Limit of fish swimming speed

Abstract

OBSERVATION and analysis of the swimming of marine fish in laboratory aquaria and in the vicinity of fishing gear (C.S.W., unpublished) have indicated that small fish (0.1 m) can reach speeds up to 25 body lengths s⁻¹ whereas larger fish (1 m) seem unable to exceed 4 body lengths s⁻¹. Bainbridge¹ showed that smaller fish were capable of higher tail beat frequencies than larger fish and forward motion resulting from one complete tail beat cycle (or one ‘stride’) was between 0.6 and 0.8 times the length of the fish. In the present study the tail beat frequency or frequency of strides is considered to be limited by the contraction time of the swimming muscle of the fish, and maximum observed swimming speeds are found to fit the dimensions of the muscle twitch time and stride length.