Atlantic salmon are caught by fisheries when the fish are migrating to spawn. A new study led by the University of Helsinki explored how salmon caught at different times during their spawning migration differ from each other genetically. The study on wild salmon in the northern Baltic Sea revealed that especially in the early part of the fishing season, fishing strongly targets salmon carrying a "large salmon genetic variant." The variant guides Atlantic salmon to grow large and to mature at an older age, which is an important trait for the fishing and viability of salmon stocks.