Growth of juvenile rainbow trout in cage farms of Karelia

The first results on the growth of juvenile rainbow trout in cage farms of Karelia (Lake Kotkozero) were obtained. 60 thousand fish of juvenile trout were examined. Environmental conditions of cultivation, growth, and survival rate of juveniles were studied. Favorable conditions for growing fry were defined: pH 7,2-7,9, water temperature 7,9-14,4 °С, oxygen content of 6,0-9,3 mg/l. Gains in length and weight for trout fry during the study period (45 days) were 3,6 cm, and 1,5 g. Correlations in the dynamics of linear and weight growth of juvenile rainbow trout was identified: in case of high linear growth accumulation of body weight slows down. The daily mortality rate among juveniles varied from 0,3 to 1,6 %. The fry survival rate was 79,2 %. The “flash” of fry deaths (mortality to 2,3 % per day) due to miksobakterioza was observed. The overall prospects for growing species taken from Karelian cage farm producers were shown.