Shoals of sticklebacks differ in their collective personalities

Date:  February 7, 2018

Source:  University of Cambridge

Summary:

Research has revealed that, among schooling fish, groups can have different collective personalities, with some shoals sticking closer together, being better coordinated, and showing clearer leadership than others.

Continued  

Fish lose their unique personalities when they join a school

September 19, 2016

by Brett Smith

Researchers have found sticklebacks-- small freshwater fish native to the United Kingdom, appear to suppress their individuality when schooling, according to a new study in the journal Science Advances.

The study team found the bravest fish led groups, and the fish stuck together when facing a risky decision, just like the tendencies seen in human decision making. However, the team found the group's consensus appeared to override the direction of the leading fish, meaning these fish lost their personalities in a group setting.

"This is the first time that the suppression of personality in groups has been linked to its underlying cause, which is conformity in group decision making,” study author Christos Ioannou, a biologist from the University of Bristol in the UK, said in a news release.
What makes up a fishy personality?

In the study, the researchers assessed personality factors with a basic foraging test. First, a fish was put into an aquarium with a hiding place. Across from the hiding place was a food reward the fish had to cross open water to get. The team assessed boldness by documenting the length of time it took fish to go out of their sanctuary and get the food.

Then, the fish were tested again as a group. The school was seen making the decision collectively and even the most anxious individuals would swim in the direction of the food reward with their colleagues. The study team said while the boldest fish tended to lead the school, even the boldest fish stuck with the group to a certain extent, making them “less brave” than in the individual trials.

Follow-up tests revealed behavior previously seen in the group did not have a lasting effect when individuals were tested again by themselves; it was as if the group trials never occurred.

 

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