Yentna River

The Susitna River is the third most productive sockeye salmon river in Upper Cook Inlet and, as its largest tributary, the Yentna River is responsible for more than half of Susitna sockeye production. But the Susitna and Yentna rivers also produce abundant populations of chum, coho, king and pink salmon. With so much diversity, it's difficult to monitor any one species. Of the four sockeye salmon sonar projects the Alaska Department of Fish and Game operates in Upper Cook Inlet, the Yentna River project is by far the most challenging.

ADF&G fisheries managers once used the Yentna River sonar sockeye estimates as an early indicator of escapement into the Susitna drainage. But after a suspiciously low estimate in 2005, ADF&G began a program to examine the accuracy of these estimates and determined by late 2008 that the project was grossly underestimating sockeye salmon returns. Consequently, ADF&G stopped using Yentna sonar as a management tool and in 2009 began operating the project for research only, implementing new studies in an attempt to resolve issues undermining the site’s ability to assess sockeye salmon stocks.

 
Yentna River Map
>The Site and River

The Yentna River is one of the most challenging rivers in which ADF&G uses sonar to detect fish. The river is extremely turbid and wide. Also, water flows fluctuate greatly due to rainfall, flushing large quantities of debris downstream.

     
Yukon River Pilot State Sonar Site
>The Fish

The longest continuous abundance record for Susitna and Yentna sockeye salmon is based on the Yentna site sonar. Learn more about these stocks and how ADF&G has been managing them since it stopped using the sonar site as a management tool.

>Sonar Tools

As a management tool the sonar site used Bendix sonar, but as a research project it has transitioned to DIDSON technology. Learn more about how ADF&G uses sonar technology on the Yentna River.

>Other Tools

ADF&G relies on fish wheels to process Yentna sonar counts into sockeye estimates. At the same time, fish wheels have been identified as a primary source of estimate error. Learn more about how ADF&G is addressing the fish wheel conundrum.

Yentna River

Print out a PDF copy of the Yentna River sonar site Brochure

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Yentna River

Yentna River Photo Gallery

See photos of the Yentna River, Susitna River, Yentna River sonar site operations and more.

Yentna River

Yentna River Sonar Site on Radio
s

Listen to a radio broadcast covering research conducted at the Yentna River sonar site. The broadcast was reported from the site and aired in August 2011 on The Alaska Fisheries Report, a show produced by Kodiak's KMXT 100.1 FM.

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