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The empirical-deterministic model of the individual fingerling body mass growth was validated on the basis of results obtained in the same ponds as those in a model setting when differentiated biotechniques were applied. The statistically evaluated accuracy of the model proved to be good and indicated that the model reflects both the carp fingerling individual growth and their yield when certain assumptions are taken into consideration.
In the temperate zone, climate warming improves the environmental conditions of warm water fish in many ways thus stimulating their growth and yield. Warming was observed in fishponds in the mid 1980s when seasonal sums of water temperature above 14°C, i.e. the temperature effective for carp, Cyprinus carpio growth, frequently exceeded the long-term average sum. There was considerable variability in the annual sums of temperature effective for carp growth with a decreasing tendency in the 1958-1980 period and an increasing tendency in the 1980-2003 period. The long-term distribution of the yield of three-year-old carp follows the sums of the effective temperature except in very warm seasons when the empirical yields were below those computed from the model. This implies that it is necessary to introduce into computations the upper temperature of the thermal limit effective for carp growth, which seems to be an average diel temperature of about 25°C. This paper presents the quantitative differentiation in thermal conditions of carp growth between Poland, France, and Bohemia.
The greatest losses in central and eastern European carp culture are caused by the high mortality of juveniles usually during the first three to four weeks after pond stocking in late spring. The pronounced weather fluctuations of this period, including drastic falls in temperature, endanger the survival of this warm-water fish. By quantifying the effect of considerable temperature decreases on the survival of juvenile carp, logarithmic increases in carp survival rate were apparent as favourable thermal conditions extended from 1 to 40 days. Simultaneously, a decrease in carp swim bladder inflammation was observed. The trend toward increasing frequency and amplitude of weather fluctuations might intensify this problem.
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