Atlantic salmon. Photo Eva B. Thorstad
This new study showed that energy content of prey was the most important factor determining food consumption required to maintain growth. Conversely, the increases in ocean temperatures expected with climate change were predicted to have limited physiological effects on energy budgets and limited impact on the food consumption needed to maintain growth.
It was concluded that the most pronounced effects of increased ocean temperatures will likely be due to alterations of ecosystems and subsequent changes in prey quality and abundance rather than direct physiological effects of increased water temperatures.
Average energy consumption of an individual adult salmon (body size 76–119 cm) was estimated to be 331–813 kJ per day. This is equivalent to every day eating 5–11 prey fish with an average body mass of ca. 15 g.
The study was done by investigating the marine food consumption of repeat ocean migrating Atlantic salmon from a northern population, by using a bioenergetic model that incorporated daily data from temperature sensing archival tags. Information on individuals’ marine growth based on body length and weight at sea entry and when they returned from the ocean migration was also used.
The results are likely representative for many northern Atlantic salmon populations in Norway, Denmark, and Canada. However, for more southern populations, for instance from Ireland, Iceland, and Spain, the direct consequences of climate change on energy consumption may be more severe, as Atlantic salmon from these regions are already experiencing warmer water temperatures and likely higher energy requirements compared to their more northern conspecifics.
Strøm, J.F., Ugedal, O., Rikardsen, A.H. & Thorstad, E.B. 2023. Marine food consumption by adult Atlantic salmon and energetic impacts of increased ocean temperatures caused by climate change. Hydrobiologia https://doi.org/10.1007/s10750-023-05234-2.