Publications & Reports

Publications & Reports

The Center supports research on issues of immediate importance to resource managers and policymakers who are challenged to manage the San Francisco Estuary’s natural resources. Obligated to provide a reliable supply of water to agriculture and urban users while protecting and recovering threatened and endangered species and restoring their degraded habitats, responsible state and federal resources agencies face misinformation and critical uncertainties about how at-risk fishes and their habitats are affected by environmental stressors. The Center recognizes Congress’ directive that determinations and decision under the federal Endangered Species Act should be informed by the best available scientific information. The Center’s investigative agenda is intended to provide that scientific information and offer procedural guidance to engage it in structured decision-making and adaptive resource management.

An investigation of factors affecting the decline of delta smelt in the Sacramento-San Joaquin Estuary

The delta smelt, endemic to the Sacramento-San Joaquin Delta and adjacent upper San Francisco Estuary, has experienced record low abundances since 2004. We address three questions in this investigation: What is the relative importance of environmental factors with direct effects on abundance? Do factors that may have indirect effects provide an explanation of abundance changes? Are effects of environmental factors better accounted for individually or as criteria defining the volume of water with suitable abiotic attributes? Strong evidence was found of density-dependent population regulation. The density of prey was the most important environmental factor explaining variation in delta smelt abundance from 1972 to 2006 and over the recent period of […]

Spatial perspective for delta smelt: A summary of contemporary survey data

The first step to understanding the ecological needs of a threatened or endangered species is to identify its geographic range and its temporal distribution within that range. Nearly two decades after the delta smelt was listed as threatened under the federal Endangered Species Act that foundational information had not been synthesized and displayed on maps. In this paper we map the distribution of the fish by life stage, providing coverages that enable resources managers to focus conservation activities, including targeted restoration efforts, where and near where delta smelt are most frequently found. Delta smelt are endemic to and narrowly distributed in the upper San Francisco Estuary wherein a single population […]

The route to best science in implementation of the Endangered Species Act’s consultation mandate: The benefits of structured effects analysis

The U.S. Fish and Wildlife Service and National Marine Fisheries Service are obliged to consult with federal agencies when the actions of those agencies may affect species listed and threatened or endangered under the Endangered Species Act and determine whether such actions are likely to jeopardize the continued existence of the species or result in the destruction or adverse modification of their critical habitats.  The heart of the consultation process is effects analysis, that is, the analysis of the effects of a proposed action on listed species and their designated critical habitats. We propose a structured framework for conducting effects analysis that includes three essential steps—the collection of reliable scientific […]
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