Using Trout Unlimited Conservation Assessment Tools for Prioritizing Fish Passage Efforts

Trout Unlimited (TU) developed the Conservation Success Index (CSI) in order to become more strategic and effective in our coldwater fishery conservation efforts including fish passage. Using the CSI, we can quantify and map the conservation status of all native coldwater fishes across watersheds, river basins, and entire species. The CSI integrates population data from various assessments completed by state and federal agencies with spatial data on habitat and threats gathered by TU scientists to create a common analytical framework applicable to all coldwater fishes (Williams et al. 2007, Fisheries 32(10) 477-492). The basic components of the CSI include 20 indicator variables that describe the range-wide condition, habitat integrity, population integrity, and future security for all sub-watersheds that historically or currently contain native salmonids. As a GIS-based, subwatershed-scale (6th level hydrologic unit code) assessment tool, it also has applications for fish passage planning and evaluation. Given that roads, dams and other water diversions have fragmented stream habitats and eliminated migratory trout and salmon from historic habitats, CSI planning for fish passage has become a TU priority. In these new TU planning efforts, selected CSI variables are combined to analyze anadromous species and habitats impacted by barriers to fish passage. The results provide landscape-scale identification of opportunities for both reconnecting fragmented fish populations and opening new portions of watersheds to fish migration. These opportunities should then be refined based on knowledge of local conditions. Additional CSI analyses for identifying and understanding risks and opportunities associated with small population persistence, metapopulation development, climate change, and invasive species can help to further inform management decisions about potential fish passage efforts.