nofima.no
Creating value
2013
31
Scientist Tale Marie Karlsson Drangsholt and colleagues have studied the heritability of the cod’s behaviour.
photo: Jon-Are Berg-Jacobsen © nofima
Terrestrial livestock are so different that they often have
nicknames, but thousands of farmed fish look so similar
that many are surprised when biologists claim that fish
may have different “personalities” too.
Sometimes understanding what happens in a large
group of farmed fish is only possible by studying individ-
ual fish. How the fish react to stressful or life-threatening
situations indicates how robust or fearless they are to
tackle life as a farmed fish. A typical fear response is that
the fish stops to determine how dangerous the situation
is.
In a project called MARWEL, the Nofima scientists
studied the extent of such behavioural differences
between cod families. The scientists measured the fear
response of individual fish in 15 different families, and
then calculated the heritability of the behaviour of the
fish.
“This pilot study showed a large variation in the re-
sponse 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. Some were not particularly scared and soon
returned to their normal behaviour, but for others the
reaction was both strong and long lasting. These are
fundamental characteristics that will probably follow the
cod throughout their whole life. Genetics accounted for
20–30% of the variations in the swimming activity,” says
Director of Research Ingrid Olesen.
The scientists use advanced video technology to study
how individual fish react.
“This trial showed that breeding can be an important
tool for developing a fish with good and desired behav-
iour, but we still have insufficient knowledge about what
influences these individual differences and which char-
acteristics we can breed for,” says Scientist Tale Karlsson
Drangsholt. There is, therefore, a need to study this in a
larger trial involving more families of farmed cod.
Scientists have studied the individual behaviour of Atlantic cod to find
out if we can breed a fish more adapted to a life in aquaculture.
Breeding fearless farmed fish
