The cost and efficiency of aerobic locomotion in the chub mackerel (Scomber japonicus)

SHADWICK, R.E.*; STEFFENSEN, J.F.: The cost and efficiency of aerobic locomotion in the chub mackerel (Scomber japonicus).

The cost of aerobic locomotion in the chub mackerel was investigated at different steady swimming speeds in a water tunnel respirometer. Eight fish, 25 to 30 cm in length (L), and 145-199g mass were used at 14-15oC. O2 consumption was measured by computer-controlled intermittent flow respirometry with a ten minute cycle. Fish were placed in the respirometer and allowed to acclimatize while swimming at a low speed (1 L/s) for at least 12 h while O2 consumption was monitored. Initially high values typically declined by 3 to 5-fold to a stable level after several hours of undisturbed swimming. Swim speeds were then raised in increments of 0.25L/s each 30 min until steady swimming was no longer possible, usually near 3L/s. A the same time, dorsal body images were recorded by video at 60Hz. O2 consumption increased exponentially with speed. Extrapolation of ln-linear plots to zero velocity gave estimates of standard metabolic rates (SMR), ranging from 90-120 mg O2/kg/h, or 0.35-0.47 Watts/kg. The aerobic scope was in excess of 6.8 times the SMR. The cost of transport was minimal (2.0-3.5 J/kg/m) at 1.5-1.75 L/s. Kinematic analysis of the dorsal body midline, using the Lighthill small amplitude bulk momentum model, provided an estimate of the thrust power and kinetic energy losses. By comparing the simultaneously determined power output and metabolic power consumed, the froude and aerobic efficiencies were calculated. These were typically >0.8 and <0.2, respectively.

the Society for
Integrative &