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Research biologists at the Columbia River Research Laboratory are using global positioning systems (GPS) in a study of the distribution of juvenile salmon in relation to dissolved gas supersaturation in the Columbia and Snake rivers. The study is being conducted between Ice Harbor Dam on the Snake River and on the Columbia River, a distance of 42 river miles. Fish exposed to water supersaturated with air, produced when water is spilled over dams, can suffer from a potentially-lethal condition called Gas Bubble Disease (GBD), which is like the "bends" of human divers. The goal of this research is to assess the risk of Gas Bubble Disease by determining the exposure of individual migrating fish. The GPS is used to determine the spatial location of radio-tagged fish, whereas the depth of the fish is determined using a miniature pressure- sensitive radio tag implanted in each fish (see Tags keep tabs on chinook). We are very interested in the depths of the fish because the risk of Gas Bubble Disease is reduced with depth, just as human divers can recover from the bends by increasing their depth. Biologists surgically implant small radio tags into juvenile spring chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) obtained at the juvenile fish collection facility at Lower Monumental Dam on the Snake River and release them below Ice Harbor Dam. The tagged fish are located by boat using special radio receivers and antennas. We record the fish depth, spatial location, ambient total dissolved gas in the river, and several other physical measures when we locate each fish at one-hour intervals. The product of this research will be a detailed exposure history of each individual fish as it migrated through this reach of river. Project Contact John W. Beeman Email: john_beeman@usgs.gov Publications
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