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Ecology

Total Dissolved Gas Effects on Incubating Chum Salmon Below Bonneville Dam

At the request of the U.S. Army Corps of Engineers (Portland District), Pacific Northwest National Laboratory is monitoring total dissolved gas (TDG) concentrations during spring spill operations at Bonneville Dam in chum salmon (Oncorhynchus keta) spawning areas – Multnomah Falls and Ives Island. Using Hydrolab continuous data loggers deployed in from mid-February through the end of July, measurements of TDG, temperature, dissolved oxygen, and specific conductance are made in the river and the hyporheic zone (i.e., the riverbed where chum salmon eggs incubate and river water and groundwater mix). This project is expected to result in an assessment of the potential effects to chum salmon fry from TDG exposure downstream from Bonneville Dam. This information will assist managers that are faced with deciding between more spill to aid downstream migrants (at the potential expense of elevated intragravel TDG) versus the reduction in TDG with reduced spill (at the potential expense of downstream migrant passage).

Effects of total dissolved gas on chum salmon

Effects of total dissolved gas on chum salmon fry survival, growth, gas bubble disease and seawater tolerance.
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