Adaptations to ice-cover conditions in salmonid fishes

• Main Author: Anders Gravbrøt Finstad
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2007
• Subjects: Arctic; Atlantic salmon
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.546.7612; http://cripe.civil.ualberta.ca/downloads/14th_workshop/finstad-2007.pdf

Here, I review a series of experiments from laboratory environment and in seminatural stream-channels where the effects of ice-cover conditions on salmonid winter performance are tested. The experiments were run using common environment on six different populations (hatchery reared fish) of Atlantic salmon from 59 °N to 70 °N, two populations of Arctic char (59 °N and 70 °N), and one population of brown trout (59 °N). Intraspecific variation in ice-cover response of Atlantic salmon indicated adaptations to ice-cover conditions in home rivers. Growth of the three southern populations from ice free rivers was significantly higher in tanks with light than in darkness, whereas the northern populations originating from rivers with ice-cover showed smaller or insignificant differences in growth between light and darkness. A similar pattern was found for food consumption. In stream channels, northern populations performed better under simulated ice-cover than without, whereas southern populations remained indifferent to ice-cover treatment. The differences in energy loss with and without simulated ice-cover increased significantly with increasing latitude of population origin. Intraspecific variation in ice-cover response was larger than the interspecific. Both northern and southern Arctic char reduced energy-loss rates under simulated ice-cover compared to no ice-cover in stream channels, whereas southern populations of Atlantic salmon and brown trout remained indifferent to ice-cover treatment. Because energetic deficiencies are assumed to be an important cause of winter mortality, our study indicates that lack of ice cover significantly may affect winter survival, particularly in northern populations. However, changes in ice-cover conditions are likely to affect different populations and species of salmonid fishes differently and the scope for evolutionary response to changes in ice-cover conditions may vary between species.