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The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessed Purple Wartyback (PWB, Cyclonaias tuberculata) as Threatened in Canada. Here population modelling is presented to assess the impacts of harm, determine abundance and habitat recovery targets, and conduct long-term projections of population recovery in support of a recovery potential assessment (RPA). The model incorporated parameter uncertainty, environmental stochasticity, and density-dependence into population projections. The analysis demonstrated that PWB populations were most sensitive to perturbations to adult survival under most circumstances. As population growth rate (λ) increased the sensitivity of juvenile survival to perturbation increased and surpassed adult survival sensitivity when λ > 1.2. Estimates of the level of harm that would reduce population growth rate to 1 were estimated for populations in the Sydenham and Thames rivers. Population viability analysis was used to identify potential recovery targets. Demographic sustainability, (i.e., a self-sustaining population over 250 years) can be achieved with population sizes of ~2,800 (CI: 1,900-4,000) adults. It was estimated that populations of minimum viable population (MVP) size would require 623.3 m² (CI: 251.9-1,396.9) and 2,900 m² (CI: 301.5-17,166.3) in the Sydenham and Thames rivers respectively. Therefore, there is sufficient habitat to support PWB populations in both systems. [ABSTRACT FROM AUTHOR]

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has assessed Lake Chubsucker (Erimyzon sucetta) in Canada as Endangered. Population modelling is presented to assess the impacts of harm and determine abundance and habitat recovery targets in support of a recovery potential assessment (RPA). This analysis demonstrated that Lake Chubsucker were most sensitive to perturbations to adult survival. Population viability analysis was used to identify potential recovery targets. Demographic sustainability (i.e., a selfsustaining population over the long term) can be achieved with population sizes of ~ 33,600 individuals of age-1 and older with a catastrophe frequency of 15% per generation and desired persistence probability of 99% over 100 years. Such a population would require 0.41 km2 of lacustrine habitat or 0.12 km² of riverine habitat. [ABSTRACT FROM AUTHOR]

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has assessed the Lake Sturgeon (Acipenser fulvescens) across 4 designatable units (DU) as Endangered in DUs 1 and 2, Threatened in DU 4 and Special Concern in DU 3. Here population modelling, using a female only matrix model, is presented to determine population-based recovery targets, assess the impact of anthropogenic harm, and conduct long-term projections of population recovery in support of a recovery potential assessment (RPA) for Lake Sturgeon populations in Canada. Simulations were conducted for populations with 5 distinct growth patterns characterized by their rate of growth and maximum size to incorporate the diversity in life-history characteristics expected across Canada. Populations with slower growth were estimated to have greater adult survival rates (~ 95%) and resultantly greater generation times (> 50 years) relative to faster growth sturgeon populations (~ 92% and ~ 30 years). Patterns in elasticity estimates were similar across growth types. Under most scenarios population growth rate (λ) was most sensitive to changes to survival of young adults (age 26-62). The exception to this was populations experiencing continued reduced adult survival (leading to population decline); which were most sensitive to changes to the survival rate of older juveniles (age 13-25). This indicates the importance of understanding the current stresses and the age distribution of a population when considering harm or determining what recovery actions to take. To achieve demographic sustainability, (i.e., a self-sustaining population over the long term) under conditions with a catastrophe probability of 0.15/generation and a quasi-extinction threshold of 25 adult females at a 1% probability of extinction over 250 years, population sizes ranging from 1,255-4,840 adult females were required. Populations with faster growth required larger population sizes (~ 5,000) to achieve demographic sustainability as their lower generation times resulted in increased frequency of catastrophic population decline (a 50% decline every 200-250 years compared to 340-360 years for slow growth Lake Sturgeon). MVP population size required between 550->13,000 ha of lake habitat and 162-3,800 ha of river habitat (inclusive of both sexes and all age classes). Recovery times are variable, dependent on initial population size and the rate of population growth. [ABSTRACT FROM AUTHOR]

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has assessed the Great Lakes-Upper St. Lawrence populations (DU 5) of Pygmy Whitefish (PWF, Prosopium coulterii) in Canada as Threatened. Here population modelling is presented to assess the impacts of harm and determine abundance and habitat recovery targets in support of a recovery potential assessment (RPA). This analysis demonstrated that PWF populations were most sensitive to perturbations to juvenile survival. Population viability analysis was used to identify potential recovery targets. Demographic sustainability, (i.e., a self-sustaining population over the long term) can be achieved with adult female population sizes of ~ 430 to 4,000 or ~ 8.4 to 75 kg of whole population age-1+ biomass depending on catastrophe frequency and desired persistence probability. The population would require up to ~ 21 km² of habitat. [ABSTRACT FROM AUTHOR]

Pygmy Whitefish (PWF, Prosopium coulterii) in Lake Superior have been assessed as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). In support of a recovery potential assessment, long-term bottom trawl survey data are used to assess trends in density, identify important habitat characteristics, and estimate population size. This analysis makes use of a statistical approach, R-INLA, that can accommodate complex covariance structures in spatial-temporal data. Trends from the spatial-temporal model indicate that lake-wide PWF biomass (kg/ha) has been in decline since 2013 (~ 1 generation) and may be at the lowest mean biomass since the nearshore bottom trawl survey was expanded to include Canadian locations. Prior to 2013, PWF biomass appeared to follow periodic fluctuations suggesting the population could rebound following successful recruitment. Depth was the only important habitat characteristic, fitted as a quadratic term, in predicting occurrence or biomass. PWF were more likely to inhabit depths between ~ 50 and 110 m, preferring 75 to 90 m, with maximum biomass occurring between 80 and 95 m. Based on lake-wide spatial projections 2018 PWF biomass is estimated to be 68,707 kg (CI: 2,465 - 1,357,612) with 9,774 km2 (CI: 712 - 26,014) of suitable habitat. [ABSTRACT FROM AUTHOR]

Population assessments of fish species often rely on data from surveys with different objectives, such as measuring biodiversity or community dynamics. These surveys often contain spatial–temporal dependencies that can greatly influence conclusions drawn from analyses. Pygmy whitefish (PWF, Prosopium coulterii) populations in Lake Superior were recently assessed as Threatened by the Committee on the Status of Endangered Species in Canada, which motivated a thorough analysis of available data to improve our understanding of its population status. The US Geological Survey conducts annual bottom trawl surveys in Lake Superior that commonly capture PWF. We used these data (1989–2018) to model temporal trends in PWF biomass density and make lake-wide population projections. We used a Bayesian approach, integrated nested Laplace approximation (INLA), and compared the impact of including different random structures on model fit. Inclusion of spatial structure improved model fit and conclusions differed from models omitting random effects. PWF populations have experienced periodic fluctuations in biomass density since 1989, though 2018 may represent the lowest density in the 30-year time series. Lake-wide biomass was estimated to be 71.5 t. [ABSTRACT FROM AUTHOR]

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has assessed the Lake Opeongo species pair (DU 13 and 14) of Lake Whitefish (LWF, Coregonus clupeaformis) in Canada as Threatened. Population modelling is presented to assess the impacts of harm and determine abundance and habitat recovery targets in support of a recovery potential assessment (RPA). This analysis demonstrated that LWF populations of both DUs were most sensitive to perturbations to adult survival. Population viability analysis was used to identify potential recovery targets. Demographic sustainability (i.e., a self-sustaining population over the long term) can be achieved with adult female population sizes of ~450 to ~2,300 for the largebodied DU or ~1,300 to ~8,700 for the small-bodied DU depending on catastrophe frequency and desired persistence probability. Lake Opeongo has sufficient habitat for populations of both DUs. [ABSTRACT FROM AUTHOR]

Eastern sand darter ( Ammocrypta pellucida) is listed as Threatened under the Canadian Species at Risk Act. Little relevant biological information is available for most Canadian populations and only limited information is available for populations in the United States. To supplement the paucity of information, this study collected biological information on eastern sand darter during field surveys in 2006-2007 from 10 sites in the lower Thames River, Ontario, Canada. Collected data were used to estimate critical life history traits including: longevity, fecundity, clutch size and number, growth, survival, age-at-first-maturity and cohort age structure. Longevity was 3+ years, with age-at-first-maturity being 1+ for both sexes. Examination of egg sizes from preserved females in 2007 showed a bimodal distribution, suggesting two spawning occurrences of 71 eggs each. Quantitative comparison of lower Thames River biological information with a more southerly eastern sand darter population in the Little Muskingum River, Ohio, demonstrated little variation between the populations. Data comparisons suggest that localised environmental factors are affecting biological traits (growth), in particular water temperature that may be controlled by differences in riparian cover and/or groundwater input. [ABSTRACT FROM AUTHOR]

Effective conservation requires that species recovery measures are informed by rigorous scientific research. For imperilled freshwater fishes and mussels in Canada, numerous research gaps exist, in part owing to the need for specialized research methods. The Canadian Freshwater Species at Risk Research Network (SARNET) was formed and identified or implemented approaches to address current research gaps, including (1) captive experimental research populations, (2) nonlethal methods for estimating abundance and distribution, (3) nonlethal field methods to measure life-history parameters, (4) species distribution models informed by co-occurring species, (5) conservation physiology to inform habitat and threat science, (6) evidence syntheses to evaluate threats and recovery measures, (7) disease-transmission models to understand mussel–host relationships, (8) experimental mesocosms and manipulative experiments to evaluate key habitat stressors, (9) threat and hazard models for predictive applications, and (10) rigorous evaluation of surrogate species. Over a dozen threat- and recovery-focused SARNET research applications are summarized, demonstrating the value of a coordinated research program between academics and government to advance scientific research on, and to support the recovery of, imperilled freshwater species. [ABSTRACT FROM AUTHOR]

More than 15 years have passed since Canada's Species at Risk Act was enacted. To evaluate scientific progress in support of the Act, we identified research accomplishments up to 2017 for imperilled aquatic species in the Great Lakes – St. Lawrence River basin based on recovery documents and an expert survey, spanning 1182 activities across 68 research topics for 45 fish and mussel species. Greatest progress was observed for population ecology (38% of activities with major progress) and habitat science (28%), with comparably less progress on threats (mechanisms and impacts; 19%) and recovery (threat mitigation and reintroduction; 21%). As a result of lagging progress, threat and reintroduction topics were prioritized for a Canadian Freshwater Species at Risk Research Network (SARNET; 2017–2020), which focused on addressing key knowledge gaps with novel applications. This special issue outlines the SARNET projects, which span novel field, laboratory, and analytical activities. Continued research investment into novel and existing approaches is necessary to advance scientific achievements for fishes and mussels in support of the Species at Risk Act in Canada. [ABSTRACT FROM AUTHOR]

The use of translocations to recover populations requires a sufficiently large number of individuals from source populations, but removing too many individuals could lead to source population collapse. To understand the trade-off between the probabilities of source population extirpation and translocation success, matrix population models that incorporate Allee effects, density dependence, and demographic and environmental stochasticity were combined with a model that simulates removals from source populations. We apply these models to eastern sand darter (Ammocrypta pellucida; Species at Risk Act status: Threatened) translocation scenarios in Canada. The results suggest that translocations most often require source populations >20 000 individuals, as source population extirpation probability increased with the number and frequency of removals. Transport mortality or losses immediately following introduction further affected translocation success. Uncertainty around life-history parameters and the strength of Allee effects led to additional uncertainty about the required source population size. Although stochastic processes affected the probability of translocation success, factors such as stocking density and frequency can be controlled, and translocation may therefore be a viable strategy for eastern sand darter recovery, even when applying cautious thresholds to guard against uncertainty. [ABSTRACT FROM AUTHOR]

In 2012, Canada's Fisheries Act was amended. New fisheries protection provisions provide for the sustainability and ongoing productivity of commercial, recreational, and Aboriginal fisheries. These provisions replace previous provisions that focused on fish habitats, and concerns have been expressed that the amended Act has lowered aquatic habitat protection. The science framework developed for implementation of the new provisions is based on the relationships between fisheries productivity and the response of habitats or populations to pressures, with pressures linked to specific classes of activities through pathways of effects models. The framework includes guidance on quantifying productivity, scales and types of impacts, establishing equivalence in offsetting, and managing risk. Risk of failing to achieve the intent of the fisheries protection provisions is only managed when impacts of activities have a net neutral or positive effect on fisheries productivity. This standard applies whether the evaluation of an activity is by self‐ or assisted assessment or a more comprehensive project evaluation. En el año 2012, el Acta Pesquera de Canadá fue enmendada. Las nuevas provisiones para la protección de pesquerías tienen como objetivo proveer sustentabilidad y productividad a las pesquerías comerciales, recreativas y nativas. Estas provisiones reemplazan varias de las anteriores que se enfocaban en el hábitat de los peces, y ahora se han suscitado ciertas preocupaciones en cuanto a que el acta enmendada reduce la protección de hábitats acuáticos. El contexto científico que se ha desarrollado para implementar las nuevas provisiones se basa en la relación entre la productividad pesquera y la respuesta de los hábitats o de las poblaciones a las presiones; presiones que a su vez se relacionan con tipos específicos de actividades mediante modelos de “rutas de efectos”. El contexto incluye guías de cómo cuantificar la productividad, tipos y escala de los impactos, establecimiento de equivalencias compensatorias y manejo del riesgo. El riesgo de que no se logren cumplir los objetivos de las provisiones de protección de las pesquerías, comienza a ser controlado sólo cuando el impacto de las actividades tiene un efecto neto neutral o positivo en la productividad pesquera. Este estándar aplica ya sea cuando la evaluación de la actividad es asistida o bien auto evaluación, o cuando se hace mediante un proyecto de evaluación más exhaustivo. [ABSTRACT FROM AUTHOR]