Impending extinction of salmon, steelhead, and trout (Salmonidae) in California

• Published in: Environmental biology of fishes 2013-11, Vol.96 (10-11), p.1169-1186
• Main Authors: Katz, Jacob, Moyle, Peter B, Quiñones, Rebecca M, Israel, Joshua, Purdy, Sabra
• Format: Article
• Language: English
• Subjects: Animal populations; Animal Systematics/Taxonomy/Biogeography; Annual variations; Biomedical and Life Sciences; Climate change; Conservation status; Environment; Extinction; Freshwater & Marine Ecology; hatcheries; humans; Life history; Life Sciences; Mediterranean climate; Native species; Nature Conservation; Oncorhynchus mykiss; Risk assessment; Salmon; Salmonidae; Salvelinus confluentus; Spatial distribution; Species extinction; Stream discharge; Stream flow; Taxa; Trout; Wildlife conservation; Zoology
• ISSN: 0378-1909; 1573-5133
• DOI: 10.1007/s10641-012-9974-8

California contains the southernmost native populations of most Pacific Coast salmon and trout, many of which appear to be rapidly headed toward extinction. A quantitative protocol was developed to determine conservation status of all salmonids native to the state. Results indicate that if present trends continue, 25 (78%) of the 32 taxa native to California will likely be extinct or extirpated within the next century, following the bull trout (Salvelinus confluentus), which was extirpated in the 1970s. California’s salmonids are adapted to living in a topographically diverse region with a Mediterranean climate, characterized by extreme seasonal and inter-annual variability in streamflow. Consequently, California salmonids have evolved extraordinary life history diversity to persist in the face of stressful conditions that often approach physiological limits. The spatial distributions of California salmonids vary from wide-ranging anadromous forms to endemic inland forms persisting in only a few kilometers of stream. Eighty-one percent of anadromous taxa are threatened with extinction and 73% inland taxa are either threatened or already extinct. Although specific drivers of decline differ across species, major causes of decline are related to increasing competition with humans for water, human degradation of watersheds, and adverse effects of hatchery propagation. Climate change, interacting with the other causes of decline, is increasing the trajectory towards extinction for most populations. Bringing all of California’s salmonid fishes back from the brink of extinction may not be possible. If there are bold changes to management policy, however, self-sustaining populations of many species may be possible due to their inherent ability to adapt to changing conditions.