Historically harvested for roe, lumpfish (Cyclopterus lumpus) has recently gained popularity as a biological control for sea lice in Atlantic salmon aquaculture across the North Atlantic. The use of lumpfish in salmon aquaculture involves both translocation and increasing domestication of this species. Given that wild lumpfish populations in several regions are conservation concerns, there is a critical need for a deeper understanding of how the escape of farmed lumpfish might affect wild populations.
With recent advances in genomic analysis, researchers are reporting fine-scale geographic diversity in marine species that traditionally show high dispersal and gene flow. Studies on a variety of marine species across the North Atlantic have revealed large genomic isolation of fish in the east and west Atlantic. Although genetic studies have identified regional population structuring of lumpfish in the Northeast and Northwest Atlantic, this work marks the first in-depth, broadscale genomic assessment of diversity in these populations.
In this Editor's Choice article from ICES Journal of Marine Science, Langille and colleagues used a comprehensive genomic dataset (70,000 single nucleotide polymorphisms) to investigate genomic diversity across North Atlantic lumpfish, the presence of genomic structural changes, and the scale of neutral and possible adaptive diversity in this species. They discovered a significant genomic division between the Northeast and Northwest Atlantic populations, similar to other species in the same regions, suggesting a divergence around the mid-Pleistocene. The authors also identified a chromosomal inversion—where a segment of the chromosome is reversed end to end—on chromosome 2. This inversion is predominantly fixed in the Northwest Atlantic and shows a clinal distribution, gradually varying in frequency, in the Northeast Atlantic. This structural variant appears crucial for the adaptive diversity of lumpfish, consistent with transatlantic secondary contact.
The study indicates parallel adaptive diversity associated with environmental factors on both sides of the Atlantic, suggesting convergent evolutionary adaptations—where different populations develop similar traits independently due to similar environmental pressures—have influenced lumpfish populations. These results provide a glimpse into the complex population structure of lumpfish and underscore the importance of further research for the effective conservation and management of this species.
Read the full paper, Trans-Atlantic genomic differentiation and parallel environmental and allelic variation in Lumpfish (Cyclopterus lumpus), in ICES Journal of Marine Science.
