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US Fish & Wildlife Service FieldNotes
STOCKTON FWO: Ecosystem Analysis of Pelagic Organism Declines in the Upper San Francisco Estuary
Region 8, February 25, 2009
Delta of the San Francisco Estuary (DWR)
Delta of the San Francisco Estuary (DWR) - Photo Credit: n/a

by Gonzalo Castillo, Stockton FWO
Abundance indices of several pelagic fishes in the upper San Francisco Estuary (delta smelt, age-0 striped bass, longfin smelt, and threadfin shad) have reached all time lows since the early 2000's. To address this issue, researchers Ken Newman and Gonzalo Castillo of the Stockton Fish and Wildlife Office (FWO) have been working with university, state and federal staff under the National Center for Ecological Analysis and Synthesis (NCEAS), an internationally renowned scientific organization affiliated to UC Santa Barbara.

The group is working to gain a better understanding of the specific causes and mechanisms behind these species declines and to further address the broader context of estuarine degradation, organism declines and approaches to solving these problems. A key component of the interagency effort is to examine simultaneously the effects of multiple potential drivers on one or more fishes and whether fishes differ in their response to given drivers.  Methods being used include Bayesian analysis, stochastic, non-mechanistic models and other modeling approaches to draw inference regarding ecological relationships among pelagic fishes, physical and biological estuarine variability.

Newman and Castillo represent the Service on the Interagency Ecological Program (IEP), a group of state and federal agencies as well as university and private scientists who conduct long-term monitoring and applied research in the San Francisco Estuary.

Contact Info: Yvette Leatherman, (209) 946-6400 x301, yvette_leatherman@fws.gov