The swimming endurance of threespine sticklebacks, Gasterosteus aculeatus L., from the Afon Rheidol, Wales

The endurance of threespine sticklebacks, Gasterosteus aculeatus, swimming with pectoral fin locomotion at 20° C in a laboratory flume was measured. Each trial lasted a maximum of 480 min. At a speed of 4 body lengths per sec (L s−1) all fish were still swimming at the end of the trial, but endurance decreased at higher speeds. At speeds of 5 or 6 L s−1 (20–30 cm s−1) a few fish still maintained labriform locomotion for the 480 min. However, at a speed of 7 L s−1 all fish furled their pectoral fins and used body and caudal fin propulsion but fatigued rapidly. During sustained swimming, fish could cover distances of 6 km or more. No significant differences between males and females were found.