Fish Larvae Move Better In Groups

By on February 17, 2016

Are fish happiest when they swim together? Well, that’s not really clear because it’s kind of hard to assess fish emotions. But there is an indication thanks to new scientific research that fish larvae may be able to swim at least a little better when they move in groups.

The study, led by researchers at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, reveals that larvae of damselfish swim straighter, faster and more consistently in one direction when they’re moving as part of a school.

The research team compared the movements of individuals and groups of 10 to 12 in a species of damselfish, Chromis atripectoralis, in their natural environment off Lizard Island on the Great Barrier Reef.

The fish larvae were observed by divers and through using a drifting image recording device, called a Drifting In Situ Chamber developed by U. of Miami scientists. Essentially, this meant that scientists released sets of the fish and watched them swim away, stalking them as they went with the imaging device.

This showed the importance of group dynamics for moving the young fish on their way. Researchers watched as groups of the young damselfish did better than those swimming alone. In all, schools of the fish swam on a 15 percent straighter course and 7 percent faster than individuals.

In addition, researchers say that this group think seems to emerge more from simple group dynamics than from the presence of more skillful leaders. This could mean that the findings apply to other organisms that operate using group dynamics amidst limited cognitive abilities.

The study is one of the few that has looked at the schooling behaviors of fish during the larval stage, before they settle into new areas, like coral reefs. Before this investigation, it wasn’t exactly clear what benefits schooling provided young fish.

For adult fish, benefits to schooling include discouraging predators from attacking and making it easier to detect or find food. For the young larval fish, it’s also that it helps them to move to new areas with speed and efficiency.

The full results, published in the open-access journal PLOS ONE, indicate that larval fish, though small in size and limited in development, still have the motor, sensory and cognitive equipment necessary for navigating the complexities of group movements.

Results of the work shed new light on the group dynamics involved in moving fish from area to area because most other studies into the space have only dealt with birds. With groups doing better than individuals, scientists think their findings will have implications for connectivity and fish recruitment success in future projects.


Top image: A group of black axil chromis (Chromis atripectoralis) larvae swimming in the Great Barrier Reef. (Credit: C.B. Paris, R. Paris / University of Miami Rosenstiel School of Marine and Atmospheric Science)

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