We should be fixing farmed fish. When was the last time people ate wild cow. It's not sustainable for a population to be exploiting wild fish, farm properly and learn to do it quickly. As long as we eat meat, we have to do it in the least intrusive way.
Problem is the farmed fish are fed on wild fish, so it's several times less efficient than just eating whatever you would have fed them.
Algae, which can be used for many things - human consumption, farmed animal/fish feed and even fuel - can also be farmed sustainably.
I think we urgently need global legislation and enforcement of rules, as well as satellite monitoring to stop overfishing. World leaders need to work together on this.
Marine ecosystems may not come back once collapsed and that would be a huge disaster. I hope there is some kind of self-limiting dynamic here where industrial fishing becomes unprofitable, but we avoid extinctions and total collapse of ecosystems - but I'm not sure that's the case.