To the distress of its opponents, the industry has grown significantly in the 13 years since Chinese officials first pledged to gradually reduce the number of captive bears to 1,500 from 7,000. These days, there are an estimated 20,000 bears on nearly 100 domestic bear farms, an expansion fueled in part by marketing efforts promoting novel uses for bear bile, like a hangover cure for well-to-do businessmen who engage in nightly carousing.

Besides China, there are bear bile farms in Vietnam, Laos, Myanmar and North Korea.

For animal welfare advocates, the challenge is to convince Chinese consumers that the barbarity of bile farming outweighs the supposed medicinal benefits of natural bile — or that the risks of consuming bile from sick bears pumped with antibiotics are high.

In addition to circulating videos of harvesting practices, organizations like Animals Asia wield a number of secret weapons, including Sun Li, Caesar and Buddha. They are among the 158 rescued bears that roam the group’s sanctuary outside Chengdu. The center receives school groups, celebrities and Chinese reporters, all of whom are invariably smitten with the bears.

Most of the animals came from farms closed by the authorities because they had fewer than 50 bears, a violation of industry rules. The bulk of the animals are Asiatic black bears, a threatened species better known as the moon bear for the distinctive white crescent that arcs across its chest.