An international investigation uncovers how criminal networks traffick parts of the totoaba, an endangered fish caught in Mexicoâs Gulf of California, to overseas underground markets. Andrea Crosta, from Earth League International, explains how.By Teresa TomassoniIn Mexicoâs Upper Gulf of California, a lucrative and deadly wildlife trade continues to threaten the survival of the worldâs most endangered marine mammalâthe vaquita porpoise. At the center of this crisis is the totoaba, a large, endangered fish whose swim bladder is prized in traditional Chinese medicine for its purported health benefits. Some of these bladders can sell for tens of thousands of dollars in illicit markets, sustaining a transnational supply chain of poachers, traffickers, and buyers that spans Mexico, the United States and various countries in Asia.