Effect of repeated exercise fatigue on the swimming performance of juvenile rock carp (Procypris rabaudi, Tchang)

The swimming performance of juvenile rock carp (Procypris rabaudi, Tchang) subjected to repeated fatigue exercise was studied using a flume-type respirometer at 20 degrees C. The critical swimming speed (U-crit) and oxygen consumption rate (MO2) of juvenile rock carp were measured during two successive stepped velocity tests, following a 60 min rest interval.U(crit)of rock carp was giving a recovery ratio (R-r) of 92.64%, and exertion exercise decreasesU(crit). When MO(2)was plotted as a linear function ofU, the slope for trial 1 was 1.06 and 1.50 for trial 2, indicating a decreasing in swimming efficiency. The maximum metabolic rate (MMR) increased from 17.06 +/- 1.14 mmol O-2/(kg center dot hr) to 19.14 +/- 1.23 mmol O-2/(kg center dot hr), and the exercise post oxygen consumption rate (EPOC) increased from 9.00 to 9.65 mmol O-2/kg. Repeated fatiguing exercise increased both the aerobic and anaerobic cost of reachingU(crit), but anaerobic metabolism accounted for a larger proportion in the trial 2. The data investigation on the swimming performance and the physiological response to fatigue provide important design criteria for fishways.