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Alaska Department of Fish and Game

Alaska Fisheries Sonar

Kenai (RM 13.7) River

Kenai River Mile 13.7— A New King Salmon Sonar Site?

The proposed new sonar site at Kenai River Mile 13.7 is above tidal influence and is narrower in width than the site at RM 8.6 allowing for more complete sonar coverage of the river by the sonar beams.

The Alaska Department of Fish and Game (ADF&G) will operate two king salmon sonar stations on the Lower Kenai River during 2013, one at the historical site at river mile (RM) 8.6 and a second at an experimental site at RM 13.7. ADF&G has operated the king salmon sonar at RM 8.6 since the late 1980s. The RM 8.6 site was originally selected because of its suitability for operating a dual-beam (and subsequently a split-beam) sonar system, which requires a near-perfect linear river bottom profile. The site, however, has many disadvantages including significant tidal influence, heavy silt load, large amounts of floating debris, and milling fish behavior. Relocating the site farther upriver will improve ADF&G's ability to more accurately estimate king salmon passage by minimizing or eliminating these negative factors. In 2011, ADF&G began the process of locating potential sites above tidal influence that would be suitable for deploying newer sonar technology. The section of river at RM 13.7 has a nearly ideal bottom profile for sonar deployment and was selected as the preferred site for further investigation. One of the main advantages of this site is the potential to achieve bank-to-bank coverage of the river with sonar, which is not possible at the RM-8.6 site. Like the sonar project at RM 8.6, the sonar project at RM 13.7 is scheduled to operate from May 16-August 10, 2013. However, because the project is considered experimental, inseason estimates will not be produced in 2013.