Genetic differentiation, temporal stability, and the absence of isolation by distance among Atlantic herring populations

The genetic variation among 17 spawning groups of Atlantic herring Clupea harengus was assessed at several temporal and spatial scales using nine tetranucleotide microsatellites. Pan-Atlantic samples were drawn from the Scotian Shelf, the Celtic Sea, the Baltic Sea, and coastal Iceland. Significant differentiation was observed between northeastern and northwestern Atlantic herring (F-ST similar to 0.065) and among northwestern Atlantic spawning groups (max F-ST = 0.014) at the spatial scale of the Scotian Shelf. Geographic distance among Scotian Shelf collections did not explain the pattern of genetic differentiation observed (e.g., lack of isolation by distance). The temporal proximity of collections (as measured by days between collections) explained 30% of the pairwise population differentiation (P = 0.0025). Allele frequencies of replicate samples and year-class analyses demonstrate temporal stability at four locations.