Trends in ocean temperatures affect the thermal habitat of Atlantic salmon during summer and autumn, but not during winter

Publisert 16.12.2019

Since 2008 we have tagged more than 1000 adult salmon from the Alta River with temperature sensing data storage tags in order to understand more about ocean migration and habitat use while at sea.


Data storage tags

Data storage tags are attached to the fish and record environmental variables during the ocean migration. These tags need to be retrieved in order to access the data, so these results are based on adult salmon that returned to the river to spawn after approximately one year at sea.


Large fish, cool waters

The data showed that the salmon spent most of their time in cold waters with temperatures ranging from 1.6–8.4°C. This suggests that adult salmon from northern areas may rely on cooler waters than previously considered.


Temperature trends may not affect salmon during winter

Trends in sea-surface temperatures influenced the thermal habitat of salmon during summer and autumn, with fish experiencing warmer temperatures in warmer years. However, this pattern was absent during the winter months, when daily mean temperatures ranged from 3.4–5.0°C in both colder and warmer years. This may indicate that the ocean distribution of salmon is flexible and could change for instance as a response to where their prey are located. 


Want to read more?

Strøm J.F., Thorstad E.B. & Rikardsen A.H. 2019. Thermal habitat of adult Atlantic salmon in a warming ocean. Journal of Fish Biology. DOI: 11.1111/jfb.14187

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