"Imagine a group of 100 fisherman faced with declining stocks and worried about the sustainability of their resource and their livelihoods. One of them works out that the total sustainable catch is about 20% of what everyone is catching now (with some uncertainty of course) but that if current trends of increasing catches (about 2% a year) continue the resource would be depleted in short order. Faced with that prospect, the fishermen gather to decide what to do. The problem is made more complicated because some groups of fishermen are much more efficient than the others. The top 5 catchers, catch 20% of the fish, and the top 20 catch almost 75% of the fish. Meanwhile the least efficient 50 catch only 10% of the fish and barely subsist. Clearly, fairness demands that the top catchers lead the way in moving towards a more sustainable future."
http://www.realclimate.org/index.php/archives/2009/05/the-tragedy-of-climate-commons/langswitch_lang/zh#more-680

Unless fishing is some form of entertainment, it seem to me that the 50 inefficient fishermen should stop fishing. Perhaps find work offering whale watching and scuba diving or whatever. Why would you want to promote inefficient fishing? What the inefficient fisherman should do if there wasn't this shortage of fish was to invest in improve their efficiency- but this supposed shortage fish would probably result in this being a poor use of capital/labor/time on the part of the fisherman.

Now, let's look at the math, 20 catch 75%, and 50 catch 10%, unmentioned is the 30 fisherman getting only 15% of the catch.
So the 50 should quit fishing- perhaps governments can buy them out. The 30 fisherman should pool the resources [merge] and invest their capital to improve their efficiency. If you want to promote fairness, one could allow the 30 which if they reduced their number to say 20 to be entitled to 8% of the 10% gained by getting rid of the 50 inefficient fisherman.

Of course fish stocks aren't this predictable, nor does it make a lot sense for the govt to be involved in this level of managing the fishing- the market will essentially do what I described above if left alone. Some reason politicians could involve themselves is to claim they are lessening tension [and make voter happier] or there could actually something wrong with what the fisherman are fishing- such as causing some imbalance in the ecology- perhaps due to irrational market forces or other unique circumstances.

Of course it is possible that the supposedly inefficient fishermen may be getting more value for their fish- they might selling the fish to high price markets like restaurants, so they may not actually be inefficient but simply selling their fish for more money per lb and be in the different market than the more "efficient fishermen". And/or the inefficient may only fish in limited times of the year or limited parts of the day- because various reasons. Or in other words, the statistics could be inadequate to capture whether or not the fisherman are inefficient or not.

But in general what should done is for marine biologists to study the environment and determine in what ways commercial fish stocks can be more productive and make sound recommendations. And in general, govt should avoid subsidizing fishing.