A common prescription to save fish stocks is to "throw it back", pertaining to immature fish that have been caught by fishers. Interesting point I didn't think about: well that strategy may have its drawbacks, according to a Scientific American article cited by Mark Thoma (posting in the Environmental Economics blog). The unintended consequence is that fishing selects in favor of small fish - leading to a gradual evolution of populations with smaller individuals. And these individuals seemed to be duller and weaker than those that end up on our dinner table.
The answer? Not throw back any fish at all! Well in tropical Asian fisheries, the entire "trash fish" industry is built on the idea of landing and selling everything. Unfit for human consumption? There's a great big aquaculture industry (shrimp, grouper, milkfish) waiting to gobble it all up.
Of course this is an ecological no-no, so the article suggests throwing back some big ones too. I can imagine environmentally-conscious fishers doing that. Especially those using hook and line, or longliners.
Kidding aside, I think nothing beats cutting down on fishing effort, period, by whatever means - state command-and-control; individual transferrable quotas; community-based controls; whatever it takes. Otherwise we would be looking to a future of - not just smaller and dumber fish - but none at all.