Fish out of Water: Impending Extinctions in California's Freshwater Fish Fauna

Eighty-three percent of California’s native freshwater fishes are extinct or at risk of becoming so, a 16% increase since 1995 and a 21% increase since 1989.  A quantitative protocol was developed to determine conservation status of all 129 freshwater fishes known to spawn in the inland waters of California.  Seven taxa were found to be extinct; 34 (26%) to be in danger of extinction in the near future (endangered); 32 (25%) to be on a trajectory towards extinction if present trends continue (vulnerable) and 34 (26%) to be declining but not in immediate danger of extinction.  Only 22 (17%) taxa were found to be relatively secure.  Twenty-nine (94%) of the 31 species officially listed under the Endangered Species Act (ESA) were rated as endangered or vulnerable by our criteria.  Among the 7 metrics used to assess extinction threat, climate change, area occupied and anthropogenic threats had the largest negative impacts on status.  Of 15 categories of anthropogenic causes of decline, those most likely to diminish status were alien species, agriculture, and dams.   The rapid decline of California’s inland fishes is probably typical of less well documented declines in other regions, indicating a strong need for improved conservation of freshwater ecosystems.