Brian P. O'Malley Brian F. Lantry Brian C. Weidel Scott D. Stahl Olivia M. Mitchinson Jessica A. Goretzke Christopher A. Osborne Dimitry Gorsky Jeremy P. Holden Emma J. Bloomfield Lucus Sunderland 20260501 tabular digital data Reston, VA U.S. Geological Survey ([Brian P. O'Malley][https://orcid.org/0000-0001-5035-3080][U.S. Geological Survey, Great Lakes Science Center, Lake Ontario Biological Station]); ([Brian F. Lantry][https://orcid.org/0000-0001-8797-3910][U.S. Geological Survey, Great Lakes Science Center, Lake Ontario Biological Station]); ([Brian C. Weidel][https://orcid.org/0000-0001-6095-2773][U.S. Geological Survey, Great Lakes Science Center, Lake Ontario Biological Station]); ([Scott D. Stahl][https://orcid.org/0009-0002-0248-4523][U.S. Geological Survey, Great Lakes Science Center, Lake Ontario Biological Station]); ([Olivia M. Mitchinson][https://orcid.org/0009-0002-7999-1160][U.S. Geological Survey, Great Lakes Science Center, Lake Ontario Biological Station]); ([Jessica A. Goretzke][New York Department of Environmental Conservation, Lake Ontario Research Unit]); ([Christopher A. Osborne][https://orcid.org/0000-0001-6387-5451][U.S. Fish and Wildlife Service, Lower Great Lakes Fish and Wildlife Conservation Office]); ([Dimitry Gorsky][https://orcid.org/0000-0003-1708-539X][U.S. Fish and Wildlife Service, Lower Great Lakes Fish and Wildlife Conservation Office]); ([Jeremy P. Holden][https://orcid.org/0000-0001-8411-5929][Ontario Ministry of Natural Resources, Lake Ontario Management Unit]); ([Emma J. Bloomfield][https://orcid.org/0000-0002-0862-4294][Ontario Ministry of Natural Resources, Lake Ontario Management Unit]); ([Lucus Sunderland][Ontario Ministry of Natural Resources, Lake Ontario Management Unit]) https://doi.org/10.5066/P14LXA9G This data release includes Lake Ontario gillnet catch and biological data from individual fish from the Lake Ontario adult lake trout survey, from 1983 to 2025. Data from gillnets fished in Canadian waters are included from 1985 to 1995, 2008, and 2024. Details about the vessel and gear descriptions, sampling protocols, and fish processing protocols are provided in the associated metadata. These data are intended for use by the research community, the public, and Great Lakes fisheries managers to monitor fish populations through time, evaluate efficacy of sea lamprey control programs, and inform lake trout rehabilitation progress. Portions of this data release follows the data model of the USGS Great Lakes Science Center Research Vessel Catalog (RVCAT). The gillnet data in this data release are a subset of the larger RVCAT data base. That larger RVCAT data set can be found here: https://doi.org/10.5066/F75M63X0. Time period information refers to the date when a gillnet was set in the lake. 19830907 20250823 See Supplemental Info Complete None planned Lake Ontario -79.7700 -76.1200 44.2900 43.1800 ISO 19115 Topic Category biota inlandWaters None Lake Trout prey Rainbow Smelt Alewife Burbot Chinook Salmon Brown Trout Rainbow Trout Lake Whitefish Coregonine Round Goby USGS Thesaurus fish freshwater ecosystems population dynamics field sampling Integrated Taxonomic Information System (ITIS) Salvelinus namaycush Salmo trutta Coregonus clupeaformis Lota lota Alosa pseudoharengus Neogobius melanostomus Osmerus mordax USGS Metadata Identifier USGS:6967bb69d4be023a0e9574cc Common Geographic Areas Lake Ontario New York Ontario Integrated Taxonomic Information System (ITIS) Salvelinus namaycush Salmo trutta Coregonus clupeaformis Lota lota Alosa pseudoharengus Neogobius melanostomus Petromyzon marinus Kingdom Animalia animals Subkingdom Bilateria triploblasts Infrakingdom Deuterostomia Phylum Chordata chordates Subphylum Vertebrata vertebrates Infraphylum Gnathostomata Superclass Actinopterygii ray-finned fishes spiny rayed fishes Class Teleostei Superorder Protacanthopterygii Order Salmoniformes salmons Family Salmonidae salmonids trouts and salmons salmons trouts Subfamily Salmoninae Genus Salvelinus chars Species Salvelinus namaycush lake trout TSN: 162002 Genus Salmo Atlantic salmon Species Salmo trutta brown trout TSN: 161997 Subfamily Coregoninae Genus Coregonus whitefishes Species Coregonus clupeaformis lake whitefish TSN: 161941 Superorder Paracanthopterygii Order Gadiformes grenadiers gadiforms cods hakes Family Gadidae codfishes true cods cods Subfamily Lotinae cuskfishes Genus Lota burbots eelpouts Species Lota lota burbot eelpout TSN: 164725 Superorder Clupeomorpha Order Clupeiformes anchovies herrings Suborder Clupeoidei Family Clupeidae herrings menhadens pilchards sardines sprats shads Subfamily Alosinae shads Genus Alosa river herrings Species Alosa pseudoharengus alewife kyak bigeye herring branch herring freshwater herring gray herring white herring sawbelly grayback TSN: 161706 Superorder Acanthopterygii Order Perciformes perch-like fishes Suborder Gobioidei gobies Family Gobiidae true gobies gobies Genus Neogobius round gobies Species Neogobius melanostomus round goby TSN: 172072 Infraphylum Agnatha Class Cephalaspidomorphi lampreys Order Petromyzontiformes lampreys Family Petromyzontidae lampreys Genus Petromyzon Species Petromyzon marinus sea lamprey lake lamprey TSN: 159722 No access constraints No use constraints Brian P. O'Malley U.S. Geological Survey Research Fish Biologist mailing and physical

17 Lake Street

Oswego NY 13126 United States 315-343-3951 bomalley@usgs.gov Measurements, counts, and species identifications were made aboard the research vessel. Data were entered into csv files, then uploaded into the the U.S. Geological Survey Great Lakes Science Center's RVCAT database. Data were downloaded from RVCAT, then checked, analyzed, and verified using R (version 4.4.2) software. Brian P. O'Malley Krystal Dixon Olivia M. Mitchinson Scott D. Stahl Brian C. Weidel Michael J. Connerton Jessica A. Goretzke 2026 publication Ann Arbor, MI Great Lakes Fishery Commission Report to the Great Lakes Fishery Commission Each variable was checked to ensure all data points fall within an expected range for Lake Ontario (e.g, no spatial data outside of the lake boundary). Species identifications that were not known or questioned were determined using local fish keys and atlases (Carlson et al., 2016; Smith 1985). Fishes in the genus Coregonus, specifically Bloater Coregonus hoyi, are difficult to visually identify compared to Cisco Coregonus artedi, therefore identifications are based on genetic analysis of fin tissue samples (Ackiss et al., 2020). Catch and weight data for species in a gillnet catch were compared to known distributions of mean weight. Total length data of individual fish was checked against maximum and minimum possible values and compared to modeled estimates to identify outliers. For all data checking procedures, if data entry errors could not be identified, outlying values were discarded and replaced with a blank. All data underwent a quality assurance process daily and at the end of each annual survey. The number of fish measured and sites sampled was checked between data tables for internal consistency. Spatial coordinates were verified that values were within the lake and intended sampling area. Data set is considered complete for the information presented, as described in the abstract. Data from U.S. waters of Lake Ontario are from 1983 to 2025. Data from Canadian waters of Lake Ontario are from years 1985 to 1995, 2008, and 2024. Users are advised to read the rest of the metadata record carefully for additional details. In 1983 and 1984, for some operations the vessel name entered was Seth Green but the actual vessel used was the R/V Kaho. This is noted in the remarks field for each record where that was the case, and was done in order to keep serials unique for database purposes. All latitude/longitude coordinates were checked to ensure data points were within the boundaries of Lake Ontario (e.g., no spatial data outside the lake) unless no coordinates were recorded. Recorded depth values were checked to ensure data points were less than the maximum depth of Lake Ontario (e.g. 245 meters). Everett King Jr. Thomas A. Edsall 1979 publication https://www.glfc.org/pubs/SpecialPubs/SP79_1.pdf Digital and/or Hardcopy 1979 publication date King Jr. and Edsall (1979) Used to grade sea lamprey wounds found on lake trout Amanda S. Ackiss Wesley A. Larson Wendylee Stott 2020 publication https://doi.org/10.1111/eva.12919 Digital and/or Hardcopy 2020 publication date Ackiss et al. 2020 Details genetic analysis used to identify coregonine species Douglas Carlson Robert Daniels Jeremy Wright 2016 tabular digital data ISBN: 978-1-55557-270-9 https://nysm.nysed.gov/sites/default/files /atlasofinlandfishes.pdf Digital and/or Hardcopy 2016 publication date Carlson et al. 2016 Used to identify unknown fish species C. Lavett Smith 1985 publication ISBN: 0961543302 Digital and/or Hardcopy 1985 publication date Smith 1985 Used to identify unknown fish species M.P. Ebener E.L King Jr. T.A. Edsall 2006 publication https://www.glfc.org/pubs/misc/2006-02.pdf Digital and/or Hardcopy 2006 publication date Ebener et al. (2006) Used to grade sea lamprey wounds found on lake trout Joseph H. Elrod Robert O'Gorman Clifford P. Schneider Thomas H. Eckert Ted Schaner James N. Bowlby Larry P. Shleen 1995 publication https://doi.org/10.1016/S0380-1330(95)71085-1 Digital and/or Hardcopy 1995 publication date Elrod et al. 1995 Used as a reference to further information about the survey gear used and overall survey design as well as its history. Brian P. O'Malley Scott P. Minihkeim Olivia M. Mitchinson Scott D. Stahl Brian C. Weidel Michael J. Connerton Jessica A. Goretzke Lucus Sunderland Emma J. Bloomfield Collin J. Farrell Dimitry Gorsky 2025 publication https://www.glfc.org/pubs/lake_committees/common_docs/OMalley_et_al_2025.pdf Digital and/or Hardcopy 2025 publication date O'Malley et al. 2025 Used as a reference to further information about the survey gear used and overall survey design as well as its history. Since 1983, annual gillnet surveys have been fished during the late-summer to early fall (typically August-September) to assess Lake Ontario’s adult lake trout population. Gillnets are fished along transects at randomly selected coordinates distributed across 12 to 17 geographic areas in the U.S waters of the lake. During 1985-1995, and in 2008 and 2024 eight to ten transects were also fished in Canadian waters at fixed locations. Transects were fished perpendicular to shore, and the standard effort was typically three to four gillnets per transect. At each transect, gillnets were set parallel to depth contours beginning at the 10 degree Celsius isotherm and then successively deeper at approximately 10-m depth increments deeper from the first gillnet. Survey design and gillnet construction (multi vs mono-filament netting) have changed through the years. For a description of survey history, including gear changes and corrections, see Elrod et al. (1995) and O'Malley et al. (2025). Since 1993, standard survey gillnets have consisted of monofilament netting with nine 15.2 x 2.4 m (50 x 8 ft) panels of 51 to 151 mm (2- to 6-in stretched measure) mesh in 12.5 mm (0.5 in) increments. Prior to 1993, standard survey gillnets were composed of multifilament netting with the same dimensions, except during 1990–1992 when one additional gillnet composed of monofilament netting was fished at each location for comparison. Elrod et al. 1995 O'Malley et al. 2025 20250823 Brian P. O'Malley U.S. Geological Survey Research Fish Biologist mailing and physical

17 Lake Street

Oswego NY 13126 United States 315-343-3951 bomalley@usgs.gov Catches for each gillnet panel were sorted by species; total lengths and weights of individual fish were measured. Sex and maturity were determined by visual inspection of gonads. Stomach contents were examined and prey were identified, measured, and counted. Presence and types of fin clips were recorded, and when present, coded wire tags were removed and decoded to retrieve information on age and strain for recaptured fish of hatchery-origin. Sea lamprey wounds on Lake Trout were counted and graded according to King Jr. and Edsall (1979) and Ebener et al. (2006). King Jr. and Edsall (1979) Ebener et al. (2006) 20250823 Brian P. O'Malley U.S. Geological Survey Research Fish Biologist mailing and physical

17 Lake Street

Oswego NY 13126 United States 315-343-3951 bomalley@usgs.gov MetaDataDictionary_LakeTroutGillnetSurvey.csv Data dictionary providing metadata which describes the tables and columns (within those tables) that are being released alongside this document. Producer Defined entityName File names or table names associated with this data release Producer Defined text value attributeName column names or field headers associated with different files or tables Producer Defined . Periods are present in cells where the row is recording table-level descriptions, which do not have column name to describe. Producer defined text value or period dataElementDescription Descriptive information about the table or column. If attributeName is a "." then the dataElementDescription is describing a table. Otherwise this column describes the attribute in attributeName in its given entityName Producer Defined text value units units the attribute name value is represented in Producer Defined . A period "." represents a cell that is either not applicable or cannot be filled in due to the type of data in the row. Producer defined text value or period dataFormat format the data is stored in Producer Defined . A period "." represents a cell that is either not applicable or cannot be filled in due to the type of data in the row. Table descriptions do not have a dataFormat Producer defined text value or period nullValueDescription describes what a null value means Producer Defined . A period "." represents a cell that is either not applicable or cannot be filled in due to the type of data in the row. In this case if null values are not allowed then there is no null value to describe in this column. Producer defined text value or period derivedValue are values derived or calculated, Y or N for yes or no Producer Defined . A period "." represents a cell that is either not applicable or cannot be filled in due to the type of data in the row. Rows that provide table descriptions in this data dictionary do not apply to the derivedValue column. Producer defined Y Yes, these values are derived and calculated in the table and column of data being described in this row Producer defined N No, these values are not derived and calculated Producer defined GS ScienceBase U.S. Geological Survey mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P14LXA9G No fees 20260501 Great Lakes Science Center mailing and physical

1451 Green Road

Ann Arbor Michigan 48105 US 734-994-3331 GS_ASK_GLSC@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999