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Recovery Potential Assessment – Fraser River Sockeye Salmon (Oncorhynchus nerka) – Ten Designatable Units

Regional Peer Review – Pacific Region

October 7-11, 2019
Richmond, BC

Chairperson: Gilles Olivier

Context

After the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses an aquatic species as Threatened, Endangered or Extirpated, Fisheries and Oceans Canada (DFO) undertakes a number of actions required to support implementation of the Species at Risk Act (SARA). Many of these actions require scientific information on the current status of the wildlife species, threats to its survival and recovery, and the feasibility of recovery. Formulation of this scientific advice has typically been developed through a Recovery Potential Assessment (RPA) that is conducted shortly after the COSEWIC assessment. This timing allows for consideration of peer-reviewed scientific analyses into SARA processes including recovery planning.

The following ten populations of Fraser River Sockeye Salmon (Oncorhynchus nerka) were designated as Endangered or Threatened by COSEWIC in 2017 based on population declines (COSEWIC 2017).

  1. Cultus Lake population (Endangered): This population was first designated by COSEWIC as Endangered in an emergency assessment in October 2002. Status was re-examined and confirmed in May 2003 and November 2017. Cultus Lake is one of the most heavily utilized lakes in BC and it has been developed for recreational, residential and agricultural purposes. The lake’s water quality has been degraded as a result of seepage from septic systems, agricultural runoff and domestic use of fertilizers as well as by an introduced Eurasian water-milfoil (Myriophyllum sp.). The spawning population has declined steadily since 1950 and the current population size remains very small.
  2. Bowron – early summer (ES) population (Endangered): The number of mature individuals in this population has been declining since the mid-1950s and there has been a large decline in the past 3 generations.
  3. Harrison - upstream (U/S) population (Endangered): The number of mature individuals increased from a low level in 1960 to a peak in 1980. Since then, the numbers have fluctuated in a downward direction to reach an historical minimum in the most recent period.
  4. Quesnel - summer (S) population (Endangered): The population has declined consistently since 2000.
  5. Seton – late (L) population (Endangered): The number of mature individuals in this population was relatively high and stable from the mid-1970s to the late-1990s. Since then the numbers have declined considerably to very low abundance and are close to a historical minimum.
  6. Takla-Trembleur- Early Stuart (EStu) population (Endangered): The number of mature individuals has been declining steadily for over 20 years despite reductions in fishing mortality. Productivity is currently very low.
  7. Takla-Trembleur-Stuart – summer (S) population (Endangered): The number of mature individuals has been declining steadily for three generations yet removals by fishing remained high.
  8. Taseko - early summer (ES) population (Endangered): The number of mature individuals was relatively high in the late 1990s. Since then the numbers have declined considerably and are close to a historical minimum.
  9. North Barriere – early summer (ES) population (Threatened): Since 1980, there has been a continuous decline to a low number today.
  10. Widgeon (River-Type) population (Threatened): The number of mature individuals was relatively stable from 1950 to 1990, and then declined considerably to a minimum in 2000. Over the past 3 generations the number of fish has returned to pre-1990 abundances. However, the small population size makes them vulnerable to stochastic events and increasing threats.

DFO Science has been asked to undertake a Recovery Potential Assessment (RPA), for these 10 populations based upon the national RPA Guidance. The advice in the RPA may be used to inform both scientific and socio-economic aspects of the listing decision, development of a recovery strategy and action plan, and to support decision making with regards to the issuance of permits or agreements, and the formulation of exemptions and related conditions, as per sections 73, 74, 75, 77, 78 and 83(4) of the Species at Risk Act (SARA 2002). The advice in the RPA may also be used to prepare for the reporting requirements of SARA section 55. The advice generated via this process will update and/or consolidate any existing advice regarding these populations of Fraser River Sockeye Salmon.

Typically, when an RPA is undertaken all 22 different elements are complied into one working paper for review to inform not only a listing decision under SARA, but subsequent recovery planning. For Fraser River Sockeye Salmon there will be three separate working papers, presented and reviewed together. The three working papers are as follows:

Objective

To provide up-to-date information, and associated uncertainties, to address the following elements:

Biology, Abundance, Distribution and Life History Parameters

Element 1: Summarize the biology of Fraser River Sockeye Salmon (10 populations).

Element 2:  Evaluate the recent species trajectory for abundance, distribution and number of populations.

Element 3: Estimate the current or recent life-history parameters for the 10 populations of Fraser River Sockeye Salmon.

Habitat and Residence Requirements

Element 4: Describe the habitat properties that Fraser River Sockeye Salmon populations need for successful completion of all life-history stages. Describe the function(s), feature(s), and attribute(s) of the habitat, and quantify by how much the biological function(s) that specific habitat feature(s) provides varies with the state or amount of habitat, including carrying capacity limits, if any.

Element 5: Provide information on the spatial extent of the areas for Fraser River Sockeye Salmon distribution (10 populations) that are likely to have these habitat properties.

Element 6: Quantify the presence and extent of spatial configuration constraints, if any, such as connectivity, barriers to access, etc.

Element 7: Evaluate to what extent the concept of residence applies to the species, and if so, describe the species’ residence.

Threats and Limiting Factors to the Survival and Recovery of Fraser River  Sockeye Salmon (10 populations)

Element 8: Assess and prioritize the threats to the survival and recovery of the 10 populations of Fraser River Sockeye Salmon.

Element 9: Identify the activities most likely to threaten (i.e., damage or destroy) the habitat properties identified in elements 4-5 and provide information on the extent and consequences of these activities.

Element 10: Assess any natural factors that will limit the survival and recovery of the 10 populations of Fraser River Sockeye Salmon.

Element 11: Discuss the potential ecological impacts of the threats identified in element 8 to the target species and other co-occurring species. List the possible benefits and disadvantages to the target species and other co-occurring species that may occur if the threats are abated. Identify existing monitoring efforts for the target species and other co-occurring species associated with each of the threats, and identify any knowledge gaps.

Recovery Targets

Element 12: Propose candidate abundance and distribution target(s) for recovery.

Element 13: Project expected population trajectories over a scientifically reasonable time frame (minimum of 10 years), and trajectories over time to the potential recovery target(s), given current Fraser River Sockeye Salmon population dynamics parameters.

Element 14: Provide advice on the degree to which supply of suitable habitat meets the demands of the species both at present and when the species reaches the potential recovery target(s) identified in element 12.

Element 15: Assess the probability that the potential recovery target(s) can be achieved under current rates of population dynamics parameters, and how that probability would vary with different mortality (especially lower) and productivity (especially higher) parameters.

Scenarios for Mitigation of Threats and Alternatives to Activities

Element 16: Develop an inventory of feasible mitigation measures and reasonable alternatives to the activities that are threats to the species and its habitat (as identified in elements 8 and 10).

Element 17: Develop an inventory of activities that could increase the productivity or survivorship parameters (as identified in elements 3 and 15).

Element 18: If current habitat supply may be insufficient to achieve recovery targets (see element 14), provide advice on the feasibility of restoring the habitat to higher values. Advice must be provided in the context of all available options for achieving abundance and distribution targets.

Element 19: Estimate the reduction in mortality rate expected by each of the mitigation measures or alternatives in element 16 and the increase in productivity or survivorship associated with each measure in element 17.

Element 20: Project expected population trajectory (and uncertainties) over a scientifically reasonable time frame and to the time of reaching recovery targets, given mortality rates and productivities associated with the specific measures identified for exploration in element 19. Include those that provide as high a probability of survivorship and recovery as possible for biologically realistic parameter values.

Element 21: Recommend parameter values for population productivity and starting mortality rates and, where necessary, specialized features of population models that would be required to allow exploration of additional scenarios as part of the assessment of economic, social, and cultural impacts in support of the listing process.

Allowable Harm Assessment

Element 22: Evaluate maximum human-induced mortality and habitat destruction that the species can sustain without jeopardizing its survival or recovery.

Expected Publications

Expected Participation

References

COSEWIC. 2017. COSEWIC Assessment and Status Report on the Sockeye Salmon (Oncorhynchus nerka) 24 Designatable Units in the Fraser River Drainage Basin in Canada 2017. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xi + 179 pp.

Notice

Participation to CSAS peer review meetings is by invitation only.

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