[@Sigma][@Ozerath][@Klomster]There is plenty of trade to go round and sounds good. 
Natural and Manufactored resources of Vesia include: metals, common along with rare earth metals, minerals, and alloys; solar panels; seafoods ranging from delicacies of tender fish to the humble seaweed; textiles (not cloth, but other fabrics made from sea animals); and crude oil and other fuels.
As for downtrodden masses leaving Vesia, not many now although that could change and some Vesi wanting a life outside water may respiratory to becoming cyborgs.