CalTrout Warns of “Almost Certain” Extinction Events for California’s Native Fish

The conservation group ties the repeal of the federal endangerment finding to accelerating threats against the state’s salmon, steelhead, and trout—and launches a once-a-decade scientific assessment to track the damage.

California Trout issued a stark warning on February 18: without science-based federal climate action, the state’s wild native fish face “almost certain extinction events.” The statement landed six days after the EPA formally rescinded its 2009 endangerment finding, stripping the legal foundation for federal greenhouse gas regulation and—in CalTrout’s view—ignoring decades of research linking rising temperatures to collapsing salmonid populations.

The numbers behind the warning come from CalTrout’s own State of the Salmonids II report, published in 2017 with UC Davis’s Center for Watershed Sciences. That assessment found that if current trends persist, 45 percent of California’s salmonids are likely to be extinct within 50 years. Climate change ranks as a critical or high threat for 27 of 31 species evaluated—87 percent of the state’s native salmon, steelhead, and trout. The drivers are straightforward: warming water temperatures, shrinking snowpack, and altered hydrology are squeezing coldwater fish out of habitat they have occupied for millennia.

“The endangerment finding reflects decades of rigorous scientific research showing that climate change poses clear risks to both human and ecological systems,” said Darren Mierau, CalTrout’s Director of Science. He pointed to warming temperatures and declining snowpack already reshaping California’s rivers and, with them, the native fish that depend on cold, clean flows.

The Policy Shift

The EPA finalized its repeal of the endangerment finding on February 12, calling it the largest deregulatory action in U.S. history. The 2009 finding had classified six greenhouse gases as threats to public health and welfare under the Clean Air Act, underpinning emissions standards for vehicles, power plants, and oil and gas operations. By withdrawing it, the administration removed the federal government’s primary legal mechanism for regulating climate pollution.

California and several other states have signaled they will sue. The state’s own climate policies rest largely on state law—cap-and-trade, clean energy mandates, vehicle standards—and some legal scholars argue the federal retreat could paradoxically expand California’s regulatory authority. But for coldwater fish, the question is less about jurisdiction than physics. Greenhouse gases trap heat. Heat warms water. Warm water kills trout.

Redgie Collins, CalTrout’s Vice President of Legal and Government Affairs, was blunt: “Decisions on climate action must be grounded in science and law, not the political whims of those in power.”

SOS III: Tracking the Decline

CalTrout’s response extends beyond a press release. In early 2026, the organization launched State of the Salmonids III (SOS III), the third installment of its once-a-decade assessment covering all 32 native salmon, steelhead, and trout species in California. Led by UC Davis researcher Robert Lusardi, the study is expected to be published in 2027.

The SOS series—first issued in 2008, updated in 2017—uses a peer-reviewed, replicable scoring methodology to rate each species on a one-through-five scale of endangerment. SOS II documented an 81 percent deterioration rate: that many of California’s salmonids had declined since the first assessment, driven largely by the historic 2012–2016 drought and mounting climate pressure. SOS III arrives at a moment when that data is nearly a decade old and California’s rivers are changing faster than the models predicted.

“SOS III is about turning data into direction,” Mierau said. Final products will include a peer-reviewed scientific report, an illustrated book for general audiences, and a communications strategy aimed at aligning agencies, policymakers, and funders around recovery priorities.

Curtis Knight, CalTrout’s Executive Director, framed the stakes plainly: the SOS reports have become the benchmark for understanding California’s salmonid health, and SOS III will give decision makers the science they need to focus resources where they can still make a difference.

What It Means for Anglers

Salmon, steelhead, and trout are the backbone of a recreational fishery worth billions, and their presence—or absence—in a watershed tells you nearly everything about its ecological health. Southern steelhead, several inland trout strains, and multiple Chinook salmon runs already teeter at the edge of viability. The SOS II data put hard numbers on what many anglers have observed firsthand: fewer fish, warmer water, shorter windows of fishable conditions.

The repeal of the endangerment finding does not, by itself, warm a single river. But it removes a layer of federal regulatory pressure that had constrained emissions contributing to exactly that outcome. California’s state-level protections remain intact, and conservation groups like CalTrout continue to fund habitat restoration, dam removal, and source-water protection. Whether that patchwork can hold against a warming climate without federal reinforcement is the open question SOS III may help answer.

The window, CalTrout argues, is closing. The data will tell us how fast.