Why not propose alternate source of income or better technique of harvesting.
The real disturbing thing we saw here is that the way they harvest is inhumane. If the shark, a known predator, is kill in short order, then there is no more problem. As for waste, may be we can create better dish using shark meat or such(that's what we are doing with lion fish) In fact, the shark are not really wasted because where they are harvested, they will be eaten by other sharks in no time. I guess the shark flesh would not pollute the ocean at that quantity. Let them die slowly is very inhumane. However, I seen how the industry skin the shrimps alive, million times a year. A lot of live shrimps are skinned live too!!!!! Do we ban all skinned shrimps end products-I guess not. We continue the cruelty for they are our food. If we can make use of the the shark flesh, and kill them in short order then it will be acceptable to our own so called high moral ground.
It's actually in the film that the fisherman know it's illegal to land the fins without the body attached, they still do it, meaning clearly that they do not care about the law banning such action. It's clear money is at play. A capitalistic way to solve the problem would be finding them something they can harvest and make more money than the shark fin industry.
I also see a problem that the fisherman do not observe the endanger list, either they don't care or they do not know. The only hope is after we promoted the idea to them about the theory of endanger list, they would start to realize the importance and act on their own.