In this study, we provide the first systematic conservation assessment of freshwater fish in California to identify catchments that contribute disproportionately to taxonomic diversity in the region. Tools for terrestrial- and marine-protected area planning have been adapted to freshwater systems over time, taking into account the unique directional connectivity of river systems and recognizing the catchment as a fundamental spatial unit for freshwater ecosystem management (Abell et al. Systematic conservation planning offers a structured framework for guiding a statewide conservation strategy for freshwater biodiversity and ecosystems (Margules & Pressey 2000 Nel et al. But proposed aquatic management areas have not been adopted by natural resource agencies, and there is no statewide plan to address impending fish extinctions, even though most native fish taxa (79%) are endemic to the state (Moyle 2002). In light of these deficiencies, some have argued that a strategic, statewide plan for freshwater fish conservation that includes designated priority catchments for aquatic biodiversity management is warranted (Moyle & Yoshiyama 1994 Moyle 2002). The current role of, and potential for, protected areas for conserving freshwater biodiversity in California remains poorly understood. Furthermore, within the state's large network of protected areas, few were designed with the intention of, or have explicit management plans for, protecting freshwater ecosystems and species. However, most fish recovery programs are driven by the federal Endangered Species Act, a powerful legal tool, but one that promotes piecemeal, river- and species-specific conservation efforts (Viers & Rheinheimer 2011). 2007), with new billion-dollar restoration efforts planned and underway in large, highly degraded systems such as the San Joaquin River (Pitzer 2011) and Los Angeles River (Zahniser 2015). Over $2 billion (USD) has been spent in California on river restoration alone since 1980 (Kondolf et al. This is in spite of the fact that substantial resources have been invested in fish conservation and recovery programs. 2011).ĭecline of the state's native fish fauna highlights the failure of past and ongoing management efforts to protect freshwater biodiversity and ecosystems. A recent conservation status assessment reports that 107, or 83%, of native fish taxa risk extinction in the next century (Moyle et al. California's native fishes, most of which are endemic, are particularly imperiled (Howard et al. In California, for example, a rapid decline of freshwater fauna has coincided with economic growth and widespread modification of freshwater ecosystems by water infrastructure, agriculture, and urbanization (Moyle et al. Worldwide, freshwater ecosystem degradation and loss of freshwater biodiversity are strongly linked to human development pressures (Vörösmarty et al. These results provide the foundation for systematic freshwater conservation planning in California and for prioritizing where limited resources are allocated for fish recovery and protection. Few high-priority catchments occur within protected areas, suggesting that fish conservation will require active management and targeted river restoration outside of reserves. Although most of the state's native fishes are found within protected areas, only a small proportion of their ranges are represented. Using high-resolution range maps of exceptional quality, we also assess the representation of fish taxa within the state's protected areas and examine the concordance of high-priority catchments with existing reserves and among distinct taxonomic groups. To guide fish conservation efforts, we provide the first systematic prioritization of river catchments and identify those that disproportionately contribute to fish taxonomic diversity.
Population growth and increasing water-use pressures threaten California's freshwater ecosystems and have led many native fishes to the brink of extinction.
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