Seafood is abundant off the San Luis Obispo coastline, but it may come as a surprise that the creeks used to teem with steelhead trout too. Sadly, the local population of this fish species was federally listed as threatened in 1997 due to their diminishing numbers.

A page in Robert A. Brown’s The Story of the Arroyo Grande Creek describes how “… steelhead would fill the creek as they propelled their great silvery bodies inland.” That was a time when as many as 20,000 steelhead were returning to Central Coast streams, estimates Don Baldwin, a California Department of Fish and Wildlife Environmental Scientist for Steelhead Habitat and Population Assessment in San Luis Obispo County. “Today, there are less than 500,” Don says.

John Piatti Jr. remembers when that fish was abundant. “All the streams leading to the ocean had steelhead,” John recalls. A council member of the Salinan Tribe of Monterey and San Luis Obispo counties, he grew up in Morro Bay and avidly fished every one of those local waterways with his father and many other family members.

In the 1960s and ’70s, they would eagerly await the first good rains that John says “would break the streams open,” allowing ocean-going steelhead access to their inland spawning grounds. As he stood in the water casting his line, the steelhead were so plentiful “they’d be running into your legs.” When he caught a really good keeper, it would be about 8 pounds and 30 inches long.

Origin Story

It’s easy to lump steelhead in with other species and assume that the population crashed because of overfishing. But steelhead’s demise in the county came from other human activity. That’s because this trout is a unique type of fish.

Technically, steelhead trout and rainbow trout are the same species, Oncorhynchus mykiss. Both spawn in freshwater. But, while rainbow remain inland after they hatch, steelhead make their way to the ocean before returning to their spawning grounds. It’s a trait they share with salmon, making them both anadromous fish.

Yet unlike salmon, steelhead don’t die after spawning. And what’s next for them varies. After heading back to the ocean, they might come back the next year to spawn. Or, at any point in their lives, they might just choose to stay put.  

Human Impact on Steelhead

What has proved nearly fatal for local steelhead populations is eliminating that “choice.” Being able to return to their native spawning grounds means physically reaching that area, where they can take advantage of when the first rains break open the streams.

Human activity on the Central Coast has interrupted that journey. John remembers catching steelhead well into the 1980s, but he knew then that the population was already compromised, he says.

“Steelhead need the four Cs: cold, clean, complex and connected,” explains Zach Crum, a San Luis Obispo-based District Fisheries Biologist with California’s Department of Fish and Wildlife. “Cold” and “clean” refer to water temperature and quality, while “connected” is the ability to get from fresh water to the ocean and back.

“Complex” indicates the diversity of habitats needed to support steelhead throughout its life cycle, notes Zach. For example, juveniles need woody debris for shelter, adults seek areas such as shady ponds for resting, and the entire ecosystem has to provide varied and adequate food sources.

With the exception of Chorro and San Luis Creeks, most of the steelhead’s local channels no longer come close to providing these conditions. Banks have been stripped of protective vegetation, streams have been polluted, dams have been constructed and overall riparian (creek-side) habitats have been degraded.

A state pollution analyst was quoted in a 2015 San Luis Obispo Tribune article as saying a particularly low point came in 1966 when San Luis Creek could be described as “an open sewer.” That may be hard to believe about a waterway that’s now a jewel in San Luis Obispo’s urban crown.

What’s Being Done?

Though securing and maintaining funds for research and restoration is always a challenge, some significant efforts are being made to protect the county’s steelhead and its habitat. Projects include removing physical barriers to migration, harvesting rainwater to maintain water levels and improving riparian corridors. Essentially, these efforts are to restore and provide the four Cs.

Other threats to steelhead are invasive species like pikeminnow. A project to eradicate them is currently underway in Chorro Creek under the aegis of the Morro Bay National Estuary Program (MBNEP). These non-natives were probably introduced as bait fish in the 1960s or ’70s, according to Carolyn Geraghty, MBNEP’s Restoration Program Manager. The pikeminnow not only compete with steelhead throughout their life cycle, but also have a voracious appetite for juvenile trout. MBNEP’s data indicate that physically removing just one pikeminnow from the creek can protect about 40 steelhead annually.

Of course, it can certainly be said that Mother Nature is what happens when humans are making other plans. Part of California’s natural cycle includes wildfires and boom-to-bust rain years, conditions being accelerated by climate change. And, as Zach puts it, “How can we manage for fire and drought?”

Why Bother Saving Steelhead?

Though steelhead provided a reliable subsistence fare for Indigenous people and later inhabitants, they weren’t considered an essential, year-round food source. And, there was only a fleeting commercial steelhead market in San Luis Obispo County circa the 1980s. So why care about their dwindling numbers? The impact is both cultural and environmental.

“The loss of steelhead may not directly affect other species, but would show a collapse of the ecosystem,” Don explains. “It would allow non-native or invasive species to populate the habitat, drastically changing the ecosystem.”

“Steelhead are a top predator in these ecosystems,” Zach says. “Their loss would have impacts throughout the food chain, and they’re a charismatic and integral part of the cultural history here.”

Further, Carolyn points out, “Steelhead are a keystone species.” In other words, they’re part of the glue that holds the local ecosystem together. If you think of them as the proverbial canaries in the coal mine, what else might we lose if we lost them?

For John Piatti Jr., something has already been lost: that multi-generational camaraderie of angling for steelhead and bringing one of those keepers home. “Anybody that has a passion for fishing has to admire them,” he says. “They’re twice as ferocious as salmon, and when you see that big silver fish jumping …” He pauses a bit wistfully before adding, “It’d be tremendous to see them come back.”