sushi tuna

If it is truly as bad as they say, the large fishing corporations will not want to blindly fish their way out of business. In the USA, some of the best conservationists are the hunters.
However I do not see anything wrong with reasonable restrictions on fishing, as long as there is adequate protection from illegal fishing. It does no good to tell the good guys to stop fishing so the bad ones can get the profit.

It also doesn't do any good to go overboard (no pun intended) to completely ban fishing for so long a period. Much of the US has way too many deer from hunting restrictions.
the fisherman will go out in competition to get as many fish as possible to earn as much money for their crew as possible. the companies will not fish their way out of business. it is the market who will eat their way out of business.
look at the ridiculousness of the 'sushi trend' in the states, and to a lesser extant the rest of the western world. A restaurant with even the slightest hint of asian cuisine now proudly boasts that they have a sushi bar. You can sushi at that chinese place, with your thai food, sushi and tacos, sushi at the grocery store, sushi at your college cafeteria, sushi at the 7-11. There is a huge demand for it and it's not going away. When the tuna is gone we'll move onto spicy bass rolls.
I loved the concerned conservationist who can't take the step to change their habits, myself included.
But even worse are the lovely folk who see multiple signs of the damage we cause to the planet and the ripples those have and toss their hands in the air saying "so now we're to blame for xyz? i thought it was abc? it's always something isn't it"
Yes it is always something. Everything action has a reaction. In the case of very interconnected ecosystems it's usually multiple reactions, and they're usually all bad.
We are witnessing the beginning of a complete collapse of life in the world's oceans. If you doubt this, please do a little research.
A complete ban on seafood is coming.
It will either be a voluntary short-term ban that will allow fish populations time to recover (and thus ensuring our children can eat fish) or the seafood ban will be involuntary as in "we've porked and polluted our way through the oceans and all the fish are gone forever and ever" kind of involuntary.
I hope I like eating jellyfish because that's pretty much all that'll be left when the fish are gone.
Oh, and the plastic. Jellyfish and floating plastic. Yum!