Shy Trout Grow Faster and Bigger

By on December 6th, 2010 15:41 GMT

Whoever believes that being shy is a sign of weakness and that only humans and pets had personality, should read about the latest discovery of University of Gothenburg (Sweden) scientists.

They have discovered that brown trout also have individual characters and different personalities.

Bart Adriaenssens and Jörgen I. Johnsson are the researchers from the Department of Zoology at the University of Gothenburg, that have been studying the behavior of young trout from watercourses on the west coast of Sweden, for many years now.

Adriaenssens explains that according to their results, “not just humans and other mammals exhibit personality.

“Also brown trout differ among each other in their level of aggression and react differently to changes in their surroundings.

He explains that the best way to figure this out is to release a foreign object into an aquarium and observe the different reactions.

“Some individuals will immediately explore this object, whereas others will rather hide in a corner and try to avoid every contact.

“But it are not always the bold and aggressive fish who are most successful,” he adds.

“When we marked trout individually and released them back in the wild, it were shy trout who grew most rapidly.”

In the case of fish, there is no single personality that works best in every situation – it all depends on the environment, AlphaGalileo reports.

The researchers say that when it is little protection available like in a tank, for example, the ones who are the more likely to get all the food are large and bold fish.

“But in the more complex environment of a stream in the wild, shy individuals can be more successful,” Adriaenssens reminds.

Normally we would expect that “if a certain personality proves to work well, and individuals with that personality grow rapidly, survive in greater numbers and have more offspring,” all individuals should “behave according to that personality.

“This is not the case, however, and there is still a lot of work to be done in this area to explain why", concludes Bart Adriaenssens.

No one has yet found out why animals have personalities, but this thesis has been successfully defended.

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