The practice of tiger farming in countries such as China, Thailand, Laos, and Vietnam is perpetuating the poaching of endangered wild tigers across the 13 nations that make up the animals’ historical range, according to conservationists.

The problem is not relegated to Asia. Thousands of captive tigers are bred in the United States—and those big cats could be exploited by wildlife traffickers, feeding demand for tiger parts on the black market.

Now, 45 wildlife and conservation groups are calling for an end to tiger breeding for commercial purposes and for a phase-out of tiger farms worldwide.

“Many tiger range states have devoted considerable resources to conserving their wild tigers—efforts that are being undermined by the existence of these farms,” Michael Baltzer, head of World Wildlife Fund’s global tigers initiative, said in a statement. “Closing tiger farms will help countries to achieve the ambitious goal of doubling wild tiger numbers by 2022.”

How does shutting down tiger farms help wild populations? According to the Environmental Investigation Agency, more than 200 tiger breeding centers operate across Asia, housing between 7,000 and 8,000 tigers. That’s thousands more than the estimated 3,900 tigers left in the wild, which occupy only about 7 percent of their historic range.

Tiger breeding centers are often tourist attractions, where people pay to have their photos taken with the big cats. One such tiger farm was Thailand’s now-closed Tiger Temple, which was found to be trafficking tiger parts.

Wildlife advocates believe Tiger Temple is not unique and that many of the breeding centers are likely to be involved in such illegal trade.

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In the U.S., it’s estimated that more than 5,000 tigers reside in captivity at petting zoos and breeding facilities.

“Our concern is that when these cats get too large, costly, and dangerous to be profitable, they can be funneled into the illegal trade in tigers and tiger parts,” said Leigh Henry, wildlife policy expert at World Wildlife Fund. “Disincentivizing private tiger breeding will gradually decrease the number of tigers in the U.S. to a more manageable number and make them less vulnerable to illegal trade. Continued strong U.S. action in our own backyard in support of tiger conservation sends a positive signal to Asian governments considering action around their tiger farms.”

In April, the U.S. Fish and Wildlife Service cracked down on unregulated trade of tigers, requiring all facilities that want to transfer tigers across state lines to be registered and in turn making it easier to detect illegal wildlife trafficking.

Still, wildlife advocates think more could be done, including banning public contact with tigers for photo ops.