Three-dimensional Tracking of Fish inside a Large School at the Rotterdam Zoo*

The three-dimensional motion of schooling of fish is a startling display of collective behavior that continues to intrigue many scientists including fluid-dynamicists. Our current understanding of the physical and social principles underlying to the emergence of coordinated group motion is limited due to a lack of three-dimensional experimental data. In this work, we perform three-dimensional tracking of a school of 1500 Harengula Clupeola (false herring) at the large-scale ocean aquarium of the Rotterdam Zoo. This aquarium is a unique facility that reproduces a tropical ocean ecosystem where the fish swim in an unconstrained environment that includes multiple species of predators. From our tracking data, we gain detailed knowledge of the kinematics and spatial organization of fish inside the large school. Using the measurement of the position and velocity of the individual fish, we study the morphology and group dynamics of the school. Our data provides new insight into the unconstrained and three-dimensional dynamics of schooling fish; we will discuss its relevance to other active biological systems.