Sole farming has a mix of aggressive and passive fish

In farming, including sole farming, different traits are more valuable. In a dairy farm, the cows that produce the most milk will be bred and encouraged. What may surprise you is that in sole farming, aggressive, pro-active fish grow faster and have higher reproductive success.

So how do you test if a fish is pro-active or not?

Tests in the past have relied on studying the body language of fish and trying to determine their personality. So what did these new researchers do?

1. Held the fish in a net in water for 90s and then in the air for 90s and marked the number of escape attempt.

2. Placed the fish into a new, smaller tank and measured how quickly they explore.

3. Flipped the fish over and recorded how long it takes to get right side up.

4. Sedated the fish and tested their plasma levels for markers of their coping styles.

5. Placed a new object in the sole’s environment (a square frame) and recorded how it takes the fish to pass through it.

6. Provided a safe, dark area and a unknown, lit area and tested how long it took fish to go from one to the other.

It seems as though passive fish are more apt to fare well in an environment that has predators. Their cautiousness and ability to adapt well to new environments makes them more suited to the wild. The aggressive, fearless fish fares well in a safe, farmed location where their natural lack of survival instincts is not a drawback.

How do these tests help sole farmers?

The aim of these tests was to provide an easily replicated way for fish farmers around the world to test the personality traits of their animals. In the past, tests required expert knowledge and more resources and had difficulty providing meaningful results.

Citation: : Ibarra-Zatarain Z, Fatsini E,Rey S, Chereguini O, Martin I, Rasines I, AlcarazC, Duncan N. 2016 Characterization of stresscoping style in Senegalese sole (Soleasenegalensis) juveniles and breeders foraquaculture. R. Soc. open sci. 3: 160495.

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