Microbiology

The Fish Health/Microbiology team performs complete health and disease diagnostics for the Captive Broodstock programs at the NWFSC Manchester Marine Field Station in Manchester, WA. In these programs, endangered stocks of chinook and sockeye salmon from locations in Idaho and Oregon are reared in captivity until spawning age. The captive broodstocks are used to help restore fish populations to their respective watersheds. The team also provides fish health services for NATURES, Reproductive Ecolog, and Marine Fish Enhancement programs at the station.

The Pathology laboratory at Manchester is responsible for monitoring the health of the captive broodstock populations during rearing. When mortality occurs, the fish are subjected to a complete necropsy to determine cause of death. Physical examination for gross abnormalities can reveal potential problems in the population. First the pathologists conduct a visual external examination to assess overall fish condition. They check the gills and look for parasites, scale loss, tumors, and lesions. Internal examinations are then made and samples of internal organs, including kidney and spleen, are collected for a variety of tests. These include culturing for common bacterial fish pathogens, microscopic examination of the tissues after treatment with reagents that stain bacteria, including a fluorescent antibody tests (FAT) for the presence of Renibacterium salmoninarum, the cause of Bacterial Kidney disease (BKD). Additional tissue samples are sent to our main Montlake lab in Seattle where a quantitative screening test for R. salmoninarum is conducted using an enzyme-linked immunosorbant assay (ELISA). In addition, the tissues are screened for the presence or absence of salmon viruses, using tissue culture techniques. If cytopathology consistent with viruses is detected in the tissue culture, identification of the virus is confirmed by serology and/or specific polymerase chain reaction (PCR) tests.

The team also screens ovarian fluid, milt, and kidney tissue of spawning adult fish in the Captive Broodstock programs for R. salmoninarum (via the ELISA) and for viruses. The information gathered is then used by federal and state co-managers of these programs to make decisions regarding the final disposition and release of the eggs and juveniles back into their native habitat.