Population Genetics of Seriola lalandi Confirm Hemispheric Divergence and Reveal Genetic Structure in the Temperate Northern Pacific and Between Wild and Captive-Reared Fish.

The Yellowtail Kingfish (Seriola lalandi) is a widely distributed marine species of high commercial value for both fisheries and aquaculture. Although the taxonomic status of S. lalandi remains unresolved, this study examined its genetic structure across two Pacific Ocean regions and evaluated the genetic differentiation between wild and captive-reared fish. Globally, our results demonstrated two genetically differentiated groups of S. lalandi: one restricted to the Temperate Northern Pacific (Mexico-United States) and another to Temperate South America (Chile), with pronounced divergence (F ST = 0.208). Among wild populations, individuals from the Northern Hemisphere displayed greater heterozygosity compared to those from the Southern Hemisphere (Chile). We also detected fine-scale population substructure within the Northern Pacific (F ST = 0.078), along with consistent genetic differentiation between wild fish and captive-reared stocks in both Chile (F ST = 0.049) and Mexico (F ST = 0.120). Together, these findings support the hypothesis of two independent evolutionary lineages in S. lalandi and challenge the current notion that a single northern stock (referred to as Seriola dorsalis) exists in the Temperate Northern Pacific, highlighting the need for region-specific management strategies for fisheries and aquaculture.