Acoustic Tracking Study on Survival of Columbia River Salmon - 2004-2005

Region of interest for the tracking of acoustically tagged Snake River Chinook during the summer of 2005.

The Bonneville Power Administration funded a project to test the feasibility of using the POST acoustic array to study the ocean survival and movements of chinook salmon runs from the Columbia River and one of its tributaries, the Snake River. The Columbia River system is highly developed for the generation of hydroelectricity and information is needed to understand the effects of dams on fish.

Cape Elizabeth	Strait of Juan de Fuca	Brooks Peninsula
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In May 2005, nearly 200 acoustically tagged chinook smolts were released into the Columbia River downriver of Bonneville Dam. These fish were detected on three acoustic listening lines placed partway across the continental shelf near Cape Elizabeth, Washington; Brooks Peninsula, northwest Vancouver Island; and across the Strait of Juan de Fuca. The smolts were found to migrate northward quickly, at average rates near 1.5 to 2 body lengths per second, or 20-25 km/d in the ocean. They did not enter the Strait of Georgia via Juan de Fuca on their way north, but instead migrated up the west coast of Vancouver Island.

In 2006, a total of almost 1000 smolts were tagged, and the project was expanded to compare survival and migration of chinook from two different tributaries of the Columbia River, with historically contrasting survival rates. Some of the smolts from each of the two rivers were barged and released downstream of the most downstream dam in the Columbia River, a method currently used by the Bonneville Power Administration to reduce mortality during the freshwater component of the smolts’ lives. The tagged fish will then be tracked as they travel over the ocean array, including two lines north of the Columbia River mouth (similar to those deployed in 2005) and soon one south of the river mouth, making it possible to compare survivals and migration routes for smolts originating from two different regions and exposed to two different methods of travel to the Columbia River estuary.

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