CLIMATE WARMING AND THE GROWTH OF WARM WATER FISH IN PONDS IN THE TEMPERATE ZONE
Maria Anna Szumiec
Institute of Ichthyobiology and Aquaculture of the Polish Academy of Sciences in Gołysz, Poland
ABSTRACT. 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.
Key words: CLIMATE WARMING, EFFECTIVE TEMPERATURE, COMMON CARP (CYPRINUS CARPIO)
CORRESPONDING AUTHOR:
Prof. dr hab. Maria Anna Szumiec, Polska Akademia Nauk, Zakład Ichtiobiologii i Gospodarki Rybackiej w Gołyszu, 43-520 Chybie: Tel./Fax: +48 (33) 8563778, +48 (33) 8589292;
e-mail: zigr@fish.com.pl, maszumiec@wp.pl