Quota systems and controls keep fisheries from immediately collapsing, but there is a real difference between "won't collapse in 3 seasons" and "sustainabe over generations." The wider ecosystem effects are not really known. Big ocean, millions of species, lots of side effects.. bycatch, pollution. There are species we don't know exist going extinct, almost certainly, because of commercial fishing.
Commercial fishing is something we need to grow out of. On land, hunting is rarely a conservation issue today. Habitat is the problem. In the ocean, there is no reason (besides fishing) why we can't have mostly undisturbed ecosystems.
Agriculture replaced market hunting. Sustainable agriculture can replace market fishing. It's the responsible choice to make as a society.