Patricia M. Dieter Ralph W. Tingley III Timothy P. O'Brien Charles P. Madenjian David M. Warner Dale Hanson Ben Turschak Steven A. Farha Kristy R. Phillips Peter C. Esselman 20260513 spreadsheet Reston, VA U.S. Geological Survey Patricia M. Dieter [USGS, ORCID 0000-0003-1686-2679]; Ralph W. Tingley III [USGS, ORCID 0000-0002-1689-2133]; Timothy P. O'Brien [USGS, ORCID 0000-0003-4502-5204]; Charles P. Madenjian [USGS, ORCID 0000-0002-0326-164X]; David M. Warner [USGS, ORCID 0000-0003-4939-5368]; Dale Hanson [FWS]; Ben Turschak [MDNR]; Steven A. Farha [USGS, ORCID 0000-0001-9953-6996]; Kristy R. Phillips [USGS, ORCID 0000-0001-8378-0660]; Peter C. Esselman [USGS, ORCID 0000-0002-0085-903X] https://doi.org/10.5066/P13MA3XE These data consist of prey fish density and biomass estimates throughout Lake Michigan during late summer-fall from 1973 to 2025 along with alewife (Alosa pseudoharengus) recent age estimates collected. Fish were collected using bottom or midwater trawls. In addition to fish data, some zebra and quagga mussel (Dreissena spp.) biomass estimates are included as well as recent native invertebrate Mysis diluviana data. These data are intended for use by Lake Michigan fisheries managers, biologists, academia, the fishing industry, and the public. The data are reported annually to provide relative abundances of prey fishes to assess the spatial distributions of prey fishes. 19730921 20250919 ground condition Complete None planned Lake Michigan -88.0500 -84.6700 46.1000 41.6000 ISO 19115 Topic Category farming inlandWaters environment USGS Thesaurus community ecology population and community ecology aquatic ecosystems food web specimen collecting field sampling species diversity fish native species invasive species long-term ecological monitoring nonindigenous species Coastal and Marine Ecological Classification Standard Planktonic Biota Marine Realms Information Bank (MRIB) keywords fisheries biology fish USGS Metadata Identifier USGS:69de4ad4b66b016611cbf1eb Common geographic areas Lake Michigan Michigan Wisconsin Illinois Indiana Integrated Taxonomic Information System (ITIS) Alosa pseudoharengus Coregonus hoyi Coregonus artedi Coregonus clupeaformis Salmo trutta Oncorhynchus tshawytscha Oncorhynchus kisutch Oncorhynchus mykiss Salvelinus namaycush Osmerus mordax Lota lota Myoxocephalus thompsonii Cottus cognatus Pungitius pungitius Gasterosteus aculeatus Neogobius melanostomus Perca flavescens Notropis atherinoides Petromyzon marinus Dreissena Mysis 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 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 Protacanthopterygii Order Salmoniformes salmons Family Salmonidae salmonids trouts and salmons salmons trouts Subfamily Coregoninae Genus Coregonus whitefishes Species Coregonus hoyi bloater TSN: 623394 Species Coregonus artedi cisco lake herring TSN: 623384 Species Coregonus clupeaformis lake whitefish TSN: 161941 Subfamily Salmoninae Genus Salmo Atlantic salmon Species Salmo trutta brown trout TSN: 161997 Genus Oncorhynchus Pacific salmon Species Oncorhynchus tshawytscha Chinook salmon king salmon TSN: 161980 Species Oncorhynchus kisutch coho salmon silver salmon TSN: 161977 Species Oncorhynchus mykiss rainbow trout steelhead redband trout TSN: 161989 Genus Salvelinus chars Species Salvelinus namaycush lake trout TSN: 162002 Order Osmeriformes argentines smelts Suborder Osmeroidei Superfamily Osmeroidea Family Osmeridae smelts Genus Osmerus rainbow smelts Species Osmerus mordax Rainbow Smelt TSN: 162041 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 Acanthopterygii Order Scorpaeniformes mail-cheeked fishes scorpion fishes sculpins Suborder Cottoidei sculpins Superfamily Cottoidea Family Cottidae sculpins bullheads scaleless sculpins Genus Myoxocephalus daddy sculpins great sculpins shorthorn sculpins fourhorn sculpins Species Myoxocephalus thompsonii deepwater sculpin TSN: 167323 Genus Cottus Miller's thumbs freshwater sculpins Species Cottus cognatus slimy sculpin TSN: 167232 Order Gasterosteiformes pipefishes sticklebacks Suborder Gasterosteoidei Family Gasterosteidae sticklebacks Genus Pungitius ninespine sticklebacks Species Pungitius pungitius ninespine stickleback tenspined stickleback TSN: 166387 Genus Gasterosteus threespine sticklebacks Species Gasterosteus aculeatus Alaskan stickleback threespine stickleback TSN: 166365 Order Perciformes perch-like fishes Suborder Gobioidei gobies Family Gobiidae true gobies gobies Genus Neogobius round gobies Species Neogobius melanostomus round goby TSN: 172072 Suborder Percoidei Family Percidae true perches perches Genus Perca yellow perches Species Perca flavescens yellow perch TSN: 168469 Superorder Ostariophysi Order Cypriniformes minnows suckers Superfamily Cyprinoidea Family Leuciscidae Subfamily Pogonichthyinae Genus Notropis eastern shiners Species Notropis atherinoides Emerald Shiner TSN: 163412 Infraphylum Agnatha Class Cephalaspidomorphi lampreys Order Petromyzontiformes lampreys Family Petromyzontidae lampreys Genus Petromyzon Species Petromyzon marinus sea lamprey lake lamprey TSN: 159722 Infrakingdom Protostomia Superphylum Spiralia Phylum Mollusca molluscs mollusks Class Bivalvia bivalves clams Subclass Autobranchia Infraclass Heteroconchia Order Myida Superfamily Dreissenoidea Family Dreissenidae Genus Dreissena TSN: 81338 Superphylum Ecdysozoa Phylum Arthropoda arthropods Subphylum Crustacea crustaceans Superclass Altocrustacea Class Malacostraca Subclass Eumalacostraca Superorder Peracarida Order Mysida mysidans opossum shrimp Family Mysidae Genus Mysis TSN: 90041 No data access constraints No data use constraints Ralph Tingley III U.S. Geological Survey, MIDCONTINENT REGION Research Fisheries Biologist mailing address

1451 Green Rd

Ann Arbor MI 48105 US 734-214-7218 734-994-8780 rtingley@usgs.gov We are grateful for the numerous science staff throughout the years with aiding in sample and data collections. We acknowledge the vessel crew members of research vessels for assisting in sample collections and keeping staff safe. David "Bo" Bunnell spent many years collecting and analyzing the bottom trawl data and provided constructive comments for this data release. We thank Tim Desorcie for the many years of field, lab, and data maintenance - including spending his birthdays on the boat. We also thank those that conducted alewife otolith extractions and preparation. Jean Adams developed code for checking and analyzing the data. Michigan Department of Natural Resources and the U.S. Fish and Wildlife Service staff greatly contributed to surveying portions of the lake for the hydroacoustics survey. Microsoft Windows 10; Oracle; SQL Developer, SQL SMS, R Studio, Image Pro Ralph Tingley III David Warner Charles Madenjian Patricia Dieter Kristy Phillips Ben Turschak Dale Hanson Peter Esselman Steve Farha 2025 publication https://glfc.org/pubs/lake_committees/common_docs/2025_LMC_FORAGE_REPORT.pdf A variety of different teams of trained biologists and technicians have participated in survey collections throughout the years. Identification guides (as noted in Source Input) and other experts were utilized during sample processing when species were not known or questioned to ensure accuracy. Data were checked with physical data sheets to ensure correct information was entered digitally. Data in all tables were checked to correct or remove values that fell outside of a plausible range for each variable. The 1998 bottom trawl survey data is not included because trawls were towed at non-standard speeds. The 2000 bottom trawl survey only sampled 3 ports instead of the standard 7 ports due to vessel issues. The 2020 bottom trawl survey only sampled 3 ports because of the COVID-19 pandemic. The 2020 hydroacoustic survey was not conducted because of the COVID-19 pandemic. Some data provided encompass multiple years, but alewife age estimates and Mysis data are only from 2025. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. All latitude/longitude coordinates were checked to ensure data points were within the boundaries of Lake Michigan (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 Michigan. Great Lakes Science Center 2019 dataset https://www.sciencebase.gov U.S. Geological Survey https://doi.org/10.5066/f75m63x0 Digital and/or Hardcopy 20170419 20201031 observed RVCAT To enter, verify, and extract data, referred to in the data entry and data extraction steps. Charles P. Madenjian Jeffrey D. Holuszko Timothy J. Desorcie 20110109 publication Transactions of the American Fisheries Society vol. 132, issue 6 n/a Oxford University Press (OUP) ppg. 1104-1116 https://doi.org/10.1577/T02-133 Digital and/or Hardcopy 20110109 publication date Madenjian et al. 2011 Field sampling in the sample collections step. J.M. Casselman 1987 publication Orlando, Florida Academic Press ppg. 209–242; from the book The biology of fish growth,.A. H. Weatherley and H.S. Gill, editors. Digital and/or Hardcopy 1987 publication date Casselman 1987 Alewife otolith age referred to in the fish processing step. Carl Hubbs Karl Lagler 1958 publication Ann Arbor, MI University of Michigan Press https://doi.org/10.3998/mpub.12946839 Digital and/or Hardcopy 1958 publication date Hubbs and Lagler 1958 Fish species identification in fish processing step. Kristy R. Phillips 2021 application/service original version created by Jean V. Adams; https://github.com/JVAdams/EchoNet2Fish https://github.com/krphillips/EchoNet2Fish Digital and/or Hardcopy 2021 publication date Phillips Estimate fish abundance from acoustic surveys combined with catch in nets for the data calculation processing step. Mary D. Balcer Nancy L. Korda Stanley I. Dodson 198405 publication Madison, Wisconsin University of Wisconsin Press Digital and/or Hardcopy 198405 publication date Balcer et al. 1984 Mysis identification and sex determination in Mysis processing step. Daniel L. Yule Jean V. Adams David M. Warner Thomas R. Hrabik Patrick M. Kocovsky Brian C. Weidel Lars G. Rudstam Patrick J. Sullivan 201312 publication Canadian Journal of Fisheries and Aquatic Sciences vol. 70, issue 12 n/a Canadian Science Publishing ppg. 1845-1857 https://doi.org/10.1139/cjfas-2013-0072 Digital and/or Hardcopy 201312 publication date Yule et al. 2013 Fish apportionment for acoustic surveys in data calculation step. David M. Warner Kristy Phillips Ben Turschak Dale Hanson Jason Smith 2019 publication https://glfc.org/pubs/lake_committees/common_docs/003_Warner%20et%20al%20LM%20acoustic%20IP-106761%20Final_tbell-edits.pdf Digital and/or Hardcopy 2019 publication date Warner et al. 2019 Information for sample collection step and analyses of acoustic data in data calculation step. David B. Bunnell Charles P. Madenjian Timothy Desorcie Patricia Armenio Jean V. Adams 2019 publication https://www.glfc.org/pubs/lake_committees/common_docs/002_2018_LMich_Prey_Fish_Report_Final%20Final%20BAO%20Approved_tbell-edits.pdf Digital and/or Hardcopy 2019 publication date Bunnell et al. 2019 Analyses of bottom trawl data in data calculation step. Sample collections: Samples were taken by the U.S. Geological Survey (USGS), Michigan Department of Natural Resources (MDNR), or U.S. Fish and Wildlife Service (FWS) from multiple transects throughout Lake Michigan annually. Multiple ships were used to collect these data throughout the years and within a given year. Bottom trawl survey: The bottom trawl survey involves standard transects that are sampled each year at designated ports and lake depths solely by USGS. Sampling occurs during the daytime using a 39' Yankee net on the bottom of the lake along depth contours at 9 meter increments. The survey typically occurs from September-October and has taken place since 1973. The length of the tow is generally 10 minutes, but is sometimes shortened if the transect is known to have a lot of dreissenid (Dreissena spp.) mussels or there is an obstruction. Hydroacoustics survey: The hydroacoustics (acoustics for short) survey randomizes where sampling occurs each year and collections are conducted at night (at least one hour after sunset) using a midwater trawl net. The survey typically occurs from August-September and has taken place since 2004 with multiple agencies (see above). Split beam transducers with 120 kilohertz frequency have been used to collect data with the exception of 2004 when MDNR used a dual beam system. For more details about this survey, see Warner et al. 2019. Vertical tows were conducted to collect Mysis diluviana using a 1000 micron mesh net with 1 meter diameter. The net went down to 3 m above the bottom of the lake during night with only red lights on the deck of the vessel (no white light). See Tingley et al. 2024 for more information regarding these surveys. RVCAT Madenjian et al. 2011 Warner et al. 2019 Tingley et al 2024 20250919 Ralph Tingley III U.S. Geological Survey, MIDCONTINENT REGION Research Fisheries Biologist mailing address

1451 Green Rd

Ann Arbor MI 48105 US 734-214-7218 734-994-8780 rtingley@usgs.gov Fish Processing: Samples from the net were removed and put on a sorting table in the wet lab of the vessel. Fish were identified, sorted by species, and weighed. Either the total catch of the species was measured for total length, or a subset was measured depending on the number of that species caught. Subsamples of some species were measured for individual length and weight. Dreissenid mussels were weighed but not counted or identified to species. A designated number of alewife (7 fish per 5 mm length bin) were kept to estimate fish age in the Great Lakes Science Center (GLSC) laboratory. Fish ages: Alewife ages were based otoliths (Casselman 1987) and estimated by trained USGS scientists at the GLSC laboratory. The protocol requires two independent estimates being generated by trained experts for each otolith. If the two readers disagree on their age for the first read, both readers estimate otolith age once more. If the two readers still disagree on the 2nd read, both readers estimate the age one last time for a 3rd read. If after the 3rd read, the two readers do not reach consensus, the age is deemed unreliable and not reported for that individual. Mysis processing: The cod end bucket with the sample contents was narcotized using an effervescent tablet until it dissolved. The sample was then concentrated by sieving out the majority of the water. The sample was preserved in 95% ethanol in a labeled plastic jar and taken to the GLSC laboratory for further processing. At the GLSC lab, Mysis were picked out of the sample, counted, and placed in a vial with fresh ethanol. Then, the length in millimeters was measured from the tip of rostrum to the cleft of the telson using a computer imaging software (software and versions varied throughout the years). Individuals were determined to be males when the third and fourth pleopods exhibited elongation and as females when the third and fourth pleopods were similar (Balcer et al. 1984). Females were checked to see if they had a marsupium. Casselman 1987 Hubbs and Lagler 1958 Balcer et al. 1984 20250919 Patricia Dieter U.S. Geological Survey, MIDCONTINENT REGION Biological Technician mailing address

1451 Green Rd

Ann Arbor MI 48105 US 734-994-3331 pdieter@usgs.gov Data entry and Quality Control: Data from biotic samples were entered into the GLSC's Research Vessel Catch (RVCAT) Information System database. See Logical Consistency Report for data quality control information. RVCAT 20250930 Patricia Dieter U.S. Geological Survey, MIDCONTINENT REGION Biological Technician mailing address

1451 Green Rd

Ann Arbor MI 48105 US 734-214-7220 734-994-8780 pdieter@usgs.gov Data extraction and calculations: Data were exported from the RVCAT database using R Studio. See Bunnell et al. 2019 and Tingley et al. 2024 for methodology regarding bottom trawl survey data processing. See Warner et al. 2019, Yule et al. 2013, and Tingley et al. 2024 for methodology regarding acoustics survey data processing. RVCAT Bunnell et al. 2019 Phillips Yule et al. 2013 Warner et al. 2019 Tingley et al. 2024 20250410 Ralph Tingley III U.S. Geological Survey, MIDCONTINENT REGION Research Fisheries Biologist mailing address

1451 Green Rd

Ann Arbor MI 48105 US 734-214-7218 734-994-8780 rtingley@usgs.gov species_codes.csv Comma Separated Value (CSV) file serving as a reference table for the names for different taxa from the other data files. Producer Defined SPECIES Species code Producer Defined 106 952 COMMON_NAME Common name associated with SCIENTIFIC_NAME Producer Defined common names of taxa SCIENTIFIC_NAME Species or scientific name associated with COMMON_NAME Producer Defined scientific names of taxa TSN Taxonomic Serial Number (TSN). Same as ITIS (Integrated Taxonomic Information System) code to record taxonomic information. Based off of the standardized ITIS codes from www.itis.gov. Producer Defined 81338 623394 mysis_op_and_dens_2025.csv Comma Separated Value (CSV) file containing data from Mysis samples collected during the 2025 acoustic survey. Each row can represents a sample taken. OP_ID is a unique identifier and used to connect to the mysis_indiv_2025.csv file. Producer Defined OP_ID Artificial operation sequence number. Unique identifier for a sampling event. Producer Defined 128248 129315 OP_DATE date of operation Producer Defined DD-MON-YY. In format day (2 digits), month (three letter abbreviation), and year (two digits). These are separated by dashes. An example is 13-Aug-25. TIME Time the fishing gear was deployed. Recorded in 24 hour clock, but some zeros are missing due to Microsoft Excel. For example, if the value is 58, it is really 0058 or 12:58 AM. Based on Eastern Time Zone. Producer Defined 19 2349 TRANSECT Name of the sampling transect. Letters are based on the stratum. A stratum is a designated portion of lake. Numbers are based on number of transects in each strata. sn=south nearshore, so=south offshore, wn=west nearshore, no=north offshore, wn=west nearshore, nnw=nearshore northwest, nne= nearshore northeast Producer Defined Alphanumeric code BEG_LATITUDE_DD Latitude where data were collected in decimal degrees. WGS84 datum. Producer Defined 41.95833333 45.63666667 BEG_LONGITUDE_DD Longitude where data were collected in decimal degrees. WGS84 datum. Producer Defined -87.6 -85.45833333 FISHING_DEPTH_MAX The depth in meters that the net went down to. This is generally 3 meters above the bottom of the lake. Producer Defined 55 168 meters VESSEL Unique numeric code representing the research vessel used for operation. Producer Defined 88 USGS R/V Sturgeon Producer defined 35 USFWS M/V Spencer F. Baird Producer defined 17 MDNR R/V Steelhead Producer defined SERIAL The nth operation by a vessel in a given year. These are recorded by the captain in the pilot house log for each vessel. At the beginning of each year the vessel starts over with serial value 1. For example if the value is 150, it is the 150th operation that year performed by a particular research vessel. These need not be sequential. Note that there can be multiple operations recorded even on one day because an operation is a unique instance of data collection defined by a unique combination of YEAR, VESSEL, SERIAL, SAMPLE_TYPE. Producer Defined 3 1073 N Total of number of Mysis identified and counted in the sample. Producer Defined 0 85 LF_N Total number of Mysis measured for the length frequency. This could be a subset of the total number caught. Producer Defined 0 82 DENSITY The calculated density (number per meter squared; #/m2) of Mysis. This is determined by dividing the number of Mysis in the sample (N) by the area of the net (0.785). Producer Defined 0.0 108.2802548 mysis_indiv_2025.csv Comma Separated Value (CSV) file containing Mysis length data from the 2025 acoustic survey .OP_ID is a unique identifier and used to connect to the mysis_op_and_dens_2025.csv file. Producer Defined OP_ID Artificial operation sequence number. Unique identifier for a sampling event. Producer Defined 128259 129315 LENGTH Individual Mysis length in millimeters. Producer Defined 3.5 22.0 millimeters SEX Sex code for the individual Mysis. Producer Defined 1 male Producer defined 0 unknown Producer defined 2 female Producer defined FECUNDITY Fecundity code for female individual Mysis. A code of 1 represents the female had a marsupium containing eggs or embryos. Producer Defined NA No Data. Not applicable for males. For females, no marsupium present. Producer defined Numeric. estimate_by_survey_all_years.csv Comma Separated Value (CSV) file containing data estimates of fish or mussel density and biomass from two survey types. Producer Defined Species species code Producer Defined see species_codes.csv for reference table Stage Number representing a total length cut off for young of year or yearling and older fish. The non-zero numbers are the total lengths determined by species to represent yearling and older fish. See value definition for more information. Producer Defined NA Not applicable for species 952 (zebra and quagga mussels) Producer defined 0 For species code = 106, 109, 203, 204, 801 it represents a young of year fish. For all other species codes, stage was not subdivided into young of year and yearling and older stages. Producer defined 100 Indicates yearling and older fish for when species code = 106 and 801. Yearling and older fish are considered individuals greater than or equal to 100 mm. Producer defined 90 Indicates yearling and older fish for when species code = 109. Yearling and older fish are considered individuals greater than or equal to 90 mm. Producer defined 170 Indicates yearling and older fish for when species code = 203. Yearling and older fish are considered individuals greater than or equal to 170 mm. Producer defined 120 Indicates yearling and older fish for when species code = 204. Yearling and older fish are considered individuals greater than or equal to 120 mm. Producer defined Year Year the data were collected. Producer Defined 1973 2025 units Units associated with the Estimate column. The type of calculation of total fish caught that year. Producer Defined nph number per hectare Producer defined kgph kilogram per hectare Producer defined Estimate The number estimate of total fish or mussels caught that year. See units column for what the number represents. Producer Defined NA No Data. The 1998 Bottom trawl survey has no data because trawls were towed at non-standard speeds. The acoustic survey was not completed in 2020 due to the COVID-19 pandemic. The number per hectare cannot be estimated for species 952 (mussels). Producer defined 0.0 3872.14326 SE Standard error for the Estimate. Producer Defined NA No Data. The 1998 Bottom trawl survey has no data because trawls were towed at non-standard speeds. The acoustic survey was not completed in 2020 due to the COVID-19 pandemic. Producer defined 0.0 1976.99539 survey Type of survey the data are estimated from. See Sample Collection Process Step for more information. Producer Defined Text. estimate_by_survey_2025.csv Comma Separated Value (CSV) file containing data estimates of fish or mussel density and biomass from two survey types from the year 2025 only. Producer Defined Species species code Producer Defined see species_codes.csv for reference table Stage Number representing a total length cut off for young of year or yearling and older fish. The non-zero numbers are the total lengths determined by species to represent yearling and older fish. See value definition for more information. Producer Defined NA Not applicable for species 952 (zebra and quagga mussels) Producer defined 0 For species code = 106, 109, 203, 204, 801 it represents a young of year fish. For all other species codes, stage was not subdivided into young of year and yearling and older stages. Producer defined 100 Indicates yearling and older fish for when species code = 106 and 801. Yearling and older fish are considered individuals greater than or equal to 100 mm. Producer defined 90 Indicates yearling and older fish for when species code = 109. Yearling and older fish are considered individuals greater than or equal to 90 mm. Producer defined 170 Indicates yearling and older fish for when species code = 203. Yearling and older fish are considered individuals greater than or equal to 170 mm. Producer defined 120 Indicates yearling and older fish for when species code = 204. Yearling and older fish are considered individuals greater than or equal to 120 mm. Producer defined al_unit Unit for alewife (species 106) if the density or biomass for 0 Stage is age or length derived. Alewife is the only fish with age data, all other fish estimates would be based on length. Producer Defined NA This column is only applicable to Species 106 (alewife) with 0 Stage. Producer defined Text. Year Year the data were collected. This is only 2025 data. Producer Defined 2025 2025 units Units associated with the Estimate column. The type of calculation of total fish caught that year. Producer Defined kgph kilogram per hectare Producer defined nph number per hectare Producer defined Estimate The number estimate of total fish or mussels caught that year. See units column for what the number represents. Producer Defined NA No Data. The number per hectare cannot be estimated for species 952 (mussels). Producer defined 0.0 11433.9148422463 LATITUDE_DD Latitude where data were collected in decimal degrees. WGS84 datum. Producer Defined 41.95465151 45.941032 LONGITUDE_DD Longitude where data were collected in decimal degrees. WGS84 datum. Producer Defined -87.82761488 -85.2122115 survey Type of survey the data are estimated from. See Sample Collection Process Step for more information. Producer Defined Text. acoustic_ale_age0.csv Comma Separated Value (CSV) file containing alewife age-0 density data from 2004 to 2025 based on the acoustic survey. Producer Defined Species species code 106 = alewife Producer Defined see species_codes.csv for reference table Age Estimated age of fish in years as determined by its otolith. See fish processing/fish ages step for more information. Producer Defined 0 0 Year Year the data were collected. Producer Defined 2004 2025 nph The number per hectare estimate of age-0 alewife for that year. Producer Defined NA No Data. The acoustic survey was not completed in 2020 due to the COVID-19 pandemic. Producer defined 4.709217381 1735.744783 SE Standard error for nph. Producer Defined NA No Data. The acoustic survey was not completed in 2020 due to the COVID-19 pandemic. Producer defined 2.117910053 737.1683546 RSE Relative standard error for nph. Producer Defined NA No Data. The acoustic survey was not completed in 2020 due to the COVID-19 pandemic. Producer defined 14.24754207 73.26003872 area The area of the lake stratum (no, wn, etc.) in hectares. See mysis_op_and_dens_2025.csv TRANSECT column for more details. Producer Defined 4877600 5396683 alewife_prop_age_2025.csv Comma Separated Value (CSV) file containing alewife fish age, density, and proportion data from two survey types in 2025. Producer Defined Species species code 106 = alewife Producer Defined see species_codes.csv for reference table Age Estimated age of fish in years as determined by its otolith. See fish processing/fish ages step for more information. Producer Defined 0 6 Year Year the data were collected. Producer Defined 2025 2025 nph The number per hectare estimate of total alewife caught. Producer Defined 0.024610799 259.48565010000004 prop The proportion of the age class of alewife within a given survey. The nph/sum of total alewife. Producer Defined 0.000196477 0.763168537 lnN natural logarithm of nph estimate. Producer Defined -3.704569935 5.558701403 survey Type of survey the data are estimated from. See Sample Collection Process Step for more information. Producer Defined Text. U.S. Geological Survey GS ScienceBase 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. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Digital Data https://doi.org/10.5066/P13MA3XE No fees 20260513 Great Lakes Science Center mailing and physical

1451 Green Road

Ann Arbor MI 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