Abstract
It is assumed that hydropeaking causes elevated degrees of fine sediments in river beds which affect negatively habitat quality for juvenile salmon. Finstad et al. (2007) developed a method to measure interstitial space (shelter abundance for fish) in running waters. Shelter availability is a candidate mechanism for survival of juvenile salmon due to reduction of predation risk and influenced by the degree of fines. The goal of this study was to find a relationship between shelter abundance (measured with the method by Finstad et al.) and grain size distribution to be implemented in predictive models for the assessment of the ecological status in running waters. The developed approach to reach this aim was conducted by gathering data in representative places both for shelter abundances and grain size distributions. The results of the study indicate that particle distribution parameters generated in grain size analysis are correlated to shelter abundance to a certain degree, especially percentiles describing the fine tail of the distribution are highly correlated to shelter abundance. Also distribution parameters show relatively high correlation quality, however under certain restrictions. The findings are used to develop assessment and management tools for hydropeaked rivers.