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Earlier spring warming and anadromous fish migrations prompted by climate change are linked to shorter freshwater residency. Impacts of phenological change on anadromous fish populations are poorly understood with limited studies focused on iteroparous non-salmonids. We assessed freshwater residence time and reproductive success in an iteroparous clupeid, alewife (Alosa pseudoharengus) using a pedigree analysis and otolith-based spawning dates from captured juveniles. The primary objectives were to (1) estimate adult spawning duration in a freshwater pond (freshwater residence time) and (2) evaluate adult freshwater residence time, arrival date, length, sex, and reproductive success across 2 years in one system. Estimated freshwater residence times varied widely (1-64 days), and longer residence times were associated with earlier arrival dates, higher reproductive success, and more mating events. Longer freshwater residence times may allow alewife to spawn with more mates, produce more gametes, and experience a range of spawning and nursery conditions. Plasticity in alewife freshwater residence time could support earlier and shorter migration periods but may result in lower reproductive output if adults spend less time in freshwater ponds. Key words: phenology, river herring, anadromous fish, iteroparous fish, clupeids, Introduction Global climate change is likely to result in the adaptation or extirpation of many organisms. One frequent adaptation to climate change is altered phenology or changes in the timing [...]

Although human fragmentation of freshwater habitats is ubiquitous, the genetic consequences of isolation and a roadmap to address them are poorly documented for most fishes. This is unfortunate, because translocation for genetic rescue could help mitigate problems. We used genetic data (32 SNPs) from 203 populations of westslope cutthroat trout (Oncorhynchus clarkii lewisi) to (1) document the effect of fragmentation on genetic variation and population structure, (2) identify candidate populations for genetic rescue, and (3) quantify the potential benefits of strategic translocation efforts. Human-isolated populations had substantially lower genetic variation and elevated genetic differentiation, indicating that many populations are strongly influenced by random genetic drift. Based on simple criteria, 23 populations were candidates for genetic rescue, which represented a majority (51%) of suitable populations in one major region (Missouri drainage). Population genetic theory suggests that translocation of a small number of individuals (~5 adults) from nearby populations could dramatically increase heterozygosity by up to 58% (average across populations). This effort provides a clear template for future conservation of westslope cutthroat trout, while simultaneously highlighting the potential need for similar efforts in many freshwater species. Si la fragmentation des habitats d'eau douce causee par l'activite humaine est ubiquiste, les consequences genetiques de l'isolement et une feuille de route pour s'y attaquer demeurent mal documentees pour la plupart des poissons. C'est dommage, puisque le deplacement a des fins de sauvegarde genetique pourrait aider a attenuer certains problemes. Nous avons utilise des donnees genetiques (32 SNP) de 203 populations de truites fardees versant de l'Ouest (Oncorhynchus clarkii lewisi) pour (1) documenter l'effet de la fragmentation sur la variation genetique et la structure des populations, (2) cerner des populations candidates a la sauvegarde genetique et (3) quantifier les avantages potentiels d'efforts de deplacement strategique. Les populations isolees par l'activite humaine presentent une variation genetique considerablement moindre et une differentiation genetique plus grande que les autres populations, ce qui indique qu'une derive genetique aleatoire influence fortement de nombreuses populations. A la lumiere de criteres simples, 23 populations sont de bonnes candidates a la sauvegarde genetique, representant une majorite (51 %) des populations convenables dans une grande region (le bassin versant de la riviere Missouri). La theorie de la genetique des populations indiquerait en outre que le deplacement d'un petit nombre d'individus (~5 adultes) de populations voisines pourrait entrainer une augmentation marquee, de jusqu'a 58 %, de l'heterozygotie (moyenne pour toutes les populations). L'etude constitue manifestement un modele pour les efforts de conservation futurs de la truite fardee versant de l'Ouest, tout en soulignant la possible necessite d'efforts semblables pour de nombreuses autres especes d'eau douce. [Traduit par la Redaction], Introduction Freshwater species are unfortunately positioned as the most-imperiled group of biota on earth (Tickner et al. 2020), and populations of freshwater vertebrates are declining at faster rates than either [...]

The persistence of small populations is influenced by the degree and cost of inbreeding, with the degree of inbreeding depending on whether close-kin mating is passively or actively avoided. Few studies have simultaneously studied these factors. We examined inbreeding in a small, isolated population of westslope cutthroat trout using extensive genetic and demographic data. Passive inbreeding avoidance was low, with predicted lifetime dispersal of approximately 36 and 74 m for females and males, respectively. Additionally, we found limited evidence for active inbreeding avoidance during reproduction. Relatives remained spatially clustered into adulthood, and observed relatedness among mate pairs was greater than expected under random mating by 0.09, suggesting that inbreeding is a concern in this population. Further, we examined sex-specific inbreeding depression throughout the life cycle and provide evidence for inbreeding depression in some fitness components, including family size, juvenile survival and reproductive success. Our results suggest that, in an at-risk trout population, limited passive and active inbreeding avoidance lead to a higher degree of inbreeding than expected under random mating. Observed inbreeding, along with evidence for fitness reduction due to inbreeding depression, could put the population at a heightened risk of decline or extirpation. [ABSTRACT FROM AUTHOR]

Brook Trout (Salvelinus fontinalis) populations have experienced marked declines throughout their native range and are presently threatened due to isolation in small habitat fragments, land use changes, and climate change. The existence of numerous, spatially distinct populations poses substantial challenges for monitoring population status (e.g., abundance, recruitment, or occupancy). Genetic monitoring with estimates of effective number of breeders (Nb) provides a potentially powerful metric to complement existing population monitoring, assessment, and prioritization. We estimated Nb for 71 Brook Trout habitat units in mid‐Atlantic region of the United States and obtained a mean Nb of 73.2 (range 6.90–493). Our modeling approach tested whether Nb estimates were sensitive to differences in habitat size, presence of non‐native salmonids, base flow index, temperature, acidic precipitation, and indices of anthropogenic disturbance. We found significant support for three of our hypotheses including the positive influences of available habitat and base flow index and negative effect of temperature. Our results are consistent with presently observed and predicted future impacts of climate change on populations of this cold‐water fish. Importantly, these findings support the use of Nb in population assessments as an index of relative population status. [ABSTRACT FROM AUTHOR]

The preservation of genetic variation is fundamental in biodiversity conservation, yet its importance for population viability remains contentious. Mixed‐source reintroductions, where individuals are translocated into a single vacant habitat from multiple genetically divergent and often depauperate populations, provide an opportunity to evaluate how genetic variation and hybridization influence individual and relative population fitness. Population genetic theory predicts that individuals with higher genetic variation and hybrids among populations should have higher fitness. We tested these two hypotheses by analyzing individual and population‐scale data for westslope cutthroat trout (Oncorhynchus clarkii lewisi) in four mixed‐source reintroductions. We observed more hybrid and fewer nonhybrid offspring than expected across four independent mixed‐source reintroductions. We also found clear evidence that heterozygosity influenced individual reproductive and relative population fitness. Overall, we found a strong, positive relationship between genetic variation, hybridization, and transplant fitness, emphasizing the importance of genetic variation and population mixing in conservation. [ABSTRACT FROM AUTHOR]

Trout and salmon commonly coexist in stream networks. Exploring similarities and differences among species can help explain coexistence and invasive ability. Here, we describe spatial distribution, cohort strengths and size-at-age of three co-occurring species in a small stream network. Spatial distributions varied dramatically among species; native brook trout (Salvellinus fontinalis) occupied all stream reaches, naturalized brown trout (Salmo trutta) were found in the mainstem and lower portions of tributaries and fry-stocked Atlantic salmon (Salmo salar) were limited to the mainstem. Size-at-age also differed among species, Atlantic salmon were consistently the smallest, brook trout were intermediate in size and brown trout were the largest. Despite size differences, mean lengths of brook trout and brown trout were highly correlated among years. Cohort strengths varied considerably across years but were also highly correlated for the two trout species, suggesting strong environmental control on cohort strength and a reduced role for species interactions. At low densities, we observed strong negative effects of density on body sizes and weaker effects otherwise. Overall, these results suggest differences in spatial distribution combined with similarities in response to environmental variation contribute to species coexistence in this small steam network. Des truites et saumons coexistent souvent dans des reseaux hydrographiques. L'examen des similitudes et differences entre especes peut aider a expliquer cette coexistence et la capacite d'envahissement. Nous decrivons la repartition dans l'espace, la force des cohortes et la taille selon l'age de trois especes coexistant dans un petit reseau hydrographique. Les repartitions spatiales presentent des variations considerables entre especes; les ombles de fontaine (Salvellinusfontinalis) indigenes occupent tous les tronqons, les truites brunes (Salmo trutta) naturalisees sont observees dans le cours d'eau principal et les cours inferieurs d'affluents et les saumons atlantiques (Salmo salar) ensemences en tant qu'alevins se limitent au cours d'eau principal. La taille selon l'age varie egalement d'une espece a l'autre, la taille des saumons atlantiques etant uniformement plus petite, les ombles de fontaine etant de taille intermediaire et les truites brunes presentant les plus grandes tailles. Malgre les differences de taille, les longueurs moyennes des ombles de fontaine et des truites brunes sont fortement correlees au sein d'une meme annee. La force des cohortes varie considerablement d'une annee a l'autre, mais est aussi fortement correlee pour les deux especes de truites, ce qui indiquerait que les conditions environnementales exercent un grand controle sur la force des cohortes et que les interactions des especes jouent un role mineur. Nous observons de forts effets negatifs de la densite sur la taille du corps a de faibles densites, mais des effets plus faibles par ailleurs. Globalement, ces resultats indiqueraient que des differences sur le plan de la repartition spatiale combinees a des similitudes des reactions aux variations de conditions environnementales jouent un role dans la coexistence d'especes dans ce petit reseau hydrographique. [Traduit par la Redaction], Introduction Species responses to both extrinsic (environmental) and intrinsic (population dynamics) factors are key to understanding patterns of distribution and abundance. Co-occurring species frequently exhibit differences in habitat use across [...]

The metabolic state of a cell is influenced by cell-extrinsic factors, including nutrient availability and growth factor signaling. Here, we present extracellular matrix (ECM) remodeling as another fundamental node of cell-extrinsic metabolic regulation. Unbiased analysis of glycolytic drivers identified the hyaluronan-mediated motility receptor as being among the most highly correlated with glycolysis in cancer. Confirming a mechanistic link between the ECM component hyaluronan and metabolism, treatment of cells and xenografts with hyaluronidase triggers a robust increase in glycolysis. This is largely achieved through rapid receptor tyrosine kinase-mediated induction of the mRNA decay factor ZFP36, which targets TXNIP transcripts for degradation. Because TXNIP promotes internalization of the glucose transporter GLUT1, its acute decline enriches GLUT1 at the plasma membrane. Functionally, induction of glycolysis by hyaluronidase is required for concomitant acceleration of cell migration. This interconnection between ECM remodeling and metabolism is exhibited in dynamic tissue states, including tumorigenesis and embryogenesis.

Removal of non-native fish populations can be crucial to the conservation of native species, but often presents a complex challenge for managers. The goal of Trojan Y chromosome (TYC) programs is to skew the non-native sex ratio until only males remain, leading to eradication. We present results from a simulation model used to explore effects of alternative management approaches on an in-progress mechanical removal and TYC program to eradicate non-native brook trout (Salvelinus fontinalis). Simulation results indicated that stocking fingerling YY males (~137 mm) was more effective than stocking catchable- sized YY males (~230 mm), although questions about intercohort competition warrant further investigation. Increasing the proportion of mature fingerling YY males reduced treatment time by increasing the number of YY male spawners and increasing density- dependent mortality on young, mature wild brook trout. Maximizing the spatial distribution of YY male releases may be crucial to program success but is also dependent upon immediate dispersal movements. Principles derived from our results can be broadly applied to the management of other aquatic invaded systems using TYC programs to eradicate non-native species. Si le retrait de populations de poissons non indigenes peut s'averer crucial pour la conservation d'especes indigenes, il constitue souvent un defi complexe pour les gestionnaires. L'objectif des programmes bases sur un chromosome Y << cheval de Troie >> (CYCT) est de modifier le rapport de masculinite d'especes non indigenes jusqu'a ce que seuls des males demeurent, menant a leur eradication. Nous presentons les resultats d'un modele de simulation utilise pour explorer les effets de differentes approches de gestion sur un programme en cours de retrait mecanique et base sur les CYCT visant l'eradication d'ombles de fontaine (Salvelinus fontinalis) non indigenes. Les resultats de simulations indiquent que l'ensemencement d'alevins males YY d'un an (~137 mm) est plus efficace que l'ensemencement de males YY de taille exploitable (~230 mm), bien que des questions concernant la concurrence entre cohortes necessitent un examen plus pousse. Une plus grande proportion d'alevins males YY matures reduit la duree du traitement en rehaussant le nombre de geniteurs males YY et la mortalite dependante de la densite des jeunes ombles de fontaine sauvages matures. La maximisation de la repartition spatiale des lachers de males YY pourrait constituer un element cle du succes de tels programmes, mais depend aussi des deplacements de dispersion immediats. Les principes derives de nos resultats peuvent s'appliquer plus largement a la gestion d'autres systemes aquatiques envahis par le recours a des programmes bases sur les CYCT pour eradiquer des especes non indigenes. [Traduit par la Redaction], Introduction The establishment and spread of non-native fish species present substantial challenges for the conservation and management of natural resources (Havel et al. 2015). One approach to the removal of [...]

Climate warming is expected to have substantial impacts on native trout across the Rocky Mountains, but there is little understanding of how these changes affect future distributions of co-occurring native fishes within population strongholds. We used mixed-effects logistic regression to investigate the role of abiotic (e.g., temperature) and biotic factors (bull trout presence, Salvelinus confluentus) on distributions of westslope cutthroat trout (Oncorhynchus clarkii lewisi; WCT) in the North Fork Flathead River, USA and Canada. The probability of WCT presence increased with stream temperature and decreased with channel gradient and bull trout presence, yet the effect of bull trout was reduced with increasing pool densities. Combining this model with spatially explicit stream temperature projections, we predict a 29% increase in suitable habitat under high emissions through 2075, with gains at mid-elevation sites predicted to exceed bull trout thermal tolerances and high-elevation sites expected to become more thermally suitable for WCT. Our study illustrates the importance of considering abiotic and biotic drivers to assess species response to climate change, helping to guide local- scale climate adaptation and management. S'il est prevu que le rechauffement climatique aura des impacts considerables sur les truites et ombles dans toute la region des montagnes Rocheuses, la comprehension de l'incidence de ces changements sur la repartition future de poissons indigenes cooccurrents dans des regions de fortes populations est tres limitee. Nous utilisons la regression logistique a effets mixtes pour examiner le role de facteurs abiotiques (p. ex. la temperature) et biotiques (la presence d'ombles a tete plate, Salvelinus confluentus) sur la repartition de la truite fardee versant de l'ouest (Oncorhynchus clarkii lewisi; TFVO) dans la riviere North Fork Flathead (Etats-Unis et Canada). La probabilite de la presence de TFVO augmente avec la temperature du cours d'eau et diminue avec la pente du chenal et la presence d'ombles a tete plate, une plus grande densite de fosses etant toutefois associee a un effet moindre de la presence d'ombles a tete plate. En combinant ce modele a des projections spatialement explicites de la temperature des cours d'eau, nous predisons une augmentation de cette derniere de 29 % dans les habitats convenables pour des conditions d'emissions fortes jusqu'en 2075, les augmentations dans les sites de moyenne altitude depassant la fourchette de tolerance thermique des ombles a tete plate et les sites de haute altitude devenant plus convenables du point de vue thermique pour la TFVO. L'etude illustre l'importance de tenir compte de facteurs abiotiques et biotiques dans l'evaluation des reactions des especes aux changements climatiques et aide a orienter les mesures d'adaptation climatique et la gestion a l'echelle locale. [Traduit par la Redaction], Introduction Global climate change is causing many species to shift their distributions poleward and towards higher altitudes to track changes in optimal habitat (Parmesan 2006). This is particularly true for [...]

The number of effective breeders ([N.sub.b]) has been touted as a means to monitor freshwater fishes, but the realized application of [N.sub.b] has been limited. Using genetic monitoring data for two Arctic grayling (Thymallus arcticus) populations of conservation concern, we describe temporal trends in genetic variation and [N.sub.b], determine how sampling and variance in reproductive success influence estimates of [N.sub.b], and quantify the relationship among [N.sub.b], effective population size (Ne), and adult abundance ([N.sub.c]). Temporal trends in allelic richness ([A.sub.R]) and [N.sub.b] tracked known or suspected population trajectories. [N.sub.b] increased in one population where there has been extensive conservation action, and both [N.sub.b] and [A.sub.R] tracked a decline in the other population where harsh winter conditions have resulted in overwinter mortality events. After accounting for population demography, [N.sub.e] estimates for each population were 190.7 and 308.8. Overall, this study demonstrates that temporal genetic data effectively resolve demographic and evolutionary status and trend in Arctic grayling, provides insight into the demographic factors that influence genetic variation, and emphasizes the value of temporal genetic data for conservation and management. Il a ete propose que le nombre de geniteurs effectifs ([N.sub.b]) pourrait constituent un moyen de surveillance des poissons d'eau douce, mais les applications qui en ont ete faites sont limitees. En utilisant des donnees de surveillance genetique pour deux populations d'ombres arctiques (Thymallus arcticus) dont la conservation est preoccupante, nous decrivons les tendances temporelles de la variation genetique et de [N.sub.b], determinons l'influence de l'echantillonnage et de la variance du succes de reproduction sur les estimations de [N.sub.b] et quantifions la relation entre [N.sub.b], la taille effective de la population (Ne) et l'abondance des adultes ([N.sub.c]). Les tendances temporelles de la richesse allelique ([A.sub.R]) et de [N.sub.b] coincident avec des trajectoires demographiques connues ou soupqonnees. [N.sub.b] a augmente dans une population qui a fait l'objet de vastes efforts de conservation, et tant [N.sub.b] que Ar temoignent d'un declin dans l'autre population, qui a connu des episodes de mortalite hivernale en raison d'hivers rigoureux. Apres prise en compte de la demographie des populations, les valeurs estimees de [N.sub.e] pour les deux populations etaient de 190,7 et 308,8. Globalement, l'etude demontre que des donnees genetiques temporelles permettent de determiner l'etat et les tendances demographiques et d'evolution chez les ombres arctiques, fournit de l'information sur les facteurs demographiques qui influencent la variation genetique et souligne l'importance des donnees genetiques temporelles pour la conservation et la gestion. [Traduit par la Redaction], Introduction Although population genetic data and theory were integral in forming the field of conservation biology (Soule 1985), systematic monitoring of intraspecific genetic variation remains neglected in the majority of [...]

Evaluating the efficacy of the use of Trojan male brook trout with two Y chromosomes (MYY) requires a better understanding of reproductive performance. We measured the reproductive performance of hatchery age-0 and age-1 MYY brook trout compared to hatchery XY males using laboratory crosses. Offspring of XY males had higher survival than offspring of age-1 MYY 1-day post-fertilization, but not offspring of age-0 MYY. We found no detectable differences in survival from eyed-egg to the juvenile-fry stage. However, size-at-age differed, where offspring of age-0 MYY were 3.6% smaller in length and 25.2% smaller in weight than those of XY males. For crosses fertilized by both MYY and XY males, we found that a significantly higher proportion of offspring within families were sired by MYY versus XY males. These results show, under controlled conditions, evidence for possible fitness advantage for MYY under sperm competition, but a possible fitness disadvantage associated with early growth of their offspring. Overall, our results hold promise for the use of MYY brook trout to serve as an effective eradication tool. [ABSTRACT FROM AUTHOR]

Environmental drivers of population vital rates, such as temperature and precipitation, often vary at short time scales, and these fluctuations can have important impacts on population dynamics. However, relationships between survival and environmental conditions are typically modeled at coarse temporal scales, ignoring the role of daily environmental variation in survival. Our goal was to determine the importance of fine-scale temporal variation in survival to population dynamics of stream salmonids. We extended the Cormack-Jolly-Seber model to estimate daily survival rates from seasonal samples of individually marked brook trout (Salvelinus fontinalis) in a stream network. Daily variation in temperature and flow were strongly associated with survival, but relationships varied between juvenile and adult trout and among streams. In all streams, juveniles had higher mortality in warm, low-flow conditions, but in the two larger streams, cold, high-flow conditions also reduced juvenile survival. Adult survival decreased during low flows, particularly in the fall spawning period. Differing survival responses among stream network components to short-term environmental events created shifts in optimal location for maximum survival across life stages, seasons, and years. Les facteurs environnementaux qui influencent les indices vitaux dans les populations, comme la temperature et les precipitations, varient souvent a de courtes echelles temporelles, et ces fluctuations peuvent avoir des effets importants sur la dynamique des populations. Cependant, les relations entre la survie et les conditions environnementales sont souvent modelisees a des echelles temporelles grossieres, evacuant du coup le role des variations environnementales journalieres sur la survie. Notre objectif etait de determiner l'importance de variations temporelles de courte duree de la survie pour la dynamique de populations de salmonides de cours d'eau. Nous avons elargi le modele de Cormack-Jolly-Seber pour estimer les taux de survie journaliers a partir d'echantillons saisonniers d'ombles de fontaine (Salvelinus fontinalis) etiquetes individuellement dans un reseau hydrographique. Les variations journalieres de temperature et de debit etaient fortement associees a la survie, mais les relations etaient differentes entre les juveniles et les adultes et d'un cours d'eau a l'autre. Dans tous les cours d'eau, les juveniles presentaient un taux de mortalite plus eleve dans des conditions chaudes et de faible debit, mais dans les deux cours d'eau plus grands, des conditions froides et de debit fort reduisaient egalement la survie des juveniles. La survie des adultes diminuait durant de faibles debits, particulierement durant la saison de frai automnale. Des reactions differentes de la survie dans differentes composantes d'un reseau hydrographique a des episodes environnementaux de courte duree modifiaient l'emplacement optimal pour une survie maximum pour les differentes etapes de cycle de vie et les differentes saisons et annees. [Traduit par la Redaction], Introduction Drivers of population vital rates, such as temperature and stream-flow, often vary at short time scales, and these fluctuations can have important impacts on population dynamics. However, studies of [...]

Environmental conditions can influence biological characteristics, such as phenology and body size, with important consequences for organismal fitness. Examining these fitness consequences under natural conditions through genetic pedigree reconstruction offers a lens into potential population responses to changing environments. Over 3 years (2013-2015), we introduced adult alewife (Alosa pseudoharengus), anadromous, iteroparous clupeids, into one Massachusetts (USA) lake to complete the first detailed examination of this species' mating system and assess relationships among body size, reproductive timing, and seasonal reproductive success. We reconstructed pedigrees using 15 microsatellites and genotypes from all possible parents and samples of naturally produced offspring within 4 months of hatching. In each of the 3 study years, spawning adults had multiple mates and spawned multiple times. Larger females that arrived and were translocated earlier had higher reproductive success. Declining body size and altered migration timing, through an influence on reproductive success, can influence population vital rates and productivity over time. Les conditions ambiantes peuvent influencer des caracteristiques biologiques comme la phenologie et la taille du corps, ce qui peut avoir d'importantes consequences sur l'aptitude des organismes. L'examen de ces consequences sur l'aptitude dans des conditions naturelles par la reconstitution du pedigree genetique jette un eclairage sur les reactions possibles de populations a des milieux changeants. Sur une periode de 3 ans (2013-2015), nous avons introduit des gaspareaux (Alosa pseudoharengus), des clupeides iteropares anadromes, dans un lac du Massachusetts (Etats-Unis) afin de realiser le premier examen detaille du systeme d'accouplement de cette espece et evaluer les relations entre la taille du corps, le moment de la reproduction et le succes de reproduction saisonnier. Nous avons reconstitue les pedigrees en utilisant 15 microsatellites et des genotypes de tous les parents et echantillons possibles de la progeniture produite naturellement, dans les 4 mois suivant l'eclosion. Durant chacune des 3 annees de l'etude, les adultes geniteurs se sont accouples avec plus d'un individu et ont fraye a plusieurs reprises. Les femelles plus grandes arrivees et ayant ete reimplantees plus tot avaient un plus grand succes de reproduction. La diminution de la taille du corps et la modification du moment de la migration au fil du temps, par leur incidence sur le succes de reproduction, peuvent influencer les indices vitaux et la productivite d'une population., Introduction Individual reproductive success provides an important link between phenotypic variation and population dynamics (Kinnison and Hairston 2007; Pelletier et al. 2007; Wright and Trippel 2009; Schoener 2011). Parental characteristics [...]