The axolotl: critically threatened in Mexico, but a popular pet in China

The smiley-faced salamander has long captivated audiences and perplexed scientists. Can its popularity as a pet help save it from extinction in the wild?

Share

Mexican axolotl

The axolotl, an animal venerated but endangered in the wild in its native Mexico, is popular as an exotic pet in China, with its fans sharing thousands of videos of the salamander online (Image: Helmut Corneli / Alamy)

Most Mexicans will agree that the axolotl, a native species of amphibian, is something of a national celebrity. It’s even set to star on the country’s 50 peso bill, due to be released next year. Axolotls were once so abundant that they were a staple in the indigenous Mexica diets.

The Mexica (or Aztecs) who inhabited central Mexico 500 years ago believed axolotls were sacred and came from the god Xólotl. Today scientists value them for their capacity to regenerate every limb, and even portions of their brains.  

But despite their historic and scientific importance, axolotls in the wild are now critically endangered. Few remain in the canal systems of Xochimilco on the southern edge of Mexico City, the salamander’s endemic habitat. The paradox is that while wild populations continue to decrease, the axolotl is also becoming one of the most widely distributed amphibians in labs and pet shops around the world, particularly in China where fans post thousands of videos of the salamander online. Meanwhile, conservation efforts in Mexico push ahead in adverse conditions.

The decrease in the wild axolotl population

A few causes are behind the axolotl’s rapidly decreasing numbers: breakneck urban growth in the Xochimilco borough and poor city planning, which allows waste water and fertiliser into the canals that choke wildlife. In addition, in the 1970s, the United Nations launched a campaign to stock the Xochimilco canals with tilapia and carp to feed residents. The fish, however, had no natural predators in the area, allowing them to quickly take over and feast on young axolotls. 

99%

The decline in the axolotl population of Xochimilco canals since 1998

According to the most recent census, the axolotl population is less than 0.6% of what it was a little over two decades ago. The first census, taken in 1998 by scientists at Mexico City’s Metropolitan Autonomous University (UAM), estimated that the area held 6,000 axolotls per square kilometre. In 2014, this had declined to 34 per square kilometre.

While biologists would like to update their study – to see if recent conservation efforts have had an effect on the amphibian’s numbers – the Covid-19 pandemic and a lack of funding from the government have stopped the project in its tracks. “It’s sad to see the amount of money that goes to these kinds of projects,” said Horacio Mena González, a biologist at Mexico’s National Autonomous University (UNAM).

Conservation efforts

Mena González and a team of scientists at UNAM have implemented a trial programme, called the Chinampa Refugio project, to create safe havens among the Xochimilco canals for axolotl to once again grow and thrive. 

Working with local residents – who have long farmed in the area’s chinampas, a kind of floating garden introduced by the Mexica – Mena González hopes to reduce the use of pesticides in favour of sustainable, organic farming to release helpful nutrients into Xochimilco’s waters. 

The introduction of a series of filters in the canals to keep out contaminants and predators from the main waterways could also provide axolotls with the space to recover their numbers. 

So far, 30 safe havens have been installed, and the team would like to increase this to 60. 

In the meantime, other organisations are looking to raise awareness and provide a home for axolotls that are sick or have been abandoned by their owners. In Mexico, axolotl vendors need a special permission from the Secretariat of Environment and Natural Resources (Semarnat) to operate, but illegal sales, especially in Mexico City’s markets, are still common. 

We get people calling us saying they found a guy selling buckets full of axolotls in a market

The country allows them to be kept as pets if they are registered and bought from an approved vendor, but many would-be pet owners turn to black market sales, which are easier and less expensive. In the capital’s markets, axolotls can sell for anywhere between 200 and 1,000 pesos (US$9–48).

El axolotl regenera su cuerpo
Axolotls are sold in Mexico City's markets, often illegally (photo: Kylie Madry)

“We’ll get people calling us saying they found a guy selling a bucket full of hundreds of axolotls in a market,” Rebeca Sánchez Graillet, a volunteer at Axolotitlán, said. “And they’ll think they’re helping us, buying some to ‘rescue’, but they don’t know how to take care of them either. We have axolotls come in with bacterial infections, or chlorine burns from being in unfiltered tap water.” 

Did you know…?


Axolotl were once a staple of indigenous Mexica diets

Pamela Valencia, a public relations specialist, felt moved to open an axolotl museum when she was given six axolotls from a man who was “giving them out like candy”. 

“I’d have neighbours come over asking to see them while I was still in my pyjamas,” she said. She then started giving tours in Xochimilco with the axolotls in tow. That turned into Axolotitlán, an association currently raising funds to complete its aquarium and build a sanctuary, to save more axolotls that are brought to the museum.

Valencia reached out to the Mexico City government years ago, hoping to get them on board with the project. Instead, the city’s mayor, Claudia Sheinbaum, announced the construction of a competing museum last year in the Chapultepec Zoo. 

“Even when the need clearly exists, the government doesn’t do anything until the people speak out,” Sánchez Graillet said. “Organisations end up doing the work of the government until they decide they want to get involved.”

Scientists try to crack the axolotl genome

Sánchez Graillet explains that axolotls can regrow limbs within 30 days of losing them. In fact, she said, one of their younger axolotls is currently in the process of regrowing a limb. “Axolotls tend to be a bit cannibalistic,” she adds. “They’ll even fight with each other. So they’ll take off an arm or a leg and, within a month, it’s grown back.”

AxolotlRegenerac
Axolotls are capable of regenerating entire limbs, and even parts of their brain (Image: Kylie Madry)

In the hopes of being able to one day develop tissue regeneration in humans, scientists have long studied just what makes axolotls tick. But the task has been daunting, until recently. Scientists were only able to sequence the axolotl genome, with 32 million base pairs, in 2018. That’s 10 times larger than the human genome, which was mapped out in 2003. A year later, scientists were able to render the axolotl genome on a chromosomal scale. 

Axolotls tend to be a bit cannibalistic. They’ll lose an arm or a leg and, within a month, it’s grown back.

But it’ll take longer to figure out exactly what enables the axolotl’s regenerative capabilities. According to Jeremiah Smith, one of the geneticists working to unravel the axolotl’s secrets, the lab-bred amphibian might not be the medical miracle it’s been touted to be. At most, he says, the science can be applied to regenerating small amounts of tissue in humans – but they’ll never be able to replicate the regrowth of entire limbs. 

After an albino tiger salamander was introduced into a laboratory’s axolotl colony in 1962, almost all captive axolotls today contain noticeable amounts of tiger salamander DNA. “The axolotl is a really good example of why wild populations and [genomic] diversity are important,” Smith explained. 

“They’re organisms that evolved over long periods of time, and do things that we don’t do, or that might be important to us. Of course, all animals have lessons that might be useful to us, but maybe the axolotl more so.”

Growing popularity in China

The captive-bred axolotl is one of the most common aquatic pets in China. It has been bred for decades since it was first introduced into the country in the 1990s. Now, the market is quite mature.

On Taobao, one of China's major e-commerce platforms, young axolotls in the most common colours, which include pink, white, gold or black, can cost a mere US$1.50. The top-ranked online retailer in terms of volume sells more than 2,000 axolotl in a month. 

Diao Kunpeng, an expert on wildlife protection, told Diálogo Chino that if the retail price of an axolotl is US$1.50, the purchase price would not even exceed 30 cents. For comparison, in the US, an axolotl can be sold for US$30 to $75, about 20 times the price in China.

The low price of the axolotl can be attributed to increasing demand and a developing market in China. Diao Kunpeng pointed out that when the axolotl came to China initially, the unit price reached several hundred yuan (200 yuan is roughly $30 dollars). 

Around 2005, South Korea’s breeding farms found the cure for saprolegniasis, a common disease in axolotls, which marked a breakthrough in breeding and led to a significant increase in the number of axolotls bred. At present, the large-scale axolotl breeding farms in China are mostly located in Shandong and Liaoning provinces.

Pet bloggers and farmers publish hundreds of videos on axolotls on various social media platforms, sharing their behaviour, how they eat and how they interact with humans. On the video-sharing website Bilibili, the most popular video about axolotl has reached nearly 420,000 views. 

But most of the owners tend to comment on their appearance, and do not mention the fact that the animal is endangered in the wild, or even that it originates in Mexico.

Will the adorable animal’s popularity be enough to save it in the wild? “It’s been great to see people getting interested in axolotls,” Sánchez Graillet said, recommending that new pet owners read about conservation efforts and consider contributing to the cause. “But we need the [Mexican] government to step in. We can’t do this all ourselves.”