Cod In Fish Families Share Personality Traits

In striking findings in Norway it seems Atlantic cod fish on farms are full of personality.

We humans have no small measure of experience with personalities of animal life we come close to. Indeed many of us share loving relationships with companions we call pets. A vast range of species animals share this companionship with us.

Such feelings of kinship with animals is less commonly transposed to those animals we keep as livestock that we raise for food, but still well known. The lesser the animal the less we connect.

In the case of fish the notion that vast schools of fish might contain individuals who would come to know us and even have different “personalities” is a new notion, and an astonishing one. Even more strange is the idea that fish have families, mum, dad, kids, grandparents all with similar character.

Scientists at Nofima, the Norwegian food research institute, outside Tromsø have been studying Atlantic cod trying to find a way to breed stocks that are adapted for a life in aquaculture. The scientists have been working for 11 years to breed Atlantic cod that will form the basis of the farmed cod of the future.

They have found that what knowing what might happen in a large school of farmed fish is made more understandable by studying individual fish. Some fish react differently to stressful or life-threatening situations, this gives a clue to  how robust or fearless they are and thus be more adaptable life as a farmed fish

A typical fear response is that the fish stops, but in all likelihood it is trying to determine how dangerous the situation is.

Nofima Facility Norway

During a project called MARWEL, the Nofima scientists have studied the extent of such behavioural difference between cod in a familial group, families.

The scientists measured the fear response of individual fish in 15 different cod families, and used this to calculate the hereditability of the behaviour of the fish.

“The trial demonstrated a large variation in the response of individual fish and clear differences between the families. All the cod reduced their swimming speed and moved towards the edge of the tanks when they sensed fear,” said Director of Research Ingrid Olesen and Senior Scientist Børge Damsgård at Nofima.

“However, some were not so scared and were able to return to their normal undisturbed behaviour more quickly. Some others had a more extreme reaction that was both stronger and lasted longer.

“These are fundamental characteristics that in all likelihood will follow the cod throughout their whole life. Genetics accounted for 20-30 percent of the variations in the swimming activity and how long the fish stayed in the middle of the tank or out along the edges.”

The scientists use advanced video technology to study how individual fish react.

Nofima has for several years developed methods to measure what influences behaviour in fish. Typical examples include swimming activity, feeding behaviour, fearlessness or response to stressful situations.

“This trial showed that breeding can be an important tool for developing a fish stocks with good and desired behaviour, but we still have insufficient knowledge about what influences these individual differences and which characteristics we can breed for,” say the two scientists.

As for the question of nature vs. nuture this news about the psychology of fish gives rise to much to think about.