Timothy P O'Brien
Timothy O’Brien is a Supervisory Fish Biologist stationed at the Great Lakes Science Center in Ann Arbor, Michigan.
Since 2004, I have conducted ecosystem assessments in Lake Huron and Lake Michigan that track long-term changes in fish populations. My work mainly focuses on Lake Huron where I lead the Pelagic Prey Fish Assessment Program. The field component of this research involves carrying out an integrated acoustic and mid-water trawl survey which includes Lake Huron’s three hydrogeomorphically distinct basins, the main basin, North Channel, and Georgian Bay. The primary deliverable of this work is to provide state, tribal, and provincial fishery managers with current data on abundance, size/age, and spatial distribution of prey-fish stocks that support fish species targeted in commercial and recreational fisheries. My research interests extend to include early life history processes in fish populations and factors affecting recruitment, growth variation, and distribution of important species including rainbow smelt (Osmerus mordax) and bloater (Coregonus hoyi).
I supervise of team of Biological Technicians in the Deepwater Sciences Branch who are responsible for conducting long-term fishery assessments in Lake Michigan and Lake Huron. Additionally, I oversee the fish age estimation laboratory for Lake Huron and Lake Michigan fishery assessment programs. In addition to my science program role, I serve as station supervisor for the Cheboygan Vessel Operations Base in Cheboygan, Michigan which is the home port for research vessels Sturgeon and Arcticus.
Professional Experience
Supervisory Fish Biologist, November 2017 – Present
Biological Science Technician (Fisheries), May 2011 - October 2017
Student Trainee (Biology), Student Career Experience Program, June 2008 - April 2011
Biological Science Technician (Fisheries) Term, January 2005 - May 2008
Student Services Contractor – February 2004-December 2004
Education and Certifications
M.S. 2010. Fisheries and Wildlife. Michigan State University, Department of Fisheries and Wildlife
B.S. 2004. Resource Ecology and Management. The University of Michigan, School of Natural Resources and Environment
Science and Products
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Filter Total Items: 39
Status of pelagic prey fishes in Lake Michigan, 2017
Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2017 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2017 survey consi
Authors
David M. Warner, Ben Turscah, Dale Hanson, Timothy J. Desorcie, Timothy P. O'Brien, Patricia M. Dieter, Jason Smith
Continued feeding on Diporeia by deepwater sculpin in Lake Huron
Monitoring changes in diets of fish is essential to understanding how food web dynamics respond to changes in native prey abundances. In the Great Lakes, Diporeia, a benthic macroinvertebrate and primary food of native benthivores, declined following the introduction of invasive Dreissena mussels and these changes were reflected in fish diets. We examined the diets of deepwater sculpin Myoxocephal
Authors
Patricia A. Thompson, Edward F. Roseman, Kevin M. Keeler, Timothy P. O'Brien, Dustin Bowser
Large-scale changes in bloater growth and condition in Lake Huron
Native Bloaters Coregonus hoyi have exhibited multiple strong year-classes since 2005 and now are the most abundant benthopelagic offshore prey fish in Lake Huron, following the crash of nonnative AlewivesAlosa pseudoharengus and substantial declines in nonnative Rainbow Smelt Osmerus mordax. Despite recent recoveries in Bloater abundance, marketable-size (>229 mm) Bloaters remain scarce. We used
Authors
Carson G. Prichard, Edward F. Roseman, Kevin M. Keeler, Timothy P. O'Brien, Stephen C. Riley
Age and growth of round gobies in Lake Huron: Implications for food web dynamics
Although the round goby (Neogobius melanostomus) has become established throughout the Laurentian Great Lakes, information is scarce on spatial variation in round goby growth between and within lakes. Based on a sample of 754 specimens captured in 2014, age, growth, and mortality of round gobies at four locations in Lake Huron were assessed via otolith analysis. Total length (TL) of round gobies r
Authors
You J. Duan, Charles P. Madenjian, Cong X. Xie, James S. Diana, Timothy P. O'Brien, Ying M. Zhao, Ji X. He, Steve A. Farha, Bin Huo
Status of pelagic prey fishes in Lake Michigan, 2015
Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2015 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2015 survey consist
Authors
David M. Warner, Randall M. Claramunt, Steve A. Farha, Dale Hanson, Timothy J. Desorcie, Timothy P. O'Brien
Status of Pelagic Prey Fishes in Lake Michigan, 2014
Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2014 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2014 survey consist
Authors
David M. Warner, Steven A. Farha, Randall M. Claramunt, Dale Hanson, Timothy P. O'Brien
Age and growth of round gobies in Lake Michigan, with preliminary mortality estimation
The round goby (Neogobius melanostomus) is a prevalent invasive species throughout Lake Michigan, as well as other Laurentian Great Lakes, yet little information is available on spatial variation in round goby growth within one body of water. Age and growth of round goby at three areas of Lake Michigan were studied by otolith analysis from a sample of 659 specimens collected from 2008 to 2012. Tot
Authors
Bin Huo, Charles P. Madenjian, Cong X. Xie, Yingming Zhao, Timothy P. O'Brien, Sergiusz J. Czesny
Ecological factors affecting Rainbow Smelt recruitment in the main basin of Lake Huron, 1976-2010
Rainbow Smelt Osmerus mordax are native to northeastern Atlantic and Pacific–Arctic drainages and have been widely introduced throughout North America. In the Great Lakes region, Rainbow Smelt are known predators and competitors of native fish and a primary prey species in pelagic food webs. Despite their widespread distribution, importance as a prey species, and potential to negatively interact w
Authors
Timothy P. O'Brien, William W. Taylor, Edward F. Roseman, Charles P. Madenjian, Stephen C. Riley
Mechanisms driving recruitment variability in fish: comparisons between the Laurentian Great Lakes and marine systems
In his seminal work, Hjort (in Fluctuations in the great fisheries of Northern Europe. Conseil Parmanent International Pour L'Exploration De La Mar. Rapports et Proces-Verbaux, 20: 1–228, 1914) observed that fish population levels fluctuated widely, year-class strength was set early in life, and egg production by adults could not alone explain variability in year-class strength. These observations
Authors
Jeremy J. Pritt, Edward F. Roseman, Timothy P. O'Brien
Status and trends of pelagic prey fish in Lake Huron, 2013
The USGS Great Lakes Science Center (GLSC) conducted acoustic and midwater trawl surveys
of Lake Huron during 1997 and annually during 2004-2013. The 2013 survey was conducted
during September and October and included transects in Lake Huron’s main basin, Georgian
Bay, and North Channel. Pelagic fish density was 1,033 fish/ha in 2013 and increased 62% over
the 2012 estimate. Total biomass in 2
Authors
Timothy P. O'Brien, David M. Warner, Steve A. Farha, Darryl W. Hondorp, Lisa A. Kaulfersch, Nicole M. Watson
Status of pelagic prey fishes in Lake Michigan, 2013
Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2013 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2013 survey consist
Authors
David M. Warner, Steven A. Farha, Timothy P. O'Brien, Lynn Ogilvie, Randall M. Claramunt, Dale Hanson
Spatial distribution of pelagic fish larvae in the northern main basin of Lake Huron
Larval fish occurrence in inshore and offshore zones in the northern main basin of Lake Huron was assessed during 2007 as part of a larger ecological examination of Lake Huron foodwebs and habitats. Day and night collections using neuston and conical nets at inshore (1.5–15 m depths) and offshore (37 and 91 m depths) locations at De Tour and Hammond Bay to assess the abundance, phenology, and spat
Authors
Edward F. Roseman, Timothy P. O'Brien
Non-USGS Publications**
O’Brien, T. 2003. “Salvelinus confluentus” (On-line), Animal Diversity Web
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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Filter Total Items: 39Status of pelagic prey fishes in Lake Michigan, 2017
Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2017 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2017 survey consiAuthorsDavid M. Warner, Ben Turscah, Dale Hanson, Timothy J. Desorcie, Timothy P. O'Brien, Patricia M. Dieter, Jason SmithContinued feeding on Diporeia by deepwater sculpin in Lake Huron
Monitoring changes in diets of fish is essential to understanding how food web dynamics respond to changes in native prey abundances. In the Great Lakes, Diporeia, a benthic macroinvertebrate and primary food of native benthivores, declined following the introduction of invasive Dreissena mussels and these changes were reflected in fish diets. We examined the diets of deepwater sculpin MyoxocephalAuthorsPatricia A. Thompson, Edward F. Roseman, Kevin M. Keeler, Timothy P. O'Brien, Dustin BowserLarge-scale changes in bloater growth and condition in Lake Huron
Native Bloaters Coregonus hoyi have exhibited multiple strong year-classes since 2005 and now are the most abundant benthopelagic offshore prey fish in Lake Huron, following the crash of nonnative AlewivesAlosa pseudoharengus and substantial declines in nonnative Rainbow Smelt Osmerus mordax. Despite recent recoveries in Bloater abundance, marketable-size (>229 mm) Bloaters remain scarce. We usedAuthorsCarson G. Prichard, Edward F. Roseman, Kevin M. Keeler, Timothy P. O'Brien, Stephen C. RileyAge and growth of round gobies in Lake Huron: Implications for food web dynamics
Although the round goby (Neogobius melanostomus) has become established throughout the Laurentian Great Lakes, information is scarce on spatial variation in round goby growth between and within lakes. Based on a sample of 754 specimens captured in 2014, age, growth, and mortality of round gobies at four locations in Lake Huron were assessed via otolith analysis. Total length (TL) of round gobies rAuthorsYou J. Duan, Charles P. Madenjian, Cong X. Xie, James S. Diana, Timothy P. O'Brien, Ying M. Zhao, Ji X. He, Steve A. Farha, Bin HuoStatus of pelagic prey fishes in Lake Michigan, 2015
Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2015 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2015 survey consistAuthorsDavid M. Warner, Randall M. Claramunt, Steve A. Farha, Dale Hanson, Timothy J. Desorcie, Timothy P. O'BrienStatus of Pelagic Prey Fishes in Lake Michigan, 2014
Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2014 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2014 survey consistAuthorsDavid M. Warner, Steven A. Farha, Randall M. Claramunt, Dale Hanson, Timothy P. O'BrienAge and growth of round gobies in Lake Michigan, with preliminary mortality estimation
The round goby (Neogobius melanostomus) is a prevalent invasive species throughout Lake Michigan, as well as other Laurentian Great Lakes, yet little information is available on spatial variation in round goby growth within one body of water. Age and growth of round goby at three areas of Lake Michigan were studied by otolith analysis from a sample of 659 specimens collected from 2008 to 2012. TotAuthorsBin Huo, Charles P. Madenjian, Cong X. Xie, Yingming Zhao, Timothy P. O'Brien, Sergiusz J. CzesnyEcological factors affecting Rainbow Smelt recruitment in the main basin of Lake Huron, 1976-2010
Rainbow Smelt Osmerus mordax are native to northeastern Atlantic and Pacific–Arctic drainages and have been widely introduced throughout North America. In the Great Lakes region, Rainbow Smelt are known predators and competitors of native fish and a primary prey species in pelagic food webs. Despite their widespread distribution, importance as a prey species, and potential to negatively interact wAuthorsTimothy P. O'Brien, William W. Taylor, Edward F. Roseman, Charles P. Madenjian, Stephen C. RileyMechanisms driving recruitment variability in fish: comparisons between the Laurentian Great Lakes and marine systems
In his seminal work, Hjort (in Fluctuations in the great fisheries of Northern Europe. Conseil Parmanent International Pour L'Exploration De La Mar. Rapports et Proces-Verbaux, 20: 1–228, 1914) observed that fish population levels fluctuated widely, year-class strength was set early in life, and egg production by adults could not alone explain variability in year-class strength. These observationsAuthorsJeremy J. Pritt, Edward F. Roseman, Timothy P. O'BrienStatus and trends of pelagic prey fish in Lake Huron, 2013
The USGS Great Lakes Science Center (GLSC) conducted acoustic and midwater trawl surveys of Lake Huron during 1997 and annually during 2004-2013. The 2013 survey was conducted during September and October and included transects in Lake Huron’s main basin, Georgian Bay, and North Channel. Pelagic fish density was 1,033 fish/ha in 2013 and increased 62% over the 2012 estimate. Total biomass in 2AuthorsTimothy P. O'Brien, David M. Warner, Steve A. Farha, Darryl W. Hondorp, Lisa A. Kaulfersch, Nicole M. WatsonStatus of pelagic prey fishes in Lake Michigan, 2013
Acoustic surveys were conducted in late summer/early fall during the years 1992-1996 and 2001-2013 to estimate pelagic prey fish biomass in Lake Michigan. Midwater trawling during the surveys as well as target strength provided a measure of species and size composition of the fish community for use in scaling acoustic data and providing species-specific abundance estimates. The 2013 survey consistAuthorsDavid M. Warner, Steven A. Farha, Timothy P. O'Brien, Lynn Ogilvie, Randall M. Claramunt, Dale HansonSpatial distribution of pelagic fish larvae in the northern main basin of Lake Huron
Larval fish occurrence in inshore and offshore zones in the northern main basin of Lake Huron was assessed during 2007 as part of a larger ecological examination of Lake Huron foodwebs and habitats. Day and night collections using neuston and conical nets at inshore (1.5–15 m depths) and offshore (37 and 91 m depths) locations at De Tour and Hammond Bay to assess the abundance, phenology, and spatAuthorsEdward F. Roseman, Timothy P. O'BrienNon-USGS Publications**
O’Brien, T. 2003. “Salvelinus confluentus” (On-line), Animal Diversity Web**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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