The native range of Japanese carpet shell is the Eastern Pacific but the species is already well-established in Northern America and Europe after the introduction in the 20^th century. A study on population genetics was performed in these 2 regions but Portuguese seabeds were not included (Cordero et al. 2017). The species can be found in different rivers (Tejo, Sado) and lagoon systems (Ria de Aveiro, Ria Formosa, Lagoa de Albufeira) but no systematic assessment is known to exist apart occasional studies to characterize the fishery (Garaulet 2011)(Ramajal et al. 2016)(Carvalho 2017).