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Many fishways were designed to facilitate upstream migration at anthropogenic barriers for targeted species, such as salmonids, though these designs may impede the passage of non-target species with different swimming capabilities. Developing passage metrics that quantify hydraulic conditions scaled to biological behaviours or traits could identify the causes of challenging passage conditions and aid design of multi-species fishways. Our objective was to test the performance of six velocity- and turbulence-derived metrics for predicting passage behaviours of Pacific Lamprey (Entosphenus tridentatus) under varying hydraulic conditions within an experimental vertical slot. These metrics were the 1) swim path-averaged water velocity, 2) swim path-averaged turbulence kinetic energy ( TKE ¯ ), 3) power, 4) work, 5) a biological turbulence intensity, I ¯ Bio , quantified as the ratio between the root of the TKE ¯ and a biological criterion (the bulk average velocity for which lampreys shift from free-swimming to attachment behaviours, UBio = 1.8 m·s−1) and 6) a flow index I ¯ Bio , which is I ¯ Bio modulated by a dimensionless velocity U* = U/UBio, where U is the mean flow through the vertical slot. We assessed the performance of these metrics by evaluating their relationship with Pacific Lamprey attachment time, which serves as an important behavioural proxy for passage difficulty. Only I ¯ Bio and F were significantly associated with attachment time and we suggest these metrics can be adapted for other fish species based on velocity thresholds inducing key behavioural responses. More broadly, our study demonstrates the importance of accounting for turbulence and employing biological criteria when quantifying fish passage within or across species. [ABSTRACT FROM AUTHOR]

The melting cryosphere adds heterogeneity to the abiotic and biotic characteristics of many high latitude and montane rivers. However, climate change threatens the cryosphere's persistence in many regions. While existing research has explored the impacts of cryospheric loss on the diversity and structure of freshwater communities, implications for functional traits of communities, such as production of aquatic invertebrates, remain unresolved. Here, we quantified aquatic invertebrate community structure and secondary production in southeast Alaska (USA) streams that represent a meltwater to non‐meltwater gradient, including streams fed primarily by: (1) glacier‐melt, (2) snowmelt, (3) rainfall, and (4) a combination of these sources. We found alpha diversity was highest in the snow‐fed stream and lowest in the glacier‐fed stream. Annual secondary production was also lowest in the glacier‐fed stream (0.56 g ash‐free dry mass m−2), but 2–5 times higher in the other stream types primarily due to greater production of shared taxa that were found in all streams. However, despite low invertebrate diversity and productivity, the glacier‐fed stream hosted distinct species assemblages associated with unique cycles of stream flow, water temperature, turbidity, and nutrient concentrations, which contributed to higher beta diversity between streams. Our findings suggest that the loss of glacier‐melt contributions to rivers may result in increased freshwater invertebrate production but reduced beta diversity, which could have implications for community stability and the capacity of landscapes to support higher‐level consumers, including fishes. [ABSTRACT FROM AUTHOR]

We used biotelemetry and genetic stock identification to assess sea-to-sea survival and run composition of 1212 late-migrating adult steelhead (anadromous Oncorhynchus mykiss) through the Columbia River and Snake River migratory corridors. The late run was predominated by steelhead from Idaho's Clearwater and Salmon rivers that must pass eight large hydroelectric dams during both prespawn and postspawn migrations. In 2 years (2013 and 2014), prespawn survival to Snake River tributaries (>500 km) was 0.48-0.67 for the most abundant populations and was higher for females and 1-sea fish (i.e., fish that spend one winter at sea). Annual survival from Snake River tributary entry to postspawn kelt status was 0.14-0.17, with higher survival for females and those without hatchery fin clips. Kelt outmigration survival was 0.31-0.39 past four Snake River dams and 0.13-0.20 past all eight dams and was highest for smaller kelts. Full-cycle adult freshwater survival (sea-to- sea) including 16 dam passage events was 0.01-0.02. Younger steelhead and those without fin clips survived at the highest rates. This study uniquely partitioned mortality across prespawn, reproductive, and kelt life history stages and informs management strategies for this conservation-priority metapopulation. Nous avons utilise la biotelemetrie et l'identification genetique du stock pour evaluer la survie de l'ocean a l'ocean et la composition de la montaison de 1212 truites arc-en-ciel anadromes (Oncorhynchus mykiss) a migration tardive dans les corridors de migration du fleuve Columbia et de la riviere Snake. Des truites arc-en-ciel anadromes provenant des rivieres Clearwater et Salmon en Idaho etaient predominantes dans la migration tardive, ces truites devant franchir huit grands barrages hydroelectriques durant leurs migrations avant et apres le frai. En 2 ans (2013 et 2014), le taux de survie avant le frai jusqu'a des affluents de la Snake (>500 km) etait de 0,48-0,67 pour les populations les plus abondantes et etait plus eleve pour les femelles et les individus ayant ete dans l'ocean une fois. La survie annuelle de l'entree dans les affluents de la riviere Snake jusqu'a l'etat de charognard etait de 0,14-0,17, les taux les plus eleves etant observes pour les femelles et les individus sans marque d'ablation de nageoire en aleviniere. Les taux de survie des charognards durant la devalaison etaient de 0,31-0,39 apres quatre barrages sur la riviere Snake et de 0,13-0,20 apres tous les huit barrages, et ce taux etait le plus eleve pour les charognards plus petits. Le taux de survie en eau douce des adultes apres un cycle complet (ocean a ocean) comptant 16 franchissements de barrage etait de 0,01-0,02. Les truites arc-en-ciel anadromes plus jeunes et celles sans marque d'ablation de nageoire en aleviniere presentaient les taux de survie les plus eleves. L'etude distingue nettement la mortalite des stades pregenesique, reproducteur et de charognard du cycle biologique et fournit de l'information utile pour l'elaboration de strategies de gestion pour cette metapopulation dont la conservation est prioritaire. [Traduit par la Redaction], Introduction Preservation of genetic and life history diversity are becoming increasingly important objectives in fish conservation and management programs. In the United States, the Endangered Species Act has essentially codified [...]

Aquatic ectotherms are predicted to harbour genomic signals of local adaptation resulting from selective pressures driven by the strong influence of climate conditions on body temperature. We investigated local adaptation in redband trout (Oncorhynchus mykiss gairdneri) using genome scans for 547 samples from 11 populations across a wide range of habitats and thermal gradients in the interior Columbia River. We estimated allele frequencies for millions of single nucleotide polymorphism loci (SNPs) across populations using low‐coverage whole genome resequencing, and used population structure outlier analyses to identify genomic regions under divergent selection between populations. Twelve genomic regions showed signatures of local adaptation, including two regions associated with genes known to influence migration and developmental timing in salmonids (GREB1L, ROCK1, SIX6). Genotype–environment association analyses indicated that diurnal temperature variation was a strong driver of local adaptation, with signatures of selection driven primarily by divergence of two populations in the northern extreme of the subspecies range. We also found evidence for adaptive differences between high‐elevation desert vs. montane habitats at a smaller geographical scale. Finally, we estimated vulnerability of redband trout to future climate change using ecological niche modelling and genetic offset analyses under two climate change scenarios. These analyses predicted substantial habitat loss and strong genetic shifts necessary for adaptation to future habitats, with the greatest vulnerability predicted for high‐elevation desert populations. Our results provide new insight into the complexity of local adaptation in salmonids, and important predictions regarding future responses of redband trout to climate change. [ABSTRACT FROM AUTHOR]

Fishways designed for salmonids often restrict passage by non-salmonids, and effective tools are needed both to identify passage problems for nontarget species and to inform remediation planning. In this case study, we used migration histories from 2170 radio-tagged adult Pacific lamprey (Entosphenus tridentatus) to identify locations of poor passage (bottlenecks) at a large, multifishway dam. Over 10 years, 49% of tagged lamprey that entered fishways failed to pass the dam. Models accounting for repeated attempts by individual lamprey indicated successful passage strongly depended on attempted passage route. Success also varied with time of fishway entry, water temperature, and lamprey body size. Most failed passage attempts terminated in lower fishway segments, but extensive seasonal shifts in bottleneck locations were detected. Ranking metrics helped prioritize bottlenecks and identified sites where structural or operational modifications should improve lamprey passage. Our integration of spatially intensive monitoring with novel analytical techniques was critical to understanding the complex relationships among fishway features, environmental variation, and lamprey behavior. The prioritization framework can be applied to a wide range of fish passage assessments. Les passes migratoires concues pour les salmonides restreignent souvent le passage d'autres poissons, et des outils efficaces sont necessaires pour cerner les problemes associes au passage d'especes non visees et eclairer la planification de mesures correctives. Dans la presente etude de cas, nous avons utilise les historiques de migration de 2170 lamproies du Pacifique (Entosphenus tridentatus) adultes munies de radio-emetteurs pour cerner les lieux de passage difficiles (goulots d'etranglement) a un important barrage comptant plusieurs passes. Sur une periode de 10 ans, 49% des lamproies munies d'emetteurs qui entraient dans ces passes ne reussissaient pas a remonter le barrage. Des modeles tenant compte de tentatives multiples par les memes lamproies ont indique que le succes du passage dependait fortement de la voie de passage employee. Le taux de succes variait egalement selon le moment de l'entree dans la passe, la temperature de l'eau et la taille du corps de la lamproie. La plupart des tentatives de passage infructueuses prenaient fin dans des sections avals des passes, mais d'importantes variations saisonnieres de l'emplacement des goulots d'etranglement ont ete decelees. Le classement des differents parametres a aide a etablir la priorite des goulets et a cerner les sites ou des modifications structurales ou operationnelles devraient ameliorer le passage des lamproies. L'integration d'une surveillance spatiale fine et de nouvelles techniques analytiques s'est averee essentielle a une meilleure comprehension des liens complexes entre les caracteristiques des passes a poissons, les variations des conditions du milieu et le comportement des lamproies. Le cadre d'etablissement de la priorite peut etre applique a un vaste eventail devaluations de passes a poissons. [Traduit par la Redaction], Introduction River systems worldwide have been fragmented by dams and other anthropogenic obstacles that restrict fish movements (Nilsson et al. 2005). A diverse array of fishways and other passage systems [...]

Increasing pinniped abundance in the Pacific Northwest has coincided with population declines of Pacific salmon (Oncorhynchus spp.) and steelhead trout (Oncorhynchus mykiss), and concentrated predation may affect the recovery of some threatened and endangered salmonid stocks. We used radiotelemetry to evaluate pinniped-caused injury effects on migration survival of 17 007 adult Columbia River Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout. Injuries from pinnipeds were common (mean injury rate across 29 run-years = 36.5%) and were most common for spring Chinook salmon and steelhead trout. Injury was not consistently associated with adult survival to spawning tributaries, but some negative survival effects were detected. Pinniped-caused injury rates decreased as annual run sizes increased, indicating density-dependent or saturation effects. Within a run, large fish generally had a higher injury incidence than small fish, suggesting pinnipeds targeted large fish or more efficiently captured small fish. Seasonal, size- dependent, and density-dependent results imply that pinniped effects likely differ widely among salmonid populations within the Columbia River basin. A better understanding of these effects is needed to guide management and conservation strategies. L'augmentation d'abondance des pinnipedes dans le Nord-Ouest Pacifique coincide avec les declins demographiques des saumons du Pacifique (Oncorhynchus spp.) et de la truite arc-en-ciel anadrome (Oncorhynchus mykiss)etla concentration de la predation peut affecter le retablissement de quelques stocks de salmonides menaces et en peril. La radiotelemetrie nous a servi a evaluer les effets des blessures causees par les pinnipedes sur la survie durant la migration de 17 007 saumons chinook (Oncorhynchus tshawytscha) et truites arc-en-ciel anadromes adultes dans le fleuve Columbia. Les blessures dues aux pinnipedes sont communes (taux moyen de blessures dans 29 montaisons-annees = 36,5%) et sont plus abondantes chez les saumons chinook et truites arc-en-ciel anadromes de printemps. Il n'y a pas d'association constante entre les blessures et la survie des adultes jusqu'aux tributaires de fraie, mais on peut deceler des effets negatifs sur la survie. Les taux de blessures dues aux pinnipedes diminuent a mesure que la taille des montaisons annuelles augmente, ce qui indique des effets de densite dependance ou de saturation. Dans une montaison, les poissons plus grands ont generalement une incidence plus elevee de blessures que les poissons plus petits, ce qui laisse croire que les pinnipedes ciblent les poissons plus grands ou alors capturent plus efficacement les plus petits. Ces resultats saisonniers et dependants de la taille et de la densite amenent a croire que les effets des pinnipedes different vraisemblablement beaucoup d'une population de salmonides a une autre au sein du bassin versant du Columbia. Une meilleure comprehension de ces effets est requise pour orienter les strategies de gestion et de conservation. [Traduit par la Redaction], Introduction Members of the Order Pinnipedia evolved >20 million years ago, and their distributions have likely overlapped those of Pacific anadromous salmonids (Oncorhynchus spp.) for much of their existence. Many [...]

Abstract: The relationships among behavior, environment, and migration success in anadromous fishes are poorly understood. We monitored migration behavior at eight Columbia and Snake river dams for 18 286 adult [...]

Abstract: Upstream-migrating adult salmon must make a series of correct navigation and route-selection decisions to successfully locate natal streams. In this field study, we examined factors influencing migration route selections [...]