Steelhead surveys happening now in Sacramento will help future generations of fish survive

Updated Feb. 27, 4:17 p.m.

On a winter’s morning, three biologists wade into the American River, leaving their motorboat docked along an embankment. Their directive is straightforward: Keep your eyes peeled for steelhead redds. 

“A redd is essentially a nest that a salmon builds to lay their eggs,” explains Mollie Ogaz, a biologist with Cramer Fish Sciences. “Then, they’re fertilizing there in the gravel and they incubate, and then they hatch.” 

Right now, it’s survey season for steelheads. These surveys typically begin in January and go until April, lining up with the species’ spawning season. This year, these efforts faced some delays; the river is more turbid than usual after January’s succession of intense storms. It’s taken weeks for the water to settle enough that researchers can conduct their search – sometimes on foot, scanning the river floor as they stand hip-deep in it, or by peeking over the side of their boat.

Some of this research is done on foot by wading into the water, while some of it can be done from a motorboat. Maeghen Wedgeworth, a senior biological technician with Cramer Fish Sciences, searches for signs of redds from the front of the boat, while Mollie Ogaz and Matthew Ziemer wade into the water.Manola Secaira/CapRadio

Ogaz says these redds look a little like ice cream cones. A steelhead or Chinook fish will dig a small ditch into the river floor with its tail. Sediment that’s kicked up in the process will leave a cone-like trail behind the ditch in the direction of the river’s flow.

“It's called the tail spill,” Ogaz says. “So the pot is the ice cream and the cone is the tail spill, and the eggs are right at that transition.”

Both Chinook and steelhead populations, which have long lived and spawned in the American River, have struggled for decades. Some of that is due to drought conditions and other changes in climate, while other impacts stem more directly from human involvement. 

“The American River is really a good example of all the stressors that humans have placed on these populations over the last couple hundred years,” said Erica Bishop, a program manager at the Water Forum who oversees salmon habitat planning and implementation projects.

Mining and the creation of dams has altered the American River’s ecosystem over the course of decades. Bishop said these changes have severely limited the historic breeding grounds for these fish. 

“We have a dam that’s blocking 80% of historical spawning and rearing habitat,” she said. “It really is a good example of the many ways that we've affected these species as humans.”

Scientists with Cramer, a consulting group that helps sustain fish populations with a team in West Sacramento, have conducted annual surveys of steelhead redds for about a decade. Their steelhead counts are funded by the Bureau of Reclamation, although these surveys generally began in 2002. Chinook surveys happen in the autumn in partnership with the Water Forum, a water planning agency that leads efforts to boost spawning habitat in the American River. 

Ogaz said research conducted during these surveys is key. 

“It's really important to be able to evaluate the effectiveness of that restoration and kind of see if needed tweaks or changes need to be made, and also get an idea for what the population actually is,” Ogaz said. 

This image shows redd (steelhead or Chinook nest) distribution at the Nimbus Basin restoration site (just below the dam) before restoration in 2021 (top) and in 2022 (below) after changes to gravel at the site were made to better accommodate steelheads. Three of the nine steelhead redds observed as of Feb. 17 this year were at this site.Courtesy of Cramer Fish Sciences

Kirsten Sellheim, a senior scientist at Cramer Fish Sciences, said they’ve long noticed that steelhead populations are on a more severe decline than Chinook. The reasons for this vary, from lacking habitat to warming waters during drought years. In 2021, Sellheim said 500,000 steelhead were moved from the hatchery by the Nimbus Dam, which is 20 minutes east of Sacramento in Fair Oaks, to a one about an hour away due to a lack of cold water available to keep them over the summer. 

“The last decade, [we’ve seen] anywhere from 50 to 100 total redds throughout the entire season,” she said. “Versus Chinook, we saw over a thousand last fall, just in the areas that we were counting.”   

In response, Sellheim said there have been efforts to create spawning habitats that better cater to the needs of steelhead. They’ve seen success in a new site built by the Water Forum in 2021. There, she said they found 28% of the steelhead redds accounted for in the 2022 survey. 

“The strongest trend with the restoration projects is, as soon as we build those spawning grounds, they flock to them,” she said. “[And] every year we do these projects, we kind of learn something new that we can then leverage for the next project.”

During that recent winter day, the researchers come across six steelhead redds. Ogaz says turbid waters make them particularly difficult to find this year, which could impact their numbers. 

Maeghen Wedgeworth, a senior biological technician assisting in the search, says the fish have evolved alongside California’s climate of extremes. 

“These fish are so well adapted and so resilient to disruption or disturbance,” she says. “If they start to decline, there is something that's been thrown off balance from what they have historically been doing here.”

The surveys play an important part in understanding the impacts of those changes, she says, and how conservation efforts can help future generations of steelhead trout and Chinook salmon thrive.

Correction: A previous version of this story incorrectly identified steelhead as salmon. It has since been updated.