If an endangered plant or animal population has become extremely small in size, then individuals should be reintroduced to achieve minimum viable population size. If a chemical threatens a species, then this chemical should be banned.They "observe that political, social and above all, economic considerations prevail instead." They also suggest that politicians like to talk about being committed to saving biodiversity, but are not willing to act decisively.
But Chapron and coauthors don't give up. They intend to keep proposing specific actions for politicians to implement and "expect a clear signal from politicians that they are committed to resolving biodiversity issues and do something concrete to counter the problem." Instead I expect more frustration for Chapron and company.
Their attitude towards political action is misguided on two counts. First, economic considerations must prevail if we want socially optimal policies. Every decision has moral consequences and economics tries to make those consequences explicit in advance. Banning a chemical has other consequences besides helping a species. We should consider those other consequences. Economics helps us identify and weigh them.
Second, political systems do not choose socially optimal policies. Understanding why they don't do so is a scientific challenge. Scientists don't get frustrated by the fact that objects often fall to the ground. Scientists try hard to understand gravity.