The horn of the rhino is prized in Asia. The rhino is hunted nearly to extinction in Kenya because the value of the horn is worth a half of year's wages. The incentives to kill the rhino are great. In South Africa, the rhino is harvested so there's an overpopulation. When a rhino dies of natural causes, the horn is hoarded in a warehouse. If the South Africans would sell the horn the supply of horns would increase, the price would go down, and less poaching in Kenya would result.
Would selling human organs give the same results? Would legalizing marijuana?