The article explains why bans may be preferable to market-based solutions in this case. The gist is that it's easier to enforce a ban ("nobody is allowed to fish here until 2022! get out!") than any kind of pricing mechanism ("let's see, yesterday a random Chinese trawler came in and picked up, I guess, 4 tons of mackerel, so add that to the week's total and..."), and many of the relevant countries with depleted fisheries may not even have the regulatory capacity for the latter.