Policies to promote biodiversity and protect endangered species can be implemented today. But government is probably the worse tool to do it. People that own private property are more likely to protect the environment. Though there are cases of mining companies poisoning the waters, for example by using acids to mine gold, but if the surrounding land owners were able to go after offending mining companies more affectively (therefore protecting their own property), them the environment would be better served. And that is why organizations like the Elk Foundation are buying land to preserve it for hunting, but as a side effect protecting all species in their land.
We can implement protective policy as a nation, that's all fine and good but there is one issue with this, It's just us. Third world countries that can't afford to implement policy will still be the ones polluting the world and killing animals that should not be killed. The fact of the matter is, we are just one small nation, and sure a few other nations will join in with us. But everyone wont, and for this policy to be effective everybody needs to cooperate on it, and that is highly unlikely to happen.