Professor Richard Griffiths quoted in Nature article about the threats facing axolotl conservation

The axolotl is on the brink of annihilation in the canals of Mexico City, its only natural habitat. But although there might be just a few hundred individuals left in the wild, tens of thousands can be found in home aquariums and research laboratories around the world. They are bred so widely in captivity that certain restaurants in Japan even serve them up deep-fried.

“The axolotl is a complete conservation paradox,” says Professor Griffiths. “Because it’s probably the most widely distributed amphibian around the world in pet shops and labs, and yet it’s almost extinct in the wild.”

This creates a problem for biologists. Thanks to its unique physiology and remarkable ability to regenerate severed limbs, the axolotl has become an important lab model for everything from tissue repair to development of cancer treatment. But after centuries of inbreeding, captive populations are vulnerable to disease. And the loss of genetic diversity in wild axolotls — owing to their diminishing population — means that scientists lose out on learning all they can about the animal’s biology.

To save the wild axolotl, policymakers must address its two primary threats. The first is non-native fish such as the common carp (Cyprinus carpio) and tilapia (Oreochromis niloticus). Ironically, these were introduced to Mexico City in the 1970s and 1980s through programmes run by the Food and Agriculture Organization of the United Nations, with the aim of getting more protein into local diets. One solution is to employ a team of local fishers to sweep the areas where axolotls still remain of fish on an ongoing basis. Although this wouldn’t remove all the fish, for a few hundred thousand dollars it might give the salamanders a window in which to re-establish themselves.

The second threat is trickier. Every time a powerful storm fills the city’s ageing sewer system, treatment facilities release human waste into the canals, carrying with it ammonia, heavy metals and untold other toxic chemicals. Amphibians, which breathe in part through their highly permeable skin, are vulnerable to these regular pollution dumps. It’s a testament to the animal’s resilience that it exists in the wild at all.

These are complex issues, but they are not unsolvable. So far, however, there have been no efforts to save the wild axolotl beyond a few halfhearted outreach programmes and some photo opportunities. When Griffiths first started working in Xochimilco in 2000, his plan was to create a breeding programme aimed at releasing axolotls into the wild. But he and his Mexican partners quickly abandoned the idea once they saw the condition of the ecosystem, which was polluted and teeming with predators.

“There’s probably not much point in doing releases into the wild until you can neutralise the threats,” says Griffiths. “You just might be increasing the fish population by just chucking out more fish food.”

Successful reintroductions, such as those of the pool frog (Pelophylax lessonae) in Britain or the hellbender salamander (Cryptobranchus alleganiensis) in the United States, require managing the ecosystem as a whole and working with the community. If axolotls do not have a suitable home, most researchers say that their extinction in the wild might be inevitable, no matter what they do.

The full article can be read here.

Leave a Reply