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Tanada Creek Weir
AITRC operates the Tanada Creek Weir to monitor sockeye salmon returning to the upper Copper River Basin. Each summer, staff count migrating salmon, collect biological data, and track run timing to support long-term population monitoring and Tribal co-management efforts. The weir provides essential information for understanding salmon abundance, improving subsistence management, and protecting this culturally important fishery for future generations.
What is a Weir?
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A weir is a structure placed across a stream that gently guides fish through a controlled opening, allowing biologists to observe them as they migrate. By slowing and organizing the flow of fish, weirs make it possible to record how many fish pass through, collect biological information, and track the timing of runs with a high level of accuracy. This method is one of the most reliable ways to monitor salmon populations and supports careful stewardship of fisheries across Alaska.
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.
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.
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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.
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Additionally, the chemical composition of otoliths can reveal details about the environments a fish traveled through, such as transitions between freshwater and saltwater habitats.
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Together, the weir counts and otolith sampling provide important long-term insights into sockeye run timing, productivity, and environmental influences within Ahtna Territory.
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2025 weir team, Dan Gorze (Fisheries Biologist) and Tim Olsen (Fisheries Technician).
Tim Olsen (2025 Fisheries Technician) counting salmon.
Weir team setting up Tanada Creek Weir for the
2025 season.