The "owner of the fish" is mankind in common, of course. Generally, the owner's interest is defended by the government of a given territory. But the government is not always the best steward of the long term sustainability of the land or its resources. This is for the same reason as before: it is very easy to measure short term success, but difficult to measure long term success. And even when you can predict long term success, many people will argue that you shouldn't take it into account.