Looked at empirically, the surest was to ensure the survival and proliferation of any species is to figure out a way to make it economically valuable. Certainly there are species made extinct by economic exploitation, but looking at that group of species compared to the number of species made extinct by less direct means such as habitat destruction and introduction of non native species, the number of species bought and sold into extinction is negligible from a mathematical standpoint. Indeed many species exist today solely because of captive populations in zoos and people's homes. Since suitable habitat no longer exists for these species, outlawing keeping them in captivity would be the final nail in their coffin. Then there are the species which are not yet extinct, but on the edge. A species with which I have considerable experience is the Blue Throated Macaw, Ara glaucogularis. Endemic to a small specialized palm savannah habitat in Bolivia, its current wild population is estimated to be between 100 and 300 individuals in disjointed populations. Its habitat is being converted into farmland, and outlook is bleak. I'm on the high side of 50, but barring unseen buses and falling pianos it is likely I will see a world without wild Blue Throats. But barring any unforeseen circumstances I will die with one on top of me. She's on my shoulder as I type this. The captive population is in the thousands. No doubt collection for the pet trade initially hurt the species, but the offspring of those individuals are the only long term future the species has. This is a complex issue, but most of the complexity is strictly because of the emotions stirred up by the mere mention of the subject. The hard numbers are not difficult to understand.
