deer population control due to different living environment, reproductive methods, and habitas. Pollution has major impact on the survival of marine lives so it is wise to take care of it first.
I don't know if China requires a fishing license or not. It is hard to limit the fishmen the numbers of fishes they can collect daily if they do this for a living. Marine biologists should have better idea how to reconstruct the disrupted ecology. I guess having the fishmen to target different kinds of fishes in different seasons helps?