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Klutina Sonar
The Klutina River Sonar Project is operated by AITRC in partnership with the Native Village of Eyak and state and federal management agencies to monitor sockeye and Chinook salmon returning to the Klutina River, one of the most important tributaries in the Copper River Basin. Each summer, staff collect real-time data on salmon passage and run timing to support long-term population monitoring, Tribal co-management, and subsistence stewardship.
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This project provides essential information for understanding salmon abundance, improving management decisions, and protecting culturally important fisheries for future generations.
What is Sonar?
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Sonar is an underwater monitoring system that uses sound waves to detect and record fish moving through a river. By creating detailed images of salmon as they migrate upstream, sonar allows biologists to count fish and track movement without handling or disturbing them.
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Because the Klutina River carries glacial silt and has low visibility, sonar is one of the most reliable tools for monitoring salmon in this system.
How Klutina River Sonar Works?
During the summer, salmon return from the ocean to their natal streams to spawn. On the Klutina River, two sonar units are installed on opposite riverbanks and operate continuously throughout the season.
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As salmon swim upstream, they pass through the sonar beams, which create moving images of each fish. Trained technicians review these recordings to count fish, determine movement direction, and estimate daily and seasonal passage.
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Sonar sites are selected based on channel configuration, flow characteristics, access, bank stability, and the ability to achieve full bank-to-bank coverage. Each site must accommodate sonar units on both banks and small picket weirs to guide fish through the insonified area.
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Once recorded, salmon continue their natural migration without being handled, delayed, or obstructed.
Data Collection & Analysis.
Sonar systems operate continuously throughout the season and record data in ten-minute increments.
For analysis, the first ten minutes of each hour are reviewed to estimate net upstream and downstream movement. Hourly passage is expanded from this subsample and summarized into daily and weekly estimates.
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This information helps managers understand:
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When salmon enter the system
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When peak migration occurs
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How strong each year’s run is
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How many fish reach spawning areas
Sonar operations were paused from 2023 to 2025 due to funding constraints.
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Future monitoring efforts will depend on the availability of sustained funding and equipment necessary to achieve full river coverage.