Figure 1.
Map depicting Discovery Islands, British Columbia, Canada, with location of salmon aquaculture sites marked by filled (red) circles.
Table 1.
Summary of virus exposure trials.
Figure 2.
Decay of infectivity of IHN virus in sterile (squares), closed (circles), and open (triangles) seawater systems that were seeded with IHNV and incubated in the dark at 8 (black), 10 (yellow), or 12 (red) degrees Celsius.
Error bars represent standard deviation based on triplicate plaque assay counts.
Table 2.
Least square fit computed decay constants (k), 95% confidence intervals and correlation coefficients (R2) for IHN virus samples incubated at 8, 10 and 12°C in open and closed containers.
Figure 3.
Decay of infectivity of IHN virus in sterile (dashed line) or raw (solid line) seawater while maintained in the dark at depth (0.5 m;squares); in the dark at the surface (diamonds); exposed to sunlight at depth (0.5 m; triangles); exposed to sunlight at the surface (circles).
Figure 4.
Rate of IHNV decay per UV A and B dosage estimated for raw (yellow) and sterile (blue) seawater samples reported in figure 3.
Decay rate of IHNV to exposure of UV radiation calculated via the exponential decay rate model (Eq. 3).
Figure 5.
Cumulative mortality of Atlantic salmon waterborne exposed to various doses of IHNV.
Data are means from triplicate experiments for doses 102-104 and duplicate experiments for 101 pfu ml−1.
Table 3.
Atlantic salmon mortalities and viral tissue titers after waterborne exposure at various IHNV doses.
Figure 6.
Atlantic salmon waterborne exposed to IHNV.
Titer of waterborne IHNV (diamonds) and daily mortality (bars) in a population of Atlantic salmon post smolts exposed to IHNV at a dose of 4.6×103 PFU ml−1. Cumulative mortality was 44% upon termination of the experiment 51 days post virus exposure.
Figure 7.
Virus shedding rate of Atlantic salmon waterborne exposed to IHNV.
Shed virus concentration calculated based on the change of waterborne virus titer over a one hour timeperiod. Only fish which had measurable levels of shed virus are graphed.
Figure 8.
Virus shedding rate of Atlantic salmon injected (i.p) with IHNV.
Shed virus concentration (PFU ml−1) calculated based on the change of waterborne virus titer over a one hour timeperiod. Only fish which had measurable levels of shed virus are graphed.
Figure 9.
Model depicting the estimated infectious dose, shedding capacity, and decay rates associated with IHN virus transmission among Atlantic salmon marine net-pen aquaculture.
Solid arrows represent the production (green) and destruction (red) of viral particles in a 10°C seawater environment while the hatched arrow represents viral transmission if free virus exceeds the minimum infectious dose.