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CA-NV FHC: Fish Health Center expands Klamath River Disease Studies to Marine Environment
California-Nevada Offices , September 18, 2013
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Juvenile Fall chinook salmon in full 'smolt' condition prior to entering the saltwater phase of the study. As fish naturally prepare for saltwater, the process that involves the many physiological changes that occur is called 'smoltification'.
Juvenile Fall chinook salmon in full 'smolt' condition prior to entering the saltwater phase of the study. As fish naturally prepare for saltwater, the process that involves the many physiological changes that occur is called 'smoltification'. - Photo Credit: USFWS

By Kimberly True

The California-Nevada Fish Health Center conducted a pilot study in June 2013 to determine the fate of an internal parasite, called ceratomyxa shasta, after juvenile Chinook salmon enter the marine environment.

Much is known about this parasite in the freshwater riverine environment, but little is known about the effects of saltwater on the parasite’s growth and survival in the salmonid host tissue, or the progression of the intestinal disease it causes (ceratomyxosis) once these young fish enter the ocean.

Chinook salmon remain in saltwater for 3-5 years before returning to the river as adults to spawn. The Center exposed juvenile Chinook salmon to the parasite in live cages placed in the Klamath River, held those fish for several weeks in a controlled freshwater environment, then transitioned half of the fish to full 30 parts per thousand saltwater (concentration of ocean water). The juvenile fish were monitored by quantitative PCR and histological assays to determine what effect the saltwater had on infection rate and severity.

The results from this study are being analyzed and will be described in a written report when completed. This information will then be used to direct the objectives and methods of a larger saltwater study to be conducted in 2014.

Kimberly True is the assistant project leader at the California-Nevada Fish Health Center in Anderson, California.  


Contact Info: Kimberly True, 530-365-4271 x201, Kimberly_True@fws.gov



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