I apologize that I am more of a lurker than an active contributor... but this is an interesting discussion for sure.
The white seabass population in California is a huge success story attributed mainly to the gill-net ban. The first recruitment year after the ban saw a stock of fish that are still being caught today. Every year the average size of seabass we catch down here is going up.
To me, the real issue is downward price pressure. Americans expect cheap and abundant protein. And at current pricing, it is not sustainable for small ma and pop shops. It encourages, perhaps even necessitates factory fishing vessels in order to make profit.
When I was young, we couldn't afford salmon or shrimp. So we ate cube steaks and burgers. Today, salmon and shrimp are $5.99/lb most times I look at the supermarket. That is cheaper than most beef. I am a free market capitalist, so I'd hate to suggest pricing regulations... but I wish there was an educational campaign to teach people that salmon, shrimp, white seabass (which often goes for $32.95/lb at Whole Foods) are resources that are meant to be consumed infrequently and to be respected and never wasted. I.E. luxury items.
When I have a BBQ and buy salmon, most people (myself included) can and will eat nearly a pound of fish. Gluttonous by any definition... and certainly far more protein than any of us need at a sitting.
To me, if I never saw salmon below $10.95 per pound, it wouldn't make a single bit of difference in my life. $15.95 I'd probably only eat what I needed when I wanted to eat salmon. Prices above that I'd consume it rarely and that would probably be the right thing.
Fishermen would need to catch less, because they could sell for a higher price. And I think the fishery would be helped tremendously.
Perhaps an economist can suggest a solution???