CalTrout News
CalTrout has over 60 active restoration projects across the state. How do we decide to focus our efforts on these specific projects? And how can we understand the impact that these projects have?
To understand where and how fish need our help most urgently, we monitor fish movement, behavior, survival, and other life history patterns. This data helps us figure out what restoration efforts to engage in and where they should take place. Simultaneously, we collect data to measure the success of completed restoration projects, ensuring that we learn from what we’ve done, and that future projects are data-driven and impactful.
Much of this scientific monitoring data centers around understanding migration patterns, essentially where the fish are moving and when. Each piece of a watershed must be functioning to support a successful lifecycle for fish. To build diversity in fish populations and resilience to disturbances, fish must also have access to multiple functional watersheds. What watersheds do they rely more heavily on? Where in a watershed are they suffering greater mortality? Do they need higher quality freshwater habitat or is their survival inhibited by poor estuary conditions? Is there a barrier blocking their access to habitat they previously utilized? Is new habitat access restored due to successful barrier removal projects? Answers to these questions illuminated by monitoring help guide our work.
Different Monitoring Methods in Different Places
Across the state, CalTrout and our partners use many different scientific methods with technologies and equipment tailored to local conditions to monitor fish throughout their lifecycles and collect this data.
In the Bay Area, CalTrout and our partners use passive integrated transponder (PIT) tags to track individual fish in Walker Creek (Marin County), Pescadero and Butano creeks (San Mateo County), and, as of this year, Branciforte Creek (Santa Cruz County). These tags are embedded in fish and detected when they swim over our antennas, which are set up at different points along waterways. The technology is similar to the tags you might embed in your pet cat or dog. Our PIT tag antenna network enhances our ability to understand when and why fish move through and between streams and how connected different fish populations are. Over the last few years, we have had some exciting findings: we detected an adult female coho salmon that swam over 100 miles from Salmon Creek to Pescadero Creek to spawn, five coho salmon from Scott and Waddell creeks straying into Pescadero Creek, and two steelhead that spawned in Pescadero Creek after spawning in Scott Creek in prior years.
In the South Fork Eel River, we use acoustic telemetry tags to track fish movements with sound. These tags send out a ping when they pass by an acoustic receiver, a type of listening device installed down the mainstem river corridor. We surgically implant these tags in juvenile salmon and steelhead, and as we track them, we use this information to understand where they are most threatened by non-native pikeminnow predation so we can focus our recovery and suppression efforts. This year, CalTrout and our partners tagged over 400 fish and removed over 1192 non-native pikeminnow predators. We also operate a sonar camera station on the river to count adult salmon and steelhead, bolstering our understanding of how non-native fish move through the system.
In the Klamath River, CalTrout and our partners use a combination of methods including sonar imaging, netting, radio telemetry, and spawner surveys to build our understanding of dam removal including how fish repopulate newly opened habitat and how they recover from landscape level restoration. In October 2024, we detected the first Chinook salmon to migrate above the former Iron Gate dam site, confirmation that fish are using the newly reconnected habitat the decades-long dam removal effort intended.
In Southern California, in the Sierra Nevada mountains, and in the Elk River on the North Coast, we use environmental DNA (eDNA) which involves analyzing small traces of DNA that fish may shed into their environment as they move through it. This allows detection of a broad assemblage of fish species over long stretches of river at a fraction of the cost of traditional visual surveys and helps us better understand where native and non-native species are present.
In the Sacramento Valley, our Fish Food Program collects data to understand aquatic food web production dynamics and develop management practices that reconnect floodplain food web resources to fish confined to food-starved, leveed river channels. We measure the volume and quality of water running through participating farm fields and managed marshes, we sample the number and type of invertebrates growing in these “surrogate marshes,” and we measure how much faster salmon grow, both on the floodplain and in the river, when they get access to this floodplain bug buffet. The answer: they grow a lot faster!
Community Science Helps Build the Picture
It’s not just scientists that can collect data — community members can get involved in this work too! On Upper Trabuco Creek, Southern California residents Kris, Ella, and Shane became scientists for the day and joined us in the field to monitor and measure creek conditions including flow rate, sediment levels, riparian vegetation, and other habitat markers. This data, in conjunction with stringent engineering data collection and analysis required for fishway design, helps us inform future restoration – like CalTrout’s upcoming Trabuco Creek fish passage project.
"I think the best part of the volunteer day was spending time outdoors with a small group of folks with such diverse backgrounds and points of view all coming together to help our local environment,” said Kris Hublitz, a volunteer with CalTrout in 2024. “Diversity matters not just in our wild spaces but in our community as well. I've found CalTrout to be a great place to share my point of view and help a great local environmental cause."
On Malibu Creek, Rindge Dam will soon be removed, and the community is instrumental to helping collect visual data throughout the project. To take part, all you need is a smart phone or camera and a visit to the watershed! The Community Science Photo Point Program allows Malibu Creek visitors to snap a picture at one of the photo monitoring sites and upload it to help us collaboratively build a bigger picture of the watershed. Two of the sites are currently installed, and five more will be live in 2025.
Sometimes, monitoring is as simple as walking along a creek and looking for different evidence of fish, like redds, or nests of eggs. In 2022 and 2023, CalTrout worked with the Alameda Creek Alliance to train and support a volunteer cohort to regularly monitor the watershed for salmon and steelhead re-entering the watershed. Volunteers were assigned different stretches of the creek, and they visited regularly to make visual observations of fish and spawning beds throughout different stretches of the watershed. The volunteer effort focused on areas that were not currently covered by regular agency monitoring and helped fill in geographical gaps in the watershed. This monitoring work was crucial to help inform future restoration efforts along the creek like CalTrout’s Sunol Valley, Alameda Creek Fish Passage Project.
Determining the appropriate type of monitoring method to use depends on various factors such as fish movement patterns, research questions, watershed size, funding available, and more. While each method collects information in different ways, they each work towards the same goal of helping us build a picture of how fish use and migrate through our watersheds.
Get Involved
At CalTrout, we know that monitoring fish migration is crucial – yet it's often underfunded and overlooked. Private donations help us lay the groundwork for monitoring to begin in watersheds where data gaps might exist – and they help us leverage larger public investments. If you’re interested in getting involved, you can join our volunteer community, attend an upcoming event, or make a gift to CalTrout today. Together, we can unravel where fish are going and how we can best help them.
