Tobyn is a Fish Biologist at the Columbia River Research Laboratory, Clarkston Duty Station.
Science and Products
Performance of subyearling fall Chinook salmon tagged with 8‐, 9‐, and 12‐mm passive integrated transponder tags in the Snake River
Inferences based on tagged individuals from a population are limited in part by the minimum size of fish that can be tagged. Smaller tags allow a greater proportion of a population to be represented by tagging and should reduce potential tag effects on fish performance. We evaluated different performance metrics of juvenile fall Chinook Salmon Oncorhynchus tshawytscha tagged with 8‐, 9‐, and 12‐mm
Authors
Kenneth Tiffan, Tobyn Rhodes, Brad Bickford, Dalton Dirk Lebeda, William P. Connor, Frank L. Mullins
Impact of smallmouth bass predation on subyearling fall Chinook salmon over a broad river continuum
Smallmouth bass (Micropterus dolomieu) predation on subyearling fall Chinook salmon (Oncorhynchus tshawytscha) was examined in the Snake River (USA) to identify seasonal and habitat-related changes in bass diets, and associated subyearling consumption and loss in various riverine and impounded reaches. Smallmouth bass diets reflected opportunistic foraging that at times showed predation on subyear
Authors
Kenneth Tiffan, John M Erhardt, Rulon J. Hemingway, Brad Bickford, Tobyn Rhodes
Research, monitoring, and evaluation of emerging issues and measures to recover the Snake River fall Chinook Salmon ESU
The portion of the Snake River fall Chinook Salmon Oncorhynchus tshawytscha ESU that spawns upstream of Lower Granite Dam transitioned from low to high abundance during 1992–2018 in association with U.S. Endangered Species Act recovery efforts and other federally mandated actions. This annual report focuses on (1) numeric and habitat use responses by natural- and hatchery-origin spawners, (2) phen
Authors
Kenneth Tiffan, Russell Perry, John Plumb, Dalton Hance, Brad Bickford, Tobyn Rhodes
Fall Chinook salmon (Oncorhynchus tshawytscha), sand roller (Percopsis transmontana), and smallmouth bass (Micropterus dolomieu) interactions in a Snake River reservoir: A tale of three species
We studied some of the relationships between federally listed fall Chinook Salmon, Oncorhynchus tshawytscha, endemic Sand Roller, Percopsis transmontana, and non-native Smallmouth Bass, Micropterus dolomieu, in Lower Granite Reservoir on the Snake River. Because of its recent reappearance and population increase, the Sand Rollers could be filling the role of a “native invader” in the reservoir foo
Authors
Rulon J. Hemingway, Kenneth F. Tiffan, John M. Erhardt, Tobyn N. Rhodes, Brad K. Bickford
Research, monitoring, and evaluation of emerging issues and measures to recover the Snake River fall Chinook salmon ESU
The portion of the Snake River fall Chinook Salmon Oncorhynchus tshawytscha ESU that spawns upstream of Lower Granite Dam transitioned from low to high abundance during 1992–2017 in association with U.S. Endangered Species Act recovery efforts and other federally mandated actions. This annual report focuses on (1) numeric and habitat use responses by natural- and hatchery-origin spawners, (2) phen
Authors
Kenneth Tiffan, John M. Plumb, Russell W. Perry, John Erhardt, Rulon J. Hemingway, Brad Bickford, Tobyn N. Rhodes, William P. Connor, Frank L. Mullins
Smallmouth bass predation on subyearling fall Chinook salmon in Lower Granite Reservoir, 2016–2017
Predation by nonnative fishes is one factor that has been implicated in the decline of juvenile salmonids in the Pacific Northwest. Impoundment of much of the Snake and Columbia Rivers has altered food webs and created habitat favorable for species such as smallmouth bass Micropterus dolomieu. Smallmouth bass are common throughout the Columbia River basin and have become the most abundant predator
Authors
John M. Erhardt, Kenneth F. Tiffan, Rulon J. Hemingway, Brad K. Bickford, Tobyn N. Rhodes
Ecology 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 abunda
Authors
Kenneth F. Tiffan, John M. Erhardt, Tobyn N. Rhodes, Rulon J. Hemingway
Research, monitoring, and evaluation of emerging issues and measures to recover the Snake River Fall Chinook Salmon ESU, 1/1/2016 - 12/31/2016
The portion of the Snake River fall Chinook Salmon Oncorhynchus tshawytscha ESU that spawns upstream of Lower Granite Dam transitioned from low to high abundance during 1992–2016 in association with U.S. Endangered Species Act recovery efforts and other federally mandated actions. This annual report focuses on (1) numeric and habitat use responses by natural- and hatchery-origin spawners, (2) phen
Authors
William P. Connor, Frank L. Mullins, Kenneth F. Tiffan, John M. Plumb, Russell W. Perry, John M. Erhardt, Rulon J. Hemingway, Brad K. Bickford, Tobyn N. Rhodes
Snake River Fall Chinook Salmon life history investigations
Predation by nonnative fishes is one factor that has been implicated in the decline of juvenile salmonids in the Pacific Northwest. Impoundment of much of the Snake and Columbia rivers has altered food webs and created habitat favorable for species such as Smallmouth Bass Micropterus dolomieu. Smallmouth Bass are common throughout the Columbia River basin and have become the most abundant predator
Authors
John M. Erhardt, Brad K. Bickford, Rulon J. Hemingway, Tobyn N. Rhodes, Kenneth F. Tiffan
Research, monitoring, and evaluation of emerging issues and measures to recover the Snake River fall Chinook salmon ESU, 1/1/2014 - 12/31/2014
The portion of the Snake River fall Chinook Salmon Oncorhynchus tshawytscha ESU that spawns upstream of Lower Granite Dam transitioned from low to high abundance during 1992–2014 in association with U.S. Endangered Species Act recovery efforts and other Federally mandated actions. This annual report focuses on (1) numeric and habitat use responses by natural- and hatchery-origin spawners, (2) phen
Authors
William P. Connor, Frank L. Mullins, Kenneth F. Tiffan, Russell W. Perry, John M. Erhardt, Scott J. St John, Brad K. Bickford, Tobyn N. Rhodes
Research, monitoring, and evaluation of emerging issues and measures to recover the Snake River fall Chinook salmon ESU, 1/1/2012 – 12/31/2013: Annual report, 1991-029-00
The portion of the Snake River fall Chinook Salmon Oncorhynchus tshawytscha ESU that spawns upstream of Lower Granite Dam transitioned from low to high abundance during 1992–2014 in association with U.S. Endangered Species Act recovery efforts and other Federally mandated actions. This annual report focuses on (1) numeric and habitat use responses by natural- and hatchery-origin spawners, (2) phen
Authors
William P. Connor, Frank Mullins, Kenneth F. Tiffan, Russell W. Perry, John M. Erhardt, Scott J. St. John, Brad K. Bickford, Tobyn N. Rhodes
Snake River fall Chinook salmon life history investigations: Annual report 2011 (April 2011 - March 2012)
Executive Summary
Chapter One – This chapter was published in the Transactions of the American Fisheries Society in 2012. We conducted a three-year radiotelemetry study in the lower Snake River to answer the questions: do fall Chinook salmon juveniles pass dams during winter when bypass systems and structures designed to prevent mortality are not operated; does downstream movement rate vary annual
Authors
Kenneth F. Tiffan, William P. Connor, Brian J. Bellgraph, Tobias J. Kock, Frank Mullins, R. Kirk Steinhorst, Helena E. Christiansen, Stephen D. McCormick, Lori A. Ortega, Kathleen M. Carter, Evan V. Arntzen, Katherine J.C. Klett, Z. Daniel Deng, Tylor K. Abel, Timothy J. Linley, Valerie I. Cullinan, Scott J. St John, John M. Erhardt, Brad K. Bickford, Amanda Schmidt, Tobyn N. Rhodes
Science and Products
- Publications
Performance of subyearling fall Chinook salmon tagged with 8‐, 9‐, and 12‐mm passive integrated transponder tags in the Snake River
Inferences based on tagged individuals from a population are limited in part by the minimum size of fish that can be tagged. Smaller tags allow a greater proportion of a population to be represented by tagging and should reduce potential tag effects on fish performance. We evaluated different performance metrics of juvenile fall Chinook Salmon Oncorhynchus tshawytscha tagged with 8‐, 9‐, and 12‐mmAuthorsKenneth Tiffan, Tobyn Rhodes, Brad Bickford, Dalton Dirk Lebeda, William P. Connor, Frank L. MullinsImpact of smallmouth bass predation on subyearling fall Chinook salmon over a broad river continuum
Smallmouth bass (Micropterus dolomieu) predation on subyearling fall Chinook salmon (Oncorhynchus tshawytscha) was examined in the Snake River (USA) to identify seasonal and habitat-related changes in bass diets, and associated subyearling consumption and loss in various riverine and impounded reaches. Smallmouth bass diets reflected opportunistic foraging that at times showed predation on subyearAuthorsKenneth Tiffan, John M Erhardt, Rulon J. Hemingway, Brad Bickford, Tobyn RhodesResearch, monitoring, and evaluation of emerging issues and measures to recover the Snake River fall Chinook Salmon ESU
The portion of the Snake River fall Chinook Salmon Oncorhynchus tshawytscha ESU that spawns upstream of Lower Granite Dam transitioned from low to high abundance during 1992–2018 in association with U.S. Endangered Species Act recovery efforts and other federally mandated actions. This annual report focuses on (1) numeric and habitat use responses by natural- and hatchery-origin spawners, (2) phenAuthorsKenneth Tiffan, Russell Perry, John Plumb, Dalton Hance, Brad Bickford, Tobyn RhodesFall Chinook salmon (Oncorhynchus tshawytscha), sand roller (Percopsis transmontana), and smallmouth bass (Micropterus dolomieu) interactions in a Snake River reservoir: A tale of three species
We studied some of the relationships between federally listed fall Chinook Salmon, Oncorhynchus tshawytscha, endemic Sand Roller, Percopsis transmontana, and non-native Smallmouth Bass, Micropterus dolomieu, in Lower Granite Reservoir on the Snake River. Because of its recent reappearance and population increase, the Sand Rollers could be filling the role of a “native invader” in the reservoir fooAuthorsRulon J. Hemingway, Kenneth F. Tiffan, John M. Erhardt, Tobyn N. Rhodes, Brad K. BickfordResearch, monitoring, and evaluation of emerging issues and measures to recover the Snake River fall Chinook salmon ESU
The portion of the Snake River fall Chinook Salmon Oncorhynchus tshawytscha ESU that spawns upstream of Lower Granite Dam transitioned from low to high abundance during 1992–2017 in association with U.S. Endangered Species Act recovery efforts and other federally mandated actions. This annual report focuses on (1) numeric and habitat use responses by natural- and hatchery-origin spawners, (2) phenAuthorsKenneth Tiffan, John M. Plumb, Russell W. Perry, John Erhardt, Rulon J. Hemingway, Brad Bickford, Tobyn N. Rhodes, William P. Connor, Frank L. MullinsSmallmouth bass predation on subyearling fall Chinook salmon in Lower Granite Reservoir, 2016–2017
Predation by nonnative fishes is one factor that has been implicated in the decline of juvenile salmonids in the Pacific Northwest. Impoundment of much of the Snake and Columbia Rivers has altered food webs and created habitat favorable for species such as smallmouth bass Micropterus dolomieu. Smallmouth bass are common throughout the Columbia River basin and have become the most abundant predatorAuthorsJohn M. Erhardt, Kenneth F. Tiffan, Rulon J. Hemingway, Brad K. Bickford, Tobyn N. RhodesEcology 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. HemingwayResearch, monitoring, and evaluation of emerging issues and measures to recover the Snake River Fall Chinook Salmon ESU, 1/1/2016 - 12/31/2016
The portion of the Snake River fall Chinook Salmon Oncorhynchus tshawytscha ESU that spawns upstream of Lower Granite Dam transitioned from low to high abundance during 1992–2016 in association with U.S. Endangered Species Act recovery efforts and other federally mandated actions. This annual report focuses on (1) numeric and habitat use responses by natural- and hatchery-origin spawners, (2) phenAuthorsWilliam P. Connor, Frank L. Mullins, Kenneth F. Tiffan, John M. Plumb, Russell W. Perry, John M. Erhardt, Rulon J. Hemingway, Brad K. Bickford, Tobyn N. RhodesSnake River Fall Chinook Salmon life history investigations
Predation by nonnative fishes is one factor that has been implicated in the decline of juvenile salmonids in the Pacific Northwest. Impoundment of much of the Snake and Columbia rivers has altered food webs and created habitat favorable for species such as Smallmouth Bass Micropterus dolomieu. Smallmouth Bass are common throughout the Columbia River basin and have become the most abundant predatorAuthorsJohn M. Erhardt, Brad K. Bickford, Rulon J. Hemingway, Tobyn N. Rhodes, Kenneth F. TiffanResearch, monitoring, and evaluation of emerging issues and measures to recover the Snake River fall Chinook salmon ESU, 1/1/2014 - 12/31/2014
The portion of the Snake River fall Chinook Salmon Oncorhynchus tshawytscha ESU that spawns upstream of Lower Granite Dam transitioned from low to high abundance during 1992–2014 in association with U.S. Endangered Species Act recovery efforts and other Federally mandated actions. This annual report focuses on (1) numeric and habitat use responses by natural- and hatchery-origin spawners, (2) phenAuthorsWilliam P. Connor, Frank L. Mullins, Kenneth F. Tiffan, Russell W. Perry, John M. Erhardt, Scott J. St John, Brad K. Bickford, Tobyn N. RhodesResearch, monitoring, and evaluation of emerging issues and measures to recover the Snake River fall Chinook salmon ESU, 1/1/2012 – 12/31/2013: Annual report, 1991-029-00
The portion of the Snake River fall Chinook Salmon Oncorhynchus tshawytscha ESU that spawns upstream of Lower Granite Dam transitioned from low to high abundance during 1992–2014 in association with U.S. Endangered Species Act recovery efforts and other Federally mandated actions. This annual report focuses on (1) numeric and habitat use responses by natural- and hatchery-origin spawners, (2) phenAuthorsWilliam P. Connor, Frank Mullins, Kenneth F. Tiffan, Russell W. Perry, John M. Erhardt, Scott J. St. John, Brad K. Bickford, Tobyn N. RhodesSnake River fall Chinook salmon life history investigations: Annual report 2011 (April 2011 - March 2012)
Executive Summary Chapter One – This chapter was published in the Transactions of the American Fisheries Society in 2012. We conducted a three-year radiotelemetry study in the lower Snake River to answer the questions: do fall Chinook salmon juveniles pass dams during winter when bypass systems and structures designed to prevent mortality are not operated; does downstream movement rate vary annualAuthorsKenneth F. Tiffan, William P. Connor, Brian J. Bellgraph, Tobias J. Kock, Frank Mullins, R. Kirk Steinhorst, Helena E. Christiansen, Stephen D. McCormick, Lori A. Ortega, Kathleen M. Carter, Evan V. Arntzen, Katherine J.C. Klett, Z. Daniel Deng, Tylor K. Abel, Timothy J. Linley, Valerie I. Cullinan, Scott J. St John, John M. Erhardt, Brad K. Bickford, Amanda Schmidt, Tobyn N. Rhodes