Fish Have Feelings Too! Personality Tests Can Boost Fish Reproduction

In a research recently published in Royal Society Open Science, researchers from the Spanish Institute of Oceanography have discovered that the way fish deal with stress is determined by their personality.

Aquaculture experts from the University of Stirling and the Institute for Food and Agricultural Research and Technology (IRTA) in Catalonia discovered that Senegalese sole cope with stress according to their existing behavior and remain consistent regardless of the situation they are in.

Around 120 Senegalese soles took part in five individual behavioral tests and two grouping tests. Cortisol, glucose, and lactate in the blood were measured at the end of the tests to measure the stress response.

One of the most direct uses of their new discovery is to help farmers screen fish from a young age to help the species reproduce in captivity and improve aquaculture production. Researchers hope the first study to test stress coping styles in mature Senegalese soles will help farmers screen fish from a young age to help the species reproduce in captivity and improve their population.

Younger Senegalese soles are known as juveniles and older fish are known as breeders. Researchers discovered that when faced with confinement, restraint or a new environment, Senegalese soles exhibit similar behavioral patterns and levels of activity, showing consistent responses in animals of different ages.

Dr. Sonia Rey Planellas, a research fellow at the Institute of Aquaculture, said: "Senegalese sole is a very valuable fish farmed across Europe. However, first generation males' failure to reproduce is still a problem affecting production of the species. Animals who are proactive and try to explore are likely to reproduce in captivity so it's important these fish can be identified at a young age."

The study shows that there was also a correlation between how individuals with the same sort of personality acted across the various tests. This finding suggests that those who are reactive and fearful or proactive and curious maintain their initial observed behavior.

"The three tests we used to simulate life in captivity was easy to apply and required no special equipment. We hope this can be replicated by fish farmers, large and small, to help establish selection-based breeding programs and easily identify fish that deal best with stress and will be able to reproduce more successfully in a variety of environments. These Operational Behavioural Screening tests (OBST) can also be used for other species of interest facing similar problems on domestication and production," concluded Planellas.