Effects of acute temperature and salinity changes, body length and starvation on the critical swimming speed of juvenile tiger puffer, Takifugu rubripes

The critical swimming speed (U crit, cm s−1) of juvenile tiger puffer Takifugu rubripes was determined under different temperatures (15, 21, 25 and 30 °C), salinities (5, 10, 20, 32 and 40), body lengths (3.32, 4.08, 5.06 and 5.74 cm) and starvation days (1, 3, 6 and 9 days). Acute temperature change, body length and starvation significantly influenced the U crit of tiger puffers, whereas acute salinity change had no significant effect. The U crit increased as the temperature increased from 15 to 30 °C. The U crit increased as the body length increased from 3.32 to 5.74 cm, whereas relative critical swimming speed (U crit’, body length s−1) decreased. The relationship between the body length (l, cm) and U crit or U crit’ can be described by the quadratic model as U crit = − 1.4088 l 2 + 16.976 l − 11.64, R 2 = 0.9698 (P