Inside a quiet, climate‑controlled room at the Aquarium of the Pacific, biologists are working to rescue one of the nation’s rarest vertebrates – the mountain yellow‑legged frog. After five years of intensive breeding and head‑starting, the aquarium and its partners released 653 frogs into the San Gabriel, San Bernardino and San Jacinto Mountains, the largest single release to date.
Program milestones and numbers
Since the program began in 2021, more than 1,000 frogs have been raised and released. The latest effort brings the total to 1,032, a figure that dwarfs the estimated 188 wild individuals counted in 2020 and the fewer than 100 adults recorded when the species was listed under the Endangered Species Act in 2002.
How the frogs are raised
Frogs are first bred at the Los Angeles Zoo’s dedicated breeding facility. Young tadpoles are then transferred to Long Beach, where aquarium staff rear them through metamorphosis. Water temperature is kept near 60°F in summer and around 52°F in winter, with reduced UV exposure to mimic the seasonal conditions of high‑elevation streams. The process can take one to two years, though some tadpoles remain in that stage for up to five years.
Local partnerships
The effort is a collaboration among the Aquarium of the Pacific, the Los Angeles Zoo, the U.S. Geological Survey, the U.S. Fish and Wildlife Service, the U.S. Forest Service and the California Department of Fish and Wildlife. Each October, a portion of the growing cohort is sent to the Santa Ana Zoo for additional development before final release.
Why the species is in danger
Mountain yellow‑legged frogs have suffered a cascade of threats: wildfire, mudslides, pesticide runoff, habitat loss, non‑native trout, bullfrogs, crayfish and, most critically, the chytrid fungus that attacks amphibian skin. The fungus can cause cardiac arrest by preventing the frogs from absorbing essential salts.
Researchers at the aquarium are exploring ways to boost the frogs’ resistance, including inoculating them before release or introducing beneficial skin microbes. “Some amphibian species have developed resistance over time,” said Erin Lundy, a conservation biologist with the aquarium. “Part of the intention of growing so many animals is hoping to find the gene that provides that resistance.”
Community impact and hope
For Lundy and the team, the work is both scientific and deeply personal. “We have a responsibility to give these animals the best chance possible,” she said. Watching the frogs disappear into mountain streams evokes a bittersweet feeling she likens to “Christmas Day.” The releases not only aim to rebuild wild populations but also to preserve genetic diversity by carefully separating frogs by their original genetic lines.
The aquarium’s work demonstrates how local institutions can play a pivotal role in conserving California’s natural heritage. By turning a modest room of tanks into a lifeline for a species on the brink, Long Beach residents are helping ensure that future generations may still hear the call of the mountain yellow‑legged frog echoing through the high‑country streams.
Original reporting: NBC4 Los Angeles — read the source article.
