Summaries of the risk assessments for the Discovery Islands area
Fisheries and Oceans Canada completed nine risk assessments on pathogens known to cause disease from aquaculture operations in the Discovery Islands area.
|Summary of risk assessment||Science advice reports and supporting documents||Risk estimation|
|Infectious Hematopoietic Necrosis Virus (IHNV)
IHNV is a virus native to the Pacific Northwest. IHNV can cause a disease called infectious hematopoietic necrosis (IHN). The virus can infect several salmon species with varying susceptibility. The disease can cause death of infected fish.
The risk assessment concluded that the risk to Fraser River Sockeye salmon from IHNV is minimal.
There are two key reasons for this:
|Science Advisory Report 2017/048
Research Document 2017/071 - Oceanographic and environmental conditions in the Discovery Islands, British Columbia
Research Document 2017/073 - Characterization of Infectious Hematopoietic Necrosis Virus (IHNV)
Research Document 2017/072 - British Columbia farmed Atlantic Salmon health management practices
Research Document 2017/074 - Ecology to inform pathogen transfer risk assessments in the Discovery Islands, BC
Research Document 2017/075 - Assessment of the risk to Fraser River Sockeye Salmon
|Aeromonas salmonicida and furunculosis
Aeromonas salmonicida is a bacteria that is native to the Pacific Northwest. It is the cause of furunculosis in salmon and trout species around the world. Salmon with furunculosis may die.
The risk assessment concluded that the risk to Fraser River Sockeye salmon from A. salmonicida is minimal.
The key reason for this conclusion is that the amount of A. salmonicida that is estimated from an infected farm is lower than what is required to cause infection or mortality in salmon. Therefore, A. salmonicida from farmed salmon is very unlikely to infect Fraser River Sockeye salmon.
The main uncertainties are:
|Science Advisory Report 2019/017
Research Document 2019/016 - Characterization of Aeromonas salmonicida and furunculosis
|Piscirickettsia salmonis and salmonid rickettsial septicaemia
Piscirickettsia salmonis is a bacteria that can cause a disease called salmonid rickettsial septicaemia (SRS) in marine fish species.
To date, there are no reports of this disease in Sockeye salmon.
The risk assessment concluded that the risk to Fraser River Sockeye salmon from P. salmonis is minimal.
The key reason is that P. salmonis on a farm is very unlikely to infect Fraser River Sockeye salmon.
There are several uncertainties in this risk assessment. These include:
|Science Advisory Report 2019/020
Research Document 2019/020 - Characterization of Piscirickettsia salmonis and salmonid rickettsial septicaemia
|Renibacterium salmoninarum and bacterial kidney disease
Renibacterium salmoninarum is a bacteria that can cause bacterial kidney disease (BKD) in salmon. BKD is a global disease and is found in both freshwater and marine environments.
The risk assessment concluded that the risk to Fraser River Sockeye salmon from R. salmoninarum is minimal.
The key reason is that the concentration estimated on a farm is much lower than the one required to cause infection or death in Chinook salmon, which are more vulnerable to R. salmoninarum infection than Sockeye salmon.
There key uncertainty is that the minimum dose of R. salmoninarum needed to infect and cause disease in Sockeye salmon in the marine environment is unknown.
As well, there is uncertainty about the consequences of R. salmoninarum infections in one generation of Sockeye salmon on the next generation.
|Science Advisory Report 2019/019
Research Document 2019/018 - Characterization of Renibacterium salmoninarum and bacterial kidney disease
|Yersinia ruckeri and enteric redmouth disease
Yersinia ruckeri is a bacteria that causes enteric redmouth disease (ERM). It is primarily a freshwater pathogen and rarely causes disease in healthy and unstressed fish.
The risk assessment concluded that the risk to Fraser River Sockeye salmon from Y. ruckeri is minimal.
The key reason is that Y. ruckeri infection on farms in the Discovery Islands area is extremely rare, and there is no evidence of spread within farmed Atlantic salmon in the area.
The main uncertainty in this risk assessment is the susceptibility of Sockeye salmon. To date, there is no evidence of ERM in Sockeye salmon.
|Science Advisory Report 2019/018
Research Document 2019/022 - Characterization of Yersinia ruckeri and enteric redmouth disease
|Piscine Orthoreovirus (PRV)
PRV is a virus found in several countries around the world. There are three distinct types: PRV-1; PRV-2; and, PRV-3. To date, PRV-1 is the only group detected in North America. The virus can infect several salmon species, but the capacity of PRV-1 to cause disease varies from region to region, and between salmon species.
The risk assessment concluded that the risk to Fraser River Sockeye salmon from PRV is minimal.
The key reason for this conclusion is that there is scientific evidence that PRV-1 infection does not cause disease, mortality or swimming impairment in Sockeye salmon.
The key uncertainties for this assessment relate to:
|Science Advisory Report 2019/022
Research Document 2019/035 - Characterization
Research Document 2019/036 - Risk Assessment
Moritella viscosa is a bacteria that causes winter ulcer. The disease occurs in farmed Atlantic salmon in the northern Atlantic Ocean. To date, there is no evidence of winter ulcer in Pacific salmon species in British Columbia.
The assessment concluded that the risk to Fraser River Sockeye salmon from M. viscosa is minimal.
The key reason is that infections on farms do not occur when Fraser River Sockeye salmon are in the Discovery Islands area.
|Science Advisory Report 2020/043||Minimal|
Tenacibaculum maritimum is a bacteria found worldwide in several species of marine fish. It is an opportunistic bacteria that can cause disease in fish that are stressed. In BC, the bacteria causes mouthrot disease (also called yellow mouth) in salmon. Mouthrot typically affects smolts in their first year at sea.
The risk assessment concluded that the risk to Fraser River Sockeye salmon from T. maritimum is minimal.
One of the key reasons for this conclusion is that mouthrot is a disease that mainly affects young Atlantic salmon shortly after they are transferred from freshwater to the marine environment. Pacific salmon appear to be less susceptible than Atlantic salmon. Fraser River Sockeye salmon have a short and limited interaction with the farms in the area.
The key uncertainty is whether or not Sockeye salmon can get infected with T. maritimum and develop mouthrot. Nevertheless, the risk assessment assumed that Sockeye salmon are susceptible.
|Science Advisory Report 2020/044||Minimal|
|Viral hemorrhagic septicemia virus (VHSV)
VHSV is the causative agent of the disease VHS, which can occur in a wide range of cultured and wild fish species in both marine and freshwater environments. Genotype IVa is the only VHSV type found in BC and the surrounding northeastern Pacific Ocean where it causes noticeable, recurring mortality events in Pacific herring and Pacific sardine. Less commonly, the virus has been detected in farmed and wild salmon. There are no confirmed reports of VHSV in Sockeye salmon in fish health records, published studies and surveillance studies, and together with the results from controlled laboratory studies demonstrate that Sockeye salmon are not susceptible to VHSV-IVa.
The assessment concluded that the risk posed by VHSV-IVa is minimal.
The key reason for this conclusion is that Sockeye salmon are not susceptible to VHSV.
There are few uncertainties in this risk assessment.
|Science Advisory Report 2020/049||Minimal|
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