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The stocking of juvenile eels and trap and transport programs of large yellow (American) eels (Anguilla rostrata) were initiated in Ontario to mitigate mortalities observed at hydroelectric dams and to increase escapement from the upper St. Lawrence River and Lake Ontario (Canada). A total of 380 migrating female silver eels (stocked, trapped and transported, and wild) were tagged with acoustic transmitters between 2011 and 2014. Their migration and escapement at the exit of the Gulf of St. Lawrence, the Cabot Strait, were recorded using acoustic receivers. Escapement rates varied between 8.9% and 20.0% annually (mean = 11.4%). A high proportion of stocked eels were detected (N = 27 of 43 detected at Cabot Strait), demonstrating their ability to escape the Gulf. No differences in migration speed or crossing locations at Cabot Strait were found among the three categories. Eels crossing Cabot Strait did not display diel and tidal patterns, but their estimated swimming depth indicated diel vertical migrations. The low escapement rates observed may be related to predation events and (or) the low and variable detection efficiency of the acoustic receivers' line. L'empoissonnement d'anguilles juveniles et des campagnes de piegeage et transport de grosses anguilles jaunes (Anguilla rostrata) ont ete entrepris en Ontario pour contrecarrer la mortalite observee a l'emplacement de barrages hydroelectriques et pour rehausser le nombre d'individus s'echappant du haut fleuve Saint-Laurent et du lac Ontario (Canada). Un total de 380 anguilles argentees femelles en migration (empoissonnees, piegees et transportees et sauvages) ont ete dotees d'un emetteur acoustique de 2011 a 2014. Leur migration et leur echappement a la sortie du golfe Saint-Laurent, dans le detroit de Cabot, ont ete enregistres a l'aide de recepteurs acoustiques. Les taux d'echappement allaient de 8,9% a 20,0% annuellement (moyenne = 11,4%). Une forte proportion d'anguilles empoissonnees ont ete detectees (N = 27 sur 43 detectees dans le detroit de Cabot), ce qui demontre leur capacite de s'echapper du golfe. Aucune difference sur le plan de la vitesse de migration ou des lieux de traversee du detroit n'a ete decelee entre les trois categories. Les anguilles qui traversent le detroit de Cabot ne presentent pas de motifs nycthemeraux ou tidaux, mais leur profondeur de nage estimee indique des migrations verticales nycthemerales. Les faibles taux d'echappement observes pourraient etre associes a des evenements de predation ou a l'efficacite de detection faible et variable de la ligne de recepteurs acoustiques. [Traduit par la Redaction], Introduction Several methods have been employed by fisheries managers and scientists to mitigate fish population declines (Cowx 1994). Two such methods are stocking (in which the early life-history stages are [...]

Adult Atlantic salmon (Salmo salar) return to natal rivers several months before spawning and during summer can be subjected to temperatures that exceed their upper temperature tolerance limits. Salmon use thermal refuges to minimize exposure to high temperatures, but little information exists regarding behavioral thermoregulation by adult Atlantic salmon. We examined behavioral thermoregulation by Atlantic salmon during summer in-river residence in a Quebec river with a novel combination of thermal infrared remote sensing, river temperature monitoring, and acoustic telemetry. Adults engaged in behavioural thermoregulation at cooler ambient river temperatures (17-19 [degrees]C) than previously recorded for this species and maintained body temperature within a narrow range (16-20 [degrees]C) via use of cool and warm refuges. Adults used large, stable, stratified pools as refuges, allowing multiple individuals to thermoregulate simultaneously without leaving the pool. Low river discharge and high temperatures can be physical barriers to salmon migration, preventing them from accessing suitable refuges (e.g., pools). Identifying and maintaining connectivity to thermal refuges may be critical for persistence of Atlantic salmon populations as climate changes and rivers warm. Les saumons atlantiques (Salmo salar) adultes reviennent dans leurs rivieres natales plusieurs mois avant le frai et, durant l'ete, peuvent etre exposes a des temperatures depassant leur limite de tolerance thermique superieure. Bien que les saumons utilisent frequemment les refuges thermiques pour minimiser leur exposition aux temperatures elevees, peu d'information existe sur la thermoregulation comportementale des saumons atlantiques adultes. Nous avons examine la thermoregulation comportementale de saumons atlantiques durant leur periode de residence estivale dans une riviere du Quebec en utilisant une combinaison novatrice de teledetection infrarouge thermique, de mesure de la temperature de la riviere et de telemetrie acoustique. Les adultes font preuve de thermoregulation comportementale a des temperatures ambiantes plus faibles (17-19 [degrees]C) que celles observees anterieurement pour cette espece et maintiennent leur temperature corporelle dans une fourchette restreinte (16-20 [degrees]C) en utilisant des refuges frais et chauds. Les adultes utilisent les fosses profondes thermiquement stratifiees comme refuges stables, ce qui permet a de multiples individus de reguler en meme temps leur temperature sans quitter la fosse. Les faibles debits et les temperatures elevees peuvent constituer des barrieres physiques a la migration des saumons, les empechant d'acceder a des refuges convenables (p. ex. fosses). La reconnaissance des refuges thermiques et le maintien de leur connectivite pourraient etre essentiels a la persistance des populations de saumons atlantiques dans un contexte de changements climatiques et de rechauffement des rivieres., Introduction Salmonid species have narrow temperature tolerance ranges, making them highly susceptible to environmental warming resulting from climate change (Brett 1956; Portner and Farrell 2008; Jonsson and Jonsson 2009). Outside [...]

Downstream migration of silver American eels (Anguilla rostrata) from the St. Lawrence system was examined using acoustic telemetry. One hundred and thirty six silver American eels were tagged, and their passage was recorded using fixed acoustic arrays covering a 420 km distance along the St. Lawrence River and Estuary. Eighty-nine percent of the tagged eels were detected. All migrant eels (111) exhibited unidirectional and downstream movements, but the migration was not completed in one continuous direct movement. High individual variability in migratory longitudinal profiles was documented as well as in individual speed with no apparent relation to river discharge or morphological traits. Migration speed increased over the season. Our observations demonstrated that migrating silver American eels are largely nocturnal and demonstrated the use of nocturnal, ebb tide transport to leave the estuary. With 44 additional eels tagged and released in the maritime estuary, escapement of 180 silver American eels from the Gulf of St. Lawrence system was monitored along a 125 km acoustic line that entirely covered Cabot Strait in 2011. Surprisingly, only four of the tagged eels were recorded escaping the Gulf of St. Lawrence. La migration de devalaison de l'anguille d'Amerique argentee (Anguilla rostrata) a ete etudiee grace a un systeme de telemetrie acoustique. Cent trente-six anguilles argentees ont ete marquees et leur passage ou presence a ete enregistre grace a des lignes acoustiques fixes couvrant une distance de 420 km le long du fleuve et de l'estuaire du St-Laurent. Quatre-vingt neuf pourcent des anguilles marquees ont ete detectees. Toutes les anguilles migrantes (111) montrent des mouvements unidirectionnels vers l'aval mais la migration n'est pas menee d'une seule traite. Une tres grande variabilite individuelle au niveau des profils de migration a ete demontree, ainsi qu'au niveau des vitesses de migration sans que ces dernieres ne puissent etre reliees ni au debit du fleuve ni a des traits morphologiques. La vitesse de migration augmente au cours de la saison. Nos observations suggerent l'utilisation du transport de jusant nocturne pour quitter l'estuaire. Avec 44 anguilles supplementaires marquees et relachees en estuaire maritime, l'echappement de 180 anguilles argentees du systeme St-Laurent a ete suivi grace a une ligne acoustique couvrant les 125 km du detroit de Cabot en 2011. Etonnamment, seulement quatre des anguilles marquees sortant du Golfe du St-Laurent ont ete detectees., Introduction The American eel (Anguilla rostrata) and the European eel (Anguilla anguilla) are facultative catadromous fishes inhabiting continental waters in fresh, brackish, or saltwater environments (e.g., Daverat et al. 2006), [...]

Canada has made numerous national and international commitments to sustain marine biodiversity. Given current and potential threats to biodiversity from climate change, fisheries, and aquaculture, we provide a summary review of Canada's progress in fulfilling its obligations to protect, conserve, recover, and responsibly exploit marine biodiversity. We conclude that Canada has made little substantive progress, when compared to most developed nations, in meeting its biodiversity commitments. Much of Canada's policy and rhetoric has not been operationalised, leaving many of the country's national and international obligations unfulfilled in some key areas, such as the establishment of marine protected areas and incorporation of the precautionary approach to fisheries management. We conclude that regulatory conflict within Canada's Department of Fisheries and Oceans (DFO) and the absolute discretion exercised by the national Minister of Fisheries and Oceans contribute significantly to an unduly slow rate of policy and statute implementation. We recommend new approaches and measures to sustain Canadian marine biodiversity and new research initiatives to support scientific advice to decision-makers. Many recommendations focus on management actions required to meet existing commitments to biodiversity conservation. Overall, we conclude that the most effective strategy is to protect existing biological diversity and to rebuild depleted populations and species to restore natural diversity. By improving and protecting the biodiversity in Canada's oceans, such a strategy will restore the natural resilience of Canada's ocean ecosystems to adapt to the challenges posed by climate change and other anthropogenic activities with consequent long-term benefits for food security and social and economic well-being. Key words: policy, statute, fisheries, marine protected area, precautionary approach. Le Canada a pris de nombreux engagements nationaux et internationaux pour assurer la biodiversite marine. Compte tenu des menaces actuelles et potentielles pour la biodiversite provenant du changement climatique, de la peche et de l'aquaculture, les auteurs presentent une revue sommaire des progres du Canada pour respecter ses engagements a proteger, conserver, rehabiliter et exploiter de facon responsable la biodiversite marine. Les auteurs concluent que le Canada a fait peu de progres substantiel, comparativement a la plupart des pays developpes, dans l'atteinte de ses engagements envers la biodiversite. Une bonne partie de la politique et de la rhetorique canadienne n'a pas ete mise en pratique, ne remplissant pas plusieurs de ses obligations nationales et internationales dans plusieurs champs importants comme l'etablissement de sites marins proteges et l'incorporation de l'approche par precaution dans l'amenagement des pecheries. Les auteurs concluent que le conflit reglementaire au sein du Departement des pecheries et oceans (DPO) et la discretion absolue exercee par le Ministere des pecheries et oceans, contribuent significativement au rythme lamentablement ralenti d'application des politiques et des statuts. Ils recommandent de nouvelles approches et mesures pour supporter la biodiversite marine du Canada et de nouvelles initiatives de recherche pour supporter les avis scientifiques adresses aux decideurs. Plusieurs recommandations mettent l'accent sur les activites d'amenagement necessaires pour rencontrer les engagements actuels sur la conservation de la biodiversite. Dans l'ensemble, ils concluent que la strategie la plus efficace consiste a proteger la biodiversite existante et a reconstruire les populations et les especes afin de restaurer la diversite naturelle, en ameliorant et protegeant la biodiversite dans les oceans du Canada. Une telle strategie retablira la resilience des ecosystemes marins du Canada afin de s'adapter aux defis poses par le changement climatique et autres activites anthropogenes et d'assurer des benefices a long terme pour la securite alimentaire et le bien-etre socio-economique. Mots-cles: politique, statut, pecheries, zones marines protegees, approche par precaution., 1. Introduction Canada faces substantive challenges in its efforts to sustain marine biodiversity. Climate change, fisheries, and aquaculture are among the key threats to ocean life, albeit operating at different [...]

5.4.3. Diadromous fishes 5.4.3.1. Pacific Within the marine and diadromous fishes in Canadian waters, Pacific salmon (Oncorhynchus spp.) are among the very few that can be termed 'iconic' (others being [...]