Amphibians
Lake Patzcuaro Salamander
Ambystoma dumerilii · also called lake patzcuaro salamander, achoque, patzcuaro salamander
The Lake Patzcuaro salamander, known locally as the achoque, is a large, gilled cousin of the axolotl that lives in exactly one place: a single shallow lake in the highlands of Michoacan, Mexico. Its wild population has crashed, and one of the reasons it still exists at all is a convent of nuns who have been breeding it for more than a hundred years.
Overview
The Lake Patzcuaro salamander is endemic to Lake Patzcuaro, at about 2,000 m elevation, and occurs naturally nowhere else. It is 25–35 cm long — larger than the axolotl — stout, dark brown to greenish, with a broad head, a paddle-like tail fin, and a crown of feathery external gills.
It never grows up
Like the axolotl, it is normally neotenic: it keeps its larval body, gills and all, and lives permanently in water rather than transforming into a land animal. It hunts insect larvae, crustaceans, worms, snails, and small fish with a fast suction gape, and, like other mole salamanders, it can regrow lost limbs and tissue.
The convent colony
For well over a century, the Dominican Sisters of the convent in Patzcuaro have raised achoques to make a traditional cough syrup. Their long expertise in keeping the animal healthy became a conservation asset when the wild population collapsed, and they now work with a Mexican university and an overseas zoo to maintain a genetically managed captive population and support efforts to clean up the lake.
Status
The Lake Patzcuaro salamander is Critically Endangered and still declining. Pollution, siltation, water extraction, and introduced carp and tilapia have devastated its lake, and recent surveys find only a handful of animals per night. Captive colonies are now an essential safeguard.
Lake Patzcuaro Salamander: common questions
How is the Lake Patzcuaro salamander different from the axolotl?
They are close relatives, both members of the mole salamander genus Ambystoma, and both are normally neotenic, keeping their gills and living permanently in water rather than metamorphosing onto land. The main differences are where they live and their size. The axolotl comes from the lake system of Mexico City and is the more famous animal in science and the pet trade. The Lake Patzcuaro salamander, or achoque, lives only in Lake Patzcuaro further west, grows somewhat larger, and has a heavier build. Both are critically endangered in the wild for similar reasons — their lakes have been polluted, drained, and stocked with predatory fish.
Why do nuns breed this salamander?
The Dominican Sisters at the convent of Our Lady of Health in Patzcuaro have for generations made a traditional remedy, a syrup that historically contained achoque extract, sold to support the convent. To have a reliable supply without stripping the lake, they learned to keep and breed the salamanders in tanks, and over many decades they became highly skilled at it, achieving survival and breeding rates that professional institutions struggled to match. When the wild population collapsed, this accumulated know-how turned out to be a conservation asset, and the nuns now collaborate with scientists to maintain a healthy captive population of the species.
Why is the Lake Patzcuaro salamander so endangered?
Because it depends entirely on one shallow lake that has been heavily degraded. Sewage and farm runoff have polluted the water and fed algal blooms, deforestation in the surrounding hills has increased silt, and water has been drawn off, lowering the lake. Introduced carp and tilapia eat the salamander's eggs and larvae and compete for food. On top of this, the animal was harvested for food and folk medicine. The combined effect has been a steep decline, and recent field surveys turn up only very small numbers, which is why the species is listed as Critically Endangered and why captive colonies are considered essential.
Can the Lake Patzcuaro salamander live on land?
Almost never. In theory the neotenic condition can be reversed, and under certain hormonal or environmental conditions a few individuals of related species do transform into a land form. But in practice the Lake Patzcuaro salamander stays in its larval, gilled, aquatic body for life, and a metamorphosed adult is a rarity that does not sustain a population. For conservation purposes it is treated as an obligately aquatic animal whose future is tied to the survival of clean, well-oxygenated water either in Lake Patzcuaro itself or in captivity.