A recent study funded by the UK's Natural Environment Research Council and conducted by researchers from the University of Bristol has revealed that shoal fish assume leader/follower roles as a safety measure.
The study found that clearly defined roles among shoaling fish were more evident in areas where there were denser concentrations of predators, suggesting that the presence of predators might impact how individuals help make group decisions.
According to researcher Dr. Christos Ioannou of the university's School of Biological Sciences, "There are many benefits of group living, and making decisions together can dramatically increase the survival of many species - this is why many birds flock and fish shoal."
The researchers studied the behavior of more than 300 fish from waters with differing levels of predation risk. Using computer tracking software, the researchers placed fish in a maze and measured decision making and shoal cohesion for each individual fish within each shoal.
The data revealed that most of the decisions a leader fish made were followed by the rest of the shoal. This increased the efficacy of the shoal. Furthermore, shoaling fish that were at a higher risk of predation were even more likely to adhere to a leader fish's decisions than lower predation fish. Conversely, the dynamics of group decision-making in the shoaling behavior of lower predation fish tended to be more egalitarian.
"This research is important as it shows that social behaviour can adapt depending on ecological factors. This could have a wider impact when considering how changes in species communities, for example due to climate change or invasive species, affects social prey," said Dr. Ioannou.
The study was published in "Science Advances" and you can check it out here.
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