Pathogenesis of Infectious Hematopoietic Necrosis Virus in Adult Sockeye Salmon (Oncorhynchus nerka)

1982 ◽  
Vol 39 (8) ◽  
pp. 1144-1149 ◽  
Author(s):  
Dan Mulcahy ◽  
John Burke ◽  
Ron Pascho ◽  
C. K. Jenes
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Virus Concentration ◽  
Ovarian Fluid ◽  
Female Fish ◽  
Fish Virus ◽  
Infectious Hematopoietic Necrosis ◽  
The Mean ◽  
Mean Concentration ◽  
Pyloric Ceca

The concentration of infectious hematopoietic necrosis (IHN) virus was determined in eight organs and two body fluids from each of 60 adult sockeye salmon (Oncorhynchus nerka). Included in the sample were 4 males and 56 prespawning, spawning, or spent female fish. All fish were infected, and virus was present in nearly all organs. There was an overall tendency for the mean concentration to increase in many of the organs over time as the fish progressed in ripeness. In prespawning females, IHN virus could be detected in all organs and in ovarian fluid but not in serum; the incidences were highest in the gills, spleen, and pyloric ceca, and the titers were highest in the pyloric ceca and liver. Incidences of infection in the organs were higher in spawning than in prespawning females and higher still in spent females in which the incidence of virus was 100% in all organs except brains (78%) and sera (67%). Virus concentrations in organs or fluids ranged from 5 to 4.0 × 109 plaque-forming units per millilitre. In males, the highest incidences of virus were found in gills, pyloric ceca, and liver. The gills were the only organ in which the virus concentration in males exceeded that of females.Key words: infectious hematopoietic necrosis, IHN, fish virus, viral pathogenesis, sockeye salmon

Fecundity and Egg Retention of Some Sockeye Salmon (Oncorhynchus nerka) Stocks in British Columbia

1986 ◽  
Vol 43 (8) ◽  
pp. 1643-1655 ◽  
Author(s):  
J. I. Manzer ◽  
I. Miki
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Absolute Fecundity ◽  
Egg Retention ◽  
Inadequate Sample Size ◽  
Egg Number ◽  
The Mean ◽  
The Relationship ◽  
Individual Fecundity

The fecundity and egg retention of anadromous female sockeye salmon (Oncorhynchus nerka) collected during 1971–82 from several stocks in British Columbia undergoing controlled fertilization to enhance adult sockeye production were examined. The relationship between egg number and postorbital–hypural length based on 863 females representing 14 stocks was not consistent between all age-types, stocks, and years, probably because of inadequate sample size in some instances. Combined samples, however, revealed a significant positive relationship between postorbital–hypural length and egg number for age 1.2, 1.3, and 2.2 females. Mean absolute fecundity for the respective age-types was 3218, 4125, and 3544 eggs. For samples of 10 or more females, significant stock and annual differences were detected when individual mean absolute fecundity was adjusted to a postorbital–hypural length of 447 mm, but not for females of different age. A comparison of mean fecundities for coastal stocks with historical data for interior British Columbia stocks suggests that coastal stocks are 18% more fecund than interior stocks. Possible causal mechanisms for this regional difference are hypothesized. Examination of 796 carcasses (representing five stocks) for egg retention revealed a range from totally spawned to totally unspawned females, with 56% of the carcasses containing 20 eggs or less and 68% containing 50 eggs or less. The mean egg retention based on all samples combined was estimated to be 6.5% of the mean individual fecundity. This value was reduced to 3.9% when stock means were averaged.

scholarly journals Importance of sample size for estimating prevalence: A case example of infectious hematopoietic necrosis viral RNA detection in mixed-stock Fraser River Sockeye salmon (Oncorhynchus nerka), British Columbia, Canada.

2020 ◽  
Author(s):  
Emilie Laurin ◽  
Julia Bradshaw ◽  
Laura Hawley ◽  
Ian A. Gardner ◽  
Kyle A Garver ◽  
...  
Keyword(s):  
British Columbia ◽  
Sample Size ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Small Sample ◽  
Viral Rna ◽  
Sample Sizes ◽  
Apparent Prevalence ◽  
Infectious Hematopoietic Necrosis ◽  
Mixed Stock

Proper sample size must be considered when designing infectious-agent prevalence studies for mixed-stock fisheries, because bias and uncertainty complicate interpretation of apparent (test)-prevalence estimates. Sample size varies between stocks, often smaller than expected during wild-salmonid surveys. Our case example of 2010-2016 survey data of Sockeye salmon (Oncorhynchus nerka) from different stocks of origin in British Columbia, Canada, illustrated the effect of sample size on apparent-prevalence interpretation. Molecular testing (viral RNA RT-qPCR) for infectious hematopoietic necrosis virus (IHNv) revealed large differences in apparent-prevalence across wild salmon stocks (much higher from Chilko Lake) and sampling location (freshwater or marine), indicating differences in both stock and host life-stage effects. Ten of the 13 marine non-Chilko stock-years with IHNv-positive results had small sample sizes (< 30 samples per stock-year) which, with imperfect diagnostic tests (particularly lower diagnostic sensitivity), could lead to inaccurate apparent-prevalence estimation. When calculating sample size for expected apparent prevalence using different approaches, smaller sample sizes often led to decreased confidence in apparent-prevalence results and decreased power to detect a true difference from a reference value.

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.

The distribution of plerocercoids of Diphyllobothrium dendriticum (Nitzsch) in sockeye salmon (Oncorhynchus nerka) smolts from Great Central Lake, British Columbia

1988 ◽  
Vol 66 (4) ◽  
pp. 850-852 ◽  
Author(s):  
Hilda Lei Ching
Keyword(s):  
British Columbia ◽  
Body Length ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Vancouver Island ◽  
Infected Fish ◽  
Mean Intensity ◽  
Diphyllobothrium Dendriticum ◽  
Pyloric Ceca

Sockeye salmon (Oncorhynchus nerka) from Great Central Lake, Vancouver Island, British Columbia, were sampled in May of 1986 and 1987 to study the locations and sizes of plerocercoids of Diphyllobothrium dendriticum. In 1986, 93% of 59 smolts were infected with a total of 222 plerocercoids (mean intensity ± SE, 4.0 ± 3.4; range, 1–15). In 1987, 77% of 168 smolts were infected with a total of 341 plerocercoids (mean ± SE, 2.6 ± 1.8; range, 1–9). More than 75% of the infected fish contained one to three plerocercoids, which were more often found free in the musculature than encysted in the viscera. Plerocercoids occurred most frequently in the midepaxial and midhypaxial musculature and encysted on the stomach and pyloric ceca. Plerocercoids varied in body length: those from the stomach area were <2 mm, and those in the viscera and musculature were 3–10 mm (a few from the musculature were >10 mm).

Environmental and Parental Influences on Age at Maturity in Sockeye Salmon (Oncorhynchus nerka) from the Fraser River, British Columbia

1986 ◽  
Vol 43 (2) ◽  
pp. 269-274 ◽  
Author(s):  
Randall M. Peterman ◽  
Michael J. Bradford ◽  
Judith L. Anderson
Keyword(s):  
British Columbia ◽  
Age Structure ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Data Series ◽  
Fraser River ◽  
Age At Maturity ◽  
Long Term Effects ◽  
River Population ◽  
The Mean

Commercial fisheries possess the potential for applying strong selection on size or age at maturity in the populations they exploit. It is therefore important to know the extent to which these traits are inherited. We examined regressions of the mean age at maturity of cohorts of offspring on the mean ages of the female and male spawners which produced them for four populations of sockeye salmon (Oncorhynchus nerka) from the Fraser River, British Columbia. Unlike previous researchers, we found that neither genetic nor maternal effects are important, relative to environmental variables, in influencing year-to-year variation in age at maturity in these stocks. The differences between our findings and earlier ones are due to a longer data series and more complete population statistics than were available previously. We further analyzed the age structure of the Adams River population, which has a cyclic pattern of abundance. Fluctuating population density appeared to account for variation in age structure among cycle years in the Adams stock. We concluded that serious concerns about the long-term effects of size-selective fishing on mean age at maturity are probably not warranted for Fraser River sockeye.

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.

Application of Dual-Beam Acoustic Survey Techniques to Limnetic Populations of juvenile Sockeye Salmon (Oncorhynchus nerka)

1986 ◽  
Vol 43 (9) ◽  
pp. 1776-1788 ◽  
Author(s):  
Janusz J. Burczynski ◽  
Robert L. Johnson
Keyword(s):  
Spatial Distribution ◽  
Cross Section ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Biological Data ◽  
Empirical Formulas ◽  
Backscattering Cross Section ◽  
Dual Beam ◽  
Abundance Estimates ◽  
The Mean

Two hydroacoustic surveys of Cultus Lake, British Columbia, were conducted in July 1983 and February 1984 to estimate the size and distribution of the juvenile sockeye salmon (Oncorhynchus nerka) population. The surveys demonstrated the application of a combined dual-beam/echo integration technique for obtaining accurate abundance estimates and other quantitative data. The dual-beam system measured in situ the target strengths (and backscattering cross section) of individual fish. For each survey the mean backscattering cross section of the sampled population was used to scale the integrator outputs to absolute fish density and abundance estimates. Based on previously derived empirical formulas, the mean target strengths compared well with the mean lengths of fish captured by trawl. For this monospecies population with a dominant single-size group of fish, the variance in integrator outputs was due almost entirely to the spatial distribution of fish and not to the variance in measured backscattering cross sections. The confidence intervals of biomass estimates depend on autocorrelation between consecutive acoustic samples, which is related to the spatial distribution of the surveyed population. Trawl catches indicated that about 95% of the fish in the lake were juvenile sockeye salmon. Population estimates made by hydroacoustics were consistent with other available biological data.

The Effect of reduction of Predaceous Fish on survival of young Sockeye Salmon at Cultus Lake

1941 ◽  
Vol 5b (4) ◽  
pp. 315-336 ◽  
Author(s):  
R. E. Foerster ◽  
W. E. Ricker
Keyword(s):  
British Columbia ◽  
Survival Rate ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Oncorhynchus Nerka ◽  
First Year ◽  
The Mean ◽  
Control Work ◽  
The Cost ◽  
Gill Netting

By persistent gill-netting in Cultus lake, British Columbia, the predaceous fish which feed on young sockeye (Oncorhynchus nerka) have been considerably, though unevenly, reduced in numbers. The populations of squawfish and char, of lengths greater than 200 millimetres, were reduced in three years to about 1/10 of their original numbers. The abundance of trout and coho salmon have been much less affected by netting, if at all, though a considerable number have been killed. From the first year of control operations the survival rate of young sockeye salmon was considerably increased. In the three years which have been tested, the mean survival rate has been increased three and a third times over average conditions prior to control. In absolute figures, this represents 3,800,000 migrants saved, which are expected to yield 380,000 adult sockeye. Even disregarding the important cumulative future increase, the immediate return from the work is a quantity of sockeye whose value is many times greater than the cost of control work.

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