A study of the swimming performance of the Crucian carp Carassius carassius (L.) in relation to the effects of exercise and recovery on biochemical changes in the myotomal muscles and liver

Abstract

A study has been made of the maximum sustained swimming speed of Crucian carp Carassius carassius (L.) using a fixed velocity technique. The data obtained from swimming tests on 214 carp have been analysed using the method of probit analysis. The 50% fatigue level for 13–16 cm fish acclimated to 9.5±0.6°C has been estimated to be 3.35 lengths/sec. Biochemical measurements have been made on the red and white myotomal muscles and liver of fish subjected to both varying intensities of sustained swimming and short periods of vigorous swimming. Free creatine was found to increase only during high speed swimming in the white muscle. Elevated lactate concentrations occurred at both low and high sustained swimming speeds in the red superficial muscle but not during short periods of strenuous exercise. Glycogen depletion from the red musculature also only took place at the sustained swimming speeds investigated. The reverse situation was operative in the white muscle, significant glycogen depletion occurring only at the highest swimming speed studied. Lactate levels were only significantly different from non‐exercised fish in the fish swimming at the higher velocities. The effects of periods of recovery following 200 min of sustained swimming were also investigated. White muscle lactate was at a higher level than non‐exercise fish 5 h post‐exercise, while both red muscle glycogen and lactate rapidly returned to pre‐exercise concentrations. Biochemical measurements on the myotomal muscle types have been discussed in relation to the swimming performance of the fish and the division of labour between red and white fibres.