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PROPOSED IHNV BROODSTOCK SAMPLING PROGRAM FOR IDFG
STEELHEAD
DOUG MUNSON And
DR. PHIL MAMER
LSRCP MEETING 2012
CONVERSATIONS WITH EXPERTS
• MOVE EGGS NOT FISH…SCOTT LAPATRA• IF YOU HAVE IHN, YOU HAVE A BIO-SECURITY
PROBLEM…SCOTT LAPATRA AND GAEL KURATH
• TO DATE THERE IS NO EVIDENCE OF VERTICAL TRANSMISSION OF IHN, THE PROBLEM IS YOU CANNOT PROVE A NEGATIVE…SCOTT AND GAEL
SUSCEPTABLE SPECIES(to natural infection)
All Pacific Salmon (Sockeye, Chinook, Coho, Pink, Chum, (Masu & Amago)Steelhead/rainbow troutAtlantic salmonBrook trout*Brown trout*Cutthroat trout*
*More resistant to clinical disease
INFECTIOUS HEMATOPOIETIC NECROSIS VIRUS (IHNV)
• Native to salmonids in NW North America.
• Rhabdovirus (bullet-shaped, ssRNA).
• Attacks the hematopoietic tissues of the kidney.
• Transmission fish-to-fish and via egg surface contamination.
TRANSMISSION
• CLINICALLY INFECTED AND COVERT CARRIERS– CULTURED, FERAL, AND WILD
• VIRUS IS SHED – URINE, OVARIAN FLUIDS, EXTERNAL MUCUS– KIDNEY, SPLEEN, OTHER INTERNAL ORGANS– GILL AND BRAIN
• VECTORS– INSECTS, ANNELIDS, CRUSTACEANS– WATER DROPLETS (FOMITE) AND EQUIPMENT
• CLINICAL OUTBREAKS AT 10⁰C– NOT NATURALLY ABOVE 15⁰C
LethargyDarkened colorPop-eye (exophthalmia; often with hemorrhage)
Anemia (loss of red color in gills and internal organs)
Spleen normal size Mortality rate often
exponential
CLINICAL SIGNS OF IHN
OregonIdaho
Washington
Salm
onR
.
Snake R.
Columbia R.
025
50
75 100 km
Pac
ific
Oce
an
SA
OX
RR
MC SF PA
POCW
DW
RRCR
EF
OregonIdaho
Washington
Salm
onR
.
Snake R.
Columbia R.
025
50
75 100 km
Pac
ific
Oce
an
SA
OX
RR
MC SF PA
POCW
DW
RRCR
EF
Management for IHN
• Avoidance– Broodstock sampling• Test all parent females at spawning and cull eggs from
positive individuals.– Egg disinfection• Iodophor is an effective surface disinfectant for both
water hardening and eyed stages.– Isolation/Quarantine• A pathogen-free water source is critical!• Do not bring a source onto your hatchery.
Management for IHN
• Successful example:– Clearwater Hatchery: test 100% brood, disinfect,
and quarantine.– Water source without anadromous fish.
• Moderate success:– Niagara Springs Hatchery: test and disinfect, but
isolation is not always complete.– IHN outbreaks usually in fry shipments.
Culture Opportunities• Bio-Security/Integrated Fish
Health Management
• Disease free water supply
• Disinfection and quarantine
• Compartmentalization: spread the risk within and between facilities
• Hatchery personnel charged with decision to destroy infected groups
CLEARWATER STEELHEAD
• RECEIVE ONLY EGGS FROM IHN NEGATIVE FEMALES
• IODOPHOR GREEN EGGS AT SPAWNING• IODOPHOR EGGS UPON ARRIVAL AT
CLEARWATER• TO DATE, NO DETECTIONS OF IHN IN
JUVENILE STEELHEAD
BIO-SECURITY
• BROODSTOCK TESTING• IODOPHOR DISINFECTION OF EGGS
– ADDITIONAL DISINFECTION IF EGGS ARE MOVED• TRANSPORT EGGS• CERTIFICATION TESTING BEFORE TRANSPORT OF FISH
– Phase out• DISINFECTION OF EQUIPMENT AND RACEWAYS
– FOOT BATHS AND HAND SANITIZER• PERIODIC JUVENILE INSPECTION• BIO-SECURITY AUDITS
PREDICTIONSVirus will become widely established in the basin
Additional host species will become involved
Virus will persist in low-level carriers much of the year
Stressors will exacerbate latent infections and disease
Disease will occur on periodic basis – especially in the spring
Recovered fish will become immune, leading to disease occurring primarily in younger age classes
Disease will have population-level effects for some species
Disease will become less explosive in most years
Disease will impact both management and commercial activities
It will be important to prevent the spread of the virus to other freshwater systems in the U.S. and Canada, as well as to the commercial aquaculture industry
CONCLUSIONS
• APPLY CLEARWATER PLAN THOUGHOUT IDFG– MORE FISH TO SAMPLE AND SPAWN– MORE HOURS SPAWNING, SAMPLING, PROCESSING– MORE $ (INCREASE COST OF DOING BUSINESS)
• MOVE EGGS – CAN DISINFECT EGGS– CANNOT DISINFECT FISH
• MAINTAIN HIGH LEVEL BIO-SECURITY