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Richard S. Brown was a respected member of the global fisheries profession, known for his expertise in winter biology and his contributions to the study of fish migration and passage through hydropower turbines. He conducted research at various universities and institutions, including the University of Alberta, the University of Waterloo, and the Pacific Northwest National Laboratory. Brown's work on barotrauma associated with hydropower turbines has had a global impact on river infrastructure development. He was also a dedicated mentor and family man. His scientific legacy will continue to be remembered and valued. [Extracted from the article]

Background: The ability to track fish in the vicinity of dams and detect the presence of fish in fishways (also referred to as fish ladders) is critical to understanding the migration biology of upstream migrating fish and their passage success. Acoustic telemetry provides a valuable method within the telemetry toolbox, but has rarely been used in noisy, constrained, swift-flowing, and air-entrained environments such as fishways because of the perceived limitations of acoustic telemetry in such environments relative to other techniques such as radio telemetry. However, there have been no published studies that represent systematic evaluations of both detection efficiency based on number of transmitted signals and detection probabilities based on number of fish detected in fishways for acoustic telemetry. As such, the efficacy of acoustic telemetry in a fishway was evaluated using both controlled field experiments and movements of live fish at the Wanapum Dam fishway on the Columbia River in Washington State. In this study, the Juvenile Salmon Acoustic Telemetry System (JSATS) was selected because of its high carrier frequency (416.7 kHz) and short signal duration yielding good system resilience in shallow, noisy, and constrained environments. Results: Detection efficiencies from the controlled field experiments were over 80 % (mean ± standard error (SE) = 85 ± 2 %) for most locations within the fishway at Wanapum Dam. Detection efficiency was nearly 100 % (mean ± SE = 97 ± 1 %) in the fishway entrance when the transmitters (also referred to as tags) were within 10 m of the hydrophones. The detection probabilities for the live fish experiment were 100 % at all deployment locations. Conclusions: This study suggests that a 416.7-kHz acoustic telemetry system with binary phase shift-keyed encoding is capable of reliably detecting fish within a large fishway, thus providing a reliable tool to enable researchers to understand and study fish behavior and their fate near and in fishways. [ABSTRACT FROM AUTHOR]

Chum Salmon Oncorhynchus keta alevins developing in gravel downstream of Bonneville Dam on the Columbia River are exposed to elevated total dissolved gas (TDG) when water is spilled to move migrating salmon smolts to the ocean. We studied whether alevins that were exposed to six levels of dissolved gas ranging from 100% to 130% TDG at three development periods between hatch and emergence (hereafter, early, middle, and late stages) experienced differential mortality, growth, gas bubble disease, or seawater tolerance. Each life stage was exposed for 49 d (early stage), 28 d (middle stage), or 15 d (late stage) beginning at 13, 34, and 47 d posthatch, respectively, through emergence. Mortality for all stages was estimated to be 8% (95% confidence interval [CI] = 4-12%) when dissolved gas levels were less than 117% TDG. Mortality increased as dissolved gas levels rose above 117% TDG; the lethal concentration producing 50% mortality was 128.7% TDG (95% CI = 127.2-130.3% TDG) in the early and middle stages. There was no evidence that gas exposure affected growth. The proportion of fish with gas bubble disease increased with increasing gas concentrations, and bubbles occurred most commonly in the nares and gastrointestinal tract. Early stage fish exhibited higher ratios of filamental to lamellar gill chloride cells than late-stage fish, and these ratios increased and decreased for early and late-stage fish, respectively, as gas levels increased; however, there were no significant differences in mortality between life stages after 96 h in seawater. The study results suggest that water quality guidelines for dissolved gas (=105% TDG) offer a conservative level of protection to Chum Salmon alevins incubating in gravel habitat downstream of Bonneville Dam. [ABSTRACT FROM AUTHOR]