Marine mammal populations worldwide greatly benefitted from conservation measures put in place since the 1970s following overexploitation, and many pinniped populations have recovered. However, threats due to bycatch, interspecific interactions or climate change remain, and detailed knowledge on vital rates, population dynamics, and their responses to environmental changes is essential for efficient management and conservation of wild populations. In this study, we quantified pup abundance and survival of individually marked harbour seal (Phoca vitulina Linnaeus, 1758) pups during the preweaning period at Bic Island and Métis sites in the St. Lawrence