Critical swimming speed of sterlet (Acipenser ruthenus): Does intraspecific hybridization affect swimming performance?

Summary We studied the effect of intraspecific hybridization on swimming performance in sterlet, hypothesizing that such hybridization increases the performance by inducing the hybrid vigor. A total of 12 purebred and hybrid crosses were reproduced from Danube (D) and Volga (V) populations of Acipenser ruthenus. Within each cross, one group of fish was exposed to temperature challenges mimicking the temperature variation in the natural environment during summer. Temperature challenges comprised a constant increase from 19°C to 24°C and then return to 19°C within 12 hr (dT