Abstract

The greater amberjack (GAJ), Seriola dumerili, is a popular gamefish found circumglobally in tropical and subtropical waters. GAJ are also commercially exploited in the US Gulf (Gulf) and South Atlantic. In US waters, a two-stock model for management that distinguishes a Gulf and an Atlantic stock has been implemented, but this division has yet to be supported with genetic data. Incorrect management of a subdivided stock, ignoring sub-units for example, can lead to local overexploi-tation and extirpation as well as the loss of unique genetic characteristics of local stocks (Carvalho & Hauser 1994). Accordingly, the definition of management units and their geographic boundaries requires understanding of the structure of populations and their connectivity patterns.