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Maria Filipa Castanheira
Maria Filipa Castanheira conducts each feeding rapidly and in a non-stop manner. The parr are in twelve monitored tanks.   
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Daily exercise with light and bubbles separates shy from bold salmon youngsters

Neglecting the iconic Norwegian landscape around her; Portuguese Ph.D.-student Maria Filipa Castanheira keeps her full attention on a dozen parr – one year old Atlantic salmon. Eight times a day she puts them through a learning regime with lights and bubbles. The reward is carefully prepared portions of shrimp and dry food. 

Maria Filipa Castanheira is a student at the Centre of Marine Sciences at the University of Algarve, but has spent the last two months at the Matre Research Station, about an hour’s drive north of Bergen; the capital of Western Norway. The research station is designed for both small and large-scale studies on present and future aquaculture species, and is fully equipped with state-of-the-art environmental control and monitoring systems. 

Coping styles screening

Maria Filipa Castanheira is involved in a behavioural project (see focus box) examining coping styles and learning capacity in young Atlantic salmon (parr).

Initially, each fish in her study was screened and deemed bold or shy using a consecutive series of behavioural tests: 1) A box confinement test (each fish is kept for 30 minutes in a small box). 2) Feeding recovery in a novel environment for 7 days. 3) Behaviour towards a novel object (balls). After conducting the box confinement test, Maria Filipa Castanheira measured the levels of the stress hormone cortisol in the water. Shy individuals exhibit stronger neuroendocrine (stress) responses such as high cortisol levels, compared to bold individuals.

Air bubbles, lightening and rewards

Individual differences in behavioural flexibility are often associated with different coping strategies.Bold animals tend to form rigid routines whereas shy animals tend to be more flexible and react more readily to environmental changes. This is likely to be reflected in differences in learning ability.

In the tanks at Matre parr are trained to associate two different signals with two different types of reward. Air bubbles are rewarded with shrimp and blinking light  with dry food, or vice versa. When the fish has learned this system, the signals will be switched and the opposite reward given. Finally the fish will get food independently from the signals. The extinction, that is how quickly the conditioned response was lost after the reinforcement ended, is considered learning of environmental change.


Jonatan Nilsson is working at the Institute of Marine Research, and takes part in the project. He and Maria Filipa Castanheira take a look at the recording of the parr and observe their behaviour.  

Who is the fastest learner?

Then it’s time to compare: Do shy and bold fish differ when it comes to learning the signal-reward relationship?

– Very little is known about the link between learning and coping styles. We expect that the shy fish are the fastest learners especially during the extinction period, says Maria Filipa Castanheira. 

– The shy ones are more aware and respond faster to environmental changes. This might also be reflected in better learning flexibility. In general the bold fish are not as concerned with their surroundings and are more likely to take chances. Because of this it may take them longer to adjust to environmental changes.

Possible with AquaExcel

Maria Filipa Castanheira’s three month long stay at the Matre Resarch Station is made possible through the AquaExcel project (see link). AquaExcel aims to coordinate and improve access to top class European aquaculture research facilities, and Maria Filipa Castanheira is the first participant at Matre. She applied for a stay at Matre for several reasons:    

– The fish welfare group at the Institute of Marine Research is very strong, and the facilities here are good. I can work with fish in twelve tanks connected  to cameras, and discuss with the other scientists during the study. It’s interesting to work with salmon, a new species for me. And of course it’s nice to experience another country and meet new people.