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7. Recovery

White sturgeon in Canada, comprised of six Nationally Significant Populations, were assessed as endangered by COSEWIC in 2003. In 2006 the Governor in Council listed four populations (Nechako River, Upper Fraser River, Upper Columbia River, and Kootenay River) under Schedule 1 of SARA, and declined to list two populations (Lower Fraser River and Mid Fraser River).  This document is a SARA-compliant recovery strategy for the four SARA-listed populations, and also provides information to support recovery of the lower and middle Fraser River populations (Appendix B). 

7.1 Recommended Approach / Scale for Recovery

This recovery strategy uses a modified single species approach (rather than an ecosystem approach) because it addresses a single taxonomic unit with multiple distinct populations.  Given the unique life history of white sturgeon and its use of large river habitats there may be limited opportunities for sharing resources with recovery efforts aimed at other species.  There are no apparent opportunities to combine such efforts across the whole range of white sturgeon, although general studies and recovery information from one area should inform efforts in other areas.  There may to be opportunities to combine efforts over smaller geographic ranges, and such opportunities should be sought wherever possible.

7.2 Recovery Goal

The recovery goal for white sturgeon is to ensure that each of the populations are sustainable throughout their natural range, are self-sustaining through natural reproduction, and to increase or restore opportunities for beneficial use, if and when feasible.

To achieve this goal, a series of population and distribution objectives and general activities have been identified, including specific recovery measures, research, and ongoing monitoring.  The objectives and timelines will be revisited as new information is collected and possible changes to priorities will be evaluated.  Objectives and activities are presented below for SARA-listed populations and in Appendix B for non-SARA-listed populations.

7.3 Recovery Feasibility

As part of the SARA process, the competent minister must determine the biological and technical feasibility of recovery for each species at risk.  To help standardize these determinations, four directives are posed and answered here for the SARA-listed populations of white sturgeon (Draft Policy on the Feasibility of Recovery, Species at Risk Act Policy. January 2005).  It is important to note that there may be substantial challenges in meeting these directives and these challenges are further discussed below, where applicable.

7.3.1 Upper Fraser River Population

  • Individuals of the wildlife species that are capable of reproduction are available now or in the foreseeable future to sustain the population or improve its abundance.

The upper Fraser population is currently self-sustaining at or near its historic abundance. However, the natural population size is small (185 mature fish), and consequently, its long-term viability remains a concern.

  • Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.

The extent of suitable habitat for the upper Fraser population is at or near historic levels.

  • The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.

The Upper Fraser population exists entirely within Canada and is not currently threatened by human activities.

  • Recovery techniques exist to achieve the recovery goal or could quickly be developed.

Recovery of the upper Fraser population does not require special techniques, but rather, effective management of future threats to maintain abundance and habitat. Long-term viability might be enhanced by increasing the genetically effective population size by artificially promoting an appropriate level of immigration (gene flow) from other, more diverse populations.

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7.3.2 Nechako, Columbia, and Kootenay River Populations

Recovery feasibility for the dam-affected populations in the Nechako, Columbia, and Kootenay rivers depend primarily on whether prolonged failures in natural recruitment can be reversed. Accordingly, even though some differences exist between these populations they are considered together, due to their many similarities and for brevity.  Directives 2 through 4 pose significant challenges, since they depend on outcomes of ongoing research programs. 

  • Individuals of the wildlife species that are capable of reproduction are available now or in the foreseeable future to sustain the population or improve its abundance.

Each population still comprises enough mature individuals to become self-supporting given favourable conditions for natural recruitment. In the meantime, conservation aquaculture programs have been initiated in each population to ensure that adequate numbers will be available for the foreseeable future.

  • Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.

Present habitat is not adequate to support sufficient survival through early life history stages (egg, yolk sac larvae, and larvae) for the Kootenay, Columbia, and Nechako river populations.  It is possible that conditions can be made more suitable through habitat management or restoration efforts.  For the Kootenay River, spawning habitat is in the U.S. and Canadian recovery efforts are limited for restoring this habitat.  Therefore, restoration of Kootenay River spawning habitats requires coordinated efforts between Canada and the U.S.

  • The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.

Based on current hypotheses and evidence, mitigating threats may be feasible.  However, proposed mechanisms leading to recruitment failure are still being studied and will dictate the mitigation measures required for reducing threats.  For example, water management for power production and flood control is considered a primary threat to the Kootenay, Columbia, and Nechako River populations.  On the Columbia River the Columbia River Treaty regulates overall water management for both the U.S. and Canada, whereas on the Nechako River flows are controlled by provincial and federal agreements within Canada.  On the Kootenay River, water is also managed under the International Joint Commission between Canada and the U.S. Managing these and other threats will require working cooperatively with stakeholders in both Canada and the U.S.  The feasibility of mitigation options is dependent upon clarifying the primary mechanisms of recruitment failure to ensure that options are focused, efficient, and as effective as possible.

  • Recovery techniques exist to achieve the recovery goal or could quickly be developed.

Conservation aquaculture has been initiated for the Kootenay and Columbia River populations, and is currently being initiated for the Nechako River population, to help avoid extirpation until natural recruitment can be restored. Research is continuing to identify the factors limiting natural recruitment, and to develop appropriate methods for restoring it.  Examination of habitat restoration measures is underway in the Nechako, Columbia and Kootenay rivers; however, success of these efforts has not yet been demonstrated.

Currently, white sturgeon are seriously imperilled through much of their natural range.  Given their very long generation time and the enormity of some of the threats, it is likely that white sturgeon will remain at risk for some time.  Recovery actions for all populations will be aimed at maintaining and enhancing current habitat conditions, monitoring populations and specific threats, and undertaking necessary research tasks.  With the support of governments, First Nations, industry, user groups and the general public, recovery is deemed to be technically and biologically feasible.  With the transboundary nature of Kootenay River and Columbia River populations, cooperation between Canada and the U.S. is critically important. 

7.4 Population and Distribution Objectives

The population and distribution objectives below have been reviewed in the DFO Recovery Potential Assessment for White Sturgeon (Wood et al. 2007), and were modified slightly relative to earlier drafts of the recovery strategy. The only population objective that is directly applicable for the Upper Fraser population is objective one, since the population is thought to be at or near historic levels.  All population and distribution objectives are applicable for the other three SARA-listed populations. 

  1. Prevent extirpation of white sturgeon in each of the four identified populations by preventing net loss of reproductive potential.
  2. Initiate, within 5 years, pilot studies towards restoration of natural recruitment for each population that is affected by dams. Within 10 years, identify methods for each population that, if and when implemented, have a high likelihood of restoring recruitment to a level sufficient to achieve the other recovery measures listed herein.
  3. Reach or exceed all of the following population and distribution targets for survival or recovery within 50 years:
    1. 1,000 mature individuals in an approximately 1:1 sex ratio at maturity;
    2. distribution over the natural range, with the exception of Duncan Reservoir, Slocan Lake, the lower Kootenay River between Corra Linn and Brilliant Dams, and the Columbia River upstream of REV6; and,
    3. ongoing natural recruitment sufficient to meet all other targets.
  4. Reach or exceed population and distribution targets for beneficial use within specified timeframes.  As success is achieved in meeting the biological recovery targets, the beneficial use targets and timelines will be established and adjusted.  Such targets may vary among populations.

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7.4.1 Population Objectives Rationale

This section provides a more detailed discussion of population recovery targets in general and the rationale for the white sturgeon targets provided here.  The rationale and feasibility of these targets have been reviewed in detail in the DFO Recovery Potential Assessment for White Sturgeon (Wood et al. 2007).

The ultimate performance measure of any conservation program is long-term viability of a species.  The recovery strategy follows McElhany et al. (2000) in defining a viable population as one “that has a negligible risk of extinction due to threats from demographic variation (random or directional), local environmental variation, and genetic diversity changes (random or directional) over a 100-year time frame.”  Viability over longer timeframes is a laudable conservation goal, but one that is more logically part of general species management than recovery efforts per se, as long as recovery goals and management do not conflict.  The role of recovery efforts is to attain sufficient viability beyond which general species management can take over.

In assessing viability under the above definition, McElhany et al. (2000) suggest that it is necessary to consider abundance, population growth rate, population structure, and population diversity, and note that the values of these four parameters would be lower or less functional in an endangered population than in a viable population.

7.4.2 Population Objectives

7.4.2.1 Abundance

 Abundance is a key component of population viability, because all else being equal, small populations are at greater risk of extinction than large ones.  Several processes affect population dynamics differently in small populations (McElhany et al. 2000).  These processes include density-dependence, environmental variation, genetic processes, demographic stochasticity, ecological feedback and catastrophes.  McElhany et al. (2000)7 suggest that, to be viable, a population’s abundance must be large enough to satisfy the following criteria:

  • a high probability of surviving historic and expected future environmental variation;
  • resilience to environmental and anthropogenic perturbation; and,
  • maintenance of genetic diversity over the long-term.

In setting abundance targets for conservation one must consider external threats to the population, and inherent causes of population vulnerability.  External threats tend to affect mean vital rates (differences in vital rates across different years or seasons) and carrying capacity.  For example, mean fecundity or survival may be reduced by pollution, carrying capacity may be low due to habitat destruction, or harvest may affect the abundance of mature individuals.  These factors are clearly important and must be addressed to meet conservation targets of threatened and endangered species.  Various threats to white sturgeon are discussed in Section 4 (Threats)and mitigation strategies are presented in Section 7.5 (Research and Management Activities Needed to Meet Population and Distribution Objectives).  However, factors affecting temporal variability in vital rates must also be considered when setting population targets for long-term viability.  Both natural and threatened populations face temporal variability in vital rates, but such variability is generally a greater concern at low abundance.  Some years (and individuals, habitats, etc.) tend to be better than others and this can have a substantial influence on population trajectories and overall population recovery probabilities.

There are multiple causes of temporal variability in vital rates, but they fall into three categories: demographic, environmental and genetic stochasticity.  Demographic stochasticity is temporal variation in population growth driven by chance variation in the fates of individuals within years (Morris and Doak 2002).  The effects of demographic stochasticity are strongly dependent on population size, and become a concern as abundance declines below several hundred spawners.

Environmental stochasticity can be defined as among-year variation in vital rates caused by changes in environmental factors.  Population viability analyses (PVAs) tend to focus on effects of environmental stochasticity on survival and reproduction rates, and population-level processes, such as density-dependence, because these are the main sources of temporal variability in population vulnerability over short and medium timeframes.  Special cases of environmental stochasticity include long-term trends in environmental factors (e.g., climate change), and bonanzas and catastrophes (i.e., especially good or especially bad years that are outside the normal range of variation).  Population targets to account for environmental stochasticity are invariably greater than and therefore supersede those for demographic stochasticity, meaning the latter can be essentially ignored if a target properly accommodates environmental stochasticity.

Random genetic changes can accumulate in small populations and further increase population vulnerability.  Inbreeding increases via genetic drift at a rate that is inversely proportional to 2Ne, where Ne is the number of breeders in an idealized population of constant size with no immigration, no natural selection, discrete non-overlapping generations and Poisson distributed variance in among-individual reproductive rates.  To assess the magnitude of genetic effects in non-ideal populations, census population size is converted to the corresponding genetically effective population size (Ne) -- the size of an idealized population that would respond genetically in the same way.  To constrain random genetic changes within acceptable levels, an early rule of thumb was the “50:500” rule, which stated that Ne > 50 individuals will eliminate short-term risks from inbreeding, and Ne > 500 individuals will maintain heterozygosity over the long-term.  More recent evidence indicates that these thresholds may have to be considerably higher (Ne of at least 1,000) to ensure evolutionary potential over the long-term (Lynch and Lande 1998, Allendorf and Ryman 2002).  Converting Ne to N can be done directly, or can be based on published Ne to N ratios, which average around 0.1 for a wide range of wildlife species (Frankham 1995).  A population target based on Ne = 1,000 should therefore be around 10,000 reproductively mature individuals.

Since there is scarce data on population-specific vital rates of white sturgeon it is useful to consider some “rules of thumb” that have been developed in the literature.  In a review of population variability in relation to population persistence, Thomas (1990) concluded that a population of “1,000 is adequate for species of normal variability, and 10,000 should permit medium- to long-term persistence of most of the most variable birds and mammals.”  In a more formal review of PVA results, Reed et al. (2003) found that minimum viable populations (MVPs) for vertebrates tend to be on the order of 1,000 to 10,000 breeding pairs in single closed populations.  They suggest a population target of 7,000 adults is appropriate for long-term persistence.  There are often good reasons to extend recovery targets beyond the MVP.  For example, to account for restricted geographic distribution or to accommodate additional safety factors to offset threats.

In setting population targets for white sturgeon effects of environmental stochasticity were focused on; it is believed that this is an adequate interim target for rebuilding over at least the next 10 years.  There is currently insufficient information to conduct a full PVA for any of the white sturgeon populations in Canada. As new information becomes available these targets may be updated.  The targets are considered sufficient for ongoing recovery planning of white sturgeon over the next 10 years.

An interim abundance target of 1,000 mature individuals (25 years of age or older) has been established  for each SARA-listed population of white sturgeon, with the exception of the Upper Fraser population.  Based on the available scientific literature, this target should be sufficient to buffer variability due to demographic and environmental stochasticity (but not catastrophes), and to maintain genetic diversity over the next 100 years.  The abundance target of 1,000 mature fish is considered interim because it may be less than needed to maintain genetic variation indefinitely. Importantly, sturgeon have a natural buffer against the loss of genetic material due to unique life history traits of longevity, late maturation, intermittent spawning, and spawning site fidelity combined with the polyploidy nature of their genome (Drauch Schreier et al. 2011). These traits, combined with the relatively recent declines in recruitment (one generation), allow for the continued refinement of hatchery protocols to ensure genetic diversity of the wild population is captured and maintained in the first few decades recovery is underway for white sturgeon. The small Upper Fraser population is believed to be maintaining itself at historic levels of just under 200 mature fish, and is likely constrained by natural limitations on the extent of suitable habitat. Accordingly, the abundance goal for this population is to maintain the current abundance of mature fish, meaning only the first population objective applies. Genetic concerns about the long-term viability of such a small population could be addressed in other ways, for example, by creating gene flow with another large population through artificial transfer. However, development of specific guidelines for incorporating genetic data into management decisions focused on population recovery is an important consideration (Welsh et al. 2010).

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7.4.2.2 Population Growth Rate

Population growth rate is a measure of how well a population is performing, and clearly links to population abundance.  McElhany et al. (2000) suggest that a salmonid population must meet the following population growth criteria to be viable:

  1. natural productivity (i.e., in the absence of hatchery supplementation) should be sufficient to maintain abundance above the viability threshold,
  2. the population should not exhibit sustained declines in abundance,
  3. the population should not exhibit trends or shifts in traits that portend declines in population growth rate, and
  4. population status evaluations should take into account uncertainty in estimates of population growth rate and productivity-related parameters.

The following growth rate targets have been established for all SARA-listed populations of white sturgeon:

  • ongoing natural recruitment, supplemented by conservation aquaculture where needed; and,
  • increasing trend in abundance for all populations that are below the abundance target.

The long-term objective is to have all populations self-supporting, but conservation aquaculture is required in some instances as an interim measure.  Minimum recruitment targets, to meet the abundance target of 1000 mature individuals, are specified by a simple population model that assumes 20% survival in the first year of release (currently 1 to 2 years of age) and 92% survival for subsequent ages (Golder Associates Ltd. 2005a).  Under these assumptions a minimum of approximately 4,000 individuals are required to recruit to the 1 year old age class each year.  At this rate the abundance target of 1000 mature fish would be reached after 40 years.  Increased recruitment or hatchery releases would allow a population to reach the abundance target sooner, but it should be remembered that a lower limit of 25 years is imposed by the late maturation of this species.

7.4.2.3 Population Structure

White sturgeon in Canada occur as six distinct populations (see Section 2.4: Distribution).  The populations are geographically separate and genetically distinct; the genetic separation indicating they have had little or no effective mixing for a considerable period of time (Smith et al. 2002).  Differences among the populations indicate that it is reasonable to consider each population distinct and manage for viability in each.  This rationale was supported by the 2003 COSEWIC status report, which acknowledged the six populations, and the 2006 SARA listing decision, which considered each population separately.  Recent evidence suggests that the designated Columbia River population might comprise two or more reproductively isolated populations (Nelson and McAdam 2012), though Drauch Schreier et al. (2013) found no detectable genetic differences. Given this uncertainty in current understanding, it is not possible to attempt to delineate finer populations in this recovery planning document. The 2012 COSEWIC reassessment of white sturgeon delineated the species into four Desginatable Units, following recent guidelines (COSEWIC 2011), though current species management and recovery efforts remain focused at the population level.

The following targets for population structure have been established for all SARA-listed populations of white sturgeon:

  • natural sex ratio (currently defined as 1:1), and
  • natural age structure.

Age structure can be defined using the same model noted in the previous paragraph.  Under this scenario, the stable age distribution is highly skewed, with the majority of individuals in immature age classes, and approximately 1000 individuals 25 years and older.

7.4.3 Distribution Objective Rationale

McElhany et al. (2000) note that long-term viability of a species hinges in part on its ability to respond to changes in the environment, which in turn is dependent on maintenance of sufficient phenotypic and genotypic diversity.  Population diversity can be maintained by ensuring a sufficient spatial and temporal array of habitat types, that dispersal among them is not altered, and general processes that give rise to diversity are maintained.  Based in large part on the need to maintain population diversity, the distribution objective focuses over most of the natural range of white sturgeon in Canada.

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7.4.3.1 Distribution Objective

The target established for species diversity is distribution across the species’ natural range.  Duncan Reservoir, Slocan Lake, and Revelstoke Reservoir are excluded from this distribution because recovery of populations in these relatively small waterbodies has been deemed infeasible, and the Kinbasket Reservoir is excluded because there is insufficient data to recommend whether or not the establishment of a self-sustaining population in that area is feasible or recommended.  At this time there is insufficient information on this topic to propose meaningful targets, beyond this distribution target.

7.5 Research and Management Activities Needed to Meet Population and Distribution Objectives

Table 5.  Recommended activities and actions to meet population and distribution objectives for SARA-listed populations. The table has four columns read left to right: Priority, Strategy, Activities, and Performance Measure. A footnote on “Priority” states the following: Priority has been assigned based on professional judgement of the National Recovery Team into one of three groups, from highest to lowest: necessary, primary, secondary. A footnote on “Performance Measure” states the following: As white sturgeon is a slow-growing, late-maturing, and long-lived species, performance measures were developed that could be measured repeatedly throughout the recovery process. Therefore, performance measures plot the progress toward meeting the stated objectives.  The performance measures are presented here as questions, the answers to which can be plotted in time to monitor progress.

Directly below the column headings are seven rows. The contents are as follows read from left to right:

Row 1: Necessary, Meet or exceed recovery population targets within specified timeframe,
1. Set up conservation aquaculture where needed, 2. Monitor population trends, 3. Establish parameters for beneficial use, Have targets been achieved? Row 2: Necessary, Protect critical habitats, 1. Identify habitat requirements for all life stages, 2. Define critical habitat (including related ecological processes), 3. Identify critical habitats for designation and protection, 4. Protect, maintain and enhance critical habitat for white sturgeon, 5. Ensure habitat diversity, connectivity & productivity, 6. Work cooperatively to develop plans to protect habitat, Has critical habitat been identified? Row 3: Necessary, Restore natural recruitment, 1. Determine accuracy of recruitment index time series, 2. Identify temporal correlations between significant recruitment shifts (peaks or drops) and environmental changes, 3. Examine potential mechanism of recruitment effect, 4. Under take meso-scale field trials, 5. Undertake larger scale field trials, 6. Design and implement longer term restoration program, 7. Determine habitat requirements for dam-affected population enhancement or recovery, 8. Initiate, within 5 years, pilot studies towards restoration of natural recruitment for each population that is affected by dams, 9. Within 10 years, identify methods for each population that, if and when implemented, can restore recruitment to a level sufficient to achieve the other recovery measures listed herein, Have experimental trials been initiated to restore natural recruitment? Have experimental results shown that natural recruitment can be restored to necessary levels? Has recruitment been restored? Row 4: Necessary, Clarify and mitigate threats, 1. Clarify the following threats and their relative risks: a. fishing; b. pollution; c. predation; 2. Clarify threats to: a. food supply; and, b. habitat (including effects of flow regulation) 3. Undertake specific actions to address risks: a. protect, maintain and enhance critical habitat; b. address illegal harvest; c. minimize bycatch and mitigate impacts from fisheries through regulation and best practices; d. limit and address pollutant discharges and contaminant loading, especially adjacent to important or critical habitats; e. protect, maintain and enhance water quality; f. mitigate interaction of white sturgeon with industrial structures and activities; g. manage risks from conservation hatchery introductions; and, h. better understand, maintain and enhance food availability for all life stages of each population. 4. Monitor threat indicators and population trends. 5. Work cooperatively to develop plans to mitigate threats to white sturgeon, Have the most serious threats been defined? Have these threats been sufficiently mitigated? Row 5: Primary, Address information gaps that inhibit conservation of white sturgeon, 1. Address basic biological data gaps (see Section 7: Knowledge Gaps and Appendix A: Studies to Address Knowledge Gaps for list of priorities), Have key information gaps been filled? Row 6: Primary, Increase stakeholder and general public awareness of white sturgeon and its conservation needs, 1. Maintain and where possible increase awareness and stewardship of white sturgeon throughout its natural range 2. Engage in effective public education of the species and its conservation needs 3. Support learning and communication across all working groups 4. Ensure participation from community and technical experts, Has general awareness of sturgeon conservation been increased? Row 7: Secondary, Maintain and where necessary restore ecosystem functions relevant to white sturgeon, 1. Incorporate the needs of healthy white sturgeon populations into the management of white sturgeon prey species, especially salmon and resident sportfish. 2. Accommodate other species’ needs during recovery of white sturgeon 3. Closely manage non-native predatory fish species 4. Dialogue with regulatory agencies that have influence or jurisdiction over white sturgeon prey species, Is the ecosystem “healthy” for white sturgeon?

Table 5.  Recommended activities and actions to meet population and distribution objectives for SARA-listed populations.
Priority8StrategyActivitiesPerformance
Measure 9
NecessaryMeet or exceed recovery population targets within specified timeframe.
  1. Set up conservation aquaculture where needed.
  2. Monitor population trends.
  3. Establish parameters for beneficial use.
Have targets been achieved?
NecessaryProtect critical habitats
  1. Identify habitat requirements for all life stages.
  2. Define critical habitat (including related ecological processes).
  3. Identify critical habitats for designation and protection.
  4. Protect, maintain and enhance critical habitat for white sturgeon.
  5. Ensure habitat diversity, connectivity & productivity.
  6. Work cooperatively to develop plans to protect habitat.
Has critical habitat been identified?
NecessaryRestore natural recruitment
  1. Determine accuracy of recruitment index time series.
  2. Identify temporal correlations between significant recruitment shifts (peaks or drops) and environmental changes.
  3. Examine potential mechanism of recruitment effect.
  4. Under take meso-scale field trials.
  5. Undertake larger scale field trials.
  6. Design and implement longer term restoration program.
  7. Determine habitat requirements for dam-affected population enhancement or recovery.
  8. Initiate, within 5 years, pilot studies towards restoration of natural recruitment for each population that is affected by dams.
  9. Within 10 years, identify methods for each population that, if and when implemented, can restore recruitment to a level sufficient to achieve the other recovery measures listed herein.
Have experimental trials been initiated to restore natural recruitment?
Have experimental results shown that natural recruitment can be restored to necessary levels?
Has recruitment been restored in dam-affected populations?
NecessaryClarify and mitigate threats
  1. Clarify the following threats and their relative risks:
    1. fishing;
    2. pollution;
    3. predation;
  2. Clarify threats to:
    1. food supply; and,
    2. habitat (including effects of flow regulation)
  3. Undertake specific actions to address risks:
    1. protect, maintain and enhance critical habitat;
    2. address illegal harvest;
    3. minimize bycatch and mitigate impacts from fisheries through regulation and best practices;
    4. limit and address pollutant discharges and contaminant loading, especially adjacent to important or critical habitats;
    5. protect, maintain and enhance water quality;
    6. mitigate interaction of white sturgeon with industrial structures and activities;
    7. manage risks from conservation hatchery introductions; and,
    8. better understand, maintain and enhance food availability for all life stages of each population.
  4. Monitor threat indicators and population trends.
  5. Work cooperatively to develop plans to mitigate threats to white sturgeon.
Have the most serious threats been defined?
Have these threats been sufficiently mitigated?
PrimaryAddress information gaps that inhibit conservation of white sturgeon.
  1. Address basic biological data gaps (see Section 6: Knowledge Gaps and Appendix A: Studies to Address Knowledge Gaps for list of priorities).
Have key information gaps been filled?
PrimaryIncrease stakeholder and general public awareness of white sturgeon and its conservation needs.
  1. Maintain and where possible increase awareness and stewardship of white sturgeon throughout its natural range
  2. Engage in effective public education of the species and its conservation needs
  3. Support learning and communication across all working groups
  4. Ensure participation from community and technical experts
Has general awareness of sturgeon conservation been increased?
SecondaryMaintain and where necessary restore ecosystem functions relevant to white sturgeon
  1. Incorporate the needs of healthy white sturgeon populations into the management of white sturgeon prey species, especially salmon and resident sportfish.
  2. Accommodate other species’ needs during recovery of white sturgeon
  3. Closely manage non-native predatory fish species
  4. Dialogue with regulatory agencies that have influence or jurisdiction over white sturgeon prey species.
Is the ecosystem “healthy” for white sturgeon?

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8. Critical habitat

Critical habitat is identified for the four SARA-listed white sturgeon populations to the extent possible, using the best available information. The critical habitat identified describes the geospatial areas that contain the biophysical functions, features, and attributes necessary for survival or recovery of the species. Activities likely to destroy these habitats, data gaps and data sources are also presented.  Maps of critical habitat areas are provided for each watershed, with each map indicating critical habitat boundaries. Corresponding geographic coordinates and river kilometers (where applicable) are also identified for critical habitat areas. The Schedule of Studies outlines the research required to identify additional critical habitats (where applicable), acquire more information about the critical habitat identified or refine the description of existing critical habitats in order to support its protection.

The critical habitat identified in this recovery strategy, when combined with functioning recruitment in each population, is thought to be sufficient to achieve the species’ population and distribution objectives. Although there remains some uncertainty regarding factors such as the precise timing and functionality of some specific critical habitats identified here, the greater uncertainty is the cause of persistent recruitment failure and identification of a feasible means of restoration.  This focus is reflected in the knowledge gaps identified in the recovery strategy, which provides a guide to future studies with a strong focus on recruitment failure diagnosis and restoration.  As a result, studies identified here emphasize those which are designed to understand habitat functionality and recruitment restoration within critical habitats. While studies of the species biology and movement may provide further information on definition of particular critical habitats, such studies should not supersede investigations of recruitment failure and its restoration because doing so may not be in the best interest of the species.

8.1 Information and Methods used to Identify Critical Habitat

Critical habitat is defined in SARA as “…the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species’ critical habitat in a recovery strategy or in an action plan for the species.” [s. 2(1)]

SARA defines habitat for aquatic species at risk as “… spawning grounds and nursery, rearing, food supply, migration and any other areas on which aquatic species depend directly or indirectly in order to carry out their life processes, or areas where aquatic species formerly occurred and have the potential to be reintroduced.” [s. 2(1)]

A reasonable approach to determine critical habitat for a species at risk is to consider the amount and type of habitat required for the species to meet and maintain its recovery target, an approach supported by existing guidance including recent DFO guidance documents (Fisheries and Oceans Canada 2012).  As all SARA-listed white sturgeon populations are at a very low abundance and hence a quantitative relationship between habitat and population size would not be possible, areas of present high use are identified as critical habitat at current population levels.  As populations expand toward target recovery levels additional critical habitats may need to be added to those identified here. 

The priority for recovery efforts should focus on resolving recruitment failure in each of the dam-affected populations.  The ongoing research, particularly to understand the causes of recruitment failure, will benefit critical habitat maintenance and restoration needs which in turn will support critical habitat protection. Identification of additional critical habitats, or further clarification of critical habitat functions, features or attributes is a task that will be addressed with future studies as recovery efforts proceed.

To the extent possible, critical habitat identification was based on habitat associations developed from detailed empirical work.  Where detailed studies were lacking or inconclusive, expert opinion and a precautionary approach was used, as described in SARA and DFO guidance documents (e.g., Fisheries and Oceans Canada 2012).  The precautionary approach recognizes that, where there is a risk of serious or irreversible harm, cost-effective measures to prevent the reduction or loss of a species should not be postponed for a lack of full scientific certainty.  This approach allowed critical habitat to be identified for less-well studied populations such as the Upper Fraser River and for early life stages in areas currently afflicted by recruitment failure.

Information related to the degree of habitat use (high, medium, low) and the overall level of certainty (confirmed use, suspected, unknown) were both categorized, based on abundance and frequency of use.  In assessing habitat use the relative size of the population or group of fish using the area was considered.  Since different expert groups have assessed habitat use for each population using their own understanding of these terms, caution is warranted when making comparisons between watersheds.

The following guidance was used to identify critical habitats for white sturgeon:

  • DFO Operational Guidelines for the Identification of Critical Habitat for Aquatic Species at Risk (Fisheries and Oceans Canada 2012) outline the process to identify the geographic location of critical habitat and the biophysical features of that area, and their attributes, that support functions necessary for the species at risk to carry out the life processes necessary for its survival or recovery.
    • The geographic or biophysical features of critical habitat can include: riparian vegetation; areas not presently occupied, or degraded, but required for recovery; the availability of food supply, water depth or flow, physical structures or substrate (i.e., for cover, spawning, rearing and forage activities); etc. 
  • The DFO Science document, Documenting Habitat Use of Species at Risk and Quantifying Habitat Quality (Fisheries and Oceans Canada 2007), suggests a series of guiding principles to consider when trying to determine critical habitat for a species at risk.
    • Provide functional descriptions of the features or attributes that a species’ aquatic habitat must have to allow successful completion of all life history stages.
    • Provide information on the spatial extent of the areas that are likely to have the necessary features or attributes.
    • Provide advice on how much habitat of various qualities / properties exists at present.
    • 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 biologically based recovery targets for abundance, range, and number of populations.
    • Provide advice on the extent to which various threats can alter the quality and/or quantity of habitat that is available.
    • Provide advice on feasibility of restoring habitat to higher values, if supply may not meet demand by the time recovery targets would be reached. 

The guidance outlined above was considered in order to identify, to the extent possible, based on the best available information, the habitat necessary for survival or recovery of white sturgeon, the features of that habitat, the life stages it supports and any threats to that habitat.

On June 23, 2009 a meeting was held by DFO’s internal scientific advisory body - the Pacific Science Advisory Review Committee (PSARC).  In attendance were BC MOE staff and invited external white sturgeon experts, First Nations, Environmental Non-Government Organizations (ENGOs), and industry stakeholders that could provide relevant technical advice on critical habitat designations. As the responsible agency, DFO assessed the information and the opinions it received during the PSARC meeting and made a precautionary identification of white sturgeon critical habitats; further information is discussed in the Canadian Science Advisory Secretariat Research Document titled Scientific Information in Support of Identifying Critical Habitat for SARA listed White Sturgeon Populations in Canada: Nechako, Columbia, Kootenay and Upper Fraser (2009) (Hatfield et al. 2012).  The scientific information from the research document was used to identify critical habitat for white sturgeon in this recovery strategy10, as outlined in DFO’s operational guidance.  

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8.2 Identification of Critical Habitat

In the following sections, critical habitat for each population of white sturgeon is described, to the extent possible, including the geographic locations and biophysical functions, features and attributes of the critical habitat identified. 

8.2.1 Biophysical Functions, Features and Attributes

Critical habitat identification includes describing the biophysical functions, features, and attributes necessary to support survival or recovery of the species. A function is a characteristic of critical habitat that corresponds to a biological need or life process requirement of the species such as spawning, rearing, feeding and migration.  Every function is the result of a single or multiple features, which are physical components or conditions of the critical habitat such as riffles, pools, riparian habitat, etc.  Features describe how the habitat provides the critical function to meet the species needs and are always associated with a function.  Attributes provide information about a feature that explain how the feature supports the function necessary for the species life process, for example the attributes of a riffle feature that supports the function of rearing may include substrate size, velocity, water chemistry, prey species and temperature.

General information on life stages and biophysical functions, features and attributes for white sturgeon is provided in Section 2.3 (Life Stages)  and Section 3 (Description of Needs of the Species)  and more specific information for each population follows in tables 7 (Upper Fraser), 10 (Nechako), 14 (Upper Columbia – ALR) , 15 (Upper Columbia – Transboundary), and 17 (Kootenay).

These tables summarize the best available information of the functions, features and attributes for each life-stage of the white sturgeon (refer to Sections 2.3 and 3 for full references). Note that in tables 7, 10, 14, 15, and 17, not all attributes may be known or identified for given features that are identified as critical habitat and in some cases existing habitat attributes as described in these tables are not ideal for the current functions sturgeon use them for.  The areas described in tables 7, 10, 14, 15,and 17 are considered critical habitat for the species, even though some of the associated attributes described are currently outside of the range needed to support habitat functionality for the species. Ongoing studies related to the recruitment failure hypothesis, and studies outlined in the Schedule of Studies (Section 8.8), will provide further clarity to this section.

8.2.2 Geographic Identification of Critical Habitat

Maps of the identified critical habitat areas are provided for each specific population (sections 8.3-8.6). The locations of the critical habitat’s functions, features and attributes have been identified using the critical habitat parcel approach (CHPA). The CHPA is defined as when:

 Critical habitat is the exact area within the identified boundaries and it is understood that this area supports the functions and features necessary for the species’ survival or recovery.

The identified critical habitat areas contain the biophysical functions, features, and attributes necessary to achieve the species’ recovery goal and population and distribution objectives (Section 7), and to support survival or recovery of the species. For geographic coordinate points, their boundary represents the annual high water mark (Hatfield et al. 2012).

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6Although Duncan Reservoir, Slocan Lake, the lower Kootenay River between Corra Linn and Brialliant Dams, and Revelstoke Reservoir are within the historic range of white sturgeon, recovery of populations in these relatively small waterbodies has been deemed infeasible.  There is insufficient data on Kinbasket Reservoir to recommend whether or not the establishment of a self-sustaining population in that area is feasible or recommended. 

7 McElhany et al. (2000) were concerned explicitly with Pacific salmon (Oncorhynchus spp.) populations.  Their discussion provides much general guidance, but some of their criteria and definitions have been adjusted for this recovery strategy to remain relevant to the biology of white sturgeon.

8 Priority has been assigned based on professional judgement of the National Recovery Team into one of three groups, from highest to lowest: necessary, primary, secondary.

9 As white sturgeon is a slow-growing, late-maturing, and long-lived species, performance measures were developed that could be measured repeatedly throughout the recovery process. Therefore, performance measures plot the progress toward meeting the stated objectives.  The performance measures are presented here as questions, the answers to which can be plotted in time to monitor progress.

10 Two critical habitat area boundaries in the Columbia River (Robson Reach and Brilliant Tailrace) were amended, through consensus of the National Recovery Team, in February 2013 and March 2014, respectively.