Fall Chinook Salmon Spawning Research Articles

Effects of Two Activated Milt Residence Times on Landlocked Fall Chinook Salmon Egg Survival to the Eyed Stage of Development

AbstractDuring salmonid spawning, the amount of time required for activated milt to successfully fertilize eggs has not been well defined. This study examined the effects of two different activated milt residence times, 20 and 60 s, during production‐scale artificial spawning of 20 landlocked fall Chinook Salmon Oncorhynchus tshawytscha. Mean (SE) survival to the eyed stage of egg development was 29.2% (5.5) in the eggs that were subjected to the 20‐s milt residence time, which was not significantly different from the 32.3% (5.7) survival rate for eggs with the 60‐s residence time. There was considerable variation in egg survival among the individual female spawns, ranging from near 0% to 76.7%. These production‐scale results indicate that activated milt residence times as low as 20 s can be used during the landlocked fall Chinook Salmon spawning, with no significant effect on egg survival to the eyed stage of development.

Effect of Activated Milt Residence Time on Landlocked Fall Chinook Salmon Egg Survival

During artificial spawning of salmonids, activated sperm is allowed to remain in contact with eggs for variable durations. This study examined multiple residence times (20, 40, 60, 90, or 120 seconds) for activated sperm on landlocked fall Chinook salmon (Oncorhynchus tshawytscha) eggs during spawning. There was no significant difference in egg survival to the eyed-stage of development or to hatch among any of the treatments, with a mean (SE) percent survival to the eyed stage of 63.9 (5.8). These results indicate that only relatively short residence times of activated milt on eggs during landlocked fall Chinook salmon spawning are needed to ensure egg survival, resulting in potentially substantial reductions in production-level spawning times and associated labor costs.

Timing of Landlocked Fall Chinook Salmon Spawning and Egg Survival

Landlocked fall Chinook salmon (Oncorhynchus tshawytscha) in Lake Oahe, South Dakota, USA return to a remote spawning station either already having ovulated (ripe) or with the eggs still retained in the ovary (green).

Effects of Dam Removal on Tule Fall Chinook salmon Spawning Habitat in the White Salmon River, Washington

Condit Dam is one of the largest hydroelectric dams ever removed in the USA. Breached in a single explosive event in October 2011, hundreds-of-thousands of cubic metres of sediment washed down the White Salmon River onto spawning grounds of a threatened species, Columbia River tule fall Chinook salmon Oncorhynchus tshawytscha. We investigated over a 3-year period (2010–2012) how dam breaching affected channel morphology, river hydraulics, sediment composition and tule fall Chinook salmon (hereafter ‘tule salmon’) spawning habitat in the lower 1.7 km of the White Salmon River (project area). As expected, dam breaching dramatically affected channel morphology and spawning habitat due to a large load of sediment released from Northwestern Lake. Forty-two per cent of the project area that was previously covered in water was converted into islands or new shoreline, while a large pool near the mouth filled with sediments and a delta formed at the mouth. A two-dimensional hydrodynamic model revealed that pool area decreased 68.7% in the project area, while glides and riffles increased 659% and 530%, respectively. A spatially explicit habitat model found the mean probability of spawning habitat increased 46.2% after dam breaching due to an increase in glides and riffles. Shifting channels and bank instability continue to negatively affect some spawning habitat as sediments continue to wash downstream from former Northwestern Lake, but 300 m of new spawning habitat (river kilometre 0.6 to 0.9) that formed immediately post-breach has persisted into 2015. Less than 10% of tule salmon have spawned upstream of the former dam site to date, but the run sizes appear healthy and stable. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

An Evaluation of Two Egg Collection and Two Fertilization Techniques during Landlocked Fall Chinook Salmon Spawning

AbstractIn an attempt to improve embryo survival of landlocked fall Chinook salmon Oncorhynchus tshawytscha, we compared two egg collection techniques and two different egg fertilization (sperm activation) protocols on egg survival to the eyed stage of development. A total of four treatments were used with 13 females: egg collection into a suspended net and fertilization either with or without ovarian fluid and egg collection into a hard plastic pan and subsequent fertilization either with or without ovarian fluid. There was no significant difference in survival to the eyed stage with respect to collection technique. However, the presence of ovarian fluid during sperm activation and fertilization had a small but significantly negative effect on egg survival, decreasing mean eyed egg survival by approximately 4.0%. Overall, eyed egg survival was improved in 10 of the 13 spawns fertilized without ovarian fluid. To maximize embryo survival, removal of ovarian fluid prior to fertilization is recommended for landlocked fall Chinook salmon eggs.

A Spatial Model to Assess the Effects of Hydropower Operations on Columbia River Fall Chinook Salmon Spawning Habitat

AbstractPriest Rapids Dam on the Columbia River produces large daily and hourly streamflow fluctuations throughout the Hanford Reach during the period when fall Chinook salmon Oncorhynchus tshawytscha are selecting spawning habitat, constructing redds, and actively engaged in spawning. Concern over the detrimental effects of these fluctuations prompted us to quantify the effects of variable flows on the amount and persistence of fall Chinook salmon spawning habitat in the Hanford Reach. Specifically, our goal was to develop a management tool capable of quantifying the effects of current and alternative hydrographs on predicted spawning habitat in a spatially explicit manner. Toward this goal, we modeled the water velocities and depths that fall Chinook salmon experienced during the 2004 spawning season, plus what they would probably have experienced under several alternative (i.e., synthetic) hydrographs, using both one‐ and two‐dimensional hydrodynamic models. To estimate spawning habitat under existing or alternative hydrographs, we used cell‐based modeling and logistic regression to construct and compare numerous spatial habitat models. We found that fall Chinook salmon were more likely to spawn at locations where velocities were persistently greater than 1 m/s and in areas where fluctuating water velocities were reduced. Simulations of alternative dam operations indicate that the quantity of spawning habitat is expected to increase as streamflow fluctuations are reduced during the spawning season. The spatial habitat models that we developed provide management agencies with a quantitative tool for predicting, in a spatially explicit manner, the effects of different flow regimes on fall Chinook salmon spawning habitat in the Hanford Reach. In addition to characterizing temporally varying habitat conditions, our research describes an analytical approach that could be applied in other highly variable aquatic systems.

A Model of the Effects of Flow Fluctuations on Fall Chinook Salmon Spawning Habitat Availability in the Columbia River

AbstractThe logistic regression models that we previously used to predict where fall Chinook salmon Oncorhynchus tshawytscha would spawn in the Hanford Reach of the Columbia River were based on so‐called static variables (i.e., the riverbed surface substrate, riverbed slope, and time‐averaged velocity and depth [representing the velocity and depth in each cell associated with the 50% exceedance flow]). Not all habitat predicted to be used for spawning contained redds, and one explanation for the overprediction is that the models did not incorporate streamflow fluctuation. Streamflow fluctuation occurs daily in the Hanford Reach owing to load‐following operations (power generation to meet short‐term electrical demand) at Priest Rapids Dam, a hydroelectric dam located at the upper end of the reach. Daily flow fluctuations could change the hydraulic characteristics to which fall Chinook salmon respond in selecting redd sites. The purpose of this study was to determine whether incorporating metrics of flow variability would improve modeling of spawning habitat availability. Flow variability was represented by so‐called dynamic variables (i.e., the standard deviations of velocity and depth for each habitat cell over a 60‐d time segment during the fall spawning period in 1994, 1995, and 2001). Both the static and dynamic models were correct at least 85% of the time in predicting habitat as spawning or nonspawning. However, incorporation of the dynamic variables into the logistic regression models reduced the amount of overpredicted habitat by 42% in 1994, 32% in 1995, and 25% in 2001. For example, the area predicted to be suitable but not used in 1994 decreased from 20.8 ha for the static model to 12.1 ha for the dynamic model for all sites combined; similar results were found for 1995 and 2001. This represents an improvement in our ability to accurately predict suitable fall Chinook salmon spawning habitat in the Hanford Reach of the Columbia River.

Influence of River Level on Temperature and Hydraulic Gradients in Chum and Fall Chinook Salmon Spawning Areas Downstream of Bonneville Dam, Columbia River

AbstractChum salmon Oncorhynchus keta and fall Chinook salmon O. tshawytscha segregate spatially during spawning in the Ives Island side channel of the lower Columbia River downstream from Bonneville Dam. Previous research during one spawning season (2000) suggested that these species selected spawning habitats based on differences in hyporheic temperature and vertical hydraulic gradient (VHG). In this study we confirmed the spatial segregation of spawning based on hyporheic characteristics over 4 years (2001–2004) and examined the effects of load‐following operations (power generation to meet short‐term electrical demand) at Bonneville Dam on hyporheic function and characteristics. We found that during the study period hyporheic temperature and VHG in chum salmon spawning areas were highly variable during periods of load‐following operation, when river levels fluctuated. In contrast, hyporheic water temperature and VHG within chum salmon spawning areas fluctuated less when river levels were not changing owing to load‐following operation. Variable temperature and VHG could affect chum and fall Chinook salmon spawning segregation and incubation success by altering the cues each species uses to select redd sites. Additional research will be required to fully assess the effects of load‐following operations on the hyporheic environment, spawning site selection, and incubation success of chum and fall Chinook salmon downstream from Bonneville Dam.

Effects of river discharge on hyporheic exchange flows in salmon spawning areas of a large gravel‐bed river

AbstractThe flow magnitude and timing from hydroelectric dams in the Snake River Basin of the Pacific north‐western US is managed in part for the benefit of salmon. The objective of this research was to evaluate the effects of Hells Canyon Dam discharge operations on hydrologic exchange flows between the river and riverbed in Snake River fall Chinook salmon spawning areas. Interactions between river water and pore water within the upper 1 m of the riverbed were quantified through the use of self‐contained temperature and water level data loggers suspended inside of piezometers. The data were recorded at 20 min intervals over a period of 200 days when the mean daily discharge was 218–605 m3 s−1, with hourly stage changes as large as 1·9 m. Differences in head pressure between the river and riverbed were small, often within ± 2 cm. Measured temperature gradients in the riverbed indicated significant interactions between the surface and subsurface water. At the majority of sites, neither hydraulic nor temperature gradients were significantly affected by either short‐ or long‐term changes in discharge operations from Hells Canyon Dam. Only 2 of 14 study sites exhibited acute flux reversals between the river and riverbed resulting from short‐term, large magnitude changes in discharge. The findings suggest that local scale measurements may not be wholly explanatory of the hydrological exchange between the river and riverbed. The processes controlling surface water exchange at the study sites are likely to be bedform‐induced advective pumping, turbulence at the riverbed surface, and large‐scale hydraulic gradients along the longitudinal profile of the riverbed. By incorporating the knowledge of hydrological exchange processes into water management planning, regional agencies will be better prepared to manage the limited water resources among competing priorities that include salmon recovery, flood control, irrigation supply, hydropower production, and recreation. Copyright © 2007 John Wiley & Sons, Ltd.

Large‐scale spatial variability of riverbed temperature gradients in Snake River fall Chinook salmon spawning areas

AbstractIn the Snake River basin of the Pacific northwestern United States, hydroelectric dam operations are often based on the predicted emergence timing of salmon fry from the riverbed. The spatial variability and complexity of surface water and riverbed temperature gradients results in emergence timing predictions that are likely to have large errors. The objectives of this study were to quantify the thermal heterogeneity between the river and riverbed in fall Chinook salmon spawning areas and to determine the effects of thermal heterogeneity on fall Chinook salmon emergence timing. This study quantified river and riverbed temperatures at 15 fall Chinook salmon spawning sites distributed in two reaches throughout 160 km of the Snake River in Hells Canyon, Idaho, USA, during 3 different water years. Temperatures were measured during the fall Chinook salmon incubation period with self‐contained data loggers placed in the river and at three different depths below the riverbed surface. At all sites, temperature increased with depth into the riverbed, including significant differences (p < 0.05) in mean hourly water temperature of up to 3.8°C between the river and the riverbed among all the sites. During each of the 3 water years studied, river and riverbed temperatures varied significantly among all the study sites, among the study sites within each reach and between sites located in the two reaches. Considerable variability in riverbed temperatures among the sites resulted in fall Chinook salmon emergence timing estimates that varied by as much as 36 days within a reach, depending on the source of temperature data used for the estimate. Monitoring of riverbed temperature gradients at a range of spatial scales throughout the Snake River would provide better information for managing hydroelectric dam operations, and would aid in the design and interpretation of future empirical research into the ecological significance of physical riverine processes. Published in 2007 by John Wiley & Sons, Ltd.

Bedform morphology of salmon spawning areas in a large gravel-bed river

While the importance of river channel morphology to salmon spawning habitat is increasingly recognized, quantitative measures of the relationships between channel morphology and habitat use are lacking. Such quantitative measures are necessary as management and regulatory agencies within the Pacific Northwest region of the USA, and elsewhere, seek to quantify potential spawning habitat and develop recovery goals for declining salmon populations. The objective of this study was to determine if fall Chinook salmon ( Oncorhynchus tshawytscha) spawning areas in the Snake River, Idaho, USA, were correlated with specific bedform types at the pool–riffle scale. A bedform differencing technique was used to objectively quantify the longitudinal riverbed profile into four distinct pool–riffle units that were independent of discharge. The vertical location of thalweg points within these units was quantified with a riffle proximity index. Chinook salmon spawning areas were mapped and correlated with the pool–riffle units through the use of cross-tabulation tables. The results indicate that 84% of fall Chinook salmon spawning areas were correlated with riffles ( χ 2 = 57.5, df = 3, p < 0.001), with 53% of those areas located on the upstream side of riffle crests. The majority of Snake River fall Chinook salmon spawning occurred at elevations greater than 80% of the difference in elevation between the nearest riffle crest and pool bottom. The analyses of bedform morphology will assist regional fish managers in quantifying existing and potential fall Chinook salmon spawning habitat, and will provide a quantitative framework for evaluating general ecological implications of channel morphology in large gravel-bed rivers.

Fall Chinook Salmon Spawning Activity versus Daylight and Flow in the Tailrace of a Large Hydroelectric Dam

AbstractWe deployed an acoustic system during the spawning season for fall Chinook salmon Oncorhynchus tshawytscha in 2001 to determine whether fall Chinook salmon spawning activity in a hydroelectric dam tailrace area was affected by daylight or river flow. Our study design allocated sampling effort nearly equally between hours of darkness and hours of daylight throughout each 24‐h period. The acoustic system recorded sounds of fall Chinook salmon spawning activity in two index areas downstream of Wanapum Dam on the Columbia River in Washington State. One index area was a deepwater spawning site located in 9–11 m of water. The other index area was a moderate‐depth midchannel bar, where water depths ranged from 2.5 to 6 m. We defined the rate of spawning activity in digs per minute. Fall Chinook salmon spawning activity rates in the Wanapum Dam tailrace were influenced by both daylight and river discharge, which had a pronounced nonlinear effect on spawning activity rates. To account for nonlinearity, a generalized additive model was used to characterize the combined effects of river flow and daylight. The final model also suggested that both flow and daylight influenced spawning activity. Spawning activity occurred during both daylight and darkness, significantly more activity occurring during daylight in both index areas. Spawning activity was generally highest at project discharges between 1,700 and 2,266 m3/s in both spawning areas; spawning activity diminished as discharge increased from 3,400 to 4,250 m3/s. We concluded that fall Chinook salmon spawning activity in this regulated discharge environment was affected more by flow (and velocity) than by daylight.

Habitat quality of historic Snake River fall Chinook salmon spawning locations and implications for incubation survival. Part 1: substrate quality

We evaluated substrate quality at two historic fall Chinook salmon (Oncorhynchus tshawytscha) spawning sites in the Snake River, Idaho, USA. The primary objective of this evaluation was to measure sediment permeability within these areas to determine the potential quality of the habitat in the event that anadromous salmonids are reintroduced to the upper Snake River. Riverbed sediments within the two sites in the upper Snake River were sampled using freeze cores and hydraulic slug tests. Sediment grain size distributions at both sites were typical of gravel-bed rivers with the surface layer coarser than the underlying substrate, suggesting the riverbed surface was armoured. Despite the armoured nature of the bed, the size of the largest material present on the riverbed surface was well within the size limit of material capable of being excavated by spawning fall Chinook salmon. The percentage of fines was low, suggesting good quality substrate for incubating salmon embryos. Geometric mean particle sizes found in this study compared to a 55% to 80% survival to emergence based on literature values. Hydraulic slug tests showed moderate to high hydraulic conductivity and were comparable to values from current fall Chinook salmon spawning areas in the Hells Canyon Reach of the Snake River and the Hanford Reach of the Columbia River. Predicted estimates of mean egg survival at both sites (48% and 74%) equalled or exceeded estimates from fall Chinook salmon spawning areas in the Hells Canyon Reach and the Hanford Reach. Copyright © 2005 John Wiley & Sons, Ltd.

Habitat quality of historic Snake River fall Chinook salmon spawning locations and implications for incubation survival. Part 2: intra-gravel water quality

Reintroduction of fall Chinook salmon into the Swan Falls Reach of the Snake River is of regional interest; however, water quality has been considerably degraded. We examined the quality of the incubation environment within historic spawning sites by monitoring temperature, dissolved oxygen (DO) and the presence of hydrogen sulphide (H2S) within the water column, the undisturbed hyporheic zone, and simulated redds, during two annual periods representative of fall through spring incubation periods. The hydrographs of the two years differed, with year one representative of high flows and year two of low flows. The thermal regime during the two years also differed: year one was warmer overall than year two. Water column DO remained near saturation throughout both years. Within the undisturbed hyporheic, DO was lower than in the water column during both years, and quickly decreased to relatively anoxic conditions. During both years, the DO within simulated redds remained sufficiently high (> 7.0 mg l−1) to support fall Chinook incubation through the hatch phase of development. However, as each incubation season progressed, conditions in simulated redds decreased to less than 6.0 mg l−1 prior to the estimated beginning of emergence, and tended toward levels less than 4.0 mg l−1 prior to the estimated completion of emergence. Hydrogen sulphide was detected at highly toxic levels in the hyporheic zone and within some simulated redds during both years. Depressed DO conditions and the presence of H2S within simulated redds prior to, and throughout the period of estimated emergence suggest that survival of incubating salmon in the Swan Falls reach would be variable and low, and that relative survival would not be sufficient to support the reintroduction and sustainability of a viable population of fall Chinook salmon to that reach. Copyright © 2005 John Wiley & Sons, Ltd.

Temperature during Incubation as One Factor Affecting the Distribution of Snake River Fall Chinook Salmon Spawning Areas

AbstractSpawning areas of ocean‐type fall Chinook salmon Oncorhynchus tshawytscha in the Pacific Northwest are largely restricted to relatively warm coastal rivers. Fall Chinook salmon spawners in the Snake River basin clearly favor the main‐stem Snake River and the relatively warm lower reaches of its tributaries. In this note, we describe how mean temperature during incubation affects fry emergence date and influences the distribution of fall Chinook salmon spawning areas in the Snake River basin. Using laboratory results and field data, we estimated fry emergence dates for three brood years of fish in seven areas that are consistently used by spawners and in five areas that are rarely used by spawners. Mean incubation temperature was significantly (P &lt; 0.0001) higher in consistently used areas (5.6 ± 0.1°C) than in rarely used areas (4.5 ± 0.1°C). The mean estimated emergence date for the consistently used areas was 12 May (± 20 d), compared with 26 June (± 20 d) for rarely used areas. A logistic discriminant rule fitted from the mean incubation temperatures of the 12 areas discriminated between consistently and rarely used areas with 97% accuracy. We conclude that temperature is one factor that influences the distribution of fall Chinook salmon spawning areas in the Snake River basin.

Use of Aerial Photography to Monitor Fall Chinook Salmon Spawning in the Columbia River

This paper compares two methods of enumerating the redds of chinook salmon Oncorhynchus tshawytscha and their application to the monitoring of spawning activity. In 1994 and 1995, aerial photographs of fall chinook salmon spawning areas in the Hanford Reach of the Columbia River were digitized and mapped by means of geographical information systems techniques as part of annual population assessments. The numbers of redds visible in these photographs were compared with the counts obtained from visual surveys made from fixed-wing aircraft. The proportions of the total redds in each of five general survey areas were similar for the two enumeration techniques. However, the total number of redds based on aerial photographs was 2.2 times as high as that observed visually in 1994 and 3.0 times as high in 1995. The divergence in redd counts was most evident near the time of peak spawning activity, when the number of redds in individual spawning clusters exceeded 500. Aerial photography thus improved our ability to determine the number of visible salmon redds and to quantify habitat use.

Spawning Habitat Used by Fall Chinook Salmon in the Snake River

Literature describing spawning habitat used by fall-run chinook salmon Oncorhynchus tshawytscha is lacking for populations using large, main-stem rivers. A stable spawning flow regime in the Snake River below Hells Canyon Dam and enhanced survey capabilities using remote underwater videography allowed us to accurately describe spawning habitat used by fall chinook salmon within this large river. Water depth measured at 205 fall chinook salmon redds ranged from 0.2 to 6.5 m. Mean water column velocity at 145 redds ranged from 0.4 to 2.1 m/s, and substrate- level water velocity at 164 redds ranged from 0.1 to 2.0 m/s. Substrate size classifications from 112 redds indicated that areas having particle sizes that are relatively homogenous with diameters of 2.5–15.0 cm are used for spawning. During our study, spawning generally began as water temperatures dropped below 16.0°C, and concluded as temperatures approached 5.0°C. Our results corroborate earlier observations of fall chinook salmon spawning in deep, fast-velocity water in the Hanford Reach of the Columbia River and significantly expand current criteria used to model spawning habitat availability for these fish within large rivers.

Fall Chinook Salmon Spawning in the Tailraces of Lower Snake River Hydroelectric Projects

Abstract We conducted studies from 1993 to 1997 to identify and characterize potential spawning habitat of “endangered” fall chinook salmon Oncorhynchus tshawytscha in areas downstream of four Snake River dams. This information was needed to provide guidelines for future operation of the lower Snake River hydroelectric system, including assessment of reservoir drawdown, and for site-specific construction planning. We used Geographic Information System mapping technology to direct our initial search efforts. Suitable spawning habitat was defined based on physical habitat characteristics of the tailrace areas. Redd surveys were conducted in primary search areas and planned construction sites from mid-November through December with an underwater video system. The survey path and redd locations were mapped by using a Global Positioning System. During the 4-year study, fall chinook salmon redds were found in the tailrace downstream of Lower Granite (LGR), Little Goose (LGO), and Ice Harbor (IH) dams. The redds...

Redd Site Selection and Spawning Habitat Use by Fall Chinook Salmon: The Importance of Geomorphic Features in Large Rivers

/ Knowledge of the three-dimensional connectivity between rivers and groundwater within the hyporheic zone can be used to improve the definition of fall chinook salmon (Oncorhynchus tshawytscha) spawning habitat. Information exists on the microhabitat characteristics that define suitable salmon spawning habitat. However, traditional spawning habitat models that use these characteristics to predict available spawning habitat are restricted because they can not account for the heterogeneous nature of rivers. We present a conceptual spawning habitat model for fall chinook salmon that describes how geomorphic features of river channels create hydraulic processes, including hyporheic flows, that influence where salmon spawn in unconstrained reaches of large mainstem alluvial rivers. Two case studies based on empirical data from fall chinook salmon spawning areas in the Hanford Reach of the Columbia River are presented to illustrate important aspects of our conceptual model. We suggest that traditional habitat models and our conceptual model be combined to predict the limits of suitable fall chinook salmon spawning habitat. This approach can incorporate quantitative measures of river channel morphology, including general descriptors of geomorphic features at different spatial scales, in order to understand the processes influencing redd site selection and spawning habitat use. This information is needed in order to protect existing salmon spawning habitat in large rivers, as well as to recover habitat already lost.KEY WORDS: Hyporheic zone; Geomorphology; Spawning habitat; Large rivers; Fall chinook salmon; Habitat management