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

Abstract

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 24oC, 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.

CORRESPONDING AUTHOR:

Dr Mirosław Szczepkowski, Instytut Rybactwa Śródlądowego, Doświadczalny Ośrodek Zarybieniowy „Dgał“, 11-610 Pozezdrze, Pieczarki 50, Tel./Fax: +48 (87) 4283666;
e-mail: szczepkowski@infish.com.pl