Seasonal variations in the swimming performance of perch (Perca fluviatilis L.) measured with the rotatory-flow technique

Abstract

Swimming in fish is composed of both propulsive and maneuvering components. Evidence is presented for a seasonal rhythm in the maneuvering capacity of a temperate area fish, the perch (P. fluviatilis L.). The rotatory-flow technique, measuring the ability of the fish to maintain its posture in a rotating water current, was used in the study. Tests on animals kept under constant conditions in the laboratory revealed that this seasonal rhythm was generated by an endogenous oscillation. Based on these observations and existing knowledge about locomotor activity and body constituent rhythms, a winter strategy in perch is proposed that implies an endogenously regulated change in behaviors leading to an economic use of stored energy.