Nushagak River

The Nushagak River sonar site was designed to estimate sockeye escapement, but the king salmon data the site also collects draws strong interest from the sport fishing community. While the site provides reliable estimates for sockeye salmon, it is less adept as a tool for estimating king salmon escapement. Across the width of the river, the sonar’s detection range adequately covers the region in which sockeye migrate, but not king salmon. In the approximately 1,000-foot wide channel, migrating sockeye salmon swim almost entirely within 50 feet of shore where sonar can easily detect them. Larger king salmon, however, often swim in the middle of the river beyond the range of sonar. Consequently, the site’s sonar only counts a proportion of the king salmon migrating past. While a full count is ideal, fisheries biologists can also use a partial count as an index to manage the fishery so long as the site counts the same proportion from year to year. Because the site’s sonar counts within the same region from year to year, biologist have been working under the assumption that it also counts the same proportion of the king salmon from year to year. To check this assumption, ADF&G launched an extensive three-year project in 2011 to track king salmon migrations past the site. To learn more about the project see Other Important Tools below.

Nushagak River Sonar Site
>The Site and River

The Nushagak River sonar site operates in a wide and shallow channel of the river. Conditions at the site are favorable for using sonar to detect shore-based migrations of salmon.

Nushagak River Sonar Site
>The Fish

The Nushagak River supports king, coho, sockeye, chum and pink salmon. Sockeye and king salmon are the river’s primary fisheries.

Nushagak River Sonar Site
>Sonar Tools

The Nushagak River sonar site has been using sonar to detect fish for 25 years and a type of sonar technology known as DIDSON since 2003.

Nushagak River Sonar Site
>Other Tools

Salmon escapement estimates are generated using a combination of sonar and inriver gillnet data.

Nushagak River

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Nushagak River

Nushagak River Photo Gallery

See Nushagak River sonar site gillnetting, sonar activities, Nushagak salmon and more.

Nushagak River

Nushagak River Sonar Site on Radio

As ADF&G began Nushagak River sonar site operations in 2011, it also launched a three-year study to better understand Nushagak king salmon migration patterns past the site. Listen to an on-site report about this unique project in this radio broadcast, which aired on Dillingham's KDLG 670 AM / 89.9 FM and on the Alaska Fisheries Report, produced by Kodiak's KMXT 100.1 FM.
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