Between 1982 and 2010, the already shallow lake declined by about 13 feet, losing a quarter of its total volume because of declining rainfall and increasing runoff carried into the lake. Various efforts to rehabilitate Pátzcuaro have met only limited success.

Achoques aren’t the only Mexican salamanders in trouble. Of the 17 species in their genus found in Mexico, 12 are listed as endangered or critically endangered by the International Union for Conservation of Nature.

Worldwide, salamanders face numerous threats, from habitat loss to the illegal pet trade. A new fungus has been killing salamanders in Europe.

At Lake Pátzcuaro, fishermen have been catching and eating achoques since before the Spanish arrived in Mexico. In the late 1970s and early 80s, achoques caught in the lake were piled high at the fish market in town, recalled Brad Shaffer, a professor of biology at the University of California, Los Angeles, who has studied the salamanders.

But the numbers of achoques started to fluctuate wildly in the 80s and crashed in 1989. In 1985, a friar suggested that the nuns start their own colony because the lake was deteriorating, according to Sister Ofelia.

It wasn’t until 2000 that the nuns had their own thriving community of salamanders in the convent. The nuns have been cooking up jarabe, however, for nearly a century.

“People have faith in it because the nuns make it,” said Dolores Huacuz , an expert on the region’s amphibians and a retired university professor.