At the moment, those areas are different from marine protected areas. The origin and journey may be different, but the outcome should be the same: in situ conservation. Your governance of it would need to ensure the continued persistence of the conservation value.
As I said earlier, governance comes in many different shapes and forms. It's about degree of control and ensuring that you have the degree of control for the persistence of the conservation value in the future. There will be fisheries areas that meet that. Large areas protected for historic wrecks and war graves may also meet that, because the outcome happens to match the sustaining of the conservation value.