If humans don't nuke themselves but keep fishing as they do, the fish will absolutely not recover. Fish aren't magic.

A few decades is a long time - we overfished the grand banks to near extinction in the 90's and they still haven't recovered[1].

1. https://en.wikipedia.org/wiki/Collapse_of_the_Atlantic_north...

A few decades... Give it like 8

Ah so the reasonable scenario is that things will be ruined for the lifetimes of almost everyone currently on earth. Not really that weird that some people would see that as a negative.

There's no recovery from extinction, and extinction is on the table here.