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 < 0.01) or U crit' = - 0.1937 l 2 + 0.9504 l + 7.7666, R 2 = 0.9493 (P < 0.01). The U crit decreased as starvation days increased from 1 to 9 days. Low temperature and starvation can reduce the swimming ability of juvenile tiger puffers. Results can be of value in evaluating the swimming ability of juvenile tiger puffers, understanding ecological processes and improving the population enhancement of tiger puffers.