The Effects of Stocking Density on Growth Performance of Brook Trout (Salvelinus fontinaiis) and Rainbow Trout (Oncorhyncus my kiss)

SUMMARY The effects of stocking density on growth performance of two Salmonidae species, brook trout {Salvelinus fontinaiis) and rainbow trout {Oncorhyncus mykiss), have been compared. Rainbow and brook trout fingerlings of 0" age-class with inital mean weights of 12.6±3.7 (n=300) and 8.9±2.6 (n=300) were used. Two stocking densities of 50 and 100 fish/tank for each species were tested with two replications for each density groups. During 217 days trial, the growth performance (mean weigths, production and daily spesific growth rates), food consumption, feed conversion ratios and condition factor values have been determined. Final mean weigth values of 50 and 100 fish/tank density groups of rainbow and brook trout were 230.2±62.2 and 238.7±66.0 g, 162.1±48.3 and 139.7±54.0 g respectively, i.e. growth performance of rainbow trout appeared increasing with increasing stocking density, whiie it is vice versa for brook trout. Density values at harvest reached 56.4 and 119.4 kg/nr* for 50 and 100 fish density groups of rainbow trout, and 40.5 and 69.2 kg/m3 for brook trout. It has been concluded that brook trout appeared to more sensitive to high stocking densities than rainbow trout. Key Words: Brook trout, Salvelinus fontinaiis, rainbow trout, Oncorhyncus mykiss, stocking density, growth performance, feed conversion rations. VI