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Arctic fishes are threatened by climatic change and other anthropogenic stressors, yet information on how such changes impact survival remains scarce. Acoustic telemetry has become valuable for studying aspects of fish ecology, including survival, which is invaluable in understanding potential responses to changing conditions. In Cambridge Bay, NU, we have been using acoustic telemetry to study movements and habitat use of the culturally and commercially important Arctic char (Salvelinus alpinus). Here, we combine acoustic telemetry data and Bayesian multistate mark-recapture models to study the survival of Arctic char from 2014 to 2018 in the region in freshwater and marine/estuarine habitats. We found that survival probabilities were high (>0.87) and models considering two environments (freshwater and marine) perform better than those considering three (including estuarine habitats). Furthermore, the survival in fresh water was higher than survival in marine/estuary environments. Overall, the results of this study further our understanding of important demographic parameters (i.e., survival) for Arctic char in the region, which will be useful in refining fishery management plans for the largest commercial fishery for this species in Canada. Key words: acoustic telemetry, Arctic char, Bayesian statistics, mark-recapture models, survival ecology Si les poissons de l'Arctique sont menaces par les changements climatiques et autres facteurs de stress d'origine humaine, l'information sur l'incidence de ces changements sur leur survie demeure rare. La telemetrie acoustique est devenue prisee pour etudier divers aspects de l'ecologie des poissons, notamment la survie, un parametre essentiel pour comprendre les possibles reactions a des conditions changeantes. Nous utilisons la telemetrie acoustique pour etudier les deplacements et l'utilisation d'habitats par les ombles chevaliers (Salvelinus alpinus), une espece d'importance culturelle et commerciale, dans la baie Cambridge (Nunavut). Nous combinons des donnees de telemetrie acoustique et des modeles bayesiens multietats de marquage-recapture afin d'etudier la survie des ombles chevaliers de 2014 a 2018 dans des habitats d'eau douce et marins/estuariens de cette region. Nous relevons que les probabilites de survie sont elevees (>0,87) et que les modeles qui integrent deux types de milieux (d'eau douce et marin) donnent de meilleurs resultats que ceux qui en integrent trois (incluant les habitats estuariens). La survie en eau douce s'avere en outre plus grande que la survie dans les milieux marins/estuariens. Globalement, les resultats de l'etude ameliorent la comprehension de parametres demographiques importants (c.-a-d., la survie) pour l'omble chevalier dans la region, ce qui sera utile pour peaufiner les plans de gestion des ressources pour la plus importante peche commerciale de cette espece au Canada. [Traduit par la Redaction] Mots-cles : telemetrie acoustique, omble chevalier, statistiques bayesiennes, modeles de marquage-recapture, ecologie de la survie, Introduction Climate change in the Canadian Arctic is occurring at some of the fastest rates on Earth (Prowse et al. 2006; Barber et al. 2008; Pithan and Mauritsen 2014). This [...]

Regulated waterways, interconnected by navigation barriers (locks and dams), are uniquely difficult to manage, given interest in enabling native species connectivity while minimizing invasions. Canada's historic Rideau Canal Waterway, a 202 km navigable route located in eastern Ontario and connected by 24 lockstations, embodies this challenge. The lock(s) and water-control dam that compose each lockstation may respectively offer a connectivity pathway, though to what extent is unclear. We used acoustic telemetry (native largemouth bass (Micropterus nigricans) and northern pike (Esox lucius), and invasive common carp (Cyprinus carpio); n = 224) to evaluate fish connectivity relative to lock operations and environmental data over three years (2019–2021). Thirty-five passages by 23 native fishes were recorded, with 49% of passages through locks. No common carp passages were detected; movements indicate that they favour higher flow areas downstream of dams, regions with no pathway upstream. Most passages were downstream and, of concern to obligate upstream migrators, we found that multi-flight and higher-lift locks appear impassable to upstream movements. Our results suggest that these lockstations limit, but not entirely restrict, connectivity. [ABSTRACT FROM AUTHOR]

Animal interactions are an integral part of a community's function, with influences ranging from the spatiotemporal habitat use of species to population effects to ecosystem management. Numerous non-native species are established or maintained through stocking in freshwater ecosystems with the potential to affect restoration of native species. Using acoustic telemetry, this study quantified the spatiotemporal co-occurrence of the native top-predator lake trout (Salvelinus namaycush) with non-native Chinook salmon (Oncorhynchus tshawytscha) in Lake Ontario over 2.5 years. Core home range overlap was observed during the summer, with depth acting as a mechanism of segregation, but with potential for interactions during vertical exploration. Fine-scale individual pairwise interactions confirmed the home range results. No horizontal overlap was observed during the winter and spring, but confidence was lower due to poor instrument coverage in deeper water, which the two species may frequent in these seasons. These results demonstrate the importance of depth in understanding fish interactions and highlight the usefulness of considering pairwise species interactions for understanding ecosystem community function to resource managers with multiple projects involving both native and non-native species. Les interactions d'animaux font partie integrante de la fonction d'une communaute et influent sur differents aspects allant de l'utilisation spatiotemporelle d'habitats a des effets demographiques, en passant par la gestion des ecosystemes. De nombreuses especes non indigenes sont etablies et maintenues par empoissonnement dans des ecosystemes d'eau douce, ce qui peut avoir une incidence sur le retablissement d'especes indigenes. La presente etude a utilise la telemetrie acoustique pour quantifier la cooccurrence spatiotemporelle d'un predateur de niveau trophique superieur indigene, le touladi (Salvelinus namaycush), et du saumon chinook (Oncorhynchus tshawytscha), non indigene, dans le lac Ontario sur une periode de 2,5 annees. Un chevauchement de leurs domaines vitaux a ete observe durant l'ete, la profondeur agissant comme mecanisme de segregation, des interactions etant toutefois possibles durant l'exploration verticale. Des interactions par paires a petite echelle ont confirme ces resultats relatifs au domaine vital. Aucun chevauchement horizontal n'a ete observe en hiver et au printemps, mais la fiabilite de ces resultats est plus faible en raison d'une couverture d'instruments moins importante dans les eaux plus profondes que les deux especes pourraient frequenter pendant ces saisons. Ces resultats demontrent l'importance de la profondeur pour la comprehension des interactions de poissons et soulignent l'utilite, pour les gestionnaires de ressources voyant a differents projets visant des especes indigenes et non indigenes, d'examiner les interactions d'especes par paires afin de comprendre la fonction ecosystemique de communautes. [Traduit par la Redaction], Introduction Ecosystem function is defined by the structure of its communities, with species interactions being a key component driving complexity (Lang and Benbow 2013). As such, species interactions are an [...]

Conceptually, trophic niche overlap and species abundance can describe the strength and number of interspecific trophic interactions to determine the competitive impact on reintroduced species or other ecosystem changes. We use an example with young-of-year (YOY) Atlantic salmon (Salmo salar) reintroductions to determine whether trophic niche overlaps and abundances limit restoration success. Using seasonal stable isotopes and abundance estimates for invertivorous fishes in three Lake Ontario tributaries, we assessed community isotopic structure, trophic niche overlap, and the impact of the niche overlap by incorporating relative abundance. Brown trout (Salmo trutta) YOY could be a strong competitor with a high trophic niche overlap with Atlantic salmon YOY, but at lower abundances relative to Atlantic salmon there is minimal impact. Stream resident fish communities appeared to partition resources across seasons such that abundant species had low trophic niche overlap to minimize overall competition with Atlantic salmon YOY given available resources, indicating niche complementarity. Through joint consideration of trophic overlap and abundance using our conceptual model, the competitive impact of community composition on a reintroduced species could be assessed. D'un point de vue conceptuel, le chevauchement de niches trophiques et l'abondance d'especes peuvent servir a decrire la force et le nombre des interactions trophiques entre especes dans le but de determiner l'impact concurrentiel sur des especes reintroduites ou d'autres modifications des ecosystemes. Nous utilisons l'exemple de reintroductions de jeunes saumons atlantiques (Salmo salar) de l'annee pour etablir si les chevauchements de niches trophiques et l'abondance limitent le succes du retablissement. En utilisant des analyses d'isotopes stables et des estimations de l'abondance saisonnieres pour des poissons invertivores dans trois affluents du lac Ontario, nous evaluons la structure isotopique des communautes, le chevauchement de niches trophiques et l'impact de ce chevauchement en tenant compte de l'abondance relative. De jeunes truites brunes (Salmo trutta) de l'annee pourraient etre d'importants concurrents dont la niche trophique chevauche fortement celle des jeunes saumons atlantiques de l'annee, mais leur faible abondance relative par rapport a celle des saumons atlantiques en minimise l'impact. Les communautes de poissons residents des cours d'eau semblent faire preuve de partage referentiel des ressources d'une saison a l'autre, de sorte que les niches trophiques des especes abondantes se chevauchent peu afin de minimiser la concurrence globale avec les jeunes saumons atlantiques de l'annee etant donne les ressources disponibles, ce qui indique une complementarite des niches. En considerant le chevauchement trophique et l'abondance ensemble dans notre modele conceptuel, nous sommes en mesure d'evaluer l'impact concurrentiel de la composition des communautes sur une espece reintroduite. [Traduit par la Redaction], Introduction In aquatic systems, stocking fish to supplement wild populations and enhance fisheries occurs globally, and it is important to determine any limitations to stocking success (Minckley 1995; Brown and [...]

The use of baselines in stable isotope studies to interpret food web structure is essential, but baseline isotope values are often assumed to be spatially homogeneous, even in large aquatic ecosystems. To test this assumption in large lakes, we quantified spatial variation in δ13C, δ15N (deposit‐feeding Oligochaeta and filter‐feeding Dreissena spp.), and δ34S (Dreissena spp. only) and density in Lake Erie between 2014 and 2016. Lake Erie's three distinct basins differ in size, bathymetry, and nutrient loading, making it an excellent system for exploring spatial variation in stable isotopes of baseline organisms. Dreissena spp. densities were highest in the western and lowest in the seasonally hypoxic central basin, while Oligochaeta densities were relatively consistent throughout Lake Erie. Values of δ13C, δ15N, and δ34S exhibited distinct spatial trends that were not related to population densities but followed the west to east direction of water flow within the lake. For both taxa, δ13C was lower in the deeper, oligotrophic east basin than the shallow, mesotrophic west basin, and δ15N and δ34S increased from west to east. Spatial patterns of low δ34S in Dreissena spp. in the western and central basins were likely related to hypoxia, whereas patterns of δ15N in both taxa were probably related to the greater influence of agricultural land uses in the western basin. Spatial trends of stable isotopes in large lake zoobenthos are driven by complex interactions of environmental gradients, which could introduce bias in evaluations of trophic structures within aquatic ecosystems that use stable isotopes. [ABSTRACT FROM AUTHOR]

Alternative reproductive tactics (ARTs) can generate considerable within-species life history variation but are often overlooked. Here, we use the invasive round goby (Neogobius melanostomus) to address a number of ecological and evolutionary questions about ARTs. Making use of a 12-year, multisite Laurentian Great Lakes data set, we show that the guarder male tactic was twice as common as the sneaker male tactic but that nonreproductive males were the most common morph. The ratio of guarder to sneaker males did not vary spatially despite a wide range of resource densities across sites. Guarders and sneakers spanned similar age ranges, suggesting that the ARTs are nonsequentially expressed. Based on short-term (gut contents) diet analyses, both reproductive tactics consumed fewer types of food and tended to consume fewer items overall when compared with nonreproductive males. Long-term (isotope) diet analyses showed that guarder males fed at a higher trophic level (higher [[delta].sup.15]N) and had a broader isotopic niche. Our results show that ARTs are an important aspect of this invasive species' breeding system and should be accounted for when assessing and managing populations. Si differentes tactiques de reproduction peuvent se traduire par des variations considerables du cycle biologique au sein d'une meme espece, dans bien des cas, elles ne sont pas prises en consideration. Nous utilisons le gobie a taches noires (Neogobius melanostomus), une espece envahissante, pour examiner differentes questions relatives a l'ecologie et Revolution touchant aux differentes tactiques de reproduction. A la lumiere d'un ensemble de donnees de 12 ans couvrant de multiples sites dans la region des Grands Lacs laurentiens, nous demontrons que les males gardiens etaient deux fois plus repandus que les males furtifs, mais que les males non reproducteurs representaient la tactique la plus repandue. Le rapport des males gardiens et furtifs ne variait pas dans l'espace, malgre une grande fourchette de densite des ressources entre les sites. Les fourchettes d'age des males gardiens et furtifs etaient semblables, donnant a penser que les differentes tactiques de reproduction ne s'expriment pas sequentiellement. A la lumiere d'analyses des regimes alimentaires a court terme (contenus stomacaux), les individus adoptant les deux tactiques de reproduction consommaient moins de types d'aliments et avaient tendance a consommer moins d'articles en general que les males non reproducteurs. Des analyses des regimes alimentaires sur le long terme (isotopiques) montrent que les males gardiens s'alimentaient a un niveau trophique plus eleve ([[delta].sup.15]N plus grands) et occupaient une niche isotopique plus large. Nos resultats montrent que l'adoption de differentes tactiques de reproduction est un aspect important du systeme de reproduction de cette espece envahissante qui devrait etre integre a l'evaluation et la gestion des populations. [Traduit par la Redaction], Introduction The round goby (Neogobius melanostomus) is a highly successful invasive species that has established new populations in both Europe and North America (Corkum et al. 2004; Kornis et al. [...]

Aquatic animals are integral to ocean and freshwater ecosystems and their resilience, are depended upon globally for food sustainability, and support coastal communities and Indigenous peoples. However, global aquatic environments are changing profoundly due to anthropogenic actions and environmental change. These changes are altering distributions, movements, and survival of aquatic animals in ways that are not well understood. The Ocean Tracking Network (OTN) is a global partnership that is filling this knowledge gap. OTN Canada, a pan-Canadian (and beyond) research network, was launched in 2010 with visionary funding by the Canadian government. In our introduction to this special issue, we briefly overview how this interdisciplinary network has used state-of-the-art technologies, infrastructure, electronic tags and sensors, and associated cutting-edge research and training programs to better understand changing marine and freshwater dynamics and their impact on ecosystems, resources, and animal ecology. These studies have provided unprecedented insights into animal ecology and resource management at a range of spatial and temporal scales and by interfacing animal movements with novel measures of environment, physiology, disease, genetics-genomics, and anthropogenic stressors. Les animaux aquatiques sont des elements essentiels des ecosystemes oceaniques et d'eau douce et de la resilience de ces systemes, ils assurent la perennite de la disponibilite de nourriture a l'echelle planetaire et supportent des collectivites cotieres et des peuples autochtones. Les milieux aquatiques planetaires font toutefois l'objet de modifications profondes causees par l'activite humaine et des changements environnementaux. L'incidence de ces modifications sur la repartition, les deplacements et la survie des animaux aquatiques n'est pas bien comprise. L'Ocean Tracking Network (OTN) est un partenariat international qui vise a combler ces lacunes dans les connaissances. OTN Canada, un reseau de recherche pancanadien (et au-dela) a ete lance en 2010 grace au financement visionnaire du gouvernement du Canada. Dans notre introduction au present numero special virtuel, nous presentons un bref survol de l'emploi fait par ce reseau interdisciplinaire des plus recentes technologies, infrastructures, des etiquettes et capteurs electroniques et de la recherche et des programmes de formation de pointe associes pour mieux comprendre la dynamique changeante des milieux marins et d'eau douce et son incidence sur les ecosystemes, les ressources et l'ecologie animale. Ces etudes jettent un eclairage sans precedent sur l'ecologie animale et la gestion des ressources a differentes echelles spatiales et temporelles, en reliant les deplacements d'animaux a de nouvelles mesures du milieu, de la physiologie, des maladies, de la genetique-genomique et de facteurs de stress d'origine humaine., Introduction Aquatic animals help meet global food needs, annually contribute billions of dollars in socioeconomic benefits and ecosystem services to society, support coastal communities, and are culturally important, particularly for [...]