The case of the deepwater redfish ( Sebastes mentella ) in the Gulf of St. Lawrence (GSL) is a compelling example of drastic fluctuations in annual recruitment strength, characteristic of spasmodic stocks. After three decades of low abundance, the emergence of three consecutive strong year classes in 2011–2013 resulted in an unprecedented increase in biomass. In spasmodic stocks such as GSL redfish, strong year classes sustain...

Greenland Halibut ( Reinhardtius hippoglossoides ) is a deepwater flatfish having a circumpolar distribution. Understanding the spatial connectivity and migratory patterns of this commercially valuable species is essential for ensuring a sustainable fishery; nonetheless, this information remains relatively scarce for many Greenland Halibut populations. Here we evaluate the connectivity and the population structure of halibut a...

Early life survival is critical to successful replenishment of fish populations, and hypotheses developed under the Growth‐Survival Paradigm (GSP) have guided investigations of controlling processes. The GSP postulates that recruitment depends on growth and mortality rates during early life stages, as well as their duration, after which the mortality declines substantially. The GSP predicts a shift in the frequency distributio...

In the northern Gulf of St. Lawrence (nGSL), redfish ( Sebastes mentella and Sebastes fasciatus combined) are at record levels of abundance following the strong recruitment of three consecutive cohorts in 2011–2013 and have become by far the most abundant demersal fish in the region. Understanding redfish trophic relationships is essential for the effective management and conservation of species in the nGSL ecosystem. To date,...

Redfish ( Sebastes mentella and S. fasciatus ) are back at spectacular record high levels in the Gulf of St. Lawrence (GSL) and the effects of this massive resurgence on other components of the food web remain largely unknown. To better understand the trophic implications of the surging redfish biomass within the GSL ecosystem, 3,690 stomachs containing food were collected during two periods: one characterised by low redfish a...

Increasing evidence shows that structural variants represent an overlooked aspect of genetic variation with consequential evolutionary roles. Among those, copy number variants (CNVs), including duplicated genomic regions and transposable elements (TEs), may contribute to local adaptation and/or reproductive isolation among divergent populations. Those mechanisms suppose that CNVs could be used to infer neutral and/or adaptive...

Gene flow has tremendous importance for local adaptation, by influencing the fate of de novo mutations, maintaining standing genetic variation and driving adaptive introgression. Furthermore, structural variation as chromosomal rearrangements may facilitate adaptation despite high gene flow. However, our understanding of the evolutionary mechanisms impending or favouring local adaptation in the presence of gene flow is still l...

The effects of introgression on parasitism in brook charr Salvelinus fontinalis were investigated in 28 lakes with various levels of stocking in Québec, Canada. No effect of genetic background on parasitism was found at the individual level. Body length seemed to explain most of the variation observed at this level, with largest fish being more infected. However, lakes with the greater average domestic genetic background were...

Understanding genomic signatures of divergent selection underlying long‐term adaptation in populations located in heterogeneous environments is a key goal in evolutionary biology. In this study, we investigated neutral, adaptive and deleterious genetic variation using 7,192 SNP s in 31 Lake Trout ( Salvelinus namaycush ) populations ( n = 673) from Québec, Canada. Average genetic diversity was low, weakly shared among lakes, a...

Understanding the emergence of species through the process of ecological speciation is a central question in evolutionary biology which also has implications for conservation and management. Lake trout ( Salvelinus namaycush ) is renowned for the occurrence of different ecotypes linked to resource and habitat use throughout North America. We aimed to unravel the fine genetic structure of the four lake trout ecotypes in Lake Su...

The capelin ( Mallotus villosus ) is a widespread marine fish species for which previous work has identified geographically distinct mtDNA clades, the frontiers of which are well within adult and larval dispersal capabilities. Here, we use AFLPs to test for the presence of nuclear gene flow among clades. In addition, we evaluate genetic structuring within one clade, the Northwest Atlantic (NWA). We found that each of the mtDNA...