Captive-breeding axolotls may help avoid their extinction

The axolotl has feathery frills and a soft smile. Lots of people love these cute salamanders. Indeed, many serve as household pets and research subjects. But in their home range, these critters are endangered. Fortunately, research shows promise for protecting the extremely small number of them left in the wild.

Their native wetlands are now so degraded that wild axolotls (Ax-uh-LOT-uls) survive in only one lake in Mexico. It’s estimated that only 50 to 1,000 individuals still live there.

In a new study, scientists bred a few of these animals in captivity. Then they released them in restored and artificial wetlands. Those freed axolotls are surviving, scientists now report.

That captive breeding might offer a promising way to save this species from dying out. Researchers shared details April 30 in PLOS One.

Finding captive-bred axolotls surviving in the wild is “really, really exciting,” says Alejandra Ramos. She’s an ecologist at Universidad Autónoma de Baja California. That’s in Ensenada, Mexico. Her team’s breeding-and-release program, she says, could prove “really important for conservation [of the species].”

Early findings are encouraging

Ramos’ group chose two suitable sites for an experiment. Both were in southern Mexico City. One was a restored canal called a chinampa. It was located in the axolotl’s native Lake Xochimilco (Sow-chee-MEEL-kow). The other site was a spring-fed artificial pond.

The scientists released 10 captive-bred axolotls into the chinampa. They placed eight more in the pond. Then they monitored all 18 with tagging devices.

For about 40 days, volunteers tracked these salamanders with radio receivers. Then they walked or took a boat to the axolotls’ locations. In this way, they could record precisely where the animals were hanging out. At first, they checked in a few times a day. Toward the end of the experiment, they checked once every hour.

All captive-raised axolotls survived. Three were recaptured. Measurements showed they had gained weight. This showed the critters were hunting well in the wild. So their new homes appear to be a good fit.

“If they had been skinny or ill,” Ramos says, “that would have been really, really bad for us.”

The tracking data show that early on the amphibians traveled more. They may have been scouting good hunting and hiding spots, Ramos says. They were most active when the temperature was about 16 degrees Celsius (60 degrees Fahrenheit). The artificial pond was slightly cooler than the restored chinampa. Past research suggests axolotls tend to prefer cool temps.

Scientists Say: Amphibian

Understanding what conditions axolotls prefer will help researchers choose the best sites to free their lab-bred animals.

But this reintroduction is really a plan B, says Luis Zambrano. He’s an ecologist on the team at Universidad Nacional Autónoma de México. That’s in Mexico City. Rather than just breed lots of them forever in the lab, his team wants to improve the habitat where wild axolotls still live. That should boost their chance of survival.

The researchers also plan to increase the number of restored chinampas in the lake. Doing so is costly and complex. To raise money for this effort, they’ve created an “Adopt an Axolotl” fundraiser.

This new research could help axolotls avoid extinction, Zambrano says.