Snake River fall Chinook salmon were listed as “threatened” under the Endangered Species Act in 1992. At that time, little was known about the spawning, rearing, migration, and life history of this species. This long-term research and monitoring project has produced much of the contemporary knowledge on fall Chinook salmon that has been used by fish managers to implement recovery measures. The population has responded positively to these measures but will likely remain a conservation-reliant species.
Snake River fall Chinook salmon mainly spawn and rear in Hells Canyon on the Snake River and in the Clearwater River basin. They are unique in that they complete the freshwater portion of their life cycle in main-stem habitats unlike other salmonids that use smaller tributaries. Initial work on this project focused on understanding the spawning and rearing requirements of these fish in main-stem habitats as well as identifying important spawning and rearing sites. Because fish must pass eight dams enroute to the ocean as juveniles and as returning adults, much research was later directed at determining appropriate spawning and migration flows. Research increased our understanding of the relationships between downstream movement behavior and water velocity, turbulence, and fish physiology that in turn helped explain life history diversity in this species.
Other research explored the growth differences between fish rearing in riverine and reservoir habitats that shed light on the food web that supports juvenile salmon. Growth is higher in the Snake River than in Lower Granite Reservoir—the first reservoir juvenile fish encounter during their seaward migration—that is due to differences the prey community between the two systems. We documented recent changes to the food webs in lower Snake River reservoirs that included describing the ecology of nonnative Siberian prawns, opossum shrimp, and resurgence of the endemic sand roller. Each of these species influences juvenile fall Chinook salmon either directly or indirectly.
Recent research has focused on estimating the loss of juvenile fall Chinook salmon to smallmouth bass predation in the Snake River. Smallmouth bass are very abundant and are effective predators of juvenile salmon. We showed that bass consumption rate of juvenile fall Chinook salmon has increased 15-fold since the mid-1990s when the last predation study was conducted. This is largely due to increased numbers of juvenile salmon available as prey that has resulted from both increases in natural production and hatchery releases. Interestingly, bass abundance has not changed appreciably through time. Efforts are currently underway to develop a method to distinguish the origin (e.g., hatchery or natural) of juvenile salmon consumed by bass to determine if one prey is more vulnerable than the other.
A list of cooperator publications related to this study can be found here.
Publications associated with this project.
Juvenile Chinook Salmon mortality in a Snake River Reservoir: Smallmouth Bass predation revisited
Migratory behavior and physiological development as potential determinants of life history diversity in fall Chinook Salmon in the Clearwater River
Ecology of the Sand Roller (Percopsis transmontana) in a lower Snake River Reservoir, Washington
Ecology of nonnative Siberian prawn (Palaemon modestus) in the lower Snake River, Washington, USA
Feeding ecology of non-native Siberian prawns, Palaemon modestus (Heller, 1862) (Decapoda, Palaemonidae), in the lower Snake River, Washington, U.S.A.
Survival, growth, and tag retention in age-0 Chinook Salmon implanted with 8-, 9-, and 12-mm PIT tags
Assessing juvenile salmon rearing habitat and associated predation risk in a lower Snake River reservoir
Prey availability, consumption, and quality contribute to variation in growth of subyearling Chinook Salmon rearing in riverine and reservoir habitats
Evidence for density-dependent changes in growth, downstream movement, and size of Chinook salmon subyearlings in a large-river landscape
The effects of juvenile American shad planktivory on zooplankton production in Columbia River food webs
Downstream movement of fall Chinook salmon juveniles in the lower Snake River reservoirs during winter and early spring
Estimating and predicting collection probability of fish at dams using multistate modeling
This has been a 28-year partnership between the U.S. Fish and Wildlife Service (project cooperator) and the Bonneville Power Administration (project funder). This long-term partnership has contributed greatly to our increased understanding of Snake River fall Chinook salmon and the peer-reviewed research products we have produced. Other partners include:
- Overview
Snake River fall Chinook salmon were listed as “threatened” under the Endangered Species Act in 1992. At that time, little was known about the spawning, rearing, migration, and life history of this species. This long-term research and monitoring project has produced much of the contemporary knowledge on fall Chinook salmon that has been used by fish managers to implement recovery measures. The population has responded positively to these measures but will likely remain a conservation-reliant species.
Hells Canyon on the Snake River. Photo credit, Ken Tiffan, USGS - Western Fisheries Research Center. (Public domain) Snake River fall Chinook salmon mainly spawn and rear in Hells Canyon on the Snake River and in the Clearwater River basin. They are unique in that they complete the freshwater portion of their life cycle in main-stem habitats unlike other salmonids that use smaller tributaries. Initial work on this project focused on understanding the spawning and rearing requirements of these fish in main-stem habitats as well as identifying important spawning and rearing sites. Because fish must pass eight dams enroute to the ocean as juveniles and as returning adults, much research was later directed at determining appropriate spawning and migration flows. Research increased our understanding of the relationships between downstream movement behavior and water velocity, turbulence, and fish physiology that in turn helped explain life history diversity in this species.
Other research explored the growth differences between fish rearing in riverine and reservoir habitats that shed light on the food web that supports juvenile salmon. Growth is higher in the Snake River than in Lower Granite Reservoir—the first reservoir juvenile fish encounter during their seaward migration—that is due to differences the prey community between the two systems. We documented recent changes to the food webs in lower Snake River reservoirs that included describing the ecology of nonnative Siberian prawns, opossum shrimp, and resurgence of the endemic sand roller. Each of these species influences juvenile fall Chinook salmon either directly or indirectly.
Beam trawling in Lower Granite Reservoir on the Snake River. Recent research has focused on estimating the loss of juvenile fall Chinook salmon to smallmouth bass predation in the Snake River. Smallmouth bass are very abundant and are effective predators of juvenile salmon. We showed that bass consumption rate of juvenile fall Chinook salmon has increased 15-fold since the mid-1990s when the last predation study was conducted. This is largely due to increased numbers of juvenile salmon available as prey that has resulted from both increases in natural production and hatchery releases. Interestingly, bass abundance has not changed appreciably through time. Efforts are currently underway to develop a method to distinguish the origin (e.g., hatchery or natural) of juvenile salmon consumed by bass to determine if one prey is more vulnerable than the other.
A list of cooperator publications related to this study can be found here.
- Publications
Publications associated with this project.
Filter Total Items: 29Juvenile Chinook Salmon mortality in a Snake River Reservoir: Smallmouth Bass predation revisited
Predation by nonnative fishes has been identified as a contributing factor in the decline of juvenile salmonids in the Columbia River basin. We examined the diet composition of Smallmouth Bass Micropterus dolomieu and estimated the consumption and predation loss of juvenile Chinook Salmon Oncorhynchus tshawytscha in Lower Granite Reservoir on the Snake River. We examined 4,852 Smallmouth Bass stomAuthorsJohn M. Erhardt, Kenneth F. Tiffan, William P. ConnorMigratory behavior and physiological development as potential determinants of life history diversity in fall Chinook Salmon in the Clearwater River
We studied the influence of behavior, water velocity, and physiological development on the downstream movement of subyearling fall‐run Chinook Salmon Oncorhynchus tshawytscha in both free‐flowing and impounded reaches of the Clearwater and Snake rivers as potential mechanisms that might explain life history diversity in this stock. Movement rates and the percentage of radio‐tagged fish that movedAuthorsKenneth F. Tiffan, Tobias J. Kock, William P. Connor, Marshall C. Richmond, William A. PerkinsEcology of the Sand Roller (Percopsis transmontana) in a lower Snake River Reservoir, Washington
The Sand Roller (Percopsis transmontana), has not been abundant in the Snake River since it was first found in the system in the 1950s, but its population has apparently increased in recent years. As a result, we initiated a study to better understand its ecology in habitats of Lower Granite Reservoir. From November 2014 to October 2015, Sand Rollers were present along shorelines, with peak abundaAuthorsKenneth F. Tiffan, John M. Erhardt, Tobyn N. Rhodes, Rulon J. HemingwayEcology of nonnative Siberian prawn (Palaemon modestus) in the lower Snake River, Washington, USA
We assessed the abundance, distribution, and ecology of the nonnative Siberian prawn Palaemon modestus in the lower Snake River, Washington, USA. Analysis of prawn passage abundance at three Snake River dams showed that populations are growing at exponential rates, especially at Little Goose Dam where over 464,000 prawns were collected in 2015. Monthly beam trawling during 2011–2013 provided inforAuthorsJohn M. Erhardt, Kenneth F. TiffanFeeding ecology of non-native Siberian prawns, Palaemon modestus (Heller, 1862) (Decapoda, Palaemonidae), in the lower Snake River, Washington, U.S.A.
We used both stomach content and stable isotope analyses to describe the feeding ecology of Siberian prawns Palaemon modestus (Heller, 1862), a non-native caridean shrimp that is a relatively recent invader of the lower Snake River. Based on identifiable prey in stomachs, the opossum shrimp Neomysis mercedis Holmes, 1896 comprised up to 34-55% (by weight) of diets of juvenile to adult P. modestus,AuthorsKenneth F. Tiffan, William HurstSurvival, growth, and tag retention in age-0 Chinook Salmon implanted with 8-, 9-, and 12-mm PIT tags
The ability to represent a population of migratory juvenile fish with PIT tags becomes difficult when the minimum tagging size is larger than the average size at which fish begin to move downstream. Tags that are smaller (e.g., 8 and 9 mm) than the commonly used 12-mm PIT tags are currently available, but their effects on survival, growth, and tag retention in small salmonid juveniles have receiveAuthorsKenneth F. Tiffan, Russell W. Perry, William P. Connor, Frank L. Mullins, Craig Rabe, Doug D NelsonAssessing juvenile salmon rearing habitat and associated predation risk in a lower Snake River reservoir
Subyearling fall Chinook salmon (Oncorhynchus tshawytscha) in the Columbia River basin exhibit a transient rearing strategy and depend on connected shoreline habitats during freshwater rearing. Impoundment has greatly reduced the amount of shallow-water rearing habitat that is exacerbated by the steep topography of reservoirs. Periodic dredging creates opportunities to strategically place spoils tAuthorsKenneth F. Tiffan, James R. Hatten, David A TrachtenbargPrey availability, consumption, and quality contribute to variation in growth of subyearling Chinook Salmon rearing in riverine and reservoir habitats
We examined prey availability, prey consumed, and diet energy content as sources of variation in growth of natural fall Chinook Salmon Oncorhynchus tshawytscha subyearlings rearing in riverine and reservoir habitats in the Snake River. Subyearlings in riverine habitat primarily consumed aquatic insects (e.g., Diptera, Ephemeroptera, Trichoptera), of which a high proportion was represented by adultAuthorsKenneth F. Tiffan, John M. Erhardt, Scott J. St. JohnEvidence for density-dependent changes in growth, downstream movement, and size of Chinook salmon subyearlings in a large-river landscape
We studied the growth rate, downstream movement, and size of naturally produced fall Chinook Salmon Oncorhynchus tshawytscha subyearlings (age 0) for 20 years in an 8th-order river landscape with regulated riverine upstream rearing areas and an impounded downstream migration corridor. The population transitioned from low to high abundance in association with U.S. Endangered Species Act and other fAuthorsWilliam P. Connor, Kenneth F. Tiffan, John M. Plumb, Christine M. MoffitThe effects of juvenile American shad planktivory on zooplankton production in Columbia River food webs
Columbia River reservoirs support a large population of nonnative American Shad Alosa sapidissima that consume the zooplankton that native fishes also rely on. We hypothesized that the unprecedented biomass of juvenile American Shad in John Day Reservoir is capable of altering the zooplankton community if these fish consume a large portion of the zooplankton production. We derived taxon-specific eAuthorsCraig A. Haskell, Kenneth F. Tiffan, Dennis W. RondorfDownstream movement of fall Chinook salmon juveniles in the lower Snake River reservoirs during winter and early spring
We conducted a 3-year radiotelemetry study in the lower Snake River to (1) determine whether juvenile fall Chinook salmon Oncorhynchus tshawytscha pass dams during winter, when bypass systems and structures designed to prevent mortality are not operated; (2) determine whether downstream movement rate varies annually, seasonally, and from reservoir to reservoir; and (3) identify some of the factorsAuthorsKenneth F. Tiffan, Tobias J. Kock, William P. Connor, Frank Mullins, R. Kirk SteinhorstEstimating and predicting collection probability of fish at dams using multistate modeling
Dams can be equipped with a bypass that routes a portion of the fish that enter the turbine intakes away from the powerhouse into flumes, where they can be counted. Daily passage abundance can be estimated by dividing the number of fish counted in the bypass by the sampling rate and then dividing the resulting quotient by the collection probability (i.e., the proportion of the fish population passAuthorsJohn M. Plumb, William P. Connor, Kenneth F. Tiffan, Christine M. Moffitt, Russell W. Perry, Noah S. Adams - Partners
This has been a 28-year partnership between the U.S. Fish and Wildlife Service (project cooperator) and the Bonneville Power Administration (project funder). This long-term partnership has contributed greatly to our increased understanding of Snake River fall Chinook salmon and the peer-reviewed research products we have produced. Other partners include: