The United Nations will mark the first official World Wildlife Day on March 3. This is welcome news, because unless a solution to the global poaching problem is found, iconic species such as the tiger, rhinoceros and elephant face extinction within 20 years.

At the recent London Conference on Illegal Wildlife Trade, 46 countries and 11 international organizations signed a declaration that sets out a three-pronged approach to protect wildlife. The declaration calls for increasing enforcement of laws against poaching, reducing demand for wildlife products, and the "sustainable utilization" of wildlife.

While enforcement and demand reduction are necessary and clear, less is known about what sustainable use actually means-and how it can solve the overharvesting and poaching of wild animals and plants.

Combating illegal trade has been the focus of much recent attention. But the real question is how to set up a well-managed legal trade that is sustainably managed and benefits the poor rural communities where many threatened species are found.

Giving rural communities the right economic incentives is critical to protecting wildlife. This is difficult in countries with weak governance and high levels of poverty. Trade bans are often undermined by strong incentives to supply the market demand for the animals and the products that can be harvested from them. Bribes and intimidation from poachers and illegal wildlife traders erode such incentives even further.

Still, good examples of legal trade do exist.

Peru has turned sustainably sourced products into export successes over the past few decades. Its sustainably sourced "superfoods," including sacha inchi, maca and cat's claw, have gained world-wide fame for their health benefits, and as a consequence, have provided rural Peruvians with increased incomes. Peru and other Andean countries have also been very successful in bringing vicuna populations-a relative of the llama-back from the brink of extinction. That achievement dates to a 1979 agreement in which vicuña range states gave communities on the high-altitude plateau in the Andean regions of Peru, Bolivia and Argentina the rights to shear, process and sell the fine wool. Communities have protected the animals from poachers and rebuilt the vicuña population to more than 400,000.

Africa also offers examples of wildlife sustainability. In Namibia, an ecotourism program helps villages to manage communal conservancies and protect wildlife, including rhinos and lions. A number of wildlife projects in Namibia are funded in part through the sale of hunting permits for old and sick rhinos selected by professional conservationists for culling.

Some wildlife value chains are more difficult to manage sustainably or ethically. A 2012 report by the International Trade Centre, which I run, found that the trade in Southeast Asian python skins is worth $1 billion, half of which is estimated to be illegal. The skins, used mainly by the luxury fashion industry, are harvested and processed in rural villages before being exported to Europe, thus creating economic opportunities for thousands of rural households in the region. My organization is currently working with the International Union for the Conservation of Nature and Kering, the parent company of Gucci, a key buyer of python skins, to strengthen transparency in the trade and ensure that smuggling, the abuse of permit systems, and poor animal welfare standards are addressed.

There is no single way to manage a sustainable trade in wildlife. A successful legal trade needs an enforceable system of export permits and harvest quotas-and animals and forests would still require protection through enforcement. A successful legal trade also depends on animal reproductive rates.

Wholesale opposition to legal trade in wildlife is mostly found in rich countries, which ignore the high financial and social costs to already vulnerable societies in enforcing trade bans. They also ignore the potential benefits of taxing the wildlife trade. This money would otherwise go to poachers. Isn't it better to have it go to the poor?

It may not be possible to stop the wildlife trade-the world-wide demand for these animals and the products they provide is just too strong. But this World Wildlife Day, let's focus on designing a global legal framework to ensure that communities have the incentives to conserve wildlife, rather than destroy it.