Some areas are getting destroyed but other countries are very good at managing their fisheries, England, Norway, Australia, Canada and more will be producing wild fish ongoing I would expect.
There definitely seems the need for some international waters rules to be agreed on, but given today's politics it seems unlikely the major powers would approach that with goodwill.
The thing with all those areas is that those countries have the resources to police their waters and would absolutely seize vessels that were in breach of their or international laws.
And if an illegal fishing armada turned up would very likely sink a few vessels to send a message.
There definitely seems the need for some international waters rules to be agreed on, but given today's politics it seems unlikely the major powers would approach that with goodwill.