The research, led by Professor Børge Damsgård, of the University Centre in Svalbard, was conducted in Tromsø, where the fish were held and sampled. Analysis of the data was carried out across a number of partner research institutions and organisations, including the Institute of Aquaculture; the Norwegian University of Life Sciences (Oslo); Radboud University (Nijmegen); Uni Research (Bergen); University of Agder (Kristiansand); Norwegian Institute of Water Research (Oslo); and Nofima (Tromsø).
The team found that fast-growing Atlantic salmon reach smoltification – where juvenile fish adapt from living in fresh water to seawater – sooner than slow-growing individuals. In addition, the fast-growing fish exhibited proactive, bold characteristics compared to the other group, including active hypoxia avoidance – where the fish attempt to escape low-oxygen conditions – and low stress responsiveness.
Professor Damsgård explained: “The hypoxia responses are proxies for a basic, individual behavioural response – which is linked to a stress response – and both traits are linked to the pace-of-life.
“It is no surprise that faster-growing fish smoltify earlier – but it is new that such individual differences exist within a population with exactly the same background and conditions.”
Dr Rey added: “This research helps us to understand the different lifecycle strategies and will lead to improvements in the management and welfare of the fish too.”
The study was part of the COPEWELL project, funded by the European Union, which included an Institute of Aquaculture-led sub-project on stress coping styles in salmon, seabass and seabream.
The research, Proactive avoidance behaviour and pace-of-life syndrome in Atlantic salmon, is published in Royal Society Open Science.