Genomic characterization and insights of local adaptation in Norwegian juvenile lumpfish populations

Abstract

The lumpfish (Cyclopterus lumpus Linnaeus, 1758) has for many years been an attractive target for the roe fisheries in Norway and has more recently become an important cleanerfish in the salmonid farming industry for the control of salmon lice (Copepoda: Caligidae). Despite this, there is a lack of knowledge about several life aspects of the species and studies on its genetic structure have been inconsistent. It is therefore uncertain how scenarios involving, for instance, overfishing or escaping of lumpfish from the fish farms might affect the natural stocks genetically and biologically. To initiate the investigations of how human activities might affect lumpfish in nature, this project aimed to clarify the genetic structure and reveal potential signatures of local adaptation in juvenile lumpfish in Norway. Whole genome sequencing was performed for 30 individuals from three different locations and a set of 607,663 SNPs were selected for downstream genetic structure analyses. Significant genetic differentiation was detected between the northern and southern parts of Norway, with further discrimination of two populations within one location in the north. Lumpfish separated by long geographical distances showed greater differentiation than those collected at locations more proximate to each other, but no significant correlation was detected. Loci putatively under selection were identified and revealed population structure at smaller geographical scales. These findings suggest that multiple driving forces may have contributed to population structuring in lumpfish. The study presents evidence for genetic structuring of Norwegian juvenile lumpfish and discriminate at least three populations, and further studies should therefore contribute to establishing sustainable management practices for the species.

Keywords: Lumpfish, Cyclopterus lumpus, population genetics, whole genome sequencing, SNPs, genetic structure