Mexican drug cartels are expanding their reach into wildlife crime. They’re strengthening their hold on the country’s legal fisheries and using them to launder illegally caught marine animals, according to a soon-to-be released report by the Brookings Institution.

The cartels previously had been linked to trafficking of marine species such as totoaba, as well as rosewood, a timber that is coveted for high-end furniture and musical instruments. But the Washington, D.C.-based think tank’s report indicates that the crime groups have recently stepped up their trafficking of wildlife species, often to China. In exchange, the cartels sometimes receive chemicals that can be converted into fentanyl or methamphetamine.

“Instead of selling lemonade, it’s like they will be selling lemons and sugar to the cartels who then make it into lemonade,” says Brookings senior fellow Vanda Felbab-Brown, the report’s author.

Her findings draw from 73 interviews with current and former officials, environmental groups, fishers, and others in Mexico, China, the United States, and elsewhere. All were conducted on condition of anonymity.

She reports that the body parts of jaguars in Mexico also are likely being smuggled out for use in traditional Chinese medicine. Reptiles, sea cucumbers, abalone, and shark fins, she adds, are trafficked from Mexico to China as well, sometimes via the U.S.