Interactions between environmental factors and complex life‐history characteristics of marine organisms produce the genetic diversity and structure observed within species. Our main goal was to test for genetic differentiation among eastern oyster populations from the coastal region of Canadian Maritimes against expected genetic homogeneity caused by historical events, taking into account spatial and environmental (temperature, salinity, turbidity) variation. This was achieved by genotyping 486 individuals originating from 13 locations using RADSeq. A total of 11,321 filtered SNPs were used in a combination of population genomics and environmental association analyses. We revealed significant neutral genetic differentiation (mean F ST = 0.009) between sampling locations, and the occurrence of six major genetic clusters within the studied system. Redundancy analyses (RDAs) revealed that spatial and environmental variables explained 3.1% and 4.9% of the neutral genetic variation and 38.6% and 12.2% of the putatively adaptive genetic variation, respectively. These results indicate that these environmental factors play a role in the distribution of both neutral and putatively adaptive genetic diversity in the system. Moreover, polygenic selection was suggested by genotype–environment association analysis and significant correlations between additive polygenic scores and temperature and salinity. We discuss our results in the context of their conservation and management implications for the eastern oyster.

Repeated adaptive ecological diversification has commonly been reported in fish and has often been associated with trophic niche diversity. The main goal of this study was to investigate the extent of parallelism in the genomic and phenotypic divergence between piscivorous and planktivorous lake trout ecotypes from Laurentian Shield lakes, Canada. This was achieved by documenting the extent of morphological differentiation using geometric morphometrics and linear measurements as well as the pattern of genomic divergence by means of RADseq genotyping (3925 filtered SNPs) in 12 lakes. Our results indicate that the two ecotypes evolved distinct body shape and several linear measurements in parallel. Neutral genetic differentiation was pronounced between all isolated populations (Mean FST  = 0.433), indicating no or very limited migration and pronounced genetic drift. Significant genetic differentiation also suggested partial reproductive isolation between ecotypes in the two lakes where they are found in sympatry. Combining different outlier detection methods, we identified 48 SNPs putatively under divergent selection between ecotypes, among which 10 could be annotated and related to functions such as developmental processes and ionic regulation. Finally, our results indicate that parallel morphological divergence is accompanied by both parallel and nonparallel genomic divergence, which is associated with the use of different trophic niches between ecotypes. The results are also discussed in the context of management and conservation of this highly exploited species throughout northern North America.

Facing challenges of the COVID-19 pandemic, government agencies had to quickly react and provide guidelines for outdoor activities such as recreational fishing. Here we review information provided by provincial and state natural resource management agencies in North America during the March-April 2020 period to collate freshwater fishing regulations implemented during the pandemic. Among the 63 jurisdictions for which information was collected, 92% of jurisdictions kept the recreational fishing season open, asking anglers to practice social distancing at all times. Although recreational fishing was open in most jurisdictions, specific measures for anglers and for the fishing industry (e.g., fishing guides) were enforced to comply with public health rules. Some management agencies altered stocking practices, restricted fishing by non-residents, withdrew permits for competitive angling events, and instituted restrictions on the charter and guide industry. This overview of fishing regulations in North America in the context of a major pandemic provides fisheries managers a portrait of some measures taken by other jurisdictions.

Entre les années 1960 et 1980, la pêche récréative hivernale au Québec est graduellement passée d’une pratique marginale à une activité souvent structurée et prenant la forme de villages de pêche offrant parfois un service de location de cabanes. Malgré l’importance de cette activité, la pêche hivernale demeure peu étudiée comparativement à la pêche estivale. Cet article présente un portrait actualisé de la pêche hivernale au Québec. Les principales espèces recherchées par les pêcheurs sportifs en hiver sont le doré jaune, le doré noir, la perchaude, le grand brochet, le poulamon atlantique et l’éperlan arc-en-ciel. Dans les systèmes du fleuve Saint-Laurent, de l’estuaire et du golfe du Saint-Laurent, de leurs tributaires et du lac Champlain (baie Missisquoi), 132 sites de pêche hivernale ont été répertoriés en 2018-2019, totalisant environ 4 700 cabanes de pêche. Les informations disponibles sur la pêche hivernale dans certaines régions du Québec, particulièrement en eaux intérieures, demeurent toutefois incomplètes. La pêche hivernale présente de grandes possibilités de mise en valeur, mais elle engendre une pression de pêche qu’il importe de considérer dans la gestion des stocks de poissons au Québec.