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PROJECT SUMMARY 



Trout populations and habitat were analyzed in 16 urban and 14 

 non-urban areas of four streams in and near Bozeman and Livingston, 

 Montana. The non-urban stream sections had generally undergone less 

 artificial alteration. 



Non-urban stream on average held 74% greater weight (biomass) of 

 trout per unit length of channel than did urban stream. Number of 

 over-20-cm (over-8-inch) trout per unit channel length was 54% greater 

 in non-urban than in urban areas. 



The urban parts of streams were clearly less favorable habitat for 

 trout in certain key respects. The most striking habitat difference 

 detected between urban and non-urban areas was that urban stream had 

 significantly less hiding cover for trout — hiding cover measured as 

 amount of solid material in the water or within a few centimeters above 

 it that could provide overhead concealment for fish. Also, in urban 

 stream, channel width was less and amount of eroding bank greater. It 

 was apparent that urban landfill along stream banks had created straight, 

 narrow channel with high, unstable banks. Such channels tended to lack 

 undercut banks that could provide shelter for trout. Within such 

 straightened and constricted waterways, the greater forces during high 

 water may have swept away logs and other woody debris that would have 

 formed trout cover. Also, people may have removed debris to tidy the 

 appearance of urban channels or to help them conduct flood water more 

 rapidly, thereby destroying trout habitat. 



