Fig. 5. The dependence of tail-beat frequency on both swimming speed and fish fork length (FL) in chub mackerel at 18 °C (blue plane and symbols) and 24 °C (green plane and symbols). Each symbol indicates the tail-beat frequency versus speed data for one individual. The maximum and minimum values of speed and FL at 18 and 24 °C were used to solve the multiple regression equation for tail-beat frequency (Table 2) for the four corners of each plane. There was no significant effect of temperature on the relationship between tail-beat frequency and speed and FL (ANCOVA, P<0.05).