Genetic structuring in Atlantic haddock contrasts with current management regimes

The advent of novel genetic methods has made it possible to investigate population structure and connectivity in mobile marine fish species: knowledge of which is essential to ensure a sustainable fishery. Haddock (Melanogrammus aeglefinus) is a highly exploited marine teleost distributed along the coast and continental shelf on both sides of the North Atlantic Ocean. However, little is known about its population structure. Here, we present the first study using single nucleotide polymorphism markers to assess the genetic population structure of haddock at multiple geographic scales, from the transatlantic to the local (fjord) level. Genotyping 138 SNP loci in 1329 individuals from 19 locations across the North Atlantic revealed three main genetic clusters, consisting of a Northwest Atlantic-, a Northeast Arctic- and a Northeast Atlantic cluster. We also observed a genetically distinct fjord population and a pattern of isolation-by-distance in the Northeast Atlantic. Our results contr...