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Freshwater ecosystems that support juvenile salmonids can be degraded by human pressures such as forestry. Forestry activities can alter water temperatures and the delivery and storage of water, nutrients, wood, and sediment in streams, resulting in changes to the habitat, growth, and survival of juvenile salmon. Previous research on forestry impacts on habitat has focused on small, intensively monitored coastal systems. Here, we examined forestry activities, watershed characteristics, physical habitat, and stream temperature for 28 mid-sized tributaries of the North Thompson River to examine relationships between forestry and juvenile coho stream habitat in interior watersheds. Forest harvest had a positive correlation to maximum summer stream temperature. Streams with 35% of the riparian area harvested since 1970 had maximum summer temperatures 3.7[degrees]C higher on average than those with 5% harvested. Stream gradient explained most of the variation in physical habitat and had negative correlations to pool cover, pool depth, and fine sediment cover. Taken together, these results indicate that watershed characteristics drive physical habitat, but forest harvest can be a primary driver of water temperatures. Key words: forestry, freshwater habitat, riparian habitat, salmonids, stream temperature, Introduction Forestry has the potential to degrade stream habitats for fish via several different pathways. Land cover regulates important watershed processes such as the delivery of water, sediment, nutrients, light, [...]

There is a need to explicitly consider metapopulation dynamics in the development of conservation strategies for spatially structured populations. We examined the spatial dynamics of sockeye salmon (Oncorhynchus nerka) that spawn in 36 streams of the Stuart River watershed in British Columbia, Canada, using a 69-year record of spawner abundance and a demographically based Bayesian dynamic occupancy model. We identified a set of 12 streams with good habitat conditions that were occupied >90% of years despite large year-to-year changes in abundance. Over 85% of spawners were concentrated in these streams. Many other streams with poorer habitat had small populations that were not persistent over time and were periodically recolonized by dispersers from other streams. Although it is often assumed population diversity and resiliency is maximized when all available habitats are used, for this salmon metapopulation, resiliency is due to the core streams of higher habitat quality. Currently, other streams make only small contributions to population abundance; however, some may have conservation value if their habitats become more suitable for spawning in the future. Une consideration explicite de la dynamique des metapopulations est necessaire dans l'elaboration de strategies de conservation pour les populations caracterisees par une structuration spatiale. Nous examinons la dynamique spatiale des saumons sockeyes (Oncorhynchus nerka) frayant dans 36 cours d'eau du bassin versant de la riviere Stuart (Colombie- Britannique, Canada), en utilisant des donnees d'abondance de geniteurs couvrant 69 annees et un modele d'occupation dynamique bayesien base sur la demographie. Nous cernons un ensemble de 12 cours d'eau caracterises par de bonnes conditions d'habitat qui etaient occupes >90 % des annees, malgre d'importantes variations interannuelles de l'abondance. Plus de 85 % des geniteurs etaient concentres dans ces cours d'eau. De nombreux autres cours d'eau presentant des habitats de moins bonne qualite ont accueilli de plus petites populations non persistantes dans le temps et ont ete recolonises periodiquement par des individus provenant d'autres cours d'eau arrives par dispersion. Bien qu'il soit souvent presume que l'utilisation de tous les habitats disponibles maximise la diversite et la resilience des populations, pour cette metapopulation de saumons, la resilience est due aux principaux cours d'eau dont les habitats sont de bonne qualite. Si la contribution actuelle d'autres cours d'eau a l'abondance des populations est faible, certains pourraient etre interessants pour la conservation a l'avenir si leurs habitats deviennent plus propices au frai. [Traduit par la Redaction], Introduction The range of many populations includes highly heterogeneous habitats, of which only a portion are suitable for the species. Those areas, often called patches, are hosts to segments of [...]

Metapopulations are often managed as a single contiguous population despite the spatial structure underlying their local and regional dynamics. Disturbances from human activities can also be spatially structured with mortality impacts concentrated to just a few local populations among the aggregate. Scale transitions between local and regional processes can generate emergent properties whereby the whole system can fail to recover as quickly as expected for an equivalent single population. Here, we draw on theory and empirical case studies to ask: what is the consequence of spatially structured ecological and disturbance processes on metapopulation recoveries? We suggest that exploring this question could help address knowledge gaps for managing metapopulations including: Why do some metapopulations recover quickly while others remain collapsed? And, what risks are unaccounted for when metapopulations are managed at aggregate scales? First, we used model simulations to examine how scale transitions among ecological and disturbance conditions interact to generate emergent metapopulation recovery outcomes. In general, we found that the spatial structure of disturbance was a strong determinant of recovery outcomes. Specifically, disturbances that unevenly impacted local populations consistently generated the slowest recoveries and highest conservation risks. Ecological conditions that dampened metapopulation recoveries included low dispersal, variable local demography, sparsely connected habitat networks, and spatially and temporally correlated stochastic processes. Second, we illustrate the unexpected challenges of managing metapopulations by examining the recoveries of three USA federally listed endangered species: Florida Everglade snail kites, California and Alaska sea otters, and Snake River Chinook salmon. Overall, our results show the pivotal role of spatial structure in metapopulation recoveries whereby the interplay between local and regional processes shapes the resilience of the whole system. With this understanding, we provide guidelines for resource managers tasked with conserving and managing metapopulations and identify opportunities for research to support the application of metapopulation theory to real‐world challenges. [ABSTRACT FROM AUTHOR]

Understanding linkages among life history traits, the environment, and population dynamics is a central goal in ecology. We compared 15 populations of sockeye salmon (Oncorhynchus nerka) to test general hypotheses for the relative importance of life history traits and environmental conditions in explaining variation in population dynamics. We used life history traits and habitat variables as covariates in mixed-effect Ricker models to evaluate the support for correlates of maximum population growth rates, density dependence, and variability in dynamics among populations. We found dramatic differences in the dynamics of populations that spawn in a small geographical area. These differences among populations were related to variation in habitats but not life history traits. Populations that spawned in deep water had higher and less variable population growth rates, and populations inhabiting streams with larger gravels experienced stronger negative density dependence. These results demonstrate, in these populations, the relative importance of environmental conditions and life histories in explaining population dynamics, which is rarely possible for multiple populations of the same species. Furthermore, they suggest that local habitat variables are important for the assessment of population status, especially when multiple populations with different dynamics are managed as aggregates. La comprehension des liens entre les caracteristiques du cycle biologique, le milieu ambiant et la dynamique des populations constitue un objectif central en ecologie. Nous avons compare 15 populations de saumons rouges (Oncorhynchus nerka) pour verifier des hypotheses generales concernant l'importance relative des caracteristiques du cycle biologique et des conditions ambiantes pour expliquer les variations de la dynamique des populations. Nous avons utilise des caracteristiques du cycle biologique et des variables reliees a l'habitat comme covariables dans des modeles de Ricker a effets mixtes pour evaluer l'appui a des correlats des taux de croissance maximums de la population, de la dependance a la densite et de la variabilite de la dynamique entre populations. Nous avons note d'importantes differences sur le plan de la dynamique de populations qui fraient dans une region geographique restreinte. Ces differences entre populations etaient reliees a des variations entre habitats, mais non a des caracteristiques du cycle biologique. Les populations qui frayaient en eau profonde presentaient des taux de croissance de la population plus eleves et moins variables et les populations residant dans des cours d'eau caracterises par des graviers plus grossiers presentaient une plus forte dependance negative a la densite. Ces resultats demontrent l'importance relative, dans ces populations, des conditions ambiantes et des cycles biologiques pour ce qui est d'expliquer la dynamique des populations, chose rarement possible pour plusieurs populations d'une meme espece. Ils donnent en outre a penser que les variables de l'habitat local sont importantes pour l'evaluation de l'etat des populations, particulierement dans les cas ou plusieurs populations presentant des dynamiques differentes sont gerees comme s'il s'agissait d'une seule population. [Traduit par la Redaction], Introduction Life history traits and environmental conditions can drive temporal changes in population abundance (Quinn et al. 2003; Hendry et al. 2004; Benton et al. 2005; Venturelli et al. 2009). [...]

We examine the importance of stream habitat characteristics in governing variation in spawning densities of sockeye salmon (Oncorhynchus nerka) across 32 streams in the Fraser River Basin, British Columbia, Canada. We used mixed-effects models to examine four competing hypotheses for the influence of abiotic stream characteristics acting on either adult salmon or embryo mortality. All models that received support using Akaike's information criterion included stream characteristics that are associated with cover. These included the percent area of pools, percentage of the banks that were undercut, and large woody debris (in that order). These results suggest the importance of stream characteristics, which reduce risk of predation on adults, in determining spawning sockeye salmon densities. Thus, identification of a small number of physical characteristics of streams provides insight into ecological processes that determine population densities. This information can be used to quantify habitat quality, which can guide habitat prioritization for conservation. Nous examinons l'importance des caracteristiques des habitats d'eau courante comme explication de la variation dans la densite de fraie des saumons rouges (Oncorhynchus nerka) dans 32 cours d'eau du bassin du fleuve Fraser, Colombie-Britannique, Canada. Des modeles a effets mixtes nous ont servi a examiner quatre hypotheses de rechange sur l'importance de l'action des facteurs abiotiques du cours d'eau sur la mortalite des saumons adultes ou sur celle des embryons. Tous les modeles qui ont ete appuyes par le critere d'information d'Akaike incluent des caracteristiques des cours d'eau associees a la couverture. Ces caracteristiques comprennent (dans l'ordre) la surface en pourcentage des fosses, le pourcentage de rives qui sont en surplomb et les grands debris ligneux. Ces resultats laissent croire que les caracteristiques du cours d'eau qui reduisent le risque de predation chez les adultes sont d'importance pour expliquer les densites des saumons rouges en fraie. Ainsi, l'identification d'un petit nombre de caracteristiques physiques des cours d'eau fournit un eclairage sur les processus ecologiques qui determinent la densite des populations. Ces renseignements peuvent servir a determiner la qualite de l'habitat, ce qui peut guider la priorisation des habitats pour fins de conservation. [Traduit par la Redaction], Introduction Impacts of habitats on animal population dynamics depend on the interplay between ecological interactions such as predation-competition and physiological requirements (Huey 1991; Parsons 2005; Parmesan 2006). Environmental conditions can [...]

Passive count technologies (e.g., resistivity counters, infrared cameras, and sonar/hydroacoustic cameras) are increasingly being used to enumerate migratory fish populations, but methodologies for converting counts into abundance estimates with uncertainty are not available. Passive counters are typically paired with a secondary data collection method, such as video, images, or direct observation, to validate or correct the count data for false positives and false negatives. We developed a framework that incorporates measurement error into passive counter estimates based on a statistical comparison with validation data. We demonstrate this framework using resistivity counter and video validation data collected for Gates Creek Sockeye Salmon Oncorhynchus nerka as they migrated through a fish passage facility at the Seton Dam in British Columbia, Canada. We also conducted simulations to evaluate the trade‐offs between validation effort and accuracy and precision of abundance estimates, which can be used to plan passive counter postprocessing and validation. We found our method to be accurate and precise when abundance was high (i.e., >1,000), even when validation effort was low (i.e., 5% validation). There was a positive estimation bias when abundance was low (i.e., 100), and a minimum of 25% validation was required to achieve a CV of 15% and relative error less than 10%. When estimating abundance for small populations, higher validation effort is required to obtain sufficient precision in abundance estimates. Measurement error should not be overlooked in passive fish count technologies, and we provide a robust method for generating uncertainty in abundance estimates that increases their utility for population assessment and conservation. [ABSTRACT FROM AUTHOR]

Timing windows refer to a mitigation measure that defines low-risk periods for harm to fish and fish habitat from works, undertaking and activities (WUAs). The Fisheries and Oceans Canada Fish and Fish Habitat Protection Program (FFHPP) has requested scientific advice on the use of timing windows. To address this request, this document is structured around three main objectives outlined in the terms of reference. First, a literature search was conducted, and found that there is a paucity of peer reviewed scientific research connected to timing windows, and that literature on timing windows is dominated by material on dredging activities. An in-depth treatment of rationale, effectiveness, and frameworks for timing windows is provided. Canadian timing window use, rationale, and considerations varies among provinces and territories, but spawning is often cited as the fish life process targeted for protection. Second, a conceptual model outlines a set of rationale and considerations for the creation or modification of timing windows focusing on (1) the timing and vulnerability of fish life processes, (2) the characteristics of WUAs and associated pressures, and (3) the characteristics of habitat and environmental conditions. Importantly, life processes vary in their vulnerability to WUAs, but characteristics such as well-defined and predictable timing were identified among the factors that make some more suitable to mitigation with timing windows than others. Further considerations for migration, spawning, feeding, natal, rearing and refuge use are also presented. Characteristics of WUA pressures, including timing and persistence, were also identified as key factors for timing windows to consider. The interaction of pressures with fish habitat will be influenced by characteristics of the habitat and the environmental context. Protecting habitat processes with timing windows will depend on the process predictability, the mechanisms that regulate the WUA pressure and the habitat process, and the degree of overlap and strength of the pressure during exposure. Finally, we present a three-tiered approach to evaluate the effectiveness of timing windows to reduce the risk of exposure of fish life or habitat processes, the effects of pressures on the exposed process, and risk at the population level. Studies at each tier can inform comparisons of how risk varies through time, which is a key consideration when choosing among timing window options. This document advances the state of knowledge on the use of timing windows and on evaluating their effectiveness. The information presented can be used by FFHPP in the development of a science-based timing window framework to guide their creation and modification, to aid practitioners to identify potential risks of WUAs outside of established windows, and to inform their adaptation to changing environmental conditions. [ABSTRACT FROM AUTHOR]

Much effort has been devoted to developing, constructing and refining fish passage facilities to enable target species to pass barriers on fluvial systems, and yet, fishway science, engineering and practice remain imperfect. In this review, 17 experts from different fish passage research fields (i.e., biology, ecology, physiology, ecohydraulics, engineering) and from different continents (i.e., North and South America, Europe, Africa, Australia) identified knowledge gaps and provided a roadmap for research priorities and technical developments. Once dominated by an engineering-focused approach, fishway science today involves a wide range of disciplines from fish behaviour to socioeconomics to complex modelling of passage prioritization options in river networks. River barrier impacts on fish migration and dispersal are currently better understood than historically, but basic ecological knowledge underpinning the need for effective fish passage in many regions of the world, including in biodiversity hotspots (e.g., equatorial Africa, South-East Asia), remains largely unknown. Designing efficient fishways, with minimal passage delay and post-passage impacts, requires adaptive management and continued innovation. While the use of fishways in river restoration demands a transition towards fish passage at the community scale, advances in selective fishways are also needed to manage invasive fish colonization. Because of the erroneous view in some literature and communities of practice that fish passage is largely a proven technology, improved international collaboration, information sharing, method standardization and multidisciplinary training are needed. Further development of regional expertise is needed in South America, Asia and Africa where hydropower dams are currently being planned and constructed. [ABSTRACT FROM AUTHOR]

Relating fish physiology, behaviour and experience to fitness-related outcomes at the individual scale is ecologically significant, but presents difficulties for free-ranging fishes in natural systems. Physiological state (e.g. level of stress or maturity) and experience (e.g. habitat use or exposure to stressors) may alter the probability of survival or reproduction. This study examined the relative influence of physiology and migratory experience on survival, migration duration, reproductive longevity, and egg retention in adult female sockeye salmon ( Oncorhynchus nerka) from a Fraser River population. One hundred and thirty-five females were plasma sampled and tagged with radio transmitters and archival temperature loggers. Fish were tracked 55 km through two natal lakes to spawning grounds, following passage of a hydroelectric dam. For 39 females, we assessed the proportion of time within an optimal temperature ( Topt) window (13.4-19.5°C), which provides ≥90% of maximum aerobic scope. Females with lower plasma glucose concentrations were more likely to reach spawning grounds. Early migrants spent longer in natal lakes. More time in the TAS) window (13.4-19.5°C), which provides ≥90% of maximum aerobic scope. Females with lower plasma glucose concentrations were more likely to reach spawning grounds. Early migrants spent longer in natal lakes. More time in the Topt AS window was associated with greater reproductive longevity and lower probability of egg retention. Later arriving females had reduced longevity on spawning grounds, as did females that retained eggs. Exposure to higher dam discharge was associated with reduced reproductive longevity and greater probability of egg retention, but not lower survival, indicating a delayed effect of dam passage. Our results underscore the complexity of factors governing fitness-related outcomes for salmonids, particularly the importance of female experience in the days and weeks prior to spawning. [ABSTRACT FROM AUTHOR]

Summary 1. Researchers usually expect to understand the ecological systems better when they examine more variables. However, we cannot measure everything because time and money are limited, so we need to make difficult choices. Decisions are complicated by the fact that variables are often either uninformative or highly correlated, leading to diminishing returns on information with new variables. Correlated variables and diminishing returns on information per variable can be explicitly incorporated with costs of data collection to design cost-effective survey programmes. 2. We develop a step-by-step quantitative protocol to evaluate the cost-effectiveness of survey designs under different cost scenarios to help scientists and managers design cost-effective surveys. We illustrate this protocol using a case study that relates physical stream habitat variables to variation in sockeye salmon spawning populations. 3. We present our protocol by comparing linear regression models containing different combinations of variables representing different survey designs. The steps of the protocol are to (i) eliminate redundant variables, (ii) calculate costs scenarios, (iii) calculate survey performance metrics and (iv) identify and compare a subset of survey designs that maximize effectiveness at a given cost. Survey designs are compared by their ranked performance using R2, AICc, average cost-effectiveness ratio and incremental cost-effectiveness ratio. 4. Our case study shows diminishing returns on the information provided by the addition of more variables as survey costs increase. The protocol supports the design of cost-effective monitoring programmes and leads to a general discussion relating changing environmental conditions to survey costs, including the need for clear and measurable objectives, which allow scientific information to be translated into management options. [ABSTRACT FROM AUTHOR]