Genome-wide SNP based population structure in European hake reveals the need for harmonizing biological and management units

Abstract

Despite its economic importance, the population structure of the European hake, Merluccius merluccius, is unresolved, and the species is assessed based on two stocks (northern and southern) separated by the Capbreton Canyon. In order to shed light into the European hake population structure, we used Restriction-site-Associated DNA sequencing (RAD-seq) to discover and genotype thousands of genome-wide single nucleotide polymorphisms in more than a hundred samples. Our population genetic inferences confirm differentiation of Mediterranean and northeast Atlantic locations and reveal management relevant information within the latter. First, hake in the Norwegian Sea is genetically different from that of the rest of the locations under study and, second, samples from the eastern Bay of Biscay and the northwestern Iberian Peninsula are not genetically different. These results imply that samples from the northern stock belong to different genetic populations, and that samples belonging to locations included in the northern and southern stocks are part of a single genetically homogeneous population. Although the definition of the boundary between the northern and southern stocks and the potential need for additional stocks still requires further analyses, the mismatch between biological and management units should already be considered in further assessments of European hake.