Pelagic Organism Decline Overview

The Interagency Ecological Program (IEP), a consortium of nine state and federal agencies, has been monitoring aquatic organisms and water quality in the San Francisco estuary for decades. Since late 2004, scientific and public attention has focused on the unexpected decline of several pelagic (open-water) fishes (delta smelt, longfin smelt, juvenile striped bass, and threadfin shad) in the freshwater portion of the estuary known as the Delta. This decline has collectively become known as the Pelagic Organism Decline (POD). In 2005, the IEP formed a multi-agency POD Management Team tasked with designing and managing a comprehensive study to evaluate the causes of the decline and to synthesize and report the results. The causes under investigation include stock-recruitment effects, a decline in habitat quality; increased mortality rates; and reduced food availability due to invasive species.

CALFED Science Program POD Support

POD 2006-07 Workplan Overview

"The overall approach for 2006-7 is intended to evaluate and refine the evidence for the conceptual models. To address the matrix models, the study design is based on temporal, spatial and species contrasts for selected fish and zooplankton. For each contrast, the variables to be evaluated include: abundance, growth rate and fecundity; and feeding success, condition factor, parasite load and histopathology (fish only). To the extent possible, these data will be collected simultaneously to help evaluate the relative importance of different stressors. The narrative models, on the other hand, posit linkages among different stressors and their possible pathways to produce the observed declines of more than one species. The workplan elements that are based on the two narrative models, therefore, emphasize analyses of the proposed linkages among stressors."

For a more detailed look at the 2006 Workplan Proposal, please read the full document:

IEP 2006-2007 Workplan Proposal