Author(s): Einar Tesaker
Linked Author(s): Einar Tesaker
Keywords: No Keywords
Abstract: The habitat conditions in water courses depend on many variables, most of which are related to geometry, flow distribution, temperature and water qUality. The formation and presence of ice will influence on these factors as compared to the ice free situation. It follows that modification of e. g. geometry or flow may introduce changes in the winter habitat to the better or worse. In natural rivers, moderate modification of local geometry usually is the only possible action, of which some cases and expelience will be referred. It is in regulated rivers that the challenge to improve the habitat is most pronounced. The regulation itself usually imposes unwanted or disputed effects. But regulation also represents a possjbiljty for improvement of the natural winter habitat, e. g. by control of discharge, reduction of ice runs, arrangement of artificial pools or under-ice passages, or even temperature control. Various ideas for improving the habitat have been launched, and some have been implemented. The paper will discuss a few of these with reference to investigations of fish habitat both under winter and ice free conditions.
Year: 1998