Stewardship is exactly the opposite of tragedy of the commons.

Yes, but I guess what I'm implying is that you're just going to have multiple actors exploiting whatever they like under the banner of "Stewardship"

Literally all actors are doing whatever they like, today.

Most particularly, they are dissolving gigatons of CO2 into surface water, acidifying it.

Besides that, a few are trying to control overfishing in coastal waters they have asserted a day over, with varying levels of success, both externally and domestically, subject to politics.

*asserted authority over