Well, the issue is essentially the ships that do not have to be registered. When you don't even have a registry it's difficult to find the official owner. Even so, we may have a former owner who sold many years ago but the registry has not been updated, so we are trying to track back and so on and so forth.
The act leaves us some leeway in terms of the definition of “shipowner”. The person who is actually in charge of a vessel may be, under some section of the act, deemed the owner, so we can try to catch this person, but it's not that easy. Definitively having a registration system that is a bit more accurate would help.