Effect of gravitational field on collective motion of fish

TL;DR

This study investigates how gravity influences fish collective behavior, revealing that gravity causes vertically elongated formations and affects cluster shape, individual motion, and overall mobility in fish schools.

Contribution

Introduces an agent-based model incorporating gravity effects, demonstrating how gravity shapes fish cluster morphology and movement patterns.

Findings

Gravity induces tornado-like vertically elongated clusters.

Vertical elongation occurs even with weak gravitational influence.

Gravity affects cluster shape, individual motion, and mobility.

Abstract

Fish exhibit various patterns of collective motion, in which individual fish sense the gravitational field and tend to move horizonally. We study the effect of gravity on the collective patterns by incorporating suppression of vertical motion in an agent-based model. The gravitational factor induces a tornado which is a vertically and highly elongated form of a torus, The vortex axis becomes almost identical to the vertical axis even when the gravitational factor is weak compared to the interaction between fish. We also obtained a vertically elongated polarized school with high frontal density. Our results clarify the effect of gravity on the shape of clusters, individual-level motion, and mobility of the entire cluster.