Sequential Tests for Infectious Hematopoietic Necrosis Virus in Individuals and Populations of Sockeye Salmon (Oncorhynchus nerka)

1986 ◽  
Vol 43 (12) ◽  
pp. 2515-2519 ◽  
Author(s):  
Dan M. Mulcahy ◽  
Ron J. Pascho
Keyword(s):  
Quantitative Data ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Virus Titer ◽  
Infectious Hematopoietic Necrosis Virus ◽  
Necrosis Virus ◽  
High Virus Titer ◽  
Sequential Tests ◽  
Infectious Hematopoietic Necrosis ◽  
High Virus

The incidence and titer distribution of infectious hematopoietic necrosis virus in cavity fluid from spent female sockeye salmon (Oncorhynchus nerka) varied little when fish from a naturally spawning population were sampled three times on alternate days. However, when prespawning female sockeye salmon from a second population were individually tagged, penned, and sampled daily, the incidence and proportion of fish with high virus titer rose over a 6-d period. In 10 instances, consecutive cavity fluid samples from the same fish reverted from virus-positive to virus-negative. We suggest that spent fish should be sampled when accurate and quantitative data on the incidence and level of the virus are required.

Control of Infectious Hematopoietic Necrosis Virus Disease by Elevating the Water Temperature

1970 ◽  
Vol 27 (2) ◽  
pp. 265-270 ◽  
Author(s):  
Donald F. Amend
Keyword(s):  
Elevated Temperature ◽  
Water Temperature ◽  
Sockeye Salmon ◽  
Virus Disease ◽  
Oncorhynchus Nerka ◽  
Infectious Hematopoietic Necrosis Virus ◽  
Temperature Treatment ◽  
Necrosis Virus ◽  
Infectious Hematopoietic Necrosis

Studies were performed to determine if increasing water temperatures could control infectious hematopoietic necrosis virus (IHN) disease in sockeye salmon (Oncorhynchus nerka). Mortalities could be prevented if the water temperature was raised to at least 18 C within the first 24 hr after infection of the fish and if the fish were maintained at this temperature for 4–6 days. The disease did not recur after the elevated temperature treatment, but the fish would still contract the disease if they were reinfected. Reasons for the protecting action are discussed.

Mortality Due to Infectious Hematopoietic Necrosis of Sockeye Salmon (Oncorhynchus nerka) Fry in Streamside Egg Incubation Boxes

1983 ◽  
Vol 40 (9) ◽  
pp. 1511-1516 ◽  
Author(s):  
Dan Mulcahy ◽  
Ron Pascho ◽  
C. K. Jenes
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Total Mortality ◽  
Infectious Hematopoietic Necrosis Virus ◽  
Necrosis Virus ◽  
Peak Incidence ◽  
Egg Incubation ◽  
Natural Spawning ◽  
Infectious Hematopoietic Necrosis ◽  
Dead Fish

Infectious hematopoietic necrosis virus caused mortality of sockeye salmon (Oncorhynchus nerka) in streamside egg incubation boxes. Virus was not detectable in eggs or alevins; its first isolation coincided with the appearance of dead fish in a trap on the outflow from the box. Mortality due to the virus did not occur in every egg box studied. However, when fry from the boxes were held in the laboratory, epizootics began as much as 3 wk later, with total mortality exceeding 90%. More than 96% of the dead fry had titers exceeding 105 plaque-forming units per gram. The peak incidence of virus in fry migrating in the river coincided with the arrival of hatchery-produced fry, although some fry believed to have been produced by natural spawning were also infected.

A Natural Epizootic of Infectious Hematopoietic Necrosis in Fry of Sockeye Salmon (Oncorhynchus nerka) at Chilko Lake, British Columbia

1976 ◽  
Vol 33 (7) ◽  
pp. 1564-1567 ◽  
Author(s):  
Ian V. Williams ◽  
Donald F. Amend
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Virus Disease ◽  
Oncorhynchus Nerka ◽  
Infectious Hematopoietic Necrosis Virus ◽  
Normal Range ◽  
Necrosis Virus ◽  
Natural Conditions ◽  
Salmon Fry ◽  
Infectious Hematopoietic Necrosis

The first confirmed epizootic of infectious hematopoietic necrosis virus disease under natural conditions is reported for sockeye salmon, Oncorhynchus nerka, in Chilko Lake, British Columbia. The outbreak occurred among fish of the 1972 brood during the spring of 1973. An estimated 825.6 million eggs were deposited in the Chilko River in 1972, and the production of 31.4 million fry that migrated into the lake in 1973 was significantly lower than the 55.1 million fry expected. The egg-to-fry survival of 3.8% was the lowest ever recorded at Chilko Lake (1949–73). The estimated fry-to-smolt survival of 57.1%, however, was well within the normal range for this lake. Apparently IHN severely reduced the survival of the 1972 brood of sockeye salmon fry at Chilko Lake, and all or nearly all of the reduction occurred during the egg-to-fry stage of the life cycle.

Testing of Male Sockeye Salmon (Oncorhynchus nerka) and Steel head Trout (Salmo gairdneri) for Infectious Hematopoietic Necrosis Virus

1987 ◽  
Vol 44 (5) ◽  
pp. 1075-1078 ◽  
Author(s):  
D. Mulcahy ◽  
R. J. Pascho ◽  
W. N. Batts
Keyword(s):  
Sockeye Salmon ◽  
Virus Isolation ◽  
Oncorhynchus Nerka ◽  
Infectious Hematopoietic Necrosis Virus ◽  
Salmo Gairdneri ◽  
Steelhead Trout ◽  
Necrosis Virus ◽  
Spleen Sample ◽  
Infectious Hematopoietic Necrosis

Infectious hematopoietic necrosis (IHN) virus has been isolated only rarely from whole milt samples of male sockeye salmon (Oncorhynchus nerka). In 3 yr of testing, virus incidences in males ranged from 0 to 13% when milt was sampled but were 60–100% with spleen or kidney. When IHN virus was isolated from sockeye salmon milt at titers less than 3.00 log10 plaque-forming units (pfu)/mL, the level of virus in the kidney or spleen exceeded 7.00 log10 pfu/g. Higher rates of IHN virus isolation from kidney or spleen than from milt were also generally found in steelhead trout (Salmo gairdneri), although the differences were less pronounced than in sockeye salmon. Furthermore, virus was sometimes isolated from steelhead trout milt when the level of virus in kidney or spleen samples was very low, and was recovered from some milt samples when none was isolated from the corresponding spleen sample. When male salmonids are tested for IHN virus, kidney or spleen samples are superior to whole milt, but milt should be included for critical examinations.

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