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Telemetry and mark-recapture provide movement information, but each approach comes with tradeoffs, potentially producing conflicting understandings of fish movement patterns. Using a Bayesian framework that allows exchanging priors from either method may help assess these inconsistencies. We evaluated channel catfish Ictalurus punctatus movements in the Red River of the North and Lake Winnipeg system, which impacts harvest management across different jurisdictions and affects different ecosystems (e.g., lotic and lentic). Channel catfish were tagged with T-bar tags or acoustic transmitters. The resulting movement data were modeled using a Bayesian multi-state Cormack-Jolly-Seber model to estimate survival, movement, and recapture probabilities. Model estimates with uninformative priors showed a greater tendency of downstream movement from the Red River into Lake Winnipeg for the T-bar tags. In contrast, the telemetry method showed fish predominantly stay in the river. However, exchanging increasingly stronger prior information from the alternative method's model revealed that telemetry movement estimates were less sensitive than the T-bar model to informative priors. Using priors from both methods provided a transparent means to assessing tagging approach tradeoffs quantitatively. Key words: Bayesian, multi-state Cormack-Jolly-Seber model, informative priors, telemetry, mark-recapture Si les techniques de telemetrie et de marquage-recapture fournissent de l'information sur les deplacements, des compromis sont associes a chacune de ces approches, qui peuvent mener a des interpretations contradictoires des motifs de deplacements des poissons. L'utilisation d'un cadre bayesien qui permet l'echange de renseignements prealables de l'une a l'autre de ces methodes peut aider a evaluer ces incoherences. Nous avons evalue les deplacements de barbues de riviere Ictalurus punctatus dans le reseau de la riviere Rouge et du lac Winnipeg, qui ont une incidence sur la gestion des prises dans differents territoires et sur differents ecosystemes (p. ex. lotiques et lentiques). Des barbues de riviere ont ete dotees d'etiquettes en T ou d'emetteurs acoustiques. Les donnees de deplacement resultantes ont ete modelisees en utilisant un modele bayesien multi-etats de Cormack-Jolly-Seber afin d'estimer la survie, les deplacements et les probabilites de recapture. Les estimations du modele integrant des renseignements prealables non informatifs montrent une plus forte tendance de deplacements vers l'aval de la riviere Rouge vers le lac Winnipeg pour les etiquettes en T. La telemetrie montre en revanche que les poissons restent de maniere preponderante dans la riviere. L'echange de renseignements prealables de plus en plus forts entre les modeles des deux methodes revele que les estimations des deplacements par telemetrie sont moins sensibles aux renseignements prealables informatifs que celles du modele pour les etiquettes en T. L'utilisation de renseignements prealables issus des deux methodes offre une approche transparente pour evaluer de maniere quantitative les compromis associes aux differentes methodes de marquage. [Traduit par la Redaction] Mots-cles : bayesien, modele mutli-etats de Cormack-Jolly-Seber, renseignements prealables informatifs, telemetrie, marquage-recapture, 1. Introduction Incorporating the spatial dynamics of fisheries into decision-making remains a challenge for fisheries management as management perspectives transition from local to ecosystem scales (Berkeley et al. 2004; Ciannelli [...]

The physiology and behaviour of fish are strongly affected by ambient water temperature. Physiological traits related to metabolism, such as aerobic scope (AS), can be measured across temperature gradients, and the resulting performance curve reflects the thermal niche that fish can occupy. We measured AS of westslope cutthroat trout (Oncorhynchus clarkii lewisi) at 5,10,15, 20, and 22[degrees]C and compared temperature preference ([T.sub.pref]) of the species with non-native brook trout (Salvelinusfontinalis), brown trout (Salmo trutta), and rainbow trout (Oncorhynchus mykiss). Intermittent-flow respirometry experiments demonstrated that metabolic performance of westslope cutthroat trout was optimal at ~15[degrees]C and decreased substantially beyond this temperature, until lethal temperatures at ~25[degrees]C. Adjusted [T.sub.pref] across species were comparatively high, ranging from 17.8 to 19.9[degrees]C, with the highest [T.sub.pref] observed for westslope cutthroat trout. Results suggest that although westslope cutthroat trout is considered a cold-water species, they do not prefer or perform as well in cold water ([less than or equal to]10[degrees]C) and thus can occupy a warmer thermal niche than previously thought. The metabolic performance curve (AS) can be used to develop species-specific thermal criteria to delineate important thermal habitats and guide conservation and recovery actions for westslope cutthroat trout. La temperature ambiante de l'eau exerce une forte influence sur la physiologie et le comportement des poissons. Des caracteres physiologiques associes au metabolisme, comme la capacite metabolique aerobie (AS), peuvent etre mesures le long de gradients de temperature, et la courbe de performance qui en resulte reflete la niche thermique que les poissons peuvent occuper. Nous avons mesure l'AS de la truite fardee versant de l'Ouest (Oncorhynchus clarkii lewisi) a 5,10,15, 20 et 22[degrees]C et compare la temperature de predilection ([T.sub.pref]) de cette espece a celles d'ombles de fontaine (Salvelinusfontinalis), de truites brunes (Salmo trutta) et de truites arc-en-ciel (Oncorhynchus mykiss), des especes non indigenes. Des experiences de respirometrie a debit intermittent ont demontre que la performance metabolique des truites fardees versant de l'Ouest est optimale a ~15[degrees]C et diminue considerablement au-dessus de cette temperature, jusqu'a des temperatures letales a ~25[degrees]C. Les [T.sub.pref] ajustees pour les differentes especes sont relativement elevees, allant de 17,8 a 19,9[degrees]C, la truite fardee versant de l'Ouest ayant la [T.sub.pref] observee la plus elevee. Les resultats portent a croire que, bien que la truite fardee versant de l'Ouest soit consideree comme etant une espece d'eau douce, elle ne prefere pas l'eau froide ([less than or equal to]10[degrees]C) ni ne performe particulierement bien dans ces conditions, et elle peut donc occuper des niches thermiques plus chaudes que ce que l'on croyait auparavant. La courbe de performance metabolique (AS) peut etre utilisee pour la determination de criteres thermiques propres a l'espece pour delimiter les habitats thermiques importants et orienter les efforts de conservation et de retablissement visant la truite fardee versant de l'Ouest. [Traduit par la Redaction], Introduction The influence of temperature on the metabolic rates of coldwater fishes has been widely studied (Imholt et al. 2011; Beauregard et al. 2013; Oligny-Hebert et al. 2015), and variation [...]

Urbanization often leads to the homogenization of species composition in aquatic ecosystems, as it introduces disturbances that can destroy the habitats of unique endemic or native species while creating alternative habitats for species capable of adapting to these conditions. This study utilized a long-term dataset from 1971 to 2010, focusing on fish species presence within three watersheds of the Greater Toronto Area, Canada. The objective was to evaluate any changes in fish communities over time across three groups of species assemblages: native, non-native species, and a combining of all species. We considered key predictor variables for which data exist: catchment area, distance to a species pool source (Lake Ontario), and percentage of urban cover, to determine their impacts on species richness over time. Three hypotheses were tested: (1) the rate of change in species richness differs among the three groups; (2) urbanization promotes the spread and homogenization of non-native species distribution; and (3) native species assemblages exhibit high nestedness initially, decreasing over time as non-native species established and replaced native species. We used general linear models and the nestedness analysis to characterize matrices of species distributions of native and non-native fish assemblages among the catchments over time. Overall, the results indicate that nestedness temperatures (NTs) for native fish were lower compared to non-native fish assemblages. Over the four decades studied, native species richness declined with increasing urban cover, while non-native species richness increased and compensated for native losses. Furthermore, native species assemblages exhibited high nestedness at the beginning of the record period, which decreased over time as non-native species became established and replaced native species. This trend suggests that further changes in fish communities are probable. As native fish communities become patchier (not nested), this process may accelerate, potentially isolating communities and making them more prone to perturbations. [ABSTRACT FROM AUTHOR]

Standard metabolic rates (SMRs) for Atlantic salmon (Salmo salar) have been calculated independently for different life stages and populations, but the absence of a comprehensive SMR model limits its application for modelling the energy use or life stage-specific growth. Atlantic salmon respiration data were compiled from a meta-analysis of 26 publications, and exponential or optimal relationships were fitted to the metadata to estimate respiration equation parameters and generate confidence intervals dependent on temperature and body mass. While model parameters were significant for both models, mass- corrected standard metabolic rates (g [O.sub.2] x [day.sup.-1]) increased as a function of water temperature ([degrees]C) and decreased beyond ~16 [degrees]C following an optimal relationship (AI[C.sub.optimal] = -9185.50 versus AI[C.sub.exponential] = -8948.95; [DELTA]AIC = 236.55). Juvenile Atlantic salmon growth (cohorts 1 and 2) from bioenergetics simulations did not vary between Little Southwest Miramichi and Northwest Miramichi rivers; however, variation between simulations using the different respiration models (i.e., exponential versus optimal) led to differences in the way fish allocate energy throughout the year. Results from this analysis will inform conservation efforts for the species throughout its current range and predict the energetic requirements at juvenile life stages. Le metabolisme standard de saumons atlantiques (Salmo salar) a ete calcule de maniere independante pour differentes etapes du cycle de vie et differentes populations, mais l'absence d'un modele exhaustif du metabolisme standard limite son application pour la modelisation de la consommation energetique ou de la croissance a differentes etapes du cycle biologique. Des donnees sur la respiration du saumon atlantique ont ete compilees a partir d'une metaanalyse de 26 publications, et des relations exponentielles ou optimales ont ete calees sur les metadonnees afin d'estimer les parametres de l'equation de la respiration et produire des intervalles de confiance dependants de la temperature et de la masse corporelle. Les parametres sont significatifs pour les deux modeles, parcontre le metabolisme standard (g [O.sub.2] x [jour.sup.-1]) corrige pour tenir compte de la masse augmente en fonction de la temperature de l'eau ([degrees]C) et diminue a plus de ~16 [degrees]C, en suivant une relation optimale (CI[A.sub.optimal] = -9185,50 et CI[A.sub.exponentiel] = -8948,95; [DELTA]CIA = 236,55). La croissance de saumons atlantiques juveniles (cohortes 1 et 2) obtenue de simulations bioenergetiques ne varie pas entre les rivieres petite Miramichi sud-ouest et Miramichi nord-ouest, mais les differences entre les simulations basees sur differents modeles de respiration (c.-a-d. exponentiel et optimal) produit des differences dans la maniere dont les poissons affectent l'energie au fil de l'annee. Les resultats de la presente analyse serviront a eclairer les efforts de conservation pour l'espece dans toute son aire de repartition actuelle et a predire les exigences energetiques durant les differentes etapes du cycle biologique des juveniles. [Traduit par la Redaction], Introduction A bioenergetics model is an energy balance equation in which the energy consumed by a fish is balanced by metabolism, waste losses, and growth (Kitchell et al. 1974; Deslauriers [...]

Objective: Documenting the movement of Channel Catfish Ictalurus punctatus through telemetry, where a transmitter tag is surgically implanted in the fish, can provide valuable insight into the species' spatial ecology and habitat use. However, since fish in the order Siluriformes can expel foreign objects such as tags from their body cavity, the utility of telemetry technology may be limited for Channel Catfish. This study aimed to determine (1) how quickly Channel Catfish reject tags that were surgically implanted into the body cavity, (2) if surgical implantation of transmitter tags causes mortality, and (3) what surgical method is best to minimize tag rejection and/or mortality. Methods: Three surgical trials were conducted on Channel Catfish (n = 24) using two tag implantation methods: a nontethered method, in which the tag was freely implanted into the body cavity, and a tethered method, where the tag was attached to the pectoral girdle. Fish were observed in the lab for 30 days for trials 1 and 2 and 225 days for trial 3 following tag implantation. Result: No complete tag rejections occurred during any of the three experimental trials. However, all five tethered fish experienced mortality during trial 3 (58-221 days postsurgery). Necropsies indicated that the tethered tagging method led to septicaemia infections and internal lacerations from the tether, which were not observed in the nontethered fish. Tags in the nontethered fish were in the process of being absorbed into the intestinal tract, which over time might have led to tag rejection. Conclusion: While rejection is possibly the end point of the nontethered tagging method, our results suggest it is nevertheless the better tagging method for Channel Catfish given higher survival. [ABSTRACT FROM AUTHOR]

Understanding how metabolic costs change in relation to increasing temperature under future climate changes is important to predict how ectotherms will be affected across the globe. In fish, whole body respiration is traditionally used to estimate aerobic performance via an organism's minimum and maximum oxygen consumption rates. However, mitochondria play a crucial role in the aerobic cascade and may be a useful surrogate of aerobic performance. To test whether whole body oxygen consumption and mitochondrial capacity are correlated, we estimated whole body metabolic and mitochondrial respiration rates (using permeabilized red muscle fibres) in brook trout (Salvelinus fontinalis (Mitchill, 1814)) at 10, 15, and 20 °C. Standard metabolic rate increased with acclimation temperature, while maximum rates were less sensitive. All mitochondrial respiration rates increased with acclimation temperature, suggesting that red muscle mitochondrial preparations may correlate to the minimal metabolic demands in this species. When expressed as relative rates of electron flow, the red muscle fibres showed no effect of temperature on mitochondrial coupling efficiency. However, there was a pattern of declining capacity to augment respiration via complex II with increasing temperature with a concomitant increase in the capacity of the phosphorylating system relative to maximal rates of mitochondrial electron flow. [ABSTRACT FROM AUTHOR]

The impact of early rearing environment on phenotypic development in teleosts has been reasonably well-documented, but only recently has attention been paid to sturgeon raised for conservation purposes. In the present study, we hypothesized that rearing environment will result in the development of distinct metabolic phenotypes in age-0 lake sturgeon (Acipenserfulvescens) and that these phenotypes will drive differential survival rates during a simulated overwintering event. Lake sturgeon gametes were fertilized and raised in one of three different environments: 16[degrees]C +100% dissolved oxygen (DO), 14[degrees]C + 100% DO, and 16[degrees]C + 80% DO, each with or without substrate. We measured standard metabolic rate, forced maximum metabolic rate, metabolic scope, energy density, hepatosomatic index, Fulton's condition factor, and enzyme activities associated with ATP production. Our results suggest that subtle changes in abiotic environments during early life history result in the development of distinct metabolic phenotypes during the first year of life. These have important implications for survival of age-0 lake sturgeon when stocked in the fall of their first year. Si l'incidence du milieu de grossissement precoce sur le developpement phenotypique chez les teleosteens est raisonnablement bien documentee, ce n'est que recemment qu'une attention a ete portee aux esturgeons eleves a des fins de conservation. Nous avons postule que differents milieux de grossissement se traduiraient par le developpement de differents phenotypes metaboliques chez les esturgeons jaunes (Acipenserfulvescens) de 0 an et que ces phenotypes produiraient des taux de survie differents durantun episode d'hivernage simule. Des gametes d'esturgeon jaune ont ete fertilises et eleves dans l'un des trois milieux suivants: 16[degrees]C +100 % d'oxygene dissous (OD), 14[degrees]C +100 % OD et 16[degrees]C + 80 % OD, avec ou sans substrat. Nous avons mesure le metabolisme standard, le metabolisme maximum force, la portee metabolique, la densite energetique, l'indice hepatosomatique, le coefficient de condition de Fulton et des activites enzymatiques associees a la production d'ATP. Nos resultats portent a croire que de petites variations du milieu abiotique au debut du cycle biologique se traduisent par le developpement de phenotypes metaboliques distincts durant la premiere annee de vie. Ces differents phenotypes ont une importante incidence sur la survie des esturgeons jaunes de 0 an ensemences a l'automne de leur premiere annee. [Traduit par la Redaction], Introduction Conservation aquaculture is a common approach used towards improving the status of fish populations at risk. Much investment has been made in this area in association with conservation efforts [...]

We assessed the metabolic response of juvenile Atlantic salmon (Salmo salar; JAS) originating from two rivers with different natural thermal regimes to different acclimation temperature (15 or 20°C) and diel temperature fluctuation (constant: [+ or-] 0.5°C; fluctuating: [+ or -] 2.5°C). Diel temperature fluctuation (15 ± 2.5°C) near the thermal optimum (16°C) for the species did not influence standard metabolic rate (SMR) compared with JAS acclimated to a constant temperature of 15°C. Diel temperature fluctuation at 20 ± 2.5°C increased SMR of JAS from the warmer river by 33.7% compared with the same fish acclimated to a constant temperature of 20°C. SMR of JAS from the cooler river held at fluctuating conditions had SMR that were 8% lower than SMR at constant conditions. The results suggest that the mean temperature to which JAS is exposed may affect their responses to diel temperature fluctuation and that this response may vary between populations originating from rivers with different natural thermal regimes. Results were used to develop the first empirical SMR model for JAS subjected to diel temperature fluctuation using fish mass (3-36 g wet) and temperature (12.5-22.5°C) as explanatory variables. Nous avons evalue la reaction metabolique de saumons atlantiques (Salmo salar) juveniles (SAJ) originaires de deux rivieres presentant des regimes thermiques naturels differents a differentes temperatures d'acclimatation (15 et 20°C) et fluctuations journalieres de temperature (constante: ± 0,5°C; fluctuante : ± 2,5°C). Les fluctuations journalieres de temperature (15 ± 2,5°C) pres de l'optimum thermique (16°C) de l'espece n'ont pas d'incidence sur le taux metabolique standard (TMS) par rapport a des SAJ acclimates a une temperature constante de 15°C. Des fluctuations journalieres de temperature a 20 ± 2,5°C produisent une augmentation de 33,7% du TMS des SAJ de la riviere chaude par rapport aux memes poissons acclimates a une temperature constante de 20°C. Les SAJ de la riviere fraiche maintenus dans des conditions fluctuantes presentent des TMS 8% plus faibles qu'a conditions constantes. Ces resultats donnent a penser que la temperature moyenne a laquelle les SAJ sont exposes pourrait avoir une incidence sur leurs reactions aux fluctuations journalieres de temperature et que ces reactions pourraient varier entre populations originaires de rivieres presentant des regimes thermiques naturels differents. Les resultats ont ete utilises pour developper le premier modele empirique du TMS pour des SAJ assujettis a des fluctuations journalieres de temperature dans lequel la masse du poisson (3-36 g humide) et la temperature (12,5-22,5°C) sont des variables explicatives. [Traduit par la Redaction], Introduction Bioenergetics models are used to evaluate energy requirement and allocation in various physiological processes such as metabolism (respiration), egestion, excretion, and growth (Warren and Davis 1967). Water temperature is [...]

Interdisciplinary approaches are required to tackle complex environmental issues as freshwater ecosystems face unprecedented pressures globally. The emerging Ecohydraulics field of research should, therefore, take steps towards developing true interdisciplinarity to adapt to a continuing changing world. This study contributes to the ongoing discussion on interdisciplinarity in Ecohydraulics and shapes its growth by identifying key actions, actors and implementation strategies that can strengthen it. Based on an online questionnaire and a workshop involving over 150 early and established careers, we present a list of 20 prioritised actions that will help engage the research community towards specific goals and will result in increased interdisciplinary outcomes. While early career researchers (ECRs) have taken the lead on creating this roadmap, its implementation should be a joint responsibility of both ECRs, established career scientists, groups, and institutions within Ecohydraulics. The list of identified actions and assigned responsibility should, therefore, be considered a conversation starter. Continued revision of the here-stated approaches will be required in the future as the field of research and its community progresses. With this contribution, we resume a critical reflection on where the Ecohydraulics field of research and community stand today and suggest where resources should be invested in the long-term to consolidate the inherent interdisciplinarity in Ecohydraulics. [ABSTRACT FROM AUTHOR]

With the continuous development of hydropower on a global scale, stranding of freshwater fishes is of growing concern, and an understanding of the mechanisms and variables affecting fish stranding in hydropeaking rivers is urgently needed. In particular, a methodology is required to identify the magnitude and timing at which fish stranding occurs in relation to environmental conditions. Here, we studied fish stranding in three reaches downstream of a hydropeaking generation station in the Saskatchewan River, Saskatchewan, Canada, using an innovative remote photography approach with 45 trail cameras and traditional transect monitoring, conducting 323 transects. We observed that juvenile sport and commercial fish species are stranding at a higher proportion than small bodied fish species. The remote photography approach provided more precise fish stranding timing and associated the environmental and physical conditions with a given stranding event, but captured fewer fish and only rarely allowed species identification. The comparison of the two methodologies resulted in similar stranded fish densities, but the remote photography allowed for continuous observations whereas the transect monitoring was limited by the observer availability in the field. Remote photography allowed for additional information on the scavenging of stranded fish, with scavenging occurring on average within 240 minutes of the fish being stranded. The probability of fish stranding increased significantly with increasing water temperature and substrate particle size resulted in greater stranding on finer substrates. Our findings have important implications for hydroelectric flow management by introducing an innovative, standardized method to study the effects of hydropeaking events on fish stranding that can be applied to increase our understanding of the impacts of hydropeaking on fish communities. [ABSTRACT FROM AUTHOR]

Fish have evolved intrinsic flight responses, allowing pre-emptive avoidance of potentially threatening situations. To direct downstream migrant fish away from deleterious conditions at dams and other barriers, mechanical devices such as travelling screens and fish bypass systems are often installed. However, field observations suggest that if these structures create areas of rapidly accelerating flow, they do not effectively guide the fish. We studied the avoidance behaviour of actively migrating fall Chinook salmon (Oncorhynchus tshawytscha) smolts in controlled experiments of low-, medium-, and high-flow accelerations. We measured the response velocity ([V.sub.R]) and the velocity gradient (VG) over body length. Although [V.sub.R] varied significantly with flow conditions and increased with increasing water temperature, the median VG at the instant at which smolts displayed an avoidance response was similar over the range of accelerating flows tested. Results from this study present the first quantitative information about the avoidance behaviour of fish to flow acceleration and should provide data needed to help engineers and biologists develop effective systems to alleviate anthropogenically altered flow regimes. Furthermore, the devised experimental setup provides a valuable means to test the effects of accelerating flow on any downstream migrant fish species. Resume: Les poissons ont developpe au cours de leur evolution des reactions intrinseques de fuite qui leur permettent d'eviter de facon preventive les situations menacantes. On installe souvent dans les barrages et autres barrieres des structures mecaniques, telles que des grilles mobiles et des voies d'evitement pour les poissons, afin de diriger les poissons qui migrent vers l'aval loin des conditions deleteres. Cependant, les observations sur le terrain laissent croire que si ces structures creent des zones de debit en acceleration rapide, elles ne reussissent pas a orienter les poissons efficacement. Nous etudions le comportement d'evitement de saumoneaux du saumon chinook (Oncorhynchus tshawytscha) d'automne en phase de migration active au cours d'experiences controlees dans des conditions d'acceleration faible, moyenne et elevee du debit. Nous avons mesure la vitesse qui elicite une reaction [V.sub.R] et le gradient de vitesse VG le long du corps. Alors que les [V.sub.R] varient de facon significative en fonction des conditions de debit et augmentent en fonction des temperatures croissantes, le VG median au moment ou les saumoneaux montrent une reaction d'evitement est semblable dans toute la gamme de debits en acceleration testes. Les resultats de notre etude apportent les premiers renseignements quantitatifs sur le comportement d'evitement des debits en acceleration chez les poissons; ils de[V.sub.R]aient fournir les donnees necessaires aux ingOnieurs et aux biologistes pour mettre au point des systemes efficaces pour attenuer les effets des modifications anthropiques des regimes de debit. De plus, le montage experimental que nous avons imagine fournit une methode interessante pour tester les effets des debits en acceleration sur toute espece de poisson lors de sa migration vers l'aval. [Traduit par la Redaction], Introduction Construction of dams, weirs, and other barriers on rivers and streams may substantially alter the natural flow regimes and migratory corridors under which fishes evolved (Williams 2008). Migratory fishes [...]