Impact of climate change on farmed salmon

Norwegian researchers in Bergen are investigating how climate change affects feed utilisation and growth in farmed salmon.

The research has come about due to statistics revealing that the sea temperature along the Norwegian coast is rising. This may, say the researchers, have consequences for salmon, which prefer temperatures below approximately 17 oC.

In 2004 and 2006 the temperatures were said to have been unusually high in western Norway, and studies suggest that we can expect more periods with high temperatures over the next 100 years. Similarly, warmer periods are also expected farther north in Norway. Fish farmers have experienced that feed intake among salmon drops in such periods, the growth is reduced and the feed factor rises. In other words, they say the fish do not utilise feed as efficiently.

“In the research project, Salmon farming in warmer seawater, funded by the Research Council of Norway, we are aiming to identify how much fat and protein salmon use for growth and how much they use to maintain bodily functions when the sea is 19 oC. We also want to find out how higher sea temperatures affect feed conversion and feed factor,” says Ernst Morten Hevrøy, a researcher at the National Institute of Nutrition and Seafood Research (NIFES).

Hevrøy will be in charge of the part of the project linked to nutrient conversion. The project is a collaboration between the Institute of Marine Research, Marine Harvest Norway, Nofima Akvaforsk/Fiskeriforskning AS, Skretting and NIFES.

“The goal is to come up with a feed whose combination of nutrients ensures the growth and wellbeing of salmon and efficient feed utilisation in warmer water. This is also important in order to ensure good fish health.” The project period is three years.

Sea temperature is also said to be rising in other countries that farm Atlantic salmon in sea cages: Chile, USA, Tasmania and Ireland, meaning this is an international issue.

A great deal of research has been done on large salmon in normal and cold temperatures, but there have been no controlled feed studies in warm seawater. The experiments will be carried out at the Institute of Marine Research’s research station at Matre, which affords researchers a unique opportunity to control the temperature of large volumes of water in tanks over a long period of time and measure various critical environmental parameters.

“Warm water contains less oxygen than cold water. There are also a whole range of other factors that makes the oxygen less available to fish in warmer water. This can affect many different bodily functions in the fish, and this is what we will be studying in the project,” says project manager Tom Hansen at the Institute of Marine Research.

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Impact of climate change on farmed salmon