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Developing methods to identify & control pathogenic microorganisms that threaten fishery resources
Developing methods to identify & control pathogenic microorganisms that threaten fishery resources
Problem Statement
Microbial infections for which no vaccines exist can sicken or kill fish in
hatcheries, aquaculture pens, and captive broodstock programs designed to
restore endangered salmon populations. In turn, these diseases may have impacts
on wild stocks.
Critical Factors
- Endangered salmon species raised in captive broodstock programs are particularly
susceptible to bacterial kidney disease (BKD) caused by the bacterial pathogen
Renibacterium salmoninarum.
- There is no vaccine and no reliable treatment for BKD.
- Bacterial pathogens called Aeromonads cause hemorrhagic septicaemia
and a debilitating disease called furunculosis in salmon.
- There is no vaccine that confers long-term immunity against diseases
caused by Aeromonads.
- Other diseases may infect captive populations of marine fish species for
which aquaculture techniques are being developed (e.g., lingcod, sablefish,
halibut).
- The Northwest Fisheries Science Center (NWFSC) provides an infectious disease
diagnostic service for endangered species captive salmon broodstock programs and
marine fish culture programs.
Status of Research
Researchers that are part of the NWFSC's Fish Health/Microbiology team are
conducting genetic studies of the bacterial pathogens R. salmoninarum
(which causes bacterial kidney disease), Aeromonas hydrophila
(which causes hemorrhagic septicaemia), and A. salmonicida (which causes
furunculosis). The scientists are characterizing what makes these pathogens
virulent and their host-pathogen interactions, including specific
immune responses. They are developing highly sensitive molecular techniques
to diagnose infections caused by the pathogens and identify molecular
markers that can differentiate among pathogen strains. One marker
that has already been identified by the team will be used in conjunction
with other molecular techniques to test whether strains of R. salmoninarum
isolated from Pacific Northwest salmon stocks can be distinguished
from one another. Such markers can also be used as tools to determine
whether hatchery fish transmit these pathogens to wild stocks.
In addition, NWFSC scientists are developing similar tests for other
important fish pathogens and evaluating antibiotic treatments and vaccines
for bacterial kidney disease.
Future Considerations
As the decline and listing of wild salmon stocks create a need for captive
broodstock rearing, the need to improve the survival of hatchery salmon both
before and after their release, and reduce their risk of infecting wild stocks,
will also increase. As a result of the methods being developed to control
pathogenic microorganisms, the NWFSC is in a position to quickly identify "new"
pathogens that threaten endangered species of captive salmon broodstock or marine
fish aquaculture programs.
Key Players
Resource Enhancement and Utilization Technologies (REUT) Division, NWFSC
Western Fisheries Research Center, U.S. Geological Survey
Pacific Northwest Fish Health Protection Committee
U.S. Food and Drug Administration
U.S. Fish and Wildlife Service
University of Washington
Idaho Department of Fish and Game
Washington Department of Fish and Wildlife
Washington Department of Agriculture
Oregon Department of Fish and Wildlife
Oregon Department of Agriculture
Contact: Dr. Walton Dickhoff, Director, REUT Division (206/860-3234)
NWFSC Issue Paper REUT 6205 (HQ ID 299)
Issue Papers Home
last modified 2002-07-30
Web site owner: Northwest Fisheries Science Center
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