DeltaCurrents

DeltaCurrents

DeltaCurrents, the Center’s blog, offers science-based observations and opinion on pressing contemporary issues in resource management and conservation planning in the Sacramento-San Joaquin Delta and adjacent upper San Francisco Estuary.

Whither habitat for the imperiled delta smelt?

Conservation science has offered one widely appreciated truism above all others. Habitat loss and fragmentation is the primary cause of imperilment and extinction for very many species. This is certainly the case for the delta smelt, which has seen its habitat diminished and transformed by human activities dating back to California’s gold rush era. Congress recognized the importance of habitat when it enacted the federal Endangered Species Act nearly five decades ago, declaring as its purpose — “to provide a means whereby the ecosystems upon which endangered species and threatened species depend may be conserved” — in other words, to protect and restore the habitats that support imperiled species. The […]
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Regulations falling behind science: the artificial distinction between rainbow trout and steelhead

Oncorhynchus mykiss is perhaps the most popular freshwater sport fish in the United States. The geographic distribution of native Oncorhynchus mykiss within the lower 48 states is limited to a handful of states along and adjacent to the west coast — California, Oregon, Washington, and Idaho, although it extends south to Baja California and north to British Columbia and Alaska.  It is artificially propagated by federal and state fish and game agencies and in private aquaculture for game fishing purposes in hundreds of hatcheries and is now established in all of the 48 lower states, at least 45 countries, and every continent except Antarctica. Fly-fishing enthusiasts who live east of the Rockies might be surprised to […]
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Ocean harvest of Central Valley Chinook salmon: a threat to viability of California’s wild salmon?

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. […]
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A regulatory Catch-22 inhibits recovery of Central Valley spring-run Chinook salmon

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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California’s Department of Fish and Wildlife must do more to conform to best practices for Independent Science Review

In recent years, the Department of Fish and Wildlife (Department) has taken steps to strengthen its science capacity in response to the enactment of AB 2402 by the Legislature and Governor in 2012. Among other things, AB 2402 required the Department and the Fish and Game Commission (Commission) to develop a strategic plan and authorized the Department to establish a Science Institute to inform the work of the Department and the Commission. To strengthen its science capacity, the Department developed a Scientific Integrity Policy in 2017. That Policy states “work that has a substantial scientific or management impact or large expenditure of funds or is especially controversial in nature should […]
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A new understanding of the status of longfin smelt and its conservation needs

Late last year the State Water Contractors hosted a first-ever Longfin Smelt Science Symposium on in Sacramento. The meeting featured and was attended by all researchers with first-hand and on-the-water experiences with the species in a forum that addressed both its ecology and genetics. Information emerged that has direct and immediate application in the conservation of the fish. The longfin smelt was listed as threatened by the State of California in 2009. The then Department of Fish and Game in its status review of the species, noted spare survey data and anecdotal records of the species across its coastal range from Alaska to just south of San Francisco Bay. The […]
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A cynical display of concern for imperiled steelhead in the Central Valley

After suing the federal government, in Spring 2020 the State of California sought an emergency injunction in federal district court requiring the U.S. Bureau of Reclamation to curtail water exports to central and southern California to protect steelhead migrating down the San Joaquin River and through the Sacramento-San Joaquin Delta on their way to the Pacific Ocean. The State argued that, if the Bureau failed to impose the San Joaquin River inflow to export ratio (referred to as the I:E ratio) in May 2020, it would undermine the overall prospects for recovery of the steelhead.
 In litigation in the same federal court less than a decade ago, the State argued […]
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