Participation des membres du RAQ au Congrès de l’Atlantic International Chapter de l’American Fisheries Society 2025

Trois membres du RAQ ont récemment pris part au Congrès de l’Atlantic International Chapter de l’American Fisheries Society, tenu du 21 au 23 septembre 2025.

• Joëlle Guitard, doctorante à l’UQAR-ISMER sous la direction du professeur David Deslauriers ;
• Eva Endres, co-chercheuse à l’INRS ;
• Raphaël Bouchard, doctorant à l’Université Laval
• Peyton Thomas, postdoctorante à l’UQAR-ISMER.

Leur participation à cet événement international témoigne du dynamisme et du rayonnement des membres du RAQ dans le domaine des sciences halieutiques.

Le résumé de la présentation de Joëlle Guitard:

Reduced aerobic capacity and growth performance for Gulf of St. Lawrence Acadian redfish (Sebastes fasciatus) under chronic hypoxia.

Ongoing climate change is driving oxygen declines in marine systems primarily as a result of ocean warming and changes in stratification, reducing both oxygen solubility and vertical mixing. In many regions, including the Gulf of St. Lawrence (GSL), Canada, oxygen levels have reached persistently low levels that are expected to get worse, creating potential constraints on the physiology of organisms and on ecosystem structure. Redfish (Sebastes fasciatus), a commercially important species that has recently resurged in the GSL, are now found largely in habitats where oxygen levels range between 20% and 60% DO saturation. Yet, little is known about how these conditions shape their physiological performance and energy balance. To address this, we experimentally quantified the effects of chronic exposure (106 days) under eight oxygen levels (25–100% DO saturation) on aerobic metabolism (standard and maximum metabolic rates, aerobic scope, factorial aerobic scope), hypoxia tolerance (O₂crit), food consumption, growth, condition and food conversion efficiency (FCE) in redfish. Maximum metabolic rate (MMR) and, to a lesser degree, standard metabolic rate (SMR) declined linearly with decreasing oxygenation, resulting in reduced aerobic scope. In contrast, food consumption, growth, condition and FCE remained stable down to 45% DO saturation, likely because the aerobic scope at this level remains sufficient to support food acquisition, digestion and growth when other expenditures are minimal. Below this threshold, as hypoxia becomes more severe, the reduction in aerobic scope appears to limit food consumption and growth. These results suggest that redfish can maintain energy balance under moderate hypoxia but face trade-offs between metabolic maintenance and growth under more severe conditions. Redfish in the GSL may already be living at or near their physiological limits for energy-based performance traits, and that further oxygen declines could act as major limiting factor on their fitness and distribution. These results show how environmental conditions can shift the balance between energy supply and demand, leading to trade-offs in metabolic allocation that may affect species performance under future ocean conditions.

De gauche à droite :
👉 Raphaël Bouchard (doctorant, Université Laval)
👉 Joëlle Guitard (doctorante, UQAR-ISMER)
👉 Peyton Thomas (postdoctorante, UQAR-ISMER)