Author: Bradley J Cavallo

Increasing Central Valley salmon populations in a highly regulated river system is a complex undertaking. Restoring habitats and ecosystem processes, augmenting fish passage, screening diversions, hatchery reform, and improved harvest management are integral components of successful conservation efforts. But restoring a semblance of a natural flow regime — sometimes termed “functional flows” — is often the focus of efforts to improve the status of salmon in Pacific Coast rivers. While it might seem straightforward to reestablish a natural hydrograph in efforts to encourage the ecological and biophysical processes to sustain salmon life stages — well, it’s not. Between obligations related to dam operations (flood control, water storage) and environmental requirements […]
Policy makers and scientists often attribute the poor progress being made toward resolving fish conservation and water allocation issues — despite billions of dollars of invested over the past half century — to the physical and ecological complexities of the Sacramento-San Joaquin Delta. The challenge of meeting the goals established in California’s Delta Reform Act, ensuring statewide water-supply reliability and restoring a vibrant and healthy Delta ecosystem, has been referred to as a “wicked” problem, one that may be not fully resolvable. It is doubtless the case that a century-and-a-half of human impacts have altered the system in many ways that are, as a practical matter, irreversible. But a recent article in […]
Off the coast of California and southern Oregon, Chinook salmon are subjected to a uniquely intense commercial and recreational fishery. The fishery relies upon the availability of abundant, hatchery-produced Central Valley fall-run Chinook. However, as currently managed, the fishery provides minimal protection for natural-origin (wild) fall-run Chinook and for winter-run and spring-run Chinook that are listed under the federal Endangered Species Act (ESA), especially fish maturing at age-4 or older. Variation in age-at-maturity is essential for the viability of all runs of Chinook salmon because it buffers populations from short-term environmental changes in freshwater habitats and from catastrophic events. The age-structure of Central Valley Chinook salmon populations is severely truncated. […]
Spring-run Chinook salmon have long played second fiddle to winter-run Chinook salmon when it comes to conservation planning for the Central Valley salmonids protected under the California and federal Endangered Species Acts. But earlier this year, the California Department of Fish and Wildlife issued an Incidental Take Permit (ITP) that promises increased attention for spring-run Chinook. The ITP calls for the aggressive development of a spring-run Juvenile Production Estimate (JPE). The purpose of the JPE is to better track the abundance of juvenile spring-run Chinook and, ostensibly, to provide a basis for setting the number of juvenile spring-run Chinook that the State Water Project is allowed to entrain at the […]
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