Report on Estimate of Mortality
Report Number AFWO-01-03
In September 2002, a devastating fish die-off occurred in the lower Klamath River, prompting an investigation by the U.S. Fish and Wildlife Service (USFWS) and other agencies. This article aims to provide an overview of the die-off and highlight the significant presence of older fish from the Trinity River Hatchery among the casualties.
Summary of Findings: The USFWS report on the estimate of mortality revealed that a total of 34,056 observable fish died during the incident. The majority of the dead fish, approximately 98.4 percent, were adult anadromous salmonids. Out of the estimated 33,527 anadromous salmonids that succumbed, 97.1 percent were fall-run Chinook salmon, 1.8 percent were steelhead, and 1.0 percent were coho salmon. Only one coastal cutthroat was found dead during the investigation.
