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Tanada Creek Weir
Tanada Creek connects Tanada Lake to the Copper River watershed and provides important spawning habitat for sockeye salmon. Each summer, AITRC operates the Tanada Creek Weir in partnership with Wrangell-St. Elias National Park and Preserve to monitor adult salmon as they migrate upstream toward Tanada Lake. Staff count migrating salmon, collect biological data, and track run timing, providing valuable information about salmon abundance and long-term population trends. This monitoring supports Tribal co-management and informed subsistence management while improving our understanding of this culturally important salmon population and helping protect it for future generations.
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Funded by the National Park Service in partnership with Wrange-St. Elais National Park and Preserve
What is a Weir?
A fish weir is a temporary structure placed across a stream to guide migrating fish through a designated passage where they can be observed and counted. Unlike methods that estimate the number of salmon passing a location, a properly operated weir allows researchers to directly observe fish moving upstream.
At Tanada Creek, the weir is installed during the summer salmon migration and maintained throughout the run. Its panels direct fish toward a passage equipped with an underwater camera, allowing salmon to continue upstream while providing researchers with a consistent way to document their return.
Because the same location and monitoring methods can be used from year to year, weir data are particularly valuable for tracking long-term changes in a salmon population.
How Tanada Creek Weir Works?
During the summer, salmon return to the streams where they were born, swimming upstream against the current to reach their spawning grounds. The Tanada Creek weir gently guides these fish toward a designated salmon entrance, where they swim through a short tunnel-like structure. Inside this passage, an underwater camera records each fish as it moves through. Once counted, the salmon exit the tunnel and continue their natural migration upstream without being handled or delayed.
Throughout the season, staff monitor the weir, record daily fish passage, maintain equipment, and collect biological information. These data help document when salmon arrive, how many return, and how the run changes throughout the summer and from year to year.
While sockeye salmon make up the majority of the monitored return, the weir also provides an opportunity to document other fish species moving through Tanada Creek.
AITRC is also exploring how artificial intelligence (AI) and computer vision can improve salmon monitoring at Tanada Creek.
During the 2026 field season, AITRC began piloting a system that uses underwater imagery and machine-learning tools to assist with identifying and counting fish as they pass through the weir. Rather than relying entirely on staff to manually review large amounts of imagery, computer-vision models can be trained to recognize fish and help process observations more efficiently.
The goal is not to replace field crews or human expertise. Instead, AI can serve as another tool for biologists—helping reduce the time required to review imagery, standardize counts, and identify portions of recordings that need closer examination by staff.
As the system develops, human-reviewed observations can also be used to evaluate and improve the model's accuracy.
Can AI help?
Otolith Collection.
AITRC contracted PWSSC to collect otolith samples from sockeye carcasses in Tanada Lake to help build an age profile of the population.
We sample otoliths, or “ear stones,” from fish to gather accurate information about their age, origin, and life history. Like tree rings, otoliths form annual growth layers that can be counted under a microscope, making them a reliable tool for determining a fish’s age—often more accurately than scales, especially in older or ocean-going fish.
In hatchery-reared fish, otoliths may carry thermal marks created by controlled temperature changes during early development. These marks help identify the fish’s hatchery of origin and brood year, which is especially valuable in managing mixed-stock fisheries and distinguishing wild from hatchery fish.
Additionally, the chemical composition of otoliths can reveal details about the environments a fish traveled through, such as transitions between freshwater and saltwater habitats.
Together, the weir counts and otolith sampling provide important long-term insights into sockeye run timing, productivity, and environmental influences within Ahtna Territory.
Project Leads: Dan Gorze | Questions on this project?