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A radiotelemetry evaluation was conducted during April-October 2011 to describe movement patterns, forebay behavior, and passage of juvenile steelhead, coho salmon, and Chinook salmon at Cowlitz Falls Dam, Washington. The primary focus of the study was to describe fish behavior near a behavioral guidance structure (BGS) and floating surface collector (FSC) deployed upstream of Cowlitz Falls Dam. A secondary focus was to determine the proportion of tagged fish that were detected near spillbays 2 and 3 on the dam, because this location has been proposed for deploying weir boxes as an additional dam-based collection alternative in the future. Juvenile steelhead (Oncorhynchus mykiss), coho salmon (Oncorhynchus kisutch), and Chinook salmon (Oncorhynchus tshawytscha) were collected and tagged at the Cowlitz Falls Fish Collection Facility and transported upstream where they were released into the Cowlitz and Cispus Rivers. We radio-tagged and released 110 juvenile steelhead, 110 juvenile coho salmon, and 110 juvenile Chinook salmon and monitored their movements in and around the BGS/FSC complex, at the dam, and downstream of the dam. We used detection records and a Markov chain model to calculate probabilities of movement between specific areas in the forebay of Cowlitz Falls Dam. These areas are referred to as states and the Markov chain model was used to create a series of tables, called transition matrices, that contained estimated probabilities of movement between states. These probabilities were insightful for understanding how radio-tagged fish moved near the BGS, FSC, and spillbays. Most tagged fish (89-91 percent) moved downstream of release sites (9 or 22 rkm upstream of the dam) and were detected in the dam forebay during the study period. Tagged fish that encountered the BGS on their first approach to the dam were distributed across the forebay, which supports the concept of using a BGS to concentrate fish near a collector entrance in the dam forebay. We found that 14 percent of the steelhead, 18 percent of the coho salmon, and 17 percent of the Chinook salmon encountered the FSC discovery area without BGS guidance on their first trip through the forebay. The BGS guided 36 percent of the steelhead, 22 percent of the coho salmon, and 46 percent of the Chinook salmon to the FSC discovery area when fish first entered the forebay, which resulted in 40-63 percent (by species) of the tagged fish arriving at the FSC discovery area. Movement patterns along the BGS showed that fish were likely to guide along the device, but also demonstrated the tendency of fish to move under the BGS and downstream to Cowlitz Falls Dam. Tagged fish that arrived at Cowlitz Falls Dam were distributed across the dam face but a high percentage of each species (65 percent of steelhead; 61 percent of coho salmon; 71 percent of Chinook salmon) arrived on the northern side of the dam. Movement probabilities near spillbays 1 and 4 showed a strong preference for tagged fish to move from the outer edges of the dam towards the center of the dam w...

A study was conducted in the lower Yakima River, Washington, during June-October 2019 to evaluate water temperature effects on adult sockeye salmon (Oncorhynchus nerka) behavior. A total of 60 sockeye salmon adults were tagged with radio transmitters and monitored during the study. Fourteen of the fish were collected and tagged at Prosser Dam in late June and the remainder were collected and tagged at the mouth of the Yakima River in late July. Water temperature exceeded 20 degrees Celsius (°C), conditions shown to block upstream migration of adult sockeye salmon in other river systems, from June 9, 2019 to September 15, 2019. These elevated temperatures seemed to affect the behavior of tagged fish during this study. Fish that were collected and tagged at Prosser Dam left the Yakima River within days of release and tagged fish that were collected and released at the mouth of the Yakima River failed to enter and move upstream until mid-September when water temperature decreased to less than (<) 20 °C. Monitoring sites were located adjacent to several known areas of cool-water inputs that may provide thermal refuge for fish in the lower Yakima River to determine if tagged fish spent time in these areas. Although several tagged fish moved repeatedly past these sites, most fish spent <30 minutes at any given site, indicating that fish were actively migrating past the sites rather than holding near cool-water inputs. A single tagged fish moved upstream to Roza Dam and was collected for upstream transport to Cle Elum Reservoir during our study. Additional research in subsequent years likely will be required to better understand how water temperature affects adult sockeye salmon in the lower Yakima River.

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