Classic perverse incentive.

From https://en.wikipedia.org/wiki/Perverse_incentive

"According to the story, the British government, concerned about the number of venomous cobras in Delhi, offered a bounty for every dead cobra. Initially, this was a successful strategy; large numbers of snakes were killed for the reward. Eventually, however, people began to breed cobras for the income. When the government became aware of this, the reward program was scrapped, and the cobra breeders set their snakes free, leading to an overall increase in the wild cobra population."