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.

Delta Smelt
Comparing smelts

Longfin Smelt

Striped Bass
DFG Striped Bass Program

Threadfin Shad