study was conducted during routine rearing in a recirculating system. No significant impact of the applied feeding schedules (P > 0.05) on the average diurnal values of OC and AE was confirmed. The values ranged from 165.88 mg O₂kg ⁻¹ h ⁻¹ (one feed) to 188.48mgO₂ kg ⁻¹ h ⁻¹ (continuous feeding) and from5.51 mgTAN kg ⁻¹ h ⁻¹ (two feeds) to 6.44 mg TAN kg ⁻¹ h ⁻¹ (continuous feeding). The feeding schedule had a significant influence on the diurnal fluctuations of oxygen consumption and ammonia excretion and was especially evident in the latter. The AEmax/AEaverage ratio in the group of fish fed once was 2.46, but the AEmax/AEmin ratio was 19.01. AE variability over a twenty- four hour cycle was much lower in other feeding schedules.The course of the diurnal profiles of OC and AE was characteristic for each of the applied experiment variants. Statistically significant dependencies were confirmed between ammonia excretion and oxygen consumption (P<0.001) and were specific to each experiment group. Correlation coefficients of the linear regression equation that describes the AE - OC relation ranged from 0.57 (three feeds) to 0.94 (two feeds). The values of OFR (kg O₂ kg ⁻¹ feed fed day ⁻¹) and AFR (kg TAN kg ⁻¹ feed fed day ⁻¹) were not determined by the applied feeding schedule (P > 0.05).
5

Effect of nutrition on growth and flower bud formation of Rhododendron cultivated on ebb and flow benches

67%
Bielenin M., Matysiak B.
Folia Horticulturae
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2004
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tom 16
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nr 1
101-105
6

Impact of selected abiotic and biotic factors on the results of rearing juvenile stages of northern pike Esox lucius L. in recirculating systems

67%
Szczepkowski M.
Archives of Polish Fisheries
|
2009
|
tom 17
|
nr 3
7

The impact of water temperature on the growth and survival of juvenile Northern pike [Esox lucius L.] reared on formulated feed

67%
Szczepkowski M.
Archives of Polish Fisheries
|
2006
|
tom 14
|
nr 1
The aim of the experiment was to determine the impact water temperature has on the growth and survival of juvenile northern pike, Esox lucius L., reared on formulated feed. The initial experimental material weighed 5.7 g and measured 8.8 cm in body length and was stocked into three recirculating systems (water temperature 20, 24, 28°C) and reared for 21 days. The highest final body weight was obtained by the fish reared at 28°C. Statistically significant differences were confirmed between these fish and those reared at a temperature of 20°C (P < 0.01), but no such differences were recorded with regard to the group of fish reared at 24°C (P > 0.05). At a temperature of 28°C, the survival of the fish was significantly higher at 98.7% (P < 0.05). A statistically significant difference (P < 0.05) was also confirmed in the feed conversion ratio (FCR) between the groups reared at water temperatures of 20 and 28°C at 0.61 ± 0.05 and 0.71 ± 0.04, respectively.
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