EFFECT OF CULTURE CONDITIONS ON REPRODUCTIVE TRAITS OF BROWN TROUT SALMO TRUTTA L

Progeny from artificial propagation of wild brown trout (Salmo trutta L.) of the Blanice river, Czech Republic, were farmed to maturity and spawned at ages three, four and five during 2002-2004. Reproductive parameters and biological quality of eggs in this farmed population were compared to those of the original wild population. ANCOVA showed no differences between wild and farmed fish in weight of eggs per female, total fecundity, or relative fecundity in any year. Significantly higher egg diameter (4.57 mm, P = 0.001) and weight (69.3 mg, P = 0.0375) were found in the wild population in 2002 and conversely in 2004, the mean egg weight was higher in the farmed population (94.7 mg, P = 0.0021). Differences in egg diameter in this year (4.64 ± 0.06 and 4.82 ± 0.06 in wild and farmed trout, respectively) were close to the level of significance (P = 0.079). Mutual correlations between length or weight and studied reproductive traits were similar in both populations. Fertilization rate, duration of incubation period, egg losses during incubation and mortality of starving hatched fry were monitored in embryos and larvae of farmed population only (FxF), crosses between farmed females and wild males (FxW) and wild population only (WxW). Altogether 6.3%, 5.8% and 5.4% of eggs died during incubation period in FxF, FxW and WxW, respectively. There were also no significant differences in duration of incubation period and mortality of starving fry. It can be concluded that farming conditions did not significantly affect the reproductive parameters and quality of eggs in the first generation of farmed broodstock.