Scientists have discovered that the last remaining steelhead trout population in the Santa Monica Mountains, believed to be lost to debris flows from the Palisades fire, has not only survived but has also reproduced. A team of biologists recently observed 30 adult trout and 21 juveniles in Topanga Creek, offering a significant conservation success.
The steelhead trout in this region are listed as endangered at both state and federal levels. Historically abundant in most streams across the Santa Monica Mountains, their numbers have drastically declined due to overfishing, coastal development, and increasingly frequent wildfires. Topanga Creek, a critical biodiversity hotspot, serves as the sole known habitat for this distinct Southern California population.
Following the January 2025 Palisades fire, the California Department of Fish and Wildlife initiated an emergency operation to rescue trout threatened by the imminent danger of sediment-laden runoff from the burned hillsides. Many of these fish were captured, transported to a hatchery, and relocated to Arroyo Hondo Creek in Santa Barbara County. The subsequent heavy rains caused Topanga Creek to become heavily silted, leading to the assumption that any remaining fish had perished.
However, in March, conservation district teams found four surviving trout. Subsequent surveys in April revealed a larger population, much to the relief of conservationists like Kyle Evans, environmental program manager for the state Department of Fish and Wildlife. Evans speculated that these fish likely found refuge under rocks or in less affected areas of the creek, avoiding the brunt of the debris flows.
Topanga Creek, though still recovering, is showing signs of ecological renewal. Significant rainfall over the past nine months has helped to scour sediment and deepen pools. This has facilitated the return of various species, including newt egg masses and a notable increase in frog populations. Plants crucial for riparian cover are also beginning to re-establish, creating a more favorable habitat.
The recovery of Topanga Creek also supports another endangered species, the northern tidewater goby. Hundreds of these fish were also relocated prior to the trout rescue. While the relocated trout are thriving and have successfully spawned in their new environment, discussions are ongoing regarding their potential return to the Santa Monica Mountains. Experts estimate the creek will require another two to three years to fully recover.
