Fish Have Individual Personalities but Conform When Schooling

A new study shows that while individual fish have unique personalities, they conform to group decisions when in a school. Braver fish take on leadership roles and the other individuals follow the lead, regardless of how they act when outside of the school. The findings are in a paper that was just published in the journal Science Advances.

Researchers from the University of Bristol tested three-spined sticklebacks (Gasterosteus aculeatus) in both group settings and alone. They measured personality factors by using a simple foraging test. A fish was placed in an aquarium with a hiding place. Opposite to the hiding place was a food reward but the fish needed to cross open water to reach the bait. The team measured boldness by recording how long it took fish to leave their refuge and seek out the food. The fish were then retested as a group.

When in a school, the sticklebacks’ individual personalities were suppressed. The school made a decision as a group and even the most nervous individuals would swim toward the food reward. The research team noted that bold fish tended to lead the group. Even the bravest fish conformed to an extent, though, and were less bold than they had been in the individual trials. When in a school, the fish acted as one unit, making decisions together.

Group decision-making offers a couple of major benefits to a school of fish. Conformity allows the group to coordinate better, helping the school evade predators. Working as a team also helps the school manage risk versus reward scenarios. If the boldest fish consistently made risky decisions, it could put the entire school in danger. Conversely, shy fish might never take risks, missing out on food and other resources. The research team’s findings provide new insights into animal social groups and the benefits of group conformity.

REFERENCE

Nicholas D. McDonald et al. Consensus and experience trump leadership, suppressing individual personality during social foraging. Science Advances (2016).

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