Here is a great article by J. Sutinen illustrating the historical failure of command-and-control approaches to fisheries management.
ITQ systems (aka: "catch share systems") are basically cap and trade for fishing, and look like a very promising policy solution. Here is an article from EDF on the basics. More here from the Fish Project (Oregon Institute of Marine Biology). Here is a nice summary from the South Atlantic Fishery Management Council.
Here is another article from EDF regarding improved fisher safety under ITQs.
Here is a map and list of ITQ managed fisheries in the world (old data, there are a lot more now).
Read about success in Iceland (from EDF).
Are there downsides and complications to this approach to fisheries management? Yes, of course. No policy will be a panacea. Perfect solutions do not exist.