SALMONIDS
Climate change and potential effects
on salmon farming The ideal water temperature for salmon appetite and growth is in the
range of 8 - 14°C.
By Asbjørn Bergheim*
I
ncreasing sea temperatures could affect performance under farming conditions: if the water is warmer than 16°C, salmon get stressed, eat less and their growth can be reduced. Atlantic salmon living at 19°C reduce their feed intake by 50% compared to salmon living at 14°C with the growth occurring at the same rate as observed for 3°C conditions. Salmon may die at temperatures above 23°C. When the temperature rises, dissolved oxygen con-
tent generally drops while the oxygen consumption of the fish increases. Additionally, algal blooms and salmon gill disease are considered more prevalent in warmer water. Since the 1980s, the open sea temperature off the Norwegian coast has increased by 1 ˚C. The temperature will continue to rise due to humancaused climate changes. This is bad news for farmed Atlantic salmon, which will be vulnerable to these temperature changes. Nevertheless,
Atlantic salmon have higher tolerance to warm water than Pacific salmon and some other species in the genus Salar such as Arctic charr and brown trout. Among other things, warm water can reduce fecundity and growth, and increase susceptibility to disease. “Salmon farming as an industry with high technological integration could react to mid- and long-term changes but may not be prepared to face sudden or temporary changes in parameters such as surface tempera» 61
