مرکز منطقه ای اطلاع رساني علوم و فناوري - A COMPARATIVE STUDY ON INCUBATION EFFICIENCY AND FRY GROWTH CHARACTERISTICS OF RAINBOW TROUT EGGS (Oncorhynchus mykiss, W., 1792) IN TWO DIFFERENT WATER SOURCES

Abstract :

In the present study, fertilized eggs obtained from rainbow trout (Oncorhynchus mykiss, W., 1792) brood stocks were left to hatch in two different water sources, and time of hatching, hatching rate, survival rate in yolk sac stage and growth characteristics of fry were compared. Eyeing of incubated eggs in ground water was 186 degree-days with an eyeing rate of 89.24%, a time of hatching as 328 degree-days and a hatching rate of 86.88% whereas eyeing in stream water was found to be as 218 degree-days, eyeing rate as 90.08%, time of hatching 356 degree-days and eyeing rate as 88.57%. Survival rates of larvae in yolk sac stage were 94.6% in ground water and 93.29% in stream water. Efficiency of incubation was detected to be 81.35% for ground water and 81.80% in stream water. During the experiment, the mean initial weight of sac-free, swimming-up active feeding larvae in ground water was 0.62±0.07 g and reached to 86.59±2.84 g at the end of the trial. The mean initial weight of larvae in stream water was 0.61±0.02 g and reached to 36.54±2.41 g at the end of the study. The mean values for feed conversion rates were 1.04±0.04 in ground water and 1.22±0.09 in stream water. It was found that ground water is more efficient than stream water in terms of initial egg growth and growth periods.