Chinook

Species-specific responses to flashing (strobe) and nonflashing (mercury vapor) lights were monitored in hatchery-reared juveniles of coho salmon Oncorhynchus kisutch and chinook salmon O. tshawytscha. Fish behaviors were characterized as attraction and avoidance responses, and as active, passive, and hiding behaviors. We investigated how basic fish behavior and activity changed when fish held under a variety of ambient light conditions were exposed to strobe and mercury light. Implications of how these behaviors may influence migrating smolts at a fish bypass system were discussed. Both chinook and coho salmon avoided strobe and full-intensity mercury light, but chinook salmon exhibited an attraction to dim mercury light. Coho and chinook salmon showed different behavior patterns under most conditions when exposed to strobe and mercury light: coho salmon hid 47% of the time, whereas chinook salmon swam actively 74% of the time. The greatest change produced by either of the stimulus lights was at night when both species normally were passive; exposure to mercury light at nighttime increased fish activity by 90%. Both species also showed similarities in their levels of excitability (e.g., sudden or explosive movements in otherwise sedentary behaviors). The results of this study showed that the behaviors were reproducible: more than 80% of the fish exhibited the same behavior during specific environmental conditions, and sudden and infrequent behaviors were strongly associated with these behavior categories. The behaviors observed in our experimental environment may give insight as to how changes in light relate to fish behavior in bypass systems.

The effects of increasing hydropower development and operation appear extremely important in the decline and near extripation of stream-type chinook salmon (Oncorhynchus tshawytscha) stocks of the upper Columbia and Snake rivers. We evaluated temporal and spatial patterns of productivity and survival rates (for index stocks from the Snake, upper Columbia, and lower Columbia regions) to determine the cause of dramatic declines of the upriver stocks. This evaluation tested hypotheses about nonstationarity (changes over time in average productivity) in the Ricker recruitment function caused by changes in the physical environment. Individual stocks showed recent declines in indicators of productivity and survival rate; however, the comparisons indicate that upriver stocks showed greater declines coincident with the development and operation of the hydropower system. Evidence from the aggregate run indicates that declines over the last 50 years were quite abrupt and corresponded to construction and completion of the hydropower system. Résumé : L'accroissement du développement et de l'exploitation de l'hydro-électricité semble jouer un rôle très important dans le déclin et la disparition presque complète des stocks de quinnat (Oncorhynchus tshawytscha) de type dulcicole dans le cours supérieur du Columbia et la Snake. Nous avons évalué les profils temporels et spatiaux de la productivité et du taux de survie (pour des stocks indicateurs des régions de la Snake, du haut Columbia et du bas Columbia) pour déterminer la cause des déclins marqués des stocks d'amont. Pour cette évaluation, on a testé des hypothèses concernant la non-stationnarité (changements temporels dans la productivité moyenne) dans la fonction de recrutement de Ricker causée par les changements dans le milieu physique. Les stocks individuels ont connu des déclins récents selon les indicateurs de la productivité et du taux de survie, mais les comparaisons montrent que les stocks d'amont ont connu des déclins plus importants par suite du développement et de l'exploitation du réseau hydroélectrique. Les données sur la remonte totale montrent que les déclins des 50 dernières années ont été assez abrupts et ont suivi la construction et la finalisation du réseau hydro-électrique. [Traduit par la Rédaction] Schaller et al. 1045

Isolates of Vibrio ordalii were recovered from salmon (Oncorhynchus tshawytscha and Oncorhynchus nerka) cultured in New Zealand. The fish suffered from clinical vibriosis, from seven outbreaks in five geographically distinct areas. Affected fish showed gross signs and histopathology similar to those reported from North America. The presence of a plasmid, designated pVO1, approximately 30 kilobases (kb) in size, was seen in all V. ordalii strains examined This plasmid was identical in size and restriction endonuclease cleavage analysis to a plasmid (pMJ101) previously found in V. ordalii strains elsewhere. After togging pVO1 with the transposon Tn1 from the R plasmid RP4, attempts to isolate plasmid-less derivatives using a variety of curing agents were unsuccessful. All of the New Zealand isolates possessed identical chromosomal DNA cleavage patterns. These patterns were only slightly different from that of the type strain but substantially different from that of the Vibrio anguillarum type strain.

Using yearling chinook salmon Oncorhynchus tshawytscha and steelhead O. mykiss tagged with passive integrated transponders (PITs), we estimated passage survival through bypass systems, turbines, and spill bays with and without flow deflectors at Snake River dams relative to survival of fish released into the tailrace below the dam. Actively migrating fish were collected and marked with PIT tags at Snake River dam smolt collection facilities. Groups of tagged fish were then released through hoses into different passage routes; releases were coincident with a tailrace release approximately 1-2 km below the dam. Relative survival was estimated by the use of tag-recapture models for paired releases from detections of individual PIT-tagged fish at juvenile collection or detection facilities at downstream dams. Detection sites included Little Goose, Lower Monumental, McNary, John Day, and Bonneville dams, depending on the release location and year. Standard errors of relative survival probability estimates were generally less than 3.0% through all potential passage routes. The estimated relative survival was highest through spill bays without flow deflectors (98.4-100%), followed by spill bays with flow deflectors (92.7-100%), bypass systems (95.3-99.4%), and turbines (86.5-93.4%). These estimates of relative survival, which include both the direct and indirect effects of passage, are generally higher than past estimates but similar to other recent estimates determined with modern techniques under present dam configurations and operating conditions.

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 (H 2 S) 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 À1 ) 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 À1 prior to the estimated beginning of emergence, and tended toward levels less than 4.0 mg l À1 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 H 2 S 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. maintain the Swan Falls Reach fall Chinook salmon run as the HCC was being constructed. Adult passage was successful, but juvenile passage was not. By 1962 it had become apparent that passage efforts would not work as juvenile fish were unable to migrate through the 90 km Brownlee reservoir , and as a result, passage of anadromous salmon upstream of the HCC was discontinued.

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 (H 2 S) 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 À1 ) 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 À1 prior to the estimated beginning of emergence, and tended toward levels less than 4.0 mg l À1 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 H 2 S 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. maintain the Swan Falls Reach fall Chinook salmon run as the HCC was being constructed. Adult passage was successful, but juvenile passage was not. By 1962 it had become apparent that passage efforts would not work as juvenile fish were unable to migrate through the 90 km Brownlee reservoir , and as a result, passage of anadromous salmon upstream of the HCC was discontinued.

During their upstream spawning migration in the Columbia River basin, some adult salmonids Oncorhynchus spp. ascend and then fall back over main-stem hydroelectric dams. Fallback can result in fish injury or death, migration delays, and biases in fishway counts, the primary index for escapement and the basis for production estimates and harvest quotas. We used radiotelemetry to calculate fallback percentages and rates, reascension percentages, biases in fishway escapement estimates due to fallback, and occurrence of behaviorally motivated fallback (correcting overshoot of natal sites) by spring-summer and fall Chinook salmon O. tshawytscha and steelhead O. mykiss. The study area included eight Columbia River and Snake River dams evaluated from 1996 to 2001. For all years combined, about 22% of spring-summer Chinook salmon, 15% of fall Chinook salmon, and 21% of steelhead fell back at least once at a dam. Fallback percentages for spring-summer Chinook salmon were generally highest at Bonneville and the Dalles dams and decreased at progressively upstream dams. Fallback rates for spring-summer Chinook salmon were positively correlated with river discharge. Fallback percentages for steelhead and fall Chinook salmon were less variable between years but were more variable between dams than those of spring-summer Chinook salmon. Reascension percentages at dams ranged widely between runs and sites and were negatively related to the number of fish that entered tributaries downstream from the fallback location. Fall Chinook salmon were the most likely to enter a downstream tributary after falling back, though this behavior was also observed in spring-summer Chinook salmon and steelhead. For all years and at all dams, fallback produced positive fishway count biases ranging from 1% to 16% for spring-summer Chinook salmon, 1% to 38% for fall Chinook salmon, and 1% to 12% for steelhead.

We evaluated the survival of juvenile salmon through turbines in Columbia River dams and found no differences between two operations but strong evidence of delayed mortality from turbine passage. After tagging with a passive integrated transponder (PIT) tag and a radio tag, yearling Chinook salmon Oncorhynchus tshawytscha were released at McNary Dam on the Columbia River through a turbine operating both within 1% of peak efficiency (a discharge rate of 317 m 3 /s) and outside the 1% range at the maximum blade angle (464 m 3 /s). Estimated relative survival to a detection array 15 km downstream was 0.871 at 317 m 3 /s and 0.856 at 464 m 3 /s and 0.858 and 0.814, respectively, to an array 46 km downstream. The highest point estimates of survival occurred under the lower discharge, suggesting that operating turbines within 1% of peak efficiency is a useful guideline for fish protection at McNary Dam. In a concurrent evaluation using balloon tags, estimated mean direct survival ranged from 0.930 to 0.946. Radio tag estimates were significantly lower than balloon tag estimates under both operations. Based on these differences, we estimated that delayed mortality comprised from 46% to 70% of total estimated mortality. We reviewed the literature and concluded that delayed mortality was caused by sublethal impacts to fish sensory systems, which increased vulnerability to predation in the tailrace. We recommend that future research to improve turbine designs and operations for fish passage focus on this major component of mortality.

From 1987 to 1992, we evaluated a fish bypass system at Bonneville Dam Powerhouse 2 on the Columbia River. The survival of subyearling Chinook salmon Oncorhynchus tshawytscha released into the system ranged from 0.774 to 0.911 and was significantly lower than the survival of test fish released into turbines and the area immediately below the powerhouse where bypass system flow reentered the river. Yearling and subyearling Chinook salmon and yearling coho salmon O. kisutch released into the bypass system were injured or descaled. Also, levels of blood plasma cortisol and lactate were significantly higher in yearling and subyearling Chinook salmon that passed through the bypass system than in fish released directly into a net located over the bypass exit. This original system was then extensively modified using updated design criteria, and the site where juvenile fish reentered the river was relocated 2.8 km further downstream to reduce predation on bypassed fish by northern pikeminnow Ptychocheilus oregonensis. Based on studies conducted from 1999 to 2001, the new bypass system resulted in high fish survival, virtually no injuries to fish, fish passage times that were generally similar to water travel times, and mild stress responses from which fish recovered quickly. The mean estimated survival of subyearling Chinook salmon passing through the new bypass system was 0.946 in 2001, which was an usually lowflow year. Survival, physical condition, passage timing, and blood physiological indicators of stress were all useful metrics for assessing the performance of both bypass systems and are discussed. The engineering and hydraulic criteria used to design the new bypass system that resulted in improved fish passage conditions are described.

Abstract: The effects of increasing hydropower development and operation appear extremely important in the decline and near extripation of stream-type chinook salmon (Oncorhynchus tshawytscha) stocks of the upper Columbia and Snake rivers. We evaluated temporal and spatial patterns of productivity and survival rates (for index stocks from the Snake, upper Columbia, and lower Columbia regions) to determine the cause of dramatic declines of the upriver stocks. This evaluation tested hypotheses about nonstationarity (changes over time in average productivity) in the Ricker recruitment function caused by changes in the physical environment. Individual stocks showed recent declines in indicators of productivity and survival rate; however, the comparisons indicate that upriver stocks showed greater declines coincident with the development and operation of the hydropower system. Evidence from the aggregate run indicates that declines over the last 50 years were quite abrupt and corresponde...

A multiple-reach model was developed to describe the downstream migration of juvenile salmonids in the Columbia River system. Migration rate for cohorts of fish was allowed to vary by reach and time step. A nested sequence of linear and nonlinear models related the variation in migration rates to river flow, date in season, and experience in the river. By comparing predicted with observed travel times at multiple observation sites along the migration route, the relative performance of the migration rate models was assessed. The analysis was applied to cohorts of yearling chinook salmon (Oncorhynchus tshawytscha) captured at the Snake River Trap near Lewiston, Idaho, and fitted with passive integrated transponder (PIT) tags over the 8-year period 1989-1996. The fish were observed at Lower Granite and Little Goose dams on the Snake River and McNary Dam on the Columbia River covering a migration distance of 277 km. The data supported a model containing two behavioral components: a flow term related to season where fish spend more time in regions of higher river velocity later in the season and a flow-independent experience effect where the fish migrate faster the longer they have been in the river. Résumé : Un modèle sur tronçons multiples a été élaboré pour décrire la dévalaison de salmonidés juvéniles dans le réseau du Columbia. Le taux de migration des cohortes de poissons pouvait varier en fonction du tronçon et de l'intervalle de temps. Une séquence hiérarchique de modèles linéaires et non linéaires liait la variation du taux de migration au débit de la rivière, au moment de la saison, et à la connaissance de la rivière. En comparant les temps de déplacement prévus et les temps observés à plusieurs points d'observation situés le long de la route migratoire, on a évalué la performance relative des modèles des taux de migration. L'analyse a été appliquée à des cohortes de saumons quinnats (Oncorhynchus tshawytscha) âgés de 1 an, capturés dans la trappe située sur la Snake près de Lewiston (Idaho) et auxquels on avait fixé des marques PIT (à transpondeur intégré passif), pendant une période de 8 ans (1989-1996). Les poissons ont été observés aux barrages de Lower Granite et de Little Goose sur la Snake et au barrage McNary sur le Columbia, ce qui couvre une distance de migration de 277 km. Les données appuient un modèle renfermant deux composantes du comportement : un effet de débit lié à la saison pour lequel les poissons restent plus longtemps dans les régions où la vitesse de la rivière est élevée tard dans la saison et un effet de connaissance de la rivière, indépendant du débit, pour lequel plus le temps de séjour du poisson dans la rivière est long, plus sa migration est rapide. [Traduit par la Rédaction]

We used a bioenergetics approach to determine the magnitude of predation by Caspian terns Sterna caspia on juvenile salmonids Oncorhynchus spp. in the mid-Columbia River during 2000 and 2001. Caspian terns nesting on Crescent Island, Washington, located below the confluence of the Snake and Columbia rivers, consumed several hundred thousand juvenile salmonids each year of the study. Tern consumption of smolts was higher in 2001 (679,000 smolts; 95% confidence interval [CI]: 533,000-825,000 smolts) than in 2000 (465,000 smolts; 95% CI: 382,000-547,000 smolts) as a result of an increase in tern breeding pairs, fledging success, and percentage of salmonids in the diet. On-colony detection rates of passive integrated transponder tags from inriver migrating smolts were also higher in 2001 (0.90-12.40%) than in 2000 (0.03-1.60%); the higher predation rates in 2001 were probably caused by extreme drought conditions that resulted in reduced spill from hydroelectric dams, lower river flows, and increased travel times for in-river migrating smolts. Tern predation rates on juvenile steelhead O. mykiss were higher than those on yearling Chinook salmon O. tshawytscha in both years. The impacts of tern predation on steelhead smolts and yearling Chinook salmon from the Snake River were slight after accounting for the high proportion of smolts collected for transportation above Crescent Island. Survival of steelhead smolts from the upper Columbia River that are not transported above Crescent Island may be significantly affected by tern predation, particularly in low-flow years. Appreciably higher predation rates on salmonids by Crescent Island terns than those observed in 2001 are unlikely considering the constraints on tern colony expansion, limited capacity for increased per capita smolt consumption by terns, and current high transportation rates for Snake River smolts.

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.

The effects of increasing hydropower development and operation appear extremely important in the decline and near extripation of stream-type chinook salmon (Oncorhynchus tshawytscha) stocks of the upper Columbia and Snake rivers. We evaluated temporal and spatial patterns of productivity and survival rates (for index stocks from the Snake, upper Columbia, and lower Columbia regions) to determine the cause of dramatic declines of the upriver stocks. This evaluation tested hypotheses about nonstationarity (changes over time in average productivity) in the Ricker recruitment function caused by changes in the physical environment. Individual stocks showed recent declines in indicators of productivity and survival rate; however, the comparisons indicate that upriver stocks showed greater declines coincident with the development and operation of the hydropower system. Evidence from the aggregate run indicates that declines over the last 50 years were quite abrupt and corresponded to construction and completion of the hydropower system. Résumé : L'accroissement du développement et de l'exploitation de l'hydro-électricité semble jouer un rôle très important dans le déclin et la disparition presque complète des stocks de quinnat (Oncorhynchus tshawytscha) de type dulcicole dans le cours supérieur du Columbia et la Snake. Nous avons évalué les profils temporels et spatiaux de la productivité et du taux de survie (pour des stocks indicateurs des régions de la Snake, du haut Columbia et du bas Columbia) pour déterminer la cause des déclins marqués des stocks d'amont. Pour cette évaluation, on a testé des hypothèses concernant la non-stationnarité (changements temporels dans la productivité moyenne) dans la fonction de recrutement de Ricker causée par les changements dans le milieu physique. Les stocks individuels ont connu des déclins récents selon les indicateurs de la productivité et du taux de survie, mais les comparaisons montrent que les stocks d'amont ont connu des déclins plus importants par suite du développement et de l'exploitation du réseau hydroélectrique. Les données sur la remonte totale montrent que les déclins des 50 dernières années ont été assez abrupts et ont suivi la construction et la finalisation du réseau hydro-électrique. [Traduit par la Rédaction] Schaller et al. 1045

A study was conducted to compare the travel times, detection probabilities, and survival of migrant hatchery-reared yearling chinook salmon Oncorhynchus tshawytscha tagged with either gastrically or surgically implanted sham radio tags (with an imbedded passive integrated transponder [PIT] tag) with those of their cohorts tagged only with PIT tags in the Snake and Columbia rivers. Juvenile chinook salmon with gastric ally implanted radio tags migrated signif icantly faster than either surgically radio-tagged or PIT-tagged fish, while migration rates were similar among surgically radio-tagged and PIT-tagged fish. The probabilities of PIT tag detection at downstream dams varied by less than 5% and were not significantly different among the three groups. Survival was similar among treatments for median travel times of less than approximately 6 d (migration distance of 106 km)_ However, for both gastricaIly and surgically radio-tagged fish, survival was significantly less than for PIT-tagged fish, for which median travel times exceeded approximately 10 d (migration distance of 225 km). The results of this study support the use of radio tags to estimate the survival of juvenile chinook salmon having a median fork length of approximately 150 mm (range, 127-285 mm) and a median travel time of migration of less than approximately 6 d.

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.