UC Davis

Freshwater biodiversity loss exceeds that in terrestrial systems; fishes are a predominant indicator of this catastrophe. Current worldwide estimates of freshwater fish species threatened with extinction are about 30%. We discuss why standard monitoring of the status of most fishes is inadequate to keep up with declines. Rapid population declines and shrinking freshwater fish distributions result in shifting baselines that make it challenging to evaluate conservation status reliably and promptly and effectively address further decreases. We present the California Method for Status Evaluation of Fishes as an alternative to existing methods for assessing the regional status of freshwater fishes. This method uses local expertise to score metrics and generates a fish status rating to inform short-term management decisions. This approach applies to Distinct Population Segments, subspecies, species, and entire regional fish faunas and is adaptable to local, changing environmental conditions. Using this method, we update the freshwater status scores for 131 native California fish species, a fauna in rapid decline.