Umbrina canosai has a continuous distribution between Rio de Janeiro (22°S) in Brazil and Rio Colorado (41°S) in Argentina, but it is mostly harvested off Rio Grande do Sul, in southern Brazil. Two stocks have been classically described with little connection between them: one migrating between Argentina, Uruguay and South of Brazil, and the other off Sao Paulo and Rio de Janeiro states, in Brazil (Zaneti Prado and Vazzoler 1976; Haimovici et al. 2006). However, this differentiation is based on old studies and cannot be considered conclusive (Vaz dos Santos et al. 2006).