Publication Abstract

The European sea bass (Dicentrarchus labrax) is a commercially and recreationally important fish species that is widely distributed across the Northeast Atlantic and Mediterranean Sea. Two distinct lineages that represent Atlantic and Mediterranean have been previously identified with a hybrid zone present close to the Almeria-Oran Front. The presence of fine-scale population structure within the Northeast Atlantic region is less clear. Here, we investigated population structure in adult samples obtained from the northern part of the Atlantic range surrounding the UK, Ireland, Belgium, the Netherlands and Norway along with outgroups from Portugal and the Mediterranean using a panel of 41K single nucleotide polymorphism (SNP) markers. Population structure among Northeast Atlantic samples was very low (global F_ST= 0.00022 & 0.00032) in spawning and feeding season data sets respectively, with very low pairwise F_ST (i.e. genetic differentiation) among sample pairs. However, average F_ST was higher among spawning samples than feeding samples, suggesting some biological meaningful population structure. The highest pairwise F_ST values at both ICES rectangle and division scale involved a sample from the west of Ireland. We found no evidence of a gradient in ‘Mediterranean’ ancestry within the samples collected around the UK, or evidence of isolation by distance within the samples collected. In summary, there is no evidence that sea bass in different ICES divisions within the Northeast Atlantic represent genetically separate populations.

Martin I Taylor, Philip D Lamb*, Ilaria Coscia, David S Murray*, Mary Brown*, Thomas C. Cameron, Phil I. Davison*, Howard A. Freeman, Katerina Georgiou, Fabio Grati, Thrond Haugen, Paraskevi K. Karachle, Richard Kennedy, Thomas Lanssens, Harriet Lincoln, Filipe Martinho, Ian McCarthy, Pablo Pita, João Carlos Oliveira Pontes, Marta PujolBaucells, Mafalda Rangel, William Roche, Valerio Sbragaglia, Anna M. Sturrock, Michelle L. Taylor, Ciara Wogerbauer, Pedro Veiga, Sieto Verver, Marc Simon Weltersbach, Kieran Hyder*