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Objective: Long‐term standardized monitoring programs are fundamental to assessing how fish populations respond to anthropogenic stressors. Standardized monitoring programs may need to adopt new methods to adapt to rapid environmental changes that are associated with a changing climate. In the upper Yellowstone River, Montana, biologists have used a standardized, mark–recapture monitoring protocol to annually estimate the abundance of trout since 1978 to assess population status and trends. However, within the past two decades, climate change has caused changes in discharge timing that have prevented standardized monitoring from occurring annually. Methods: We investigated the feasibility of using two analytical methods, N‐mixture models and mean capture probability, for estimating the abundance of three trout species in the upper Yellowstone River using the historical long‐term data set; these methods allow abundance to be estimated when a mark–recapture estimate cannot be obtained due to hydrologic conditions. Result: When compared with abundance estimates from mark–recapture methods, N‐mixture models most often resulted in negatively biased abundance estimates, whereas mean capture probability analyses resulted in positively biased abundance estimates. Additionally, N‐mixture models produced negatively biased estimates when tested against true abundance values from simulated data sets. The bias in the N‐mixture model estimates was caused by poor model fit and variation in capture probability. The bias in the mean capture probability estimates was caused by heterogeneity in capture probability, likely caused by variable environmental conditions, which were not accounted for in the models. Conclusion: N‐mixture models and mean capture probability are not viable alternatives for estimating abundance in the upper Yellowstone River. Thus, exploring additional adaptations to sampling methodologies and analytical approaches, including models that require individually marked fish, will be valuable for this system. Climate change will undoubtedly necessitate changes to standardized sampling methods throughout the world; thus, developing alternative sampling and analytical methods will be important for maintaining the utility of long‐term data sets. Impact StatementClimate change is causing conditions that prevent mark–recapture trout monitoring in the Yellowstone River. Two alternative analysis methods, N‐mixture models and mean catchability, showed limited utility; thus, other alternate sampling and analytical methods could be explored. [ABSTRACT FROM AUTHOR]

Multistate modeling was used to estimate survival and movement of brown trout (Salmo trutta) and westslope cutthroat trout (Oncorhynchus clarkii lewisi) in relation to copper concentrations in the mining-impacted Clark Fork River, Montana. Survival probability in the uppermost river segment, where dissolved copper concentrations frequently exceeded acute criteria for aquatic life (range: 31-60 days > 13.4 [micro]gx[L.sup.-1]), was 2.1 times lower for brown trout and 122 times lower for westslope cutthroat trout compared with survival rates in the lowermost segment that had relatively low dissolved copper (0 days exceedance of acute concentration). Lowest survival for both species occurred in the spring-summer period when dissolved copper concentrations were elevated coincident with higher discharge. Movement among study segments was generally low, and cutthroat trout showed low movement into the uppermost river segment with the most elevated copper levels. Both species showed high rates of movement into tributaries, which coincided with their respective spawning migrations rather than as an apparent avoidance of elevated copper levels. The linkage between survival rate and level of copper exposure for both trout species suggests that additional removal of tailings deposits could improve survival rates. La modelisation multi-etats est utilisee pour estimer la survie et les deplacements de truites brunes (Salmo trutta) et de truites fardees versant de l'ouest (Oncorhynchus clarkii lewisi) au vu des concentrations de cuivre dans la riviere Clark Fork (Montana), une riviere touchee par les impacts de l'activite miniere. La probabilite de survie dans le troncon le plus amont de la riviere, ou les concentrations de cuivre dissous depassent frequemment les criteres d'exposition aigue pour la vie aquatique (fourchette: 31-60 jours > 13,4 [micro]gx[L.sup.-1]), etait 2,1 fois plus faible pour la truite brune et 122 fois plus faible pour la truite fardee versant de l'ouest que les taux de survie dans le troncon le plus aval, caracterise par des concentrations de cuivre dissous relativement faibles (0 jour de depassement de la concentration associee a une exposition aigue). Les taux de survie les plus faibles pour les deux especes ont ete observes durant la periode printaniere et estivale, moment ou de fortes concentrations de cuivre dissous coincidaient avec des debits plus importants. Il y avait generalement peu de deplacements entre les troncons etudies, et les truites fardees versant de l'ouest presentaient des deplacements limites dans le troncon le plus amont de la riviere caracterise par les plus fortes concentrations de cuivre. Les deux especes presentaient des frequences elevees de deplacements vers les affluents, qui coincidaient avec leurs migrations de frai respectives plutot que de refleter d'apparents efforts pour eviter de fortes concentrations de cuivre. Le lien entre le taux de survie et le niveau d'exposition au cuivre pour les deux especes de truite donne a penser que la poursuite du retrait des depots de steriles pourrait ameliorer les taux de survie. [Traduit par la Redaction], Introduction Water pollution from mining is one of the most detrimental and persistent anthropogenic impacts in fresh waters. Mining can release of large volumes of trace metals and waste material, [...]

For species that exist at low abundance or are otherwise difficult to study, it is challenging to estimate vital rates such as survival and fecundity and common to assume that survival rates are constant across ages and sexes. Population assessments based on overly simplistic vital rates can lead to erroneous conclusions. We estimated sex- and length-based annual apparent survival rates for white sharks (Carcharodon carcharias). We found evidence that annual apparent survival differed over ontogeny in a system with competitive foraging aggregations, from 0.63 (standard error (SE) = 0.08) for newly recruiting subadults to 0.95 (SE = 0.02) for the largest sharks. Our results reveal a potential challenge to ontogenetic recruitment in a long-lived, highly mobile top marine predator, as survival rates for subadult white sharks may be lower than previously assumed. Alternatively, younger and competitively inferior individuals may be forced to permanently emigrate from primary foraging sites. This study provides new methodology for estimating apparent survival as a function of diverse covariates by capture-recapture study, including when sex assignment is uncertain. Pour les especes qui existent en faible abondance ou dont l'etude presente par ailleurs un defi, il est difficile d'estimer des indices vitaux comme la survie et la fecondite et il est couramment presume que les taux de survie ne varient pas selon le sexe et le groupe d'age. Des evaluations de populations reposant sur des indices vitaux trop simplistes peuvent mener a des conclusions erronees. Nous avons estime les taux de survie annuels apparents en fonction du sexe et de la longueur pour de grands requins blancs (Carcharodon carcharias). Nous avons releve des preuves de variation du taux de survie annuel apparent au fil de l'ontogenie dans un systeme caracterise par des regroupements concurrents d'individus en quete de nourriture, ce taux allant de 0,63 (l'ecart-type (ET) = 0,08) pour les individus subadultes recemment recrutes a 0,95 (ET = 0,02) pour les requins les plus grands. Nos resultats revelent une difficulte potentielle en ce qui concerne le recrutement ontogenique chez un predateur marin de niveau trophique superieur tres mobile et longevif, puisque les taux de survie de grands requins blancs subadultes pourraient etre plus faibles que presumes auparavant. Une autre explication est que les individus plus jeunes ou moins concurrentiels pourraient etre forces d'emigrer des meilleurs sites d'approvisionnement de maniere permanente. L'etude presente une nouvelle methodologie pour estimer la survie apparente en fonction de differentes variables reliees, par une approche de capture- recapture, y compris pour les cas ou l'affectation du sexe est incertaine. [Traduit par la Redaction], Introduction Effective assessment of population viability and temporal variability in abundance depends on accurate estimation of population vital rates (i.e., survival and reproductive rates) and variation in these vital rates [...]

Variations in the reproductive and survival abilities of individuals within a population are ubiquitous in nature, key to individual fitness, and affect population dynamics, which leads to strong interest in understanding causes and consequences of vital‐rate variation. For long‐lived species, long‐term studies of large samples of known‐age individuals are ideal for evaluating vital‐rate variation.A population of Weddell seals in Erebus Bay, Antarctica, has been studied each Austral spring since the 1960s. Since 1982, all newborns have been tagged each year and multiple capture‐mark‐recapture (CMR) surveys have been conducted annually.Over the past 20 years, a series of analyses have built on results of earlier research by taking advantage of steady improvements in the project's long‐term CMR data and available analytical methods. Here, I summarize progress made on four major topics related to variation in age‐specific vital rates for females: early‐life survival and age at first reproduction, costs of reproduction, demographic buffering, and demographic senescence.Multistate modelling found that age at first reproduction varies widely (4–14 years of age) and identified contrasting influences of maternal age on survival and recruitment rates of offspring. Subsequent analyses of data for females after recruitment revealed costs of reproduction to both survival and future reproduction and provided strong evidence of demographic buffering. Recent results indicated that important levels of among‐individual variation exist in vital rates and revealed contrasting patterns for senescence in reproduction and survival.Sources of variation in vital rates include age, reproductive state, year, and individual. The combination of luck and individual quality results in strong variation in individual fitness outcomes: ~80% of females born in the population produce no offspring, and the remaining 20% vary strongly in lifetime reproductive output (range: 1–23 pups).Further research is needed to identify the specific environmental conditions that lead to annual variation in vital rates and to better understand the origins of individual heterogeneity. Work is also needed to better quantify the relative roles of luck, maternal effects, and environmental conditions on variation in vital rates and to learn the importance of such variation to demographic performance of offspring and on overall population dynamics. [ABSTRACT FROM AUTHOR]