Nonetheless, bears continue to be hunted in the wild to supply the bile farms. A survey in 2000 reported that almost all of the farms in the study supplemented their captive population of bile bears with wild-caught bears. This is claimed to be necessary because of difficulties with captive breeding. Consumers of bear bile have a strong preference for bile produced from wild bears; bile from farms may, therefore, not be a perfect substitute for bile from wild bears. Bear farming in Laos may be increasing the incentive to poach wild bears.