Aquaculture research related to Cohen Commission recommendation 19

The research our scientists conduct, which is often done in collaboration with other researchers, is helping to better understand the extent and impact of interactions between wild Pacific salmon and farmed salmon. These scientific conclusions help address recommendation 19 in determining if operations of net-pen salmon farming in the Discovery Islands area of British Columbia pose more than a minimal risk to the health of migrating Fraser River Sockeye salmon. Moving forward, this research will inform best practices and discussions as we engage with local First Nations on the options around aquaculture licence renewals in the Discovery Islands.

Determining risks and impacts on wild salmon

To respond to recommendation 19, the Department looked at the overall risk to Fraser River Sockeye salmon from diseases that can occur on Atlantic salmon farms. Fisheries and Oceans Canada (DFO) completed nine risk assessments on pathogens known to cause disease from aquaculture operations in the Discovery Islands area.

Risk is the chance of encountering some form of harm, loss or damage. Risk is assessed by considering how likely an event is to occur and the severity of the potential impact(s).

For this task, researchers used the outcome of the Aquaculture Science Environmental Risk Assessment Initiative. This model brings together all relevant data and scientific information to provide scientific advice on the risk of aquaculture stressors on wild fish and the environment across the country.

They determine scientific risk by first estimating the likelihood of events to take place. Then the magnitude and severity of the potential impacts on the environment are characterized. The likelihood and consequences are then combined to estimate the risk associated to the stressor – in this case, the transfer of a specific pathogen.

An important aspect of the risk assessment is to identify the uncertainties related to every step. Uncertainty is the lack of knowledge about the parameters being assessed. There is uncertainty that is due to natural variability and uncertainty because of a lack of knowledge.

By identifying uncertainties, we can then select key areas for data collection, research, or monitoring activities that will help to address these uncertainties in the future.

How we provide science advice

Science advice that is evidence-based, objective, and impartial is generated through the Canadian Science Advisory Secretariat (CSAS). This formal, transparent process involves a thorough peer review that analyses and challenges scientific information to come to a consensus perspective.

When DFO receives a request for science advice on a specific subject, a steering committee is formed to define the scope of the request and to develop the terms of reference for the review. This committee typically includes DFO Science staff, the requester, and sometimes other interested and knowledgeable parties from outside DFO (such as Indigenous or academic participants).

Next, scientists collect and analyze relevant data to prepare working paper(s), which is a collection of technical and scientific information that will be analyzed to generate advice. These working papers are then reviewed by experts identified by the steering committee. These experts could come from DFO, academia, another Government department, or elsewhere in the international scientific community.

The next step in the process is the peer-review meeting. The people invited to participate in these meetings are selected for their expertise and knowledge in the subject matter being reviewed. Participants can include:

Participants analyze the working papers and the input of the expert reviewers to develop consensus advice. Consensus is reached if all parties can generally accept the working paper and support its conclusions and proposed science advice. Once a working paper has been accepted, it becomes the final research document.

Once the process is concluded, the findings generate a Science Advice Report. All CSAS process documents are available online.

Findings of the risk assessments for the Discovery Islands area

The nine assessments determined the risk those pathogens pose to Fraser River Sockeye salmon. The assessments focused on farms located in the Discovery Islands area. Considerations included the current fish health management practices, ocean currents, and salmon ecology.

For each pathogen, the assessment determined a risk estimate, which combines how likely the event is to occur and the level of impact or consequence of the event. Risk estimates can be illustrated in a risk matrix.

All of the assessments concluded that the pathogens on Atlantic salmon farms in the Discovery Islands area pose no more than a minimal risk to Fraser River Sockeye salmon abundance and diversity under the current fish health management practices.

Please see the summaries for each risk assessment.

Other research on the interactions between Wild Pacific salmon and farmed salmon

Understanding the scale and effect of any interactions between salmon aquaculture operations and wild fish populations can inform regulatory decisions and the development of mitigation measures.

Fish health

Research to understand interactions between wild and farmed salmon is an area of priority research.

In addition to the risk assessments completed to respond to the Cohen Commission recommendations, DFO supports research to better understand interactions between aquaculture and the aquatic environment. The Program for Aquaculture Regulatory Research (PARR) funds research project that address fish pest and pathogen treatment and management.

Sea lice

There are concerns about the impacts of sea lice from Atlantic salmon farms on Pacific salmon, and on the health of Fraser River Sockeye salmon.

More than 15 years of intensive research evaluating the effects of farmed-derived sea lice on wild salmon in Canada have resulted in substantial improvements in our knowledge of sea lice biology (genetics, life history, distribution, abundances, and tolerances) and of the relative susceptibility and resistance of Pacific salmon species to sea lice.

A science assessment provided scientific advice on sea lice management measures, monitoring, and interactions between cultured and wild fish. Sea lice dynamics are influenced by salinity and water temperature (which affect survival, growth, development rate, and reproductive success of sea lice), water movement (tides and currents), behaviour of infective larval stages and motile pre-adult and adult stages, and the abundance and proximity of suitable fish hosts.

Additionally, there is a wide range of susceptibilities to sea lice infestation among Pacific salmon species; and Atlantic salmon are generally more susceptible to sea lice infestation than Pacific salmon species. Scientists have has demonstrated that risk posed by sea lice to wild salmon diminishes with increased fish size. Laboratory study results indicate both size and species-specific resistance to sea lice in juvenile salmon, and laboratory studies have also shown that lethal sea lice numbers is species and size dependent. The data from these lab studies provides an opportunity to better understand natural infections, and the development of lethal infection density thresholds could potentially be useful as a management tool.

Science advice resulting from the 2012 peer review included several measures that have been initiated and /or implemented through DFO management and science activities.

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