SCHAEFER*, Justin T; CANNAS, Marcella; STEFFENSEN, John F; Univ. of California, Irvine; International Marine Center, Oristano Italy; Univ. of Copenhagen: Respirometry across the gait transition in a labriform swimmer (Embiotoca lateralis)

Gait transition, a speed-dependent change of swimming modes, has been described in several species of fish and for different modes of swimming. Labriform swimmers (e.g. surfperches and wrasses) are those fish that exclusively use their pectoral fins at low to medium speeds, and their caudal fins at high speeds. This change in gait at high speed may be due to the necessity for increased metabolic efficiency in the swimming stroke, or a biomechanical limit on stroke frequency. Gait transition in the striped surf perch (Embiotoca lateralis) took the form of burst-and-coast swimming at high speeds, with the pectoral fins used in between tail beats. We measured the oxygen consumption of striped surf perch before, during, and after the gait transition. Metabolic oxygen consumption increased after the gait transition, and plateaued immediately before the critical speed was reached. The cost of transport did not increase across the gait transition, indicating that the additional speed was produced by anaerobic musculature.