Kenai River Mile 8.6—
King Salmon Sonar Site

Detecting Kenai king salmon is extremely challenging. It takes some special know-how to catch Kenai king salmon (Chinook)—and not just with a rod and reel, but with sonar too. Most salmon swim close to shore where Alaska Department of Fish and Game fisheries biologists can more easily detect them with sonar. But Kenai king salmon swim far from shore where only advanced sonar technology can detect fish. Detecting Kenai king salmon is further complicated by the need to separate them from sockeye salmon, which in July migrate into the Kenai alongside king salmon at a ratio of about 20-to-one.

The Kenai king salmon site is the only site where ADF&G uses sonar to distinguish fish by size. The site is also field-testing a newly-developed technology that allows us to capture high-resolution images of fish swimming up to 100 feet from shore. Even as the Kenai king salmon site maintains a pioneering position in fisheries sonar, ADF&G relies on sonar as only one of the tools it uses to generate estimates and gauge run strength. ADF&G also relies heavily on information from non-sonar tools including inriver gillnets and sport fish creel surveys.

>The Site and River

The Kenai River Mile 8.6 Chinook sonar site—not to be confused with the Kenai River Mile 19 Sockeye sonar site—operates in a location that faces strong tidal influences and other challenges.

>The Fish

Anglers from all over the world travel to Alaska to catch a king salmon from the Kenai River—known for producing some of the world’s largest.

>Sonar Tools

The Kenai king salmon site uses advanced sonar detection methods and technology used at no other site in the state. 

>Other Tools

ADF&G gauges run strength based primarily on two estimates and three indicators, all of which rely on non-sonar information.

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Kenai River Mile 8.6
Photo Gallery

See photos of the Kenai River, Kenai River 8.6 sonar site operations and more.

Kenai River sonar site radio tagging story
Follow an ADF&G researcher in this audio story, as he tracks radio-tagged Kenai king salmon by boat and airplane, and listens for signals from live salmon—three beeps—and from salmon that have spawned and died—five beeps. The radio tags are being used to document Kenai king salmon migration histories and as part of a bigger project to produce an independent estimate of abundance that can be compared with sonar site estimates.

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