China’s insatiable appetite for animal parts that have no apparent scientific value as either medicines or tonics is playing havoc with a rare fish and the world's smallest porpoise, both of which inhabit Mexico’s Gulf of California.

The fish, the totoaba, can grow to as long as two meters and weigh as much as 100 kg. The vaquita – Spanish for "little cow” – is very much smaller. The totoaba’s swim bladder, which allows the fish to regulate buoyancy to dive or rise as it fills with air or empties, is in huge demand in Hong Kong and the Pearl River Delta as fish maw, known as jin qian min, translated as “golden coin maw” or “money maw” because of its perceived kinship to the Chinese bahaba, or giant yellow croaker, a prized species used in traditional medicines and tonics that itself has been overfished to the point that it is now critically endangered.

The fish maw is known colloquially as “aquatic cocaine” because of the huge prices it fetches. The illegal catch are believed to be smuggled into Californian and then shipped to China and Hong Kong, according to Greenpeace., although the price has lately nosedived from as much as HK$1 million in 2011, Greenpeace said, to about HK$200,000 today. The bladders are used to make soups that supposedly cure joint pain or relieve pregnancy discomfort. For a short period, the fish maws became a speculative investment. Since the price has fallen, fishermen in Mexico and in the illegal supply pipeline are believed to be holding their catch off the market until it recovers.

The smaller vaquita is basically collateral damage, according to the Environmental Investigation Agency, a London-based independent environmental watchdog, in a report to the Convention on International Trade in Endangered Species (Cites). Despite the fact that both the totoaba and the vaquita are critically endangered and fishing has been banned for totoaba since 1975, poaching using gill nets is rampant. While the totoaba is the main target, gill nets take the vaquita as well. The smaller fish’s population was estimated at 547 in 1997 but since has plummeted to just 95 because of fishery bycatch. It is now considered to be the world’s most critically endangered fish, expected to go extinct in 2018 unless drastic measures are taken to save it.

Like shark’s fin, tiger penis and other tiger bones, rhino horn, bear bile, Saiga antelope horn, turtle fat and sea horses, scientific tests have found no medicinal value in fish maw. Nonetheless, all are being hunted to extinction or, in the case of tigers and bears, farmed for their parts to be used in medicines. But despite the fact that traditional Chinese medicine – TCM, as it is known – has been incorporated into China’s state medical system and given full backing in universities, becoming a US$60 billion industry in China and Hong Kong, there are few drugs with true medicinal value. It is believed an herb that looks like the heart, the hand or the penis can be used to treat ailments in those body parts. The power of a tiger can supposedly be extracted from its bones, the strength of an ox from its gallstones.

“This alarming, accelerated decline (in vaquita) is attributed to the resurgence of an illegal fishery for totoaba, the swim bladders of which are highly sought in Hong Kong and southern mainland China,” according to the IEA. “The demand for dried totoaba swim bladders is threatening not just the totoaba but also the vaquita – the world’s most endangered marine mammal, which is accidentally caught in the illegal nets set for totoaba. The totoaba itself has been listed as critically endangered since 1996 although no population estimates have been carried out since fishing for the species was banned in 1975.

Greenpeace conducted an undercover investigation in Hong Kong, particularly in the Sheung Wan district north of Central and identified at least 13 shops including both wholesalers and retailers as potential sellers. Seven showed Greenpeace researchers dried totoaba bladder samples in the shop. Others sent photos of their inventory bladders, often stored in other regions including China or the US via Wechat.

“This investigation offers a snapshot of the market: these are just a few examples Greenpeace has come across which may or may not be enough to summarize the whole black market situation in Hong Kong.”

The EIA, in its own investigation, identified numerous online platforms including Facebook that trade in fish maw. Many users even post information on the best routes to smuggle totoabas into Hong Kong and China, according to the organization.

The EIA recommends strengthening enforcement efforts and increasing information sharing, cooperation and raising awareness. The report also recommends making the two-year gillnet ban permanent.

Over the past five years the Mexican government has increased efforts to protect the vaquita, investing more than $30 million in conservation efforts including a compensation scheme (‘rent-out’, ‘buy-out’, and ‘switch-out’) to eliminate gillnetting and industrial trawling within the refuge, but the vaquita has continued to decline.