Zachary Crum looked like a member of the Ghostbusters as he sloshed through San Luis Obispo Creek wearing an electrofisher backpack — an instrument that safely stuns fish so he can study them.

The backpack contained a battery, a control board and a 6-foot fiberglass pole topped with a metal ring. When the biologist dipped the pole in the water, an electrical current briefly stunned the nearby fish.

A handful of silver, speckled steelhead trout floated to the surface of the creek for a moment — just enough time for Crum to net them and drop them into a bucket of water.

"It's actually very athletic," Crum said with a laugh. "Generally, you only have a very short second to scoop up the fish before they're swimming as normal."

Most importantly, Crum said, the fish aren't harmed in the process.

So why was the fisheries biologist decked out like he was ready to hunt Slimer?

Crum is the lead on a California Department of Fish and Wildlife pilot project to track steelhead trout in San Luis Obispo Creek.

Steelhead trout are listed as threatened under the Endangered Species Act, according to a 2023 NOAA Fisheries report, and researchers have been working to understand the fish locally.

According to San Luis Obispo city biologist Freddy Otte, San Luis Obispo Creek was once one of the best locations for steelhead trout fishing in California, but pollution and obstructions to the trout's migration path have caused the fish population to dwindle.

Otte, who called himself a "fish nerd by trade," described steelhead trout as "an iconic species of the creek."

"We've stepped on them, kicked them, polluted them, fished them — they're still here. That's an incredible story," Otte said. "They're the definition of resiliency."

Steelhead trout are born in freshwater rivers like San Luis Obispo Creek, then some migrate to the ocean to grow. Two to four years later, the trout return to the creek as adults to spawn.

From Oct. 9 to Nov. 7, Crum and his team implanted tags in 193 juvenile trout in four areas of the creek. The tags will detect if and when those fish swim by an antenna placed in the creek near Avila Valley Barn.

The study will show how many trout migrate to sea from the creek — and eventually, biologists will learn how many of those trout return.

"We're really excited to be able to better understand the species and their movements and numbers," Crum recently told The Tribune.

Biologist launches new trout tracking program

Trout are difficult to study, Crum said.

Much of the creek runs through private property, which restricts where biologists can observe the fish — and steelhead are good at hiding, as their speckled bodies blend in with the rocky bottom of the creek.

"It's like tracking ghosts," Crum said.

From 2018 to 2024, the California Department of Fish and Wildlife counted trout with a Didson camera, which took sonar images of fish as they swam by. The camera ran for 24 hours a day, and last year, the camera captured about 30 fish, Crum said.

Sonar imaging wasn't a particularly efficient way to keep track of the trout, however, as staff had to review countless hours of footage to identify the fish, Crum said.

This fall, the California Department of Fish and Wildlife launched a pilot project to tag and count steelhead trout in San Luis Obispo Creek.

Crum and his team sampled a total of 193 juvenile trout in four parts of the creek: city property near Stagecoach Road, city property near San Luis Obispo High School, city property near the Octagon Barn and a SLO County Land Conservancy property near San Luis Bay Drive.

After two to four years, the California Department of Fish and Wildlife will observe which of those tagged fish return to the creek. An estimated 1% to 3% of juvenile trout that migrate to the ocean return to freshwater as adults, Crum said.

"It's risky," Crum said. "There are a lot more resources out in the ocean for these fish to get much bigger than they could if they stayed here in the creek, but then again, there are a lot of big predators out there that can eat them."

On Nov. 7, Crum and his team completed their last tagging effort of the season near San Luis Bay Drive.

First, Crum's team netted off the 100-meter stretch of the creek, which is about the size of two Olympic swimming pools.

Then, they used the electrofisher backpack to stun the fish. The backpack is "kind of Ghostbusterish," Crum acknowledged, with a battery on the bottom and a control board on the top. A 6-foot, fiberglass pole topped with a metal ring extended from the backpack into the water, generating an electrical current that temporarily stunned the fish.

The group then used drip nets to collect the trout and deposit them into buckets of water before implanting a tag in each fish.

The tag, which is about the size of a grain of rice, contains a copper wire that sends a signal to a tag reader when the fish passes by an antenna in San Luis Obispo Creek near Avila Valley Barn.

There are two ways to embed the tag. One way is to use a small gun with a hypodermic needle on the end that injects the tag into the fish's body cavity. The other is making a small incision on the fish and placing the tag inside. Neither method harms the fish, Crum said.

The agency's goal is to learn how many young trout, known as smolts, successfully migrate from their juvenile habitat in the creek out to sea. This will show whether the trout population is recovering or marching further toward extinction, he said.

A Sport Fish Restoration Act grant from the U.S. Fish and Wildlife Service partly funded Crum's work, a scientific aide and some supplies for the trout counting effort.

Meanwhile, the city of San Luis Obispo lent the California Department of Fish and Wildlife the majority of the tagging and tracking supplies for the effort.

Restoring trout habitat in SLO Creek

San Luis Obispo Creek is home to two types of oncorhynchus mykiss: rainbow trout, who live their whole lives in freshwater, and steelhead trout, who migrate to the ocean then return to the creek to spawn.

"There's a rhythm and a beauty and sort of a majesty, I think, to these amazing animals that can thrive in both fresh and salt water," Creek Lands Conservation executive director Don Chartrand said. "It's a tough little species that lives right alongside the freeway."

The trout population may be dwindling right now, but it hasn't always been that way.

The creek was overflowing with steelhead trout during the Great Depression, Rose McKeen wrote in a 1988 book about San Luis Obispo history.

"If one had nothing else for dinner, there were always the fish in San Luis Obispo Creek," she wrote. "During those disastrous years, the creek literally fed many people, just as it had once fed the Mission Padres and the Chumash Indians."

A 1995 steelhead trout inventory prepared by the Land Conservancy of San Luis Obispo County showed a "severe lack" of trout habitat in the creek, primarily due to flood control measures that removed shaded pools that offered cool water and safety to the fish.

The report recommended placing boulders and logs in the creek to provide hiding places for the trout and vegetating the corridor along the creek to provide shade for the fish.

Creek Lands Conservation, a local nonprofit dedicated to restoring ecosystems on the Central Coast, is working to improve steelhead trout habitat in San Luis Obispo Creek.

"We want to make it better, because populations have gone down tremendously since, essentially, people started to live here," Creek Lands Conservation watershed projects manager Steph Wald said.

Creek Lands Conservation is in the process of developing the San Luis Obispo Creek Resiliency and Rewilding Project plan, which is partly funded by the Harold J. Miosi Charitable Trust.

The plan will recommend areas in the creek for habit restoration projects that would best support steelhead trout.

Right now, Creek Lands Conservation is working with the San Miguelito Mutual Water Co. to improve fish passage at the Marre Weir, a sheet pile that extends across the creek installed to prevent saltwater from mixing with freshwater upstream. There's a notch in the sheet pile to allow fish to pass through, but Creek Lands Conservation secured funding from the California Department of Fish and Wildlife to redesign it so fish can more easily travel upstream, Wald said.

Projects recommended in the plan will be similar to the Marre Weir project, she said.

Creek Lands Conservation is also interested in enhancing stream flow in San Luis Creek.

This would look like timing agricultural and municipal water use in a way that leaves enough water in the creek for steelhead trout to migrate to and from the ocean. Farmers and cities could concentrate their water use in the winter, set some aside and release it into the creek in summer and fall when fish need it most, Wald said.

The project will also develop educational programs to teach students and other community members about the importance of the creek, steelhead trout and how natural ecosystems can coexist with human uses.

"Steelhead trout, rainbow trout, are incredibly resilient creatures. They have become an incredible example of how people and wildlife can coexist," Wald said. "If you do good things for steelhead trout, you will do good things for the entire ecosystem."

As part of the project, Creek Lands Conservation collaborated with City Farm SLO to restore a stretch of Prefumo Creek, a tributary of San Luis Obispo Creek. The farm installed a trail with interpretive signs explaining how farmland can coexist with a healthy riparian ecosystem.

"You can have a thriving natural ecosystem right next to functional working lands," Chartrand said. "The two can benefit each other."

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