Group movement dynamics improves aerobic performance and conserves anaerobic energy in schooling fish

Abstract

AbstractSchooling fish move in a viscous fluid environment and are a model system for understanding how group movement dynamics enables energy conservation1. But how group movement in the water reduces locomotor cost remains elusive. We measured both aerobic and anaerobic metabolic contributions to energy use in schools of giant danio, and show an energetic reduction per tail beat of up to 126% compared to solitary fish. Fish in schools used a smaller proportion of their aerobic capacity to swim and reduced the anaerobic cost by 2.8 fold, which lowered the total energy expenditure and cost of transport by up to 112% at higher speeds. Fish schools also exhibit aU-shaped metabolism–speed curve, with a minimum metabolic cost at 1 body length s-1, the migratory speed of diverse fish species2,3. This finding suggests that physical constraints on movement through water may be a key driver for the evolution of active directional schooling behaviour in fishes.One-Sentence SummaryFish schools reduce the metabolic cost of swimming by up to 112% and the energy used per tail beat of up to 126% compared to solitary fish.