
About​​​
The Nushagak weir projects were started in 2024 as part of BBSRI's Nushagak Chinook Assessment Program.
We operate two fish counting weirs on the Upper Nushagak and Koktuli Rivers, both major Chinook-producing tributaries of the Nushagak. ​​​​​​​​​​​​​
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Nushagak Weir Projects​​​​​​​​​​​​​​

The weirs provide counts of adult salmon migrating upstream to spawn between June 28 and August 15, which covers all of the Chinook run and the majority of the chum and sockeye runs.​​
Upper Nushagak River Weir
The Upper Nushagak weir site is on the upper reaches of the Nushagak mainstem, almost 200 river miles upriver from Dillingham, AK and just above the confluence of the Chichitnok River. ​
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​​​​Koktuli River Weir
The Koktuli weir site is on the lower section of the Koktuli River, downstream from where the river splits into its north and south forks and just below the outlet of the Swan River. It is approximately 160 river miles from Dillingham.
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Weir Design​​​​​
​​​Both of the Nushagak weirs use a fixed panel, tripod design. Steel tripods are anchored in a line across the river, and aluminum panels are rested against them and held in place by water pressure.​​​​​​​​​​​​​
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This creates a barrier across the river, so that migrating salmon can only pass the weir when the gates of the livebox are opened.
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Both weirs are also fitted with floating panel "boat gates" which small skiffs and rafts to pass through the weir at any time.
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The weirs are around 180-200 feet long, and use between 20-24 tripods.​​​​
Data Collection

At the weirs, technicians collect three types of data:​​​​​​​​​​​​​
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Passage Counts​
Technicians perform 4-8 hour-long counts per day, counting all the fish that pass through the weir by species.
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Biological Sampling
Once or twice per day, technicians sample Chinook, chum and sockeye salmon and then release them above the weir. Species, sex and length are recorded and scale and tissue samples are taken from each fish.​
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Environmental Data
​Twice per day, technicians record the river stage, precipitation, weather, water clarity and air and water temperatures.
A full report and data from the 2024 season will be available below in early 2025.