As a portuguese I can tell you that sardine stocks are heavily controlled and regulated and there are years where the catchable tonnage is severely reduced. As

As a portuguese I can tell you that sardine stocks are heavily controlled and regulated and there are years where the catchable tonnage is severely reduced. As the fish markets are centralized, meaning fishermen need to sell their catch in a government auction house, you cannot really do industrial fishing out of allowed stock quotas. Sardines quotas are the target of heavy diplomatic negotiations with EU.