Rivers and streams are essential for the exchange of energy , organic matter and nutrients between inland and coastal areas. They drive local as well as global biochemical cycles. Many species are adapted to life in and around running waters including insects , mollusks, birds ,mammals and a wide array of fish species. Streams worldwide are also the subject of human impacts that degrade habitat conditions. In Sweden more than 70% of the  rivers are regulated and more than 33,000 km channelized.

Channelization results in loss of structural complexity, simplified flow patterns, and decreased availability of microhabitats for a wide array of lotic organisms. Channelization are known to have an effect on the fish population. However no study has been found so far that investigates the fish fauna along a gradient of increasing channelization severeness . The present study has been conducted with a new sampling method, Nordic Multi-mesh Stream Survey Net, designed to operate in running waters making investigations of whole streams possible.

The main aim of this study was to investigate the effects of channelization on fish biota in lotic habitats over a gradient of channelization severeness.

The other aim was to evaluate the Nordic Multi-mesh Stream Survey Net as a tool for these kinds of investigations.