Beneath the tourist gondolas in the remains of a great Aztec lake lives a creature that resembles a monster – and a Muppet – with its slimy tail, plumage-like gills and mouth that curls into an odd smile.
The axolotl, also known as the “water monster” and the “Mexican walking fish,” was a key part of Aztec legend and diet. Against all odds, it survived until now amid Mexico City's urban sprawl in the polluted canals of Lake Xochimilco, now a Venice-style destination for revelers poled along by Mexican gondoliers, or trajineros, in brightly painted party boats.
But scientists are racing to save the foot-long salamander from extinction, a victim of the draining of its lake habitat and deteriorating water quality. In what may be the final blow, non-native fish introduced into the canals are eating its lunch – and its babies.
The long-standing International Union for Conservation of Nature includes the axolotl on its annual Red List of threatened species, while researchers say it could disappear in just five years.
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Some are pushing for a series of axolotl sanctuaries in canals cleared of invasive species, while others are considering repopulating Xochimilco with axolotls bred in captivity.
“If the axolotl disappears, it would not only be a great loss to biodiversity but to Mexican culture, and would reflect the degeneration of a once-great lake system,” says Luis Zambrano, a biologist at the Autonomous University of Mexico, or UNAM.
The number of axolotls (pronounced ACK-suh-LAH-tuhl) in the wild is not known. But the population has dropped from roughly 1,500 per square mile in 1998 to a mere 25 per square mile this year, according to a survey by Zambrano's scientists using casting nets.
It has been a steep fall from grace for the salamander with a feathery mane of gills and a visage reminiscent of a 1970s Smiley Face that inspired American poet Ogden Nash to pen: “I've never met an axolotl, But Harvard has one in a bottle.”
Millions once lived in the giant lakes of Xochimilco and Chalco on which Mexico City was built. Using four stubby legs to drag themselves along lake bottoms or their thick tails to swim like mini-alligators, they hunted plentiful aquatic insects, small fish and crustaceans.
Legend has it that Xolotl — the dog-headed Aztec god of death, lightning and monstrosities – feared he was about to be banished or killed by other gods and changed into an axolotl to flee into Lake Xochimilco.
The axolotl's decline began when Spanish conquerors started draining the lakes, which were further emptied over time to slake the thirst of one of the world's largest and fastest-growing cities. In the 1970s, Lake Chalco was completely drained to prevent flooding. In the 1980s, Mexico City began pumping its wastewater into the few canals and lagoons that remained of Xochimilco.
About 20 years ago, African tilapia were introduced into Xochimilco in a misguided effort to create fisheries. They joined with Asian carp to dominate the ecosystem and eat the axolotl's eggs and compete with it for food.
The axolotl is also threatened by agrochemical runoff from nearby farms and treated wastewater from a Mexico City sewage plant, researchers say.