Growth parameters of brook trout (salvelinus fontinalis, Mitchill 1814)in sea and freswater in the East Blacksea condition

SUMMARY The aim of this study was to compare the daily food consumption, food conversion ratio, death ratio and growth parameters of brook trout (salvelinus fontinalis) reared in sea and freshwater tanks. Juveniles of 0" age group obtained from a private trout form were used and the study lasted until the experimental fish reached age of 18 months. During Janury- April the group of seawater fish has shown a better growth, whereas in the rest of the study the group of seawater fish grew faster. So the mean weights, which were 5.74+1.63 g for seawater and 6.02±1.69 g for freshwater at the beginning of the trial, reached 96.07±31.78 g and 86.17±27.17 g in April, and 230.28±75.73 g and 318.50199.39 g respectively, at the end of the study. Differences between mean weights were not significant in April, but the final differences were significant in favor of freshwater group (P<0.01). Daily specific growth rate was determined to be 0.92 (0.09-2.00) for seawater group and 0.98 (0.57-2.00) for freshwater group. Daily average food consumption and food conversion rates were calculated to be %1.30 (0.20-2.16) and %1.44 (0.93-2.39) and 2.29 (1.03-5.00) and 1.7 (1.09-2.43) for seawater and freshwater group respectively. The death rate was %58.5 for seawater group and %49.2 for freshwater group. In conclusion, results show that growth in seawater appears to be better during the winter months, but the drops rapidly in summer when the seawater temperature exceeds 20°C, and significant losses occur. Keywords: Brook trout, Salvelinus fontinalis, growth performance, food conversion ratio, food consumption, feeding regime, freshwater and seawater. VI