December 7, 2010
Personality is not just a feature unique to humans and pets. Scientists at the Univ. of Gothenburg have revealed that brown trout also have individual characters and show different personalities.
Researcher Bart Adriaenssens from the Department of Zoology at the Univ. of Gothenburg has studied the behavior of juvenile trout from watercourses on the west coast of Sweden.
"My results show that it is not just humans and other mammals that exhibit personality. Brown trout differ among each other in their level of aggression and react differently to changes in their surroundings," says Adriaenssens. "The release of a novel object in the aquarium causes very 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 is not always the bold and aggressive fish who are most successful. When we marked trout individually and released them back in the wild, it was shy trout that grew most rapidly."
What fish personality works best depends on the environment: if there is little protection available, as is the case, for example, in a tank at an aquaculture facility, large and bold fish are likely able to grab most of the food. But in the more complex environment of a stream in the wild, shy individuals can be more successful.
The question of why animals have personalities remains still to be answered.
"If a certain personality proves to work well, and individuals with that personality grow rapidly, survive in greater numbers and have more offspring, we would expect all individuals to 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," says Adriaenssens.
Source: Univ. of Gothenburg