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Amy C. Hansen

Publications and source records attributed to Amy C. Hansen.

33 records · Page 2Linked to original sources
USGS2019

Evaluation of Chinook salmon (Oncorhynchus tshawytscha) fry survival at Lookout Point Reservoir, western Oregon, 2017

A field study was conducted to estimate survival of fry-sized juvenile Chinook salmon ( Oncorhynchus tshawytscha ) in Lookout Point Reservoir, western Oregon, during 2017. The field study consisted of releasing three groups of genetically marked fish in the reservoir and monthly fish sampling. Fish were released during April 18–19 (43,950 fish), May 30–June 2 (44,145 fish), and on June 28, 2017 (3,920 fish). Reservoir sampling began in May and occurred monthly through October, consisting of 5-day events where juvenile Chinook salmon were collected using various gear types (electrofishing, shoreline traps, gill nets). Data were analyzed using two models: (1) a staggered release-recovery model (SRRM), and (2) a parentage-based tagging (PBT) N -mixture model. The SRRM provided survival estimates from two periods: (1) mid-April to late May (S SRRM1 ), and (2) late May to late June (S SRRM2 ). Multiple estimates of survival were possible for each period using different combinations of recovery data from the three groups of fish that were released. Survival estimates for S SRRM1 ranged from 0.470 to 0.520. Estimates for S SRRM2 ranged from 0.968 to 0.969; cumulative survival from mid-April to late June (S SRRM2 ) was estimated at 0.870. We suspect that issues with the third release group led to biased survival results using the SRRM. The PBT N -mixture model provided survival estimates from six periods: (1) mid-April to mid-May (S NMIX1 ), (2) mid-May to mid-June (S NMIX2 ), (3) mid-June to mid-July (S NMIX3 ), (4) mid-July to mid-August (S NMIX4 ), (5) mid-August to mid-September (S NMIX5 ), and (6) mid-September to mid-October (S NMIX6 ). Survival estimates from the PBT N -mixture model were lowest for S NMIX1 (0.461) and increased monthly to a high of 0.970 for S NMIX6 . Cumulative survival from mid-April to mid-July was 0.233 and overall survival from mid-April to mid-October was 0.188. This suggests that most mortality occurred early in the study when juvenile Chinook salmon were small. This could be because these fish were most vulnerable to predation in the reservoir at that time. We determined that mortality of juvenile Chinook salmon was high in the reservoir during this study and similar estimates of parr-to-smolt survival have been observed in other systems. Additional analyses are required, including results from the second year of study (2018), and potentially similar evaluations will need to be made at other locations to determine if reservoir mortality is a limiting survival factor for Chinook salmon in the Middle Fork Willamette River.

Oregon↗
USGS2018

Emigration and transportation stress of juvenile Chinook salmon relative to their reintroduction upriver of Shasta Dam, California, 2017–18

The Bureau of Reclamation supports the Shasta Dam Fish Passage Evaluation (SDFPE; Yip, 2015) program, and in 2016 set out to determine the feasibility of reintroducing winter-run and spring-run Chinook salmon ( Oncorhynchus tshawytscha ) and steelhead ( O. mykiss ) to tributaries upstream of Shasta Dam. Ideally, reintroduction strategy includes trapping naturally produced downstream-migrating juvenile fish at the head of Lake Shasta (upstream of Shasta Dam), or near the mouth of the tributaries where they flow into the lake. However, evaluations of a juvenile collection system in one of the target tributaries (McCloud River) was delayed because of concerns about the fish source to be used as surrogate for winter-run Chinook salmon and the location and impact of the trap-and-haul operations. In 2017, the U.S. Geological Survey (USGS) was contracted to evaluate the reintroduction of winter-run salmon into tributaries upstream of Shasta Dam, and the McCloud River, having the most suitable spawning and rearing habitat for salmon adjacent to Shasta Reservoir (Lake) was the chosen study area. The first stage of the project was to assess the feasibility using a head-of-reservoir fish trap to collect juvenile salmon, but these efforts were delayed, so efforts were used to assess how juvenile Chinook salmon would distribute within the McCloud River and Shasta Reservoir and help determine the feasibility of collecting fish at Shasta Dam. Importantly, NOAA fisheries was also conducting an acoustic telemetry project through the Sacramento River, and they provided the additional acoustic detection data on our tagged fish to San Francisco Bay. These data were collected beyond original study goals, but added a large contribution to the findings and inferences from this study.

California↗
USGS2018

Evaluation of sockeye salmon after passage through an innovative upstream fish-passage system at Cle Elum Dam, Washington, 2017

Executive Summary The Bureau of Reclamation (Reclamation) and the Washington State Department of Ecology (Ecology), working with the Yakima River Basin Water Enhancement Project Workgroup (composed of representatives of the Yakama Nation; Federal, State, county, and city governments; environmental organizations; and irrigation districts), developed the Yakima Basin Integrated Plan (Integrated Plan). The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima Basin to be implemented over a 30-year period. The Integrated Plan includes seven elements: Reservoir fish passage, Structural and operational changes to existing facilities, Surface water storage, Groundwater storage, Habitat/watershed protection and enhancement, Enhanced water conservation, and Market reallocation. The first listed element, reservoir fish passage, will be expensive and take many years to accomplish. Reclamation and Ecology decided to look at new and innovative means to provide passage that could help reduce project cost and construction timing while maintaining survival rates of traditional upstream passage facilities. Reclamation contracted with the U.S. Geological Survey to do a study to evaluate the outcome of passage through one innovative fish-passage system at Cle Elum Dam, the first Integrated Plan reservoir fish-passage project being implemented.

Washington↗
USGS2017

Synthesis of downstream fish passage information at projects owned by the U.S. Army Corps of Engineers in the Willamette River Basin, Oregon

The U.S. Army Corps of Engineers (USACE) operates the Willamette Valley Project (Project) in northwestern Oregon, which includes a series of dams, reservoirs, revetments, and fish hatcheries. Project dams were constructed during the 1950s and 1960s on rivers that supported populations of spring Chinook salmon ( Oncorhynchus tshawytscha ), winter steelhead ( O. mykiss ), and other anadromous fish species in the Willamette River Basin. These dams, and the reservoirs they created, negatively affected anadromous fish populations. Efforts are currently underway to improve passage conditions within the Project and enhance populations of anadromous fish species. Research on downstream fish passage within the Project has occurred since 1960 and these efforts are documented in numerous reports and publications. These studies are important resources to managers in the Project, so the USACE requested a synthesis of existing literature that could serve as a resource for future decision-making processes. In 2016, the U.S. Geological Survey conducted an extensive literature review on downstream fish passage studies within the Project. We identified 116 documents that described studies conducted during 1960–2016. Each of these documents were obtained, reviewed, and organized by their content to describe the state-of-knowledge within four subbasins in the Project, which include the North Santiam, South Santiam, McKenzie, and Middle Fork Willamette Rivers. In this document, we summarize key findings from various studies on downstream fish passage in the Willamette Project. Readers are advised to review specific reports of interest to insure that study methods, results, and additional considerations are fully understood.

Oregon↗
USGS2016

Survival of juvenile chinook salmon and coho salmon in the Roza Dam fish bypass and in downstream reaches of the Yakima River, Washington, 2016

Estimates of juvenile salmon survival are important data for fishery managers in the Yakima River Basin. Radiotelemetry studies during 2012–14 showed that tagged juvenile Chinook salmon ( Oncorhynchus tshawytscha ) that passed through the fish bypass at Roza Dam had lower survival than fish that passed through other routes at the dam. That study also identified flow-survival relationships in the reaches between the Roza Dam tailrace and Sunnyside Dam. During 2012–14, survival also was estimated through reaches downstream of Sunnyside Dam, but generally, sample sizes were low and the estimates were imprecise. In 2016, we conducted an evaluation using acoustic cameras and acoustic telemetry to build on information collected during the previous study. The goal of the 2016 research was to identify areas where mortality occurs in the fish bypass at Roza Dam, and to estimate reach-specific survival in reaches downstream of the dam. The 2016 study included juvenile Chinook salmon and coho salmon ( O. kisutch ). Three acoustic cameras were used to observe fish behavior (1) near the entrances to the fish bypass, (2) at a midway point in the fish bypass (convergence vault), and (3) at the bypass outfall. In total, 504 hours of acoustic camera footage was collected at these locations. We determined that smolt-sized fish (95–170 millimeters [mm]) were present in the highest proportions at each location, but predator-sized fish (greater than 250 mm) also were present at each site. Fish presence generally peaked during nighttime hours and crepuscular periods, and was low during daytime hours. In the convergence vault, smolt-sized fish exhibited holding behavior patterns, which may explain why some fish delayed while passing through the bypass. Some of the acoustic-tagged fish were delayed in the fish bypass following release, but there was no evidence to suggest that they experienced higher mortality than fish that were released at the bypass outfall or downstream of the dam. Most of the tagged fish that were released in the fish bypass moved downstream and re-entered the river within 12 hours, but 9.8 percent of the Chinook salmon and 15.7 percent of the coho salmon remained in the bypass for 2.5–17.4 days. We developed a set of models for Chinook salmon and coho salmon and used model selection to determine if release site was an important predictor of survival of tagged fish. The models that provided the best fit to the Chinook salmon and coho salmon datasets did not include release site as a covariate. Furthermore, survival estimates for groups of fish from the various release sites were nearly identical for both species. Based on these observations, it appears that passage through the fish bypass did not result in increased mortality relative to groups of fish released downstream of the bypass. Juvenile Chinook salmon migrated downstream faster than juvenile coho salmon and survival for each species varied with release timing. Median travel time from release at Roza Dam to arrival at a detection gate located at river kilometer (rkm) 527.8 on the Columbia River was 15.4 days for Chinook salmon and 37.4 days for coho salmon. Cumulative survival from Roza Dam to the Columbia River detection gate ranged from 0.299 to 0.678 for Chinook salmon, and from 0.321 to 0.627 for coho salmon. Survival was highest for both species when tagged fish were released in mid-April and lowest when tagged fish were released in early-May. Reach-specific survival estimates were standardized to create estimates that described survival per 100 rkm, which showed that survival was very low (less than 0.500) for some release groups, particularly in the Roza, Sunnyside, and Chandler diversion reaches. A more extensive analysis of reach-specific survival is planned for this dataset, which should provide insights into covariates that affected survival during 2016.

Washington↗
USGS2016

Evaluation of the biological and hydraulic performance of the portable floating fish collector at Cougar Reservoir and Dam, Oregon, September 2015–January 2016

The biological and hydraulic performance of a portable floating fish collector (PFFC) located in the cul-de-sac of Cougar Dam and Reservoir, Oregon, was evaluated during 2015–16. The PFFC, first commissioned in May 2014, was modified during winter 2014–15 to address several deficiencies identified during operation and testing in 2014. These modifications included raising the water inflow structures to reduce the depth and volume of inflow to improve the internal hydraulic profiles, and moving the anchors so the PFFC could be positioned closer to the existing reservoir outlet, a water temperature control tower. The PFFC was positioned about 18 meters (m) upstream of the intake of the water temperature control tower and faced into the prevailing water current. Like several floating surface collectors operating in the Pacific Northwest at the time, the PFFC used pumps to draw water and fish over an inclined plane, past dewatering screens, and into a collection area. The portable and experimental nature of the PFFC required a smaller size, shallower entrance (about 2.5-m deep), and smaller inflow rate (72 cubic feet per second [ft 3 /s] inflow during the Low treatment, 122 ft 3 /s during the High treatment) than other collectors in the region. The collection of the target species, juvenile Chinook salmon ( Oncorhynchus tshawytscha ) , during 2015–16 was an order of magnitude larger than in 2014. Subyearling-age Chinook salmon comprised most of the catch (2,616 subyearling compared to 258 yearling) and was greatest during the spring during the High inflow treatment. Bycatch consisted predominantly of cyprinids and centrarchids. Trap mortality (fish found dead in the trap) of juvenile Chinook salmon, at 9.2 percent of the subyearlings and 5.0 percent of yearlings, was about 30 percent of the level in 2014. Fish mortality from handling the live catch was about 1 percent. Data from fish tagged with passive integrated transponder (PIT) tags and those with acoustic+PIT tags released near the head of the reservoir indicated the catch rates of the PFFC were low. Eight of the 1,497 PIT-tagged fish and 5 of the 534 acoustic+PIT-tagged fish were collected by the PFFC. Fish collection efficiencies—the number collected by the PFFC out of the number detected at the head of the forebay (FCE FB ) or in the cul-de-sac (FCE CDS ) —were 0.002 and 0.003 during the Low treatment and 0.008 and 0.009 during the High treatment. The low FCEs were attributed to the following factors: Few acoustic+PIT-tagged fish were detected within 10 m of the PFFC entrance, Most fish were detected between the stern of the PFFC and the entrance to the tower, Fish depths commonly were several times greater than the PFFC entrance depth, and Surface water temperatures were warm. The data suggest that the shallow entrance and low inflow rate reduced fish guidance near the PFFC entrance and the hydraulic characteristics resulting from the outflow plumes (and perhaps water entering the temperature control tower) attracted fish to that area. Catch of juvenile Chinook salmon likely would increase if the collector entrance were deepened, the inflow rate were increased, and measures were taken to constrain fish presence to the area upstream of the trap entrance.

Oregon↗
USGS2016

Evaluation of the hydraulic and biological performance of the portable floating fish collector at Cougar Reservoir and Dam, Oregon, 2014

The biological and hydraulic performance of a new portable floating fish collector (PFFC) located in a cul-de-sac within the forebay of Cougar Dam, Oregon, was evaluated during 2014. The purpose of the PFFC was to explore surface collection as a means to capture juvenile salmonids at one or more sites using a small, cost-effective, pilot-scale device. The PFFC used internal pumps to draw attraction flow over an inclined plane about 3 meters (m) deep, through a flume at a design velocity of as much as 6 feet per second (ft/s), and to empty a small amount of water and any entrained fish into a collection box. Performance of the PFFC was evaluated at 64 cubic feet per second (ft 3 /s) (Low) and 109 ft 3 /s (High) inflow rates alternated using a randomized-block schedule from May 27 to December 16, 2014. The evaluation of the biological performance was based on trap catch; behaviors, locations, and collection of juvenile Chinook salmon ( Oncorhynchus tshawytscha ) tagged with acoustic transmitters plus passive integrated transponder (PIT) tags; collection of juvenile Chinook salmon implanted with only PIT tags; and untagged fish monitored near and within the PFFC using acoustic cameras. The evaluation of hydraulic performance was based on measurements of water velocity and direction of flow in the PFFC. The PFFC collected 156 juvenile Chinook salmon and 280 individuals of other species, primarily dace (Cyprinidae) and largemouth bass ( Micropterus salmoides ). The collection included one of the 212 acoustic+PIT-tagged fish detected near the PFFC and two of the 1,505 PIT-tagged fish released near the head of the reservoir. No juvenile salmonids were collected between early July and early September when water temperatures near the water surface were greater than about 16 degrees Celsius (°C). Depths of acoustic+PIT-tagged fish indicated a preferential selection of water temperature of 13–15 °C, which was often deeper than the entrance to the PFFC, and those fish rarely were at depths with water temperatures greater than 16 °C. Dam passage of acoustic+PIT-tagged fish was similar to previous years, but much of the passage occurred prior to the date the PFFC began operation. Discovery Efficiency, the proportion of acoustic+PIT-tagged fish detected in the cul-de-sac that were within 10 m of the PFFC entrance and 0–6 m deep (the Discovery Zone), was 0.736 during the Low treatment and 0.639 during the High treatment. Entrance Efficiency, the proportion of fish in the Discovery Zone that were collected by the PFFC, was 0.007 during the Low treatment and 0.000 during the High treatment. Fish Collection Efficiency, the proportion of acoustic+PIT-tagged fish collected of those detected in the cul-de-sac, was 0.005 and 0.000 during the Low and High treatments, respectively. The areas of highest use by acoustic+PIT-tagged fish were between the stern of the PFFC and the outlet of the reservoir (a water temperature control tower), with the greatest use being near the tower. Results from untagged fish detected with acoustic cameras indicated that most fish near and within the PFFC were in the 90–250-millimeter length bin and few were less than 60 millimeters long; most fish were present during crepuscular periods; trajectories of fish outside the PFFC were rarely directed toward the entrance; and many fish entering the PFFC swam back out before they could be collected. The hydraulic performance of the PFFC did not achieve the design goals of smooth acceleration of inflow culminating in a peak water velocity of 6 ft/s and, as a result, the hydraulic performance likely contributed to the low biological performance. The greatest water velocity measured in the PFFC (1.87 ft/s) was lower than designed due at least in part to the PFFC being lower in the water column than expected. Additionally, difficulties during anchor deployment prevented placement of the PFFC as near to the reservoir outlet as planned, resulting in a PFFC position outside the prevailing flow field and known areas of high fish densities. Overall, the results indicate that location, hydraulic conditions, water temperature, and shallow depth of the entrance were among the factors contributing to the low biological performance of the PFFC in 2014.

Oregon↗
USGS2015

Behavior, passage, and downstream migration of juvenile Chinook salmon from Detroit Reservoir to Portland, Oregon, 2014–15

An evaluation was conducted to estimate dam passage survival of juvenile Chinook salmon ( Oncorhynchus tshawytscha ) at Detroit Dam during a period of spill. To estimate dam passage survival, we used a paired-release recapture study design and released groups of tagged fish upstream (997 fish) and downstream (625 fish) of Detroit Dam. A total of 43 fish (6.8 percent) passed Detroit Dam from the upstream release group and passage occurred through regulating outlets (54.8 percent), spill bays (31.0 percent), and turbines (14.3 percent). We do not present dam passage survival estimates from 2014 because these estimates would have been highly uncertain due to the low number of fish that passed Detroit Dam during the study. Secondary objectives were addressed using data collected from tagged fish that were released at the downstream release site. Juvenile salmonids have multiple passage options at the Bennett Dam complex, which includes a series of dams and braided channels. A pair of Passive Integrated Transponder (PIT) monitoring arrays were installed at Upper Bennett Dam and in the Stayton Canal by the U.S. Army Corps of Engineers and the Oregon Department of Fish and Wildlife during 2014. We deployed acoustic telemetry hydrophones near these arrays to detect acoustic-tagged fish from our study and used these detections to quantify proportions of tagged fish passing through the two routes. About one-fourth (0.257) of the tagged fish that were released downstream of Big Cliff Dam were detected on the new PIT tag array while passing the Bennett Dam complex. A total of 402 acoustic-tagged fish were detected at the complex and many (248 fish; 62 percent) eventually entered the Stayton Canal. Median residence time in the canal was 6.5 hours, but 12.7 percent of the fish had extended residence times (7–37 days). Passage also was monitored at the Sullivan Project at Willamette Falls and about 40 percent (0.398) of the tagged fish passing the project were detected on the PIT tag array. A Cormack-Jolly-Seber mark-recapture model was developed to provide reach-specific survival estimates for juvenile Chinook salmon. A portion of the tagged population overwintered in the Willamette River Basin and outmigrated several months after release. As a result, survival estimates from the model would have been negatively biased by factors such as acoustic tag failure and tag loss. Data from laboratory studies were incorporated into the model to provide survival estimates that accounted for these factors. In the North Santiam River between Minto Dam and the Bennett Dam complex, a distance of 37.2 kilometers, survival was estimated to be 0.844 (95-percent confidence interval 0.795–0.893). The survival estimate for the 203.7 kilometer reach between the Bennett Dam complex and Portland, Oregon, was 0.279 (95-percent confidence interval 0.234–0.324), and included portions of the North Santiam, Santiam, and Willamette Rivers. The cumulative survival estimate in the 240.9 kilometer reach from the Minto Dam tailrace to Portland was 0.236 (95-percent confidence interval 0.197–0.275).

Oregon↗
USGS2015

Observational data on the effects of infection by the copepod Salmincola californiensis on the short- and long-term viability of juvenile Chinook salmon ( Oncorhynchus tshawytscha ) implanted with telemetry tags

Background Fish movements are often studied using radio or acoustic tags assuming the handling and tagging procedures have little effect on the behavior of the animal. Indeed, many studies provide guidelines for acceptable methods. However, these studies generally assume the fish are otherwise healthy but this may not always be the case. One example is the infection of juvenile salmon in the western USA by the naturally-occurring parasitic copepod Salmincola californiensis, for which little is known about the effects on results from tagged animals. We report on observational data from juvenile Chinook salmon ( Oncorhynchus tshawytscha ) surgically implanted with telemetry tags relative to the numbers of S. californiensis within their branchial cavities and on their bodies to determine if the intensity of infection resulted in differences in mortality shortly after tagging or post-release activity in a reservoir over a period of about 4 months. Results The data indicate a negative effect of copepods in the branchial cavities on short-term mortality (within 24 h of tagging) and suggest negative effects on movements after release into the reservoir. Short-term mortalities were infrequent and, due to the observational nature of the data, few tagged fish had more than three copepods in their branchial cavities, although surveys of fish in the reservoir indicate much greater infection intensities are common. Copepod numbers on the body did not appear to be associated with short-term mortality or movements after release. The number of copepods on the body was unrelated to the number within the branchial cavities, indicating site-specific counts are needed to assess the infection. Conclusion Infection with Salmincola californiensis is common in juvenile Chinook salmon in western USA reservoirs and may affect the viability of fish used in studies of telemetered animals. Our limited assessment suggests infection by Salmincola californiensis affects the short-term morality of tagged fish and may affect long-term viability of tagged fish after release; however, the intensity of infection in the sample population did not represent the source population due to the observational nature of the data. We suggest these results warrant further study into the effects of infection by Salmincola californiensis on the results obtained through active telemetry and perhaps other methods requiring handling of infected fish.

Animal Biotelemetry↗
USGS2014

Passage and survival probabilities of juvenile Chinook salmon at Cougar Dam, Oregon, 2012

This report describes studies of juvenile-salmon dam passage and apparent survival at Cougar Dam, Oregon, during two operating conditions in 2012. Cougar Dam is a 158-meter tall rock-fill dam used primarily for flood control, and passes water through a temperature control tower to either a powerhouse penstock or to a regulating outlet (RO). The temperature control tower has moveable weir gates to enable water of different elevations and temperatures to be drawn through the dam to control water temperatures downstream. A series of studies of downstream dam passage of juvenile salmonids were begun after the National Oceanic and Atmospheric Administration determined that Cougar Dam was impacting the viability of anadromous fish stocks. The primary objectives of the studies described in this report were to estimate the route-specific fish passage probabilities at the dam and to estimate the survival probabilities of fish passing through the RO. The first set of dam operating conditions, studied in November, consisted of (1) a mean reservoir elevation of 1,589 feet, (2) water entering the temperature control tower through the weir gates, (3) most water routed through the turbines during the day and through the RO during the night, and (4) mean RO gate openings of 1.2 feet during the day and 3.2 feet during the night. The second set of dam operating conditions, studied in December, consisted of (1) a mean reservoir elevation of 1,507 ft, (2) water entering the temperature control tower through the RO bypass, (3) all water passing through the RO, and (4) mean RO gate openings of 7.3 feet during the day and 7.5 feet during the night. The studies were based on juvenile Chinook salmon (Oncorhynchus tshawytscha) surgically implanted with radio transmitters and passive integrated transponder (PIT) tags. Inferences about general dam passage percentage and timing of volitional migrants were based on surface-acclimated fish released in the reservoir. Dam passage and apparent survival probabilities were estimated using the Route-Specific-Survival Model with data from surface-acclimated fish released near the water surface directly upstream of the temperature control tower (treatment group) and slightly downstream of the dam (control group). In this study, apparent survival is the joint probability of surviving and migrating through the study area during the life of the transmitters. Two rearing groups were used to enable sufficient sample sizes for the studies. The groups differed in feed type, and for the December study only, the rearing location. Fish from each group were divided nearly equally among all combinations of release sites, release times, and surgeons. The sizes, travel times, and survivals of the two rearing groups were similar. There were statistical differences in fish lengths and travel times of the two groups, but they were small and likely were not biologically meaningful. There also was evidence of a difference in single-release estimates of survival between the rearing groups during the December study, but the differences had little effect on the relative survival estimates so the analyses of passage and survival were based on data from the rearing groups pooled. Conditions during the December study were more conducive to passing volitionally migrating fish than conditions during the November study. The passage percentage of the fish released in the reservoir was similar between studies (about 70 percent), but the passage occurred in a median of 1.0 day during the December study and a median of 9.3 days during the November study. More than 93 percent of the dam passage of volitionally migrating fish occurred at night during each study. This finding corroborates results of previous studies at Cougar Dam and suggests that the operating conditions at night are most important to volitionally migrating fish, given the current configuration of the dam. Most fish released near the temperature control tower passed through the RO. A total of 92.2 percent of the treatment group passed through the RO during the November study and the RO was the only route open during the December study. The assumptions of the survival model were either met or adjusted for during each study. There was little evidence that tagger skill or premature failure of radio transmitters had an effect on survival estimates. There were statistically significant differences in travel times between treatment and control groups through several of the river reaches they had in common, but the differences were typically only a few hours, and the two groups likely experienced the same in-river conditions. There was direct evidence of bias due to detection of euthanized fish with live transmitters released as part of the study design. The bias was ameliorated by adjusting the survival estimates for the probability of detecting dead fish with live transmitters, which reduced the estimated survival probabilities by about 0.02. The data and models indicated that the treatment effect was not fully expressed until the study reach terminating with Marshall Island Park on the Willamette River, a distance of 105.8 kilometers downstream of Cougar Dam. This was the first reach in which the 95-percent confidence interval of the estimated reach-specific relative survival overlapped 1.0, indicating similar survival of treatment and control groups. The median travel time of the treatment group from release to Marshall Island Park was 1.64 days during the November study and 1.36 days during the December study. The survival probability of fish that passed into the RO was greater during the December study than during the November study. The relative survival probability of fish passing through the RO was 0.4594 (standard error [SE] 0.0543) during the November study and 0.7389 (SE 0.1160) during the December study. These estimates represent relative survival probabilities from release near Cougar Dam to the Marshall Island site. The estimated survival probability of RO passage was lower than previous studies based on balloon and PIT tags, but higher than a similar study based on radio transmitters. We suggest that, apart from dam operations, the differences in survival primarily are due to the release location. We hypothesize that the balloon- and PIT-tagged fish released through a hose at a point near the RO gate opening experienced more benign conditions than the radio-tagged fish passing the RO volitionally. This hypothesis could be tested with further study. An alternative hypothesis is that some live fish remained within the study area beyond the life of their radio transmitter. The results from these and previous studies indicate that entrainment and survival of juvenile salmonids passing Cougar Dam varies with dam operating conditions. The condition most conducive to dam passage has been the discharge and low pool elevation condition tested during December 2012. That condition included large RO gate openings and was the condition with the highest dam passage survival.

Oregon↗
USGS2014

Behavior and dam passage of juvenile Chinook salmon and juvenile steelhead at Detroit Reservoir and Dam, Oregon, March 2012-February 2013

The in-reservoir movements and dam passage of individual juvenile Chinook salmon ( Oncorhynchus tshawytscha ) and juvenile steelhead ( Oncorhynchus mykiss ) were studied at Detroit Reservoir and Dam, near Detroit, Oregon, during 2012 and 2013. The goal of the study was to provide data to inform decisions about future downstream passage alternatives and factors affecting downstream passage rates with the existing dam configuration. In 2012, 468 juvenile Chinook salmon and 200 juvenile steelhead were tagged and released during a 3-month period in the spring, and another 514 juvenile Chinook salmon were tagged and released during a 3-month period in the fall. The fish were surgically implanted with a small acoustic transmitter with an expected life of about 3 months and a passive integrated transponder tag with an indefinite life, and were released into the two main tributaries several kilometers upstream of the reservoir. Juvenile Chinook salmon migrated from the release sites to the reservoir in a greater proportion than juvenile steelhead, but once in the reservoir, juvenile steelhead migrated to the forebay faster and had a higher dam passage rate than juvenile Chinook salmon. The routes available for passing water and fish varied throughout the year, with low reservoir elevations in winter and high reservoir elevations in summer in accordance with the flood-control purpose of the dam. Most dam passage was through the spillway during the spring and summer, when the reservoir elevation was high and the spillway and powerhouse were the most common routes in operation, and via the powerhouse during the fall and winter period, when the reservoir elevation was low and the regulating outlet and powerhouse were the most common routes in operation. Few tagged fish passed when the powerhouse was the only route in operation. Dam passage rates during the spring and summer were greatest at night, increased with dam discharge, and were greater when water was passed freely over the spillway compared to when it was controlled by the spillway Tainter gates. Dam passage rates during the fall and winter, when the reservoir elevation usually was too low for spillway operation, were lower than during the spring and summer, negatively related to reservoir elevation, and positively related to dam discharge, though the latter relation diminished as reservoir elevation decreased. Fish locations near the dam from estimates of three-dimensional positions often were near the locations of dam discharge and fish depths were surface oriented relative to the depth of the forebay. Fish passage rates with the existing dam configuration were greatest when the spillway was in operation and were lowest when the powerhouse was the only route in operation; the latter result may be related to the relatively low magnitude or variability in discharge during that condition. The available data suggest that a properly designed surface outlet could be a viable passage route for juvenile Chinook salmon and juvenile steelhead at Detroit Dam. A second year of data collection based on a similar study design was complete at the time of this report.

Oregon↗
USGS2014

Behavior and dam passage of juvenile Chinook salmon at Cougar Reservoir and Dam, Oregon, March 2012 - February 2013

The movements and dam passage of individual juvenile Chinook salmon ( Oncorhynchus tshawytscha ) were studied at Cougar Reservoir and Dam, near Springfield, Oregon, during 2012 and 2013. Cougar Dam is a high-head flood-control reservoir with a temperature control tower as its outlet enabling selective withdrawals of water at various depths to control the temperature of water passed downstream. This report describes the second year of a 2-year study with the goal of providing information to inform decisions about future downstream passage alternatives. Inferences were based on the behavior of yearling-size juvenile Chinook salmon implanted with acoustic transmitters. The fish were released near the head of the reservoir during the spring (March, April, and May) and fall (September, October, and November) of 2012. Most tagged fish were of hatchery origin (468 spring, 449 fall) because of the low number of wild fish captured from within the reservoir (0 spring, 65 fall). Detections at hydrophones placed in several lines across the reservoir and within a collective system used to estimate three-dimensional positions near the temperature control tower were used to determine fish behavior and factors affecting dam passage rates. Most tagged fish made repeated non-random migrations from one end of the reservoir to the other and took a median of 3.7–11.7 days to travel about 7 kilometers from the release site to within about 100 meters of the temperature control tower, depending on season and origin. Reservoir passage efficiency (percentage of tagged fish detected at the head of the forebay) was 97.8 percent for hatchery fish and 74.2 percent for wild fish. Tagged fish commonly were within about 100 meters of the temperature control tower, and often spent considerable time near the entrance to the tower; however, the dam passage efficiency (percentage of dam passage of fish detected at the head of the forebay) was low for fish released during the spring (11.1 percent) and moderate for fish released during the fall (58.1 percent for hatchery fish, 65.2 percent for wild fish) over the 90th percentile of the empirically determined tag life, which was about 90 days. The primary factors affecting the dam passage rate were diel period, dam discharge, and reservoir elevation, and most passage occurred during conditions of night, high dam discharge, and low reservoir elevation. Most fish entering the temperature control tower passed the dam without returning to the reservoir. The common presence of tagged fish near the tower entrance and high proportion of dam passage after tower entry suggests that the primary cause of the poor dam passage rate was the low rate of tower entry. We hypothesize that fish reject the tower entrance because of low water velocities contributing to a small flow field, an abrupt deceleration at the trash rack, or a combination of those two conditions. Results of a controlled test of head differential (the difference between water elevation outside and inside the temperature control tower) indicated weak statistical support (P= 0.0930) for a greater tower entry rate when the differential was 0.65–1.00 foot compared to 0.00–0.30 foot. Results from hatchery and wild fish were similar, with the exception of the reservoir passage efficiency, indicating hatchery fish were suitable surrogates for the wild fish for the purpose of this study.

Oregon↗
USGS2013

Behavior and dam passage of juvenile Chinook salmon at Cougar Reservoir and Dam, Oregon, March 2011 - February 2012

The movements and dam passage of juvenile Chinook salmon implanted with acoustic transmitters and passive integrated transponder tags were studied at Cougar Reservoir and Dam, near Springfield, Oregon. The purpose of the study was to provide information to aid with decisions about potential alternatives for improving downstream passage conditions for juvenile salmonids in this flood-control reservoir. In 2011, a total of 411 hatchery fish and 26 wild fish were tagged and released during a 3-month period in the spring, and another 356 hatchery fish and 117 wild fish were released during a 3-month period in the fall. A series of 16 autonomous hydrophones throughout the reservoir and 12 hydrophones in a collective system near the dam outlet were used to determine general movements and dam passage of the fish over the life of the acoustic transmitter, which was expected to be about 3 months. Movements within the reservoir were directional, and it was common for fish to migrate repeatedly from the head of the reservoir downstream to the dam outlet and back to the head of the reservoir. Most fish were detected near the temperature control tower at least once. The median time from release near the head of the reservoir to detection within about 100 meters of the dam outlet at the temperature control tower was between 5.7 and 10.8 days, depending on season and fish origin. Dam passage events occurred over a wider range of dates in the spring and summer than in the fall and winter, but dam passage numbers were greatest during the fall and winter. A total of 10.5 percent (43 of 411) of the hatchery fish and 15.4 percent (4 of 26) of the wild fish released in the spring are assumed to have passed the dam, whereas a total of 25.3 percent (90 of 356) of the hatchery fish and 16.9 percent (30 of 117) of the wild fish released in the fall are assumed to have passed the dam. A small number of fish passed the dam after their transmitters had stopped working and were detected at passive integrated transponder detectors at various locations downstream of the dam, indicating some tagged fish passed the dam undetected. The rate of dam passage was affected by diel period, discharge, and reservoir elevation. Diel period was the most influential factor of those examined, with nighttime dam passage rates about 9 times greater than daytime rates, depending on the distance of fish from the dam outlet. Dam passage rates also were positively related to dam discharge, and negatively related to reservoir elevation. In the operational condition used as an example, fish approached the dam outlet at the temperature control tower from the south and east and, when most fish got near the tower, they were directly in front of it. In many cases, the results for wild and hatchery fish were similar, or the results suggested hatchery fish could be reasonable surrogates for wild fish. Hatchery-origin and wild-origin fish behaved similarly in the following ways: their general movements in the reservoir; the timing of their dam passage; and the effects of diel period, discharge, and elevation on their passage rates. Parasitic copepods were present on most wild fish examined, and the mortality of wild fish during capture, handling and tagging was much greater than that of hatchery fish. This suggests that the ability of wild fish to cope with stressors may be less than that of fish directly from the hatchery.

Oregon↗
USGS2012

Interim results from a study of the behavior of juvenile Chinook salmon at Cougar Reservoir and Dam, Oregon, March--August 2011

The movements and dam passage of yearling juvenile Chinook salmon implanted with acoustic transmitters and passive integrated transponder tags were studied at Cougar Reservoir and Dam, near Springfield, Oregon. A total of 411 hatchery fish and 26 wild fish were tagged and released between March 7 and May 21, 2011. A series of 16 autonomous hydrophones placed throughout the reservoir were used to determine general fish movements over the life of the acoustic transmitter, which was expected to be 91 days. Movements within the reservoir were directional, and it was common for fish to migrate repeatedly from the head of the reservoir downstream to the dam outlet and back. The dam passage rate was 11.2 percent (95-percent confidence interval 7.8–14.6 percent) for hatchery fish and 15.4 percent (95-percent confidence interval -1.0–31.8 percent) for wild fish within 91 days from release. Most fish passage occurred at night. The median time from release to dam passage was 34.5 days for hatchery fish and 34.2 days for wild fish. A system of hydrophones near the dam outlet, a temperature control tower, was used to estimate positions of fish in three dimensions to enable detailed analyses of fish behavior near the tower. Analyses of these data indicate that hourly averaged depths of fish within a distance of 74 m from the upstream face of the tower ranged from 0.6 to 9.6 meters, with a median depth of 3.6 meters for hatchery fish and 3.4 meters for wild fish. Dam discharge rates and the diurnal period affected the rates of dam passage. Rates of dam passage were similar when the dam discharge rate was less than 1,200 cubic feet per second, but increased sharply at higher discharges. The rate of dam passage at night was 4.4–7.8 times greater than during the day, depending on the distance of fish from the dam. This report is an interim summary of data collected as of August 3, 2011, for planning purposes.

Oregon↗
USGS2012

Passage probabilities of juvenile Chinook salmon through the powerhouse and regulating outlet at Cougar Dam, Oregon, 2011

Cougar Dam near Springfield, Oregon, is one of several federally owned and operated flood-control projects within the Willamette Valley of western Oregon that were determined by the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service in 2008 to impact the long-term viability of several salmonid stocks. In response to this ruling, the U.S. Army Corps of Engineers is looking for means to reduce impacts to salmonids, including improving downstream passage of juvenile salmonids at Cougar Dam. This study of juvenile Chinook salmon ( Oncorhynchus tshawytscha ) passage at Cougar Dam was conducted to inform decisions about potential improvements for downstream fish passage. The primary objective of the study was to estimate route-specific passage probabilities of yearling Chinook salmon at Cougar Dam. The study was conducted using fish from a nearby hatchery surgically implanted with radio transmitters and passive integrated transponder (PIT) tags and released near the entrance of a temperature control tower through which all water going through the dam must pass. Water passing through the temperature control tower may be routed through a penstock to a powerhouse with two Francis turbines, or to a spillway-like structure called the regulating outlet. Secondary objectives of the study were to estimate the probability that fish enter a bypass at a non-federal facility downstream, and to estimate dam-passage and in-river fish survival. Dam operating conditions during the study included an average forebay elevation of 1,580 feet (National Geodetic Vertical Datum of 1929) and an average of 48.2 percent of the total dam discharge of 1,106 cubic feet per second passing through a regulating outlet opening of 1.25 feet. Dam passage probability was greatest at night (0.8741 standard error [SE] 0.0265) and primarily through the regulating outlet (0.8896 SE 0.0617 day; 0.9417 SE 0.0175 night). The joint probability of entering the bypass at Leaburg Dam and being detected at the PIT system within the bypass was 0.0755 (SE 0.0363), but some fish were known to pass the PIT system undetected, indicating that the true probability of entering the bypass was underestimated. The estimated survival of fish passing through the temperature control tower, through the dam, and to a site at a bridge over the South Fork of the McKenzie River 3.9 kilometers downstream was 0.3680 (SE 0.1322) for fish passing through the powerhouse, and 0.4247 (SE 0.0440) for fish passing through the regulating outlet. The estimated in-river survival through the 37.3 kilometers from the bridge to a site at Leaburg Hatchery on the McKenzie River was 0.5857 (SE 0.2227) for fish that had passed through the powerhouse, and 0.4537 (SE 0.0551) for fish that had passed through the regulating outlet.

Oregon↗