Wildlife Forever surveyed 12 professional biologists asking them to rank their top 20 most harmful Nonindigenous Aquatic Species (NAS) in the West from a list of 104 NAS provided by the U.S. Geological Survey (USGS). The Wildlife Forever “Battle of the Bads” report focuses on ten states West of the 100th Meridian that all have significant Bureau of Land Management (BLM) acreage. Survey responses from the biologists narrowed the 104 NAS down to 25 species. We then had the biologists do a second ranking from the distilled top 25 NAS. After tallying the points from the second round of surveys, a list of the 25 most harmful NAS was created for what Wildlife Forever calls the results from the “Battle of the Bads.”
Each Top 25 species was given a “Harm Score” (HS) based on their rank, with the 1st place given a score of 25, 2nd place a score of 24, and so on. To estimate the severity of a Congressional District’s NAS problem, Wildlife Forever calculated an “Infestation Score” for each District. The “Infestation Score” was calculated by summing up the “Harm Scores” of each species prevalent in that District, with the full HS of a species used if the species is prevalent to a ‘major’ extent and half the HS used if the species is prevalent to a ‘minor’ extent. The prevalence of each of the NAS species was determined using species prevalence maps from the Nonindigenous Aquatic Species Database by the USGS.