Sept. 21, 2026 3:21 PM PT <\/p>\n
Inside three water tanks in a tucked-away room at the Aquarium of the Pacific, biologists are trying to bring back a kind of frog that once thrived across the state\u2019s mountain streams, but has since reached the brink of extinction.<\/p>\n
It\u2019s a program that\u2019s approaching its sixth year with a major milestone: more than 1,000 frogs raised and released into the wild. That\u2019s more than five times as many mountain yellow-legged frogs as are believed to have been in the wild when they were last counted in 2019, reduced to small pockets of wild streams in the San Gabriel, San Bernardino and San Jacinto Mountains. <\/p>\n
The amphibian is named for the lemon streak along its hind legs. By the time the frog was listed<\/a> under the federal Endangered Species Act in 2002, fewer than 100 adults remained in Southern California. The 2019 count was published in 2020 at 188 frogs in the wild.<\/p>\n The species\u2019 collapse is tied to compounding<\/a> threats: wildfire, mudslides, pesticides, fungal disease, habitat loss and the appetites of nonnative trout, bullfrogs and crayfish. It\u2019s a decline so severe that biologists consider the species among the rarest vertebrates on Earth.<\/p>\n Staff at the Aquarium of the Pacific in Long Beach are working to change that, one tadpole at a time.<\/p>\n In the latest release, about 653 of the critically endangered frogs were returned to their native mountain habitat by staff from the Aquarium of the Pacific, the Los Angeles Zoo and the U.S. Geological Survey. Of those, 394 had been head-started at the aquarium \u2014 its largest release of the species yet, bringing its total to 1,032.<\/p>\n The frogs were bred at the Los Angeles Zoo\u2019s breeding program, then transferred to Long Beach as tadpoles, where aquarium staff reared them through their metamorphosis into froglets and frogs. The process<\/a> typically takes one to two years, though the species can remain in its tadpole stage for up to five years, making a given frog\u2019s age something of a mystery even to the people who raised it.<\/p>\n Inside the aquarium, the water is engineered to mimic the mountains \u2014 kept near 60 degrees in summer, the temperature currently found in the streams the frogs call home, and cooled to around 52 degrees in winter, with reduced UV exposure to simulate the season\u2019s shorter, dimmer days.<\/p>\n The aquarium\u2019s involvement began in 2021, in the aftermath of the 2020 Bobcat fire<\/a>, which tore through the central San Gabriel Mountains and destroyed an estimated 95% of the frog\u2019s remaining usable habitat.<\/p>\n \u201cThey had salvaged some tadpoles from the fire-impacted areas, and they ended up bringing a handful of them here,\u201d said Erin Lundy, with the aquarium\u2019s conservation team. \u201cAnd then we also had some captive-bred ones from the L.A. Zoo that year, and that was our first group.\u201d<\/p>\n