Global, regional, and cryptic population structure in a high gene-flow transatlantic fish

Area of Science:

• Marine Biology
• Population Genetics
• Fisheries Science

Background:

• Lumpfish (Cyclopterus lumpus) are widespread North Atlantic fish with high dispersal potential.
• This potential suggests weak population structure, contrary to initial expectations.
• Understanding genetic structure is crucial for effective fisheries management and aquaculture.

Purpose of the Study:

• To investigate the population genetic structure of lumpfish across its North Atlantic range.
• To identify distinct genetic groupings and assess gene flow.
• To inform management strategies for lumpfish stocks and aquaculture applications.

Main Methods:

• Utilized two genetic approaches: 4,393 genome-wide SNPs in 95 individuals and 139 discriminatory SNPs in 1,669 individuals.
• Analyzed samples from 10 and 40 locations across the North Atlantic, respectively.
• Employed population genetic analyses to infer structure and divergence.

Main Results:

• Identified significant population genetic structuring, with a primary East-West Atlantic split and a distinct Baltic Sea population.
• Revealed further differentiation in the English Channel, Iceland, and Greenland.
• Discriminatory loci showed higher divergence, uncovering finer-scale substructures within regions like North America, Iceland, and Norway.

Conclusions:

• Observed high population structuring contradicts lumpfish's dispersal potential, suggesting natal homing behavior.
• Distinct genetic groups indicate local adaptation and necessitate careful consideration for management units.
• Findings impact decisions regarding lumpfish stock exploitation and sourcing for cleaner fish use in aquaculture.