Genetic analyses of ling (Molva molva) in the Northeast Atlantic reveal patterns relevant to stock assessments and management advice

AbstractThe ling, Molva molva, is a commercially exploited demersal gadid fish distributed throughout the Northeast Atlantic. Here, we provide the first study of population genetic structure by genotyping 6 geographically distinct samples with 11 microsatellite DNA markers. The results rejected the hypothesis of a single ling stock in the Northeast Atlantic, and rather suggested the existence of two or more groups, with the main grouping represented by a western (comprising Rockall and Iceland) and an eastern group (Faroe Bank, Norway). Significant genetic differences coincide with an expanse of deep water that probably limits connectivity facilitated by migration. Retention in gyres and directional oceanic circulation may also prevent drift and admixture during planktonic life stages. On the other hand, the apparent absence of genetic differentiation within the eastern part of the distribution range indicates gene flow, perhaps by larval drift and migration, over considerable distances. Our findings should contribute to improving stock assessments and monitoring and thus fisheries management advice for the ling.