ScholarWorks at University of Montana

Wild Trout Recovery Shows Effectiveness of 20 years of Blackfoot River Basin Restoration Efforts

To recover wild trout populations in Montana’s Blackfoot River, stream restoration efforts began in 1990 to improve degraded stream habitats. About 30 high priority tributaries received various combinations of channel reconstruction, instream habitat structures, instream flow restoration, fish ladders and screens , and modification of grazing practices. To assess the effectiveness of these efforts, wild trout abundance in 18 of the streams was monitored for a minimum of 5 years post-restoration from 1989 and 2010. Before restoration, average trout abundance was significantly lower in the degraded streams when compared to reference sites. But only 3 years after restoration, trout abundance had increased and was no longer significantly different from the reference sites. In 15 of the streams, trout abundance continued to improve over 5 to 20 years after restoration. In 3 streams abundance declined due to the return of heavy riparian grazing and detrimental irrigation practices. Trout responded more quickly using restoration techniques that emphasized irrigation and instream flow techniques and more slowly for streams that required full channel reconstruction. Native trout responded more strongly to restoration efforts in the upper basin compared to the lower basin. Long-term monitoring (1988-2014) shows increases native trout numbers throughout the main stem river.