Prolonged and burst swimming in anadromous and freshwater threespine stickleback, Gasterosteus aculeatus

Prolonged and burst, or "fast-start," swimming were measured in anadromous and resident freshwater sticklebacks. In prolonged swimming tests conducted at 5 body lengths/s, anadromous sticklebacks fatigued less easily than freshwater sticklebacks. Anadromous sticklebacks also had larger pectoral fins and less robust bodies than freshwater sticklebacks. At the start of a burst swimming sequence (kinematic stage 1), freshwater sticklebacks curved their bodies more than anadromous sticklebacks, but trailing-edge amplitudes were the same in both forms. During kinematic stage 2, freshwater sticklebacks had greater trailing-edge amplitudes than anadromous fish, but body curvature was the same in both forms. During burst swimming, freshwater sticklebacks attained both higher maximum and mean velocities than anadromous sticklebacks and also travelled a greater distance in the first 50 ms (2.67 vs. 1.98 cm). These results are discussed with respect to differences in habitat and life histories in the two forms of Gasterosteus.