Perhaps the govt can do with the rat as they've done with the trees?
Each rat can receive an identification number, printed on a bright yellow tag in numeric and also in Braille form that can then be affixed somehow to the rat itself.
A series of PSAs can be run on television explaining that rats are an integral part of a vibrant and harmonious Hong Kong but that some rats are dangerous and must be dealt with by government specialists.
It's worked well with trees. Why not do the same for rats?