The California Department of Fish and Game announced Friday the release of its final fish-kill evaluation titled "September 2002 Klamath River Fish-Kill: Final Analysis of Contributing Factors and Impacts.”

This evaluation finalizes the preliminary report that was released to the public in January 2003.

A draft of the final report received peer review from several cooperating state and federal agencies, tribes and stakeholders, as well as Humboldt State University fisheries pathologist Gary Hendrickson and Oregon State University fisheries biologist Doug Markel.

"Our goal with this report was to document the conditions in the river that contributed to this fish kill," said Don Koch, regional manager for the Northern California-North Coast Region of DFG. "It is our hope that the information will be useful to the decision-makers as they balance and manage the limited resources of the entire Klamath Basin. We also hope that the analysis and recommendations in this report will help minimize the risks of future fish kills in the Klamath Basin."

Copies of the report are available on DFG's Web site at www.dfg.ca.gov

, or can be accessed directly at www.dfg.ca.gov/html/krfishkill-2004.pdf

.

"Our findings are very similar to those of two other reports prepared by the U. S. Fish and Wildlife Service and the Yurok Tribal Fisheries Program," said Steve Turek, a DFG senior environmental scientist and one of the authors of the report. "We found that the primary cause of the fish kill was a disease outbreak caused by two pathogens brought on by stressful environmental conditions and high densities of fish."

The two pathogens responsible for the death of more than 33,000 adult salmon and steelhead in September 2002 were the myxozoan parasite Icthyopthirius multifilus commonly referred to as Ich, and the bacterial pathogen Flavobacterium columnare referred to as Columnaris.

These pathogens are common in aquatic systems and are present at all times in the Klamath River.

The report finds that unusually low flows, low river volumes and an above-average run of salmon resulted in abnormally high fish densities in the lower 36 miles of the Klamath River. Apparently, large numbers of fish congregated in the lower river one to two weeks before the onset of the fish-kill.

"While we do not fully understand why these fish held in the lower river in such large numbers, we can hypothesize that upstream migration was impaired due to physical, water quantity or water quality barriers, the disease itself, or a lack of environmental cues for the fish to head upstream," Turek said.

The report concludes that abnormally high densities of primarily natural fall-run Chinook salmon, coupled with the normal presence of pathogens and typical warm river temperatures, created ideal conditions for the disease outbreak which ultimately resulted in the fish kill.

"This was an unprecedented event in the Klamath River and one of, if not the largest, fish kills of adult anadromous salmonids recorded on the West Coast," Turek said.

Other adult fish kills have occurred on the Rogue River in Oregon, Butte Creek in California, and the Babine and Frasier rivers in British Columbia.

Common threads in many of these fish-kill events include disease, high fish densities, low flows and warm water temperatures.