Illegal fishing is a problem alright, and it's not just shark fins. For years now, foreign poachers have been strip-mining Australia's off-shore reefs for trochus shells as well. Some local aboriginals recently caught an Indonesian boat
in flagrante delicto.
Story is at:
http://www.theaustralian.news.com.au/common/story_page/0,5744,17025163%5E2702,00.html
The root cause of all this is the large profits to be had from poaching shark fin and trochus are just too attractive to impoverished Indonesian fishermen. They have families to feed, and they will risk large fines, arrest and imprisonment, not to mention drowning in unseaworthy little boats.
Some poverty-stricken fishermen can be caught in a vicious cycle. After we arrest a crew and burn their boat, the crew are returned to Indonesia, where the boat owner demands that the crew pay back some of the cost of the lost boat. Of course the fishermen have no money, so they are effectively indentured to the boat owner, who then orders the hapless guy back to Australia on the next illegal fishing trip.
How do we solve the problem? Just like heroin, or ivory, or rare animals, people will traffic, smuggle and poach their way past all the deterrents on earth if the potential rewards are big enough. So, it comes back to demand. Unfortunately with many Asian economies growing rapidly, and with fewer sharks around (the Indonesians have fished theirs out), we have a combination of richer consumers competing for a dwindling "resource", so we shouldn't expect the price to come down soon. You could always attack the demand by attempting to change the attitudes of the final consumers in Asia, but no-one seems to be enjoying much success there. And look at the Japanese whaling situation.
If anyone's interested, the Australian government's official strategy is outlined here,
http://www.afma.gov.au/management/compliance/illegal/default.htm
but the long term outlook is not good. All anyone can really do at the moment is make it as expensive as possible for the illegal fishermen and their bosses back in their home villages. We can't do much about the rewards on offer, but we can certainly raise the risk that they won't make a profit.