Lake trout historically supported the most valuable freshwater commercial fisheries in North America, but their populations crashed in parts of the Great Lakes during the 1950s and 1960s due to overfishing and invasive species.
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
Lakebed features extracted from single-beam sonar in two Laurentian Great Lakes
Hydroacoustic data from uncrewed surface vehicle (USV) overtakes in Lakes Huron and Michigan, 2021
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Lake trout historically supported the most valuable freshwater commercial fisheries in North America, but their populations crashed in parts of the Great Lakes during the 1950s and 1960s due to overfishing and invasive species.
Publications by this scientist
Intra-lake trends and inter-lake comparisons of Mysis diluviana life history variables and their relationships to food limitation
Large-scale variation in lakebed properties interpreted from single-beam sonar in two Laurentian Great Lakes
Status and trends of the Lake Huron prey fish community, 1976-2022
Comparison of traditional and geometric morphometrics using Lake Huron ciscoes of the Coregonus artedi complex
Status and trends of the Lake Huron prey fish community, 1976-2021
Status and trends of the Lake Huron prey fish community, 1976-2019
Status and trends of the Lake Huron prey fish community, 1976-2020
Replacement of the typical artedi form of Coregonus artedi in Lake Huron by endemic shallow-water Ciscoes, including putative hybrids
Status and trends of pelagic prey fish in Lake Huron, 2018
Spatial patterns of rainbow smelt energetic condition in Lakes Huron and Erie in 2017: Evidence for Lake Huron resource limitation
Phenology and species diversity in a Lake Huron ichthyoplankton community: Ecological implications of invasive species dominance
Status and trends of pelagic prey fish in Lake Huron, 2017
Non-USGS Publications**
**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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Science and Products
- Data
Lakebed features extracted from single-beam sonar in two Laurentian Great Lakes
Acoustic seabed classification (ASC) is an important method for understanding landscape-level physical and biological patterns in the aquatic environment. Bottom habitats in the Laurentian Great Lakes are poorly mapped to date, and will require a variety of contributors and data sources to complete. We repurposed a long-term split-beam echosounder dataset gathered for purposes of fisheries assessmHydroacoustic data from uncrewed surface vehicle (USV) overtakes in Lakes Huron and Michigan, 2021
These data were derived from hydroacoustic data collected by uncrewed surface vehicles (USVs) and powered research vessels. The powered vessels overtook the USVs in Lakes Huron and Michigan to study fish avoidance of survey vessels during traditional acoustic surveys. The water column was divided into three depth groups (epilimnion, metalimnion, hypolimnion) for analysis. Each drone transect was b - Multimedia
Multimedia related to this scientist
Lake TroutLake trout historically supported the most valuable freshwater commercial fisheries in North America, but their populations crashed in parts of the Great Lakes during the 1950s and 1960s due to overfishing and invasive species.
Lake trout historically supported the most valuable freshwater commercial fisheries in North America, but their populations crashed in parts of the Great Lakes during the 1950s and 1960s due to overfishing and invasive species.
- Publications
Publications by this scientist
Filter Total Items: 39Intra-lake trends and inter-lake comparisons of Mysis diluviana life history variables and their relationships to food limitation
The opossum shrimp, Mysis diluviana, is an important member of the offshore food webs of the Laurentian Great Lakes, but its response to ecosystem changes that have occurred over the past several decades is not well understood. We combined the data of four long-term sampling programs, adding several years of data (post and prior) to previously published analyses to offer a longer-term, cross-basinAuthorsToby J. Holda, J.M. Watkins, Anne E. Scofield, Stephen Pothoven, David Warner, Timothy P. O'Brien, Kelly L. Bowen, Warren J.S. Currie, David J. Jude, Patrick Boynton, Lars G. RudstamLarge-scale variation in lakebed properties interpreted from single-beam sonar in two Laurentian Great Lakes
Acoustic seabed classification (ASC) is an important method for understanding landscape-level physical and biological patterns in the aquatic environment. Bottom habitats in the Laurentian Great Lakes are poorly mapped to date, and will require a variety of contributors and data sources to complete. We repurposed a long-term split-beam echosounder dataset gathered for purposes of fisheries assessmAuthorsSamuel Pecoraro, Peter C. Esselman, Timothy P. O'Brien, Steve A. Farha, David WarnerStatus and trends of the Lake Huron prey fish community, 1976-2022
The United States Geological Survey-Great Lakes Science Center has monitored annual changes in the offshore prey fish community of Lake Huron since 1973. Monitoring of prey fish populations in Lake Huron is based on a bottom trawl survey that targets demersal (benthic) species and an acoustic-midwater trawl survey that targets pelagic species and life stages. Status of the main basin prey fish comAuthorsDarryl W. Hondorp, Timothy P. O'Brien, Edward F. Roseman, Peter EsselmanComparison of traditional and geometric morphometrics using Lake Huron ciscoes of the Coregonus artedi complex
Here we determine how traditional morphometrics (TM) compares with geometric morphometrics (GM) in discriminating among morphologies of four forms of ciscoes of the Coregonus artedi complex collected from Lake Huron. One of the forms comprised two groups of the same deepwater cisco separated by capture depth, whereas the other three forms were shallow-water ciscoes. Our three groups of shallow-watAuthorsBenjamin E Martin, Brian O'Malley, Randy E Eshenroder, Yu-Chun Kao, Chris Olds, Timothy P. O'Brien, Chris L. DavisStatus and trends of the Lake Huron prey fish community, 1976-2021
The U.S. Geological Survey Great Lakes Science Center has assessed annual changes in the offshore prey fish community of Lake Huron since 1973. Assessments are based on a bottom trawl survey conducted in October of each year and an acoustics-midwater trawl survey, which began in 2004 and is conducted in September-October. Due to weather delays and continued travel restrictions during 2021, thereAuthorsTimothy P. O'Brien, Darryl W. Hondorp, Peter Esselman, Edward F. RosemanStatus and trends of the Lake Huron prey fish community, 1976-2019
The USGS Great Lakes Science Center has assessed annual changes in the offshore prey fish community of Lake Huron since 1973. Assessments are based on a bottom trawl survey conducted in October of each year and an acoustics-midwater trawl survey, which began in 2004 and is conducted in September-October. Both surveys were completed in their entirety in 2019. Prey fish biomass in Lake Huron in 2019AuthorsDarryl W. Hondorp, Timothy P. O'Brien, Peter Esselman, Edward F. RosemanStatus and trends of the Lake Huron prey fish community, 1976-2020
The USGS Great Lakes Science Center (GLSC) has assessed annual changes in the offshore prey fish community of Lake Huron since 1973. Assessments are based on a bottom trawl survey conducted in October and an acoustics-midwater trawl survey conducted in September-October. In 2020, USGS-GLSC vessels were not permitted to cross into Canada due to the COVID-19 pandemic, so prey fish surveys sampledAuthorsDarryl W. Hondorp, Timothy P. O'Brien, Peter Esselman, Edward F. RosemanReplacement of the typical artedi form of Coregonus artedi in Lake Huron by endemic shallow-water Ciscoes, including putative hybrids
Various ecomorphs of shallow-water Cisco Coregonus artedi were the dominant fish planktivores in each of the Great Lakes until invasive species and over fishing resulted in extirpations and extinctions. In this paper we describe the present morphological diversity and distribution of shallow-water Ciscoes in each of Lake Huron’s three basins: the main basin, Georgian Bay, and North Channel. TypicaAuthorsRandy L. Eshenroder, Yu-Chun Kao, Timothy P. O'Brien, Chris M. Olds, Chris L. Davis, Alexander T. DuncanStatus and trends of pelagic prey fish in Lake Huron, 2018
Scientists from the U.S. Geological Survey’s Great Lakes Science Center conducted integrated acoustic and mid-water trawl surveys of Lake Huron annually from 2004-2018. The 2018 survey was conducted during September and included transects in Lake Huron’s main basin, Georgian Bay, and North Channel. Mean lake-wide pelagic fish density was 1532 fish/ha and mean pelagic fish biomass was 4151 g/ha inAuthorsTimothy P. O'Brien, Steve A. Farha, David Warner, Peter Esselman, Kristy Phillips, Steven Lenart, Chris OldsSpatial patterns of rainbow smelt energetic condition in Lakes Huron and Erie in 2017: Evidence for Lake Huron resource limitation
Rainbow smelt (Osmerus mordax) is a key planktivore and prey fish in Lake Huron. Given the declining offshore productivity in the lake since the early 2000s, we described the energy content of rainbow smelt in 2017 across five different regions (North Channel, Georgian Bay, Saginaw Bay, northern main basin, southern main basin) where phytoplankton and zooplankton productivity likely varied. To incAuthorsQihong Dai, David Bunnell, James S. Diana, Steven A. Pothoven, Lauren A. Eaton, Timothy P. O'Brien, Richard KrausPhenology and species diversity in a Lake Huron ichthyoplankton community: Ecological implications of invasive species dominance
Ichthyoplankton communities are dynamic and vary spatiotemporally based on factors such as wind, water currents, and phenology. Nonetheless, ichthyoplankton are an indicator of spawning success in fish populations and examining their community diversity and composition can serve to provide information on ecosystem integrity. Although some ichthyoplankton species may be transient, understanding theAuthorsTimothy P. O'Brien, Stacey Ireland, Edward F. Roseman, Andrew S Briggs, William W. TaylorStatus and trends of pelagic prey fish in Lake Huron, 2017
Scientists from the U.S. Geological Survey’s Great Lakes Science Center conducted integrated acoustic and mid-water trawl surveys of Lake Huron in 1997 and annually from 2004-2017. The 2017 survey was conducted during September and included transects in Lake Huron’s main basin, Georgian Bay, and North Channel. Mean lake-wide pelagic fish density was 1582 fish/ha and mean pelagic fish biomass was 1AuthorsTimothy P. O'Brien, David M. Warner, Peter Esselman, Steve A. Farha, Steve Lenart, Chris Olds, Kristy PhillipsNon-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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