Estimating the sustained swimming ability of coral reef fishes

Sustained swimming ability can play a critical role in the ecology of fishes, particularly in terms of their distribution among habitats of differing flow conditions. However, the relative utility of various measures of swimming ability remains to be determined. The present study assessed the swimming speed performances of coral reef fishes using a range of experimental methods. This included a novel technique that measures the speed at which labriform fishes change gait from purely pectoral to pectoral-and-caudal propulsion over sustained time scales of >200 min (termed Up–nE). Measures of Up–cE were compared with two commonly used experimental metrics: critical swimming speed (Ucrit) and critical transition speed (Up–c). All three methods revealed consistent differences among taxa, and provided a reliable means of comparing swimming speed performances. Notably, two experimental measures (Up–c and Up–cE) appeared to more closely reflect the swimming speeds displayed by the same coral reef fishes in the field.