Fischbach, Anthony S. (ORCID: 0000-0002-6555-865X) Douglas, David C. (ORCID: 0000-0003-0186-1104) 20220907 satellite maps, vector digital data, tabular digital data Pacific Walrus Coastal Haulout Occurrences Interpreted from Satellite Imagery ver 6.0, December 2025 Anchorage, Alaska U.S. Geological Survey, Alaska Science Center Suggested Citation: Fischbach, A.S., Douglas, D.C., 2022. Pacific Walrus coastal haulout occurrences interpreted from satellite imagery (ver 6.0, December 2025): U.S. Geological Survey data release, https://doi.org/10.5066/P9CSM0KN https://doi.org/10.5066/P9CSM0KN This dataset is derived from images from a variety of Earth observing satellite imagery sources collected at known walrus coastal haulouts in Alaska and Chukotka, Russia. Earth observing imagery sources used in this data release include (but are not limited to) optical imagery collections by: (1) the European Space Agency's Sentinel-2 mission, (2) the Plant Labs Planet Scope constellation, and (3) Maxar satellites, as well as synthetic aperture radar imagery collected by: (1) European Space Agency's Sentinel-1 mission, (2) the DLR (German Aerospace Agency) TerraSAR-X satellite, (3) the Umbra Space satellite constellation, (4) the Canadian Radarsat-2 satellite, (5) the Capella Space satellite constellation and (6) the Finnish Iceye constellation. This data package provides: A) geospatial polygon outlines of walrus herds apparent to trained interpreters in satellite images; B) a table listing the satellite images examined that had clear views of the walrus coastal haulout study sites and the area of all walrus herds (if any were present) summarized from the geospatial polygon outlines of walrus herds apparent to trained interpreters, and C) maps (not available for all haulouts in all years) showing interpreted herd outlines superimposed on the satellite images. These data were collected and interpreted to support near real time management decisions of Pacific walruses at coastal haulouts, and to improve satellite interpretation methods of walrus herds and carcasses on shore. Additional walrus satellite image-derived walrus haulout outlines from near Point Lay, Alaska, are available in another USGS data release (Fischbach and Douglas 2021; https://doi.org/10.5066/P9S2UL7N) This dataset includes previously released data and supersedes that USGS data release (https://doi.org/10.5066/P97NFTDU) 2017 2025 observed In work As needed Chukchi Sea coast Alaska and Russia -180.0000 -158.0273 71.8836 64.9794 USGS Metadata Identifier USGS:ASC482 ISO 19115 Topic Category Biota Environment NASA GCMD Earth Science Keyword Thesaurus Animals/Vertebrates Mammals Carnivores Seals/sea lions/walruses USGS CSA Biocomplexity Thesaurus Marine mammals Seasonal distribution USGS Thesaurus Wildlife Migratory species Marine ecosystems Coastal ecosystems Remote sensing Image collections Field inventory and monitoring None Satellite imagery Pinniped Walrus Pacific Walrus Odobenus rosmarus divergens USGS Geographic Names Information System (GNIS) Alaska Chukchi Sea NGA GEOnet Names Server Russia Chukotka None Marine mammals Pacific Walrus Odobenus rosmarus divergens ITIS Integrated Taxonomic Information System Unknown online database online ITIS-North America Taxonomic details retrieved December 4, 2025 from the Integrated Taxonomic Information System online database https://www.itis.gov https://doi.org/10.5066/F7KH0KBK Species were identified by experienced satellite imagery interpreters who applied methods described in Fischbach and Douglas (2021). Kingdom Animalia Subkingdom Bilateria Infrakingdom Deuterostomia Phylum Chordata Subphylum Vertebrata Infraphylum Gnathostomata Superclass Tetrapoda Class Mammalia Subclass Theria Infraclass Eutheria Order Carnivora Suborder Caniformia Family Odobenidae Genus Odobenus Species Odobenus rosmarus Walrus TSN: 180639 Subspecies Odobenus rosmarus divergens Pacific Walrus TSN: 622045 No access constraints. Any reproduction of the cartographic maps which include imagery from the Capella Space, DLR TerraSAR-X, MAXAR, Umbra Space, ICEYE, or Planet Labs must retain the copyright symbol and credit the respective imagery source. We request that the suggested citation of this USGS data release be included in any publications that reference or utilize these data. U.S. Geological Survey, Alaska Science Center Mailing and Physical

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Anchorage Alaska 99508 USA 907-786-7000 gs-ak_asc_datamanagers@usgs.gov Data are geospatial vector polygon outlines of walrus herds and a CSV table of data about each polygon (where, when, how large, etc.) as well as records of all images that were interpreted. Users of this data may note that digitized herd locations vary with respect to an apparent coastline. The variation is due to inaccuracies in the georeferencing of the various Earth observing satellite imagery. It is understood that georeferencing of satellite imagery is highly variable from image to image and the degree of this variability is expected to vary among Earth observing missions. The variability of georeferencing is expected to be greatest at study sites lacking established ground control points and or lacking high resolution mapping data, such as the case in the Russian Far East portions of the Pacific walrus range. At best, georeferenced imagery may match other imagery within meters. At worst, the authors have observed that common features in imagery may be shifted by more than one hundred meters. Although the authors recognized this problem, they did not attempt to perform post-processing co-registration of imagery provided by the various missions. Rather, the authors worked with the imagery as it was georeferenced by each mission. The authors do not expect that the variable georeferencing will introduce substantial variation or bias to the estimated area occupied by walrus herds. However, because the outlines of the digitized herd may be shifted substantially away from a common referenced coastline, it is not possible to analyze the digitized herd outlines from different images for spatial overlap. Attribute values fall within expected ranges. The dataset is complete, no data were omitted. We examined and interpreted available satellite imagery over the study area through the autumn study period, before, during and after dates when walruses had been previously reported at known haulout sites. Results are provided here in downloadable ZIP packages, organized by haulout site and year. **NOTE** Because some methods and processing details vary across sites and years, a "Methods and Image Processing" document is included with each ZIP package, providing details about the processing of each haulout site and year. Unknown LITERATURE CITED: Fischbach, A.S., Douglas, D.C. 2021. Evaluation of satellite imagery for monitoring Pacific Walruses at a large coastal haulout. Remote Sensing 13(21):4266 https://doi.org/10.3390/rs13214266 Fischbach, A.S., Douglas, D.C., Monette, C.J. 2021, Walrus haulout outlines apparent from satellite imagery near Point Lay Alaska, autumn 2018-2020: U.S. Geological Survey data release, https://doi.org/10.5066/P9S2UL7N Fischbach, A.S., Kochnev A.A., Garlich-Miller, J.M., Jay, C.V., 2016. Pacific walrus coastal haulout database 1852-2016: U.S. Geological Survey data release, https://doi.org/10.5066/F7RX994P Unknown Haulout site names and locations are defined in the Pacific Walrus Coastal Haulout Database https://doi.org/10.5066/F7RX994P Vector World Geodetic System of 1984 (WGS84) World Geodetic System of 1984 (WGS84) 6378137 298.257223563 [FOLDER] walrus_hauloutAreaEstimates_chukchi_PNG Zip folder with graphs for each year showing the herd area data through the fall haulout season. They are graphical summaries of the data provided in the "walrus_hauloutAreaEstimates_chukchi.csv" table included with the data release. Presented in PNG format. Author defined walrus_hauloutAreaEstimates_chukchi.csv Table with the records of all satellite images examined at each coastal haulout study site and estimates of the herd area of walruses interpreted to be resting on shore from the satellite image. Presented in comma Separated Value (CSV) formatted table. Author defined Year Year when the satellite image was collected. Author defined Year when the satellite image was collected (YYYY). StudySite Name of the walrus haulout site. Site names and locations are defined in the Pacific Walrus Coastal Haulout Database. Author defined PointLay Point Lay Barrier Island, Eastern Chukchi Sea, Alaska (approximately 69.795 N, 163.032 W; EPSG:32603, UTM zone 3N, WGS84) Pacific Walrus Coastal Haulout Database IcyCape Icy Cape, Eastern Chukchi Sea, Alaska (approximately 70.327 N, 161.881 W; EPSG:32604, UTM zone 4N, WGS84) Pacific Walrus Coastal Haulout Database CapeBlossom Cape Blossom, Wrangle Island area, Russia (approximately 70.783 N, 178.769 E; EPSG:32601, UTM zone 1N, WGS84) Pacific Walrus Coastal Haulout Database SomnitelnayaSpit Somnitel'naya Spit, Wrangle Island area, Russia (approximately 70.862 N, 179.562 W; EPSG:32601, UTM zone 1N, WGS84) Pacific Walrus Coastal Haulout Database CapeIkigur Cape Inkigur, Western Chukchi Coast, Russia (approximately 66.735 N, 171.379 W; EPSG:32602, UTM zone 2N, WGS84) Pacific Walrus Coastal Haulout Database CapeSerdtseKamen Cape Serdtse-Kamen', Western Chukchi Coast, Russia (approximately 66.808 N, 171.569 W; EPSG:32602, UTM zone 2N, WGS84) Pacific Walrus Coastal Haulout Database ChegitunRiverMouth Chegitun River Mouth, Western Chukchi Coast, Russia (approximately 66.557 N, 171.052 W; EPSG:32602, UTM zone 2N, WGS84) Pacific Walrus Coastal Haulout Database Vankarem Cape Vankarem, Western Chukchi Coast, Russia (approximately 67.848 N, 175.814 W; EPSG:32601, UTM zone 1N, WGS84) Pacific Walrus Coastal Haulout Database Date Date and time (UTC) when the satellite image was collected. Author defined Date and time (UTC) when the satellite image was collected (YYYY-MM-DDThh:mm:ssZ). Source Name of the satellite the mission that collected the image. Author defined Capella Capella Space mission: Small satellite commercial constellation collecting X-band single polarization (HH) synthetic aperture radar imagery with resolution less than or equal to 0.5 m when tasked. Data provider DG Maxar / DigitalGlobe mission: Commercial large satellite missions collecting optical sub-meter resolution when tasked. Data provider Iceye Iceye: Small satellite commercial constellation collecting X-band single polarization (HH) synthetic aperture radar imagery with resolution less than or equal to 0.5 m when tasked. Data provider Planet PlanetLabs PlanetScope mission: Commercial constellation of 3U small satellites systematically collecting optical imagery planet-wide daily at approximately 3 m resolution. Data provider RS RADARSAT-2 mission: Commercial large satellite collecting C-band single polarization (HH) synthetic aperture radar imagery with approximately 1 m resolution when tasked. Data provider S1 European Space Agency's Copernicus Sentinel-1 mission: Agency large satellite mission systematically collecting C-band cross-polarized (VH) synthetic aperture radar in at 10 m resolution across most of the Earth's surface on a 5 to 11 day cadence. Data provider S2 European Space Agency's Copernicus Sentinel-2 mission: Agency large satellite mission systematically collecting optical imagery  with 10 m resolution across most of the Earth's surface daily. Data provider TS Deutsches Zentrum fuer Luft- und Raumfahrt's TerraSAR-X mission: Agency large satellite mission systematically collecting X-band single polarization (HH) synthetic aperture radar with approximately 1 m resolution when tasked. Data provider Umbra Umbra Space mission: Small satellite commercial constellation collecting X-band single polarization (HH) synthetic aperture radar imagery with resolution less than or equal to 0.5 m when tasked. Data provider MapFile Name of the map in the "walrus_dailySatelliteHauloutMaps" folder for each site, if provided. Maps have not been produced for all haulouts in all years. The maps show the satellite image from which the haulout area was estimated with an outline of the herd area superimposed on the image.) Filenames are derived from image collection time and a satellite mission code: [four-digit year][two-digit month][two-digit day of month]T[two-digit hour of day][two-digit minute of hour]Z_[two-character satellite mission abbreviation (defined below)] Author defined Name of the map in the "walrus_dailySatelliteHauloutMaps" folder for each site, if provided. HauloutSize Land area encompassed by haulout group outlines, in square meters. Author defined Land area encompassed by haulout group outlines, in square meters [FOLDER] walrus_dailyHauloutOutlines Folder (found within each [haulout]_[year].zip package) with vector geospatial polygon outlines derived from walrus haulouts apparent in satellite imagery of each site. Presented in Esri shapefile (SHP) format. **NOTE: This folder may be empty - if no walruses were apparent in any satellite images at the haulout site during the year** Shapefile polygons are geocoded with the local UTM coordinate reference system (defined above and provided in each shapefile projection (.prj) metadata file) Filenames are derived from image collection time and a satellite mission code: [four-digit year][two-digit month][two-digit day of month]T[two-digit hour of day][two-digit minute of hour]Z_[two-character satellite mission abbreviation] Author defined [FOLDER] walrus_dailySatelliteMaps Folder (found within each [haulout]_[year].zip package) containing maps in JPG format. The maps are derived from a variety of Earth observing satellite imagery sources collected over coastal areas of the Chukchi Sea (northwestern Alaska and northeastern Russia) in autumn when walruses come ashore in large numbers to rest in the absence of sea ice. Filenames are derived from image collection time and a satellite mission code: [four-digit year][two-digit month][two-digit day of month]T[two-digit hour of day][two-digit minute of hour]Z_[two-character satellite mission abbreviation] Users of this data may note that digitized herd locations vary with respect to an apparent coastline. See the Attribute_Accuracy_Report section (above) for details about inconsistencies in the image georeferencing. Author defined README_MethodsAndImageProcessing.pdf Some methods and processing details vary across sites and years. Each ZIP package contains a "Methods and Image Processing" document, providing details about the processing used to produce the data contained in the package. Author defined U.S. Geological Survey USGS ScienceBase Team Mailing and Physical

Denver Federal Center, Building 810, Mail Stop 302

Denver Colorado 80225 USA 1-888-275-8747 sciencebase@usgs.gov The U.S. Geological Survey, Alaska Science Center is the authoritative source of these data, distributed by ScienceBase (a USGS Trusted Digital Repository). 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, no warranty expressed or implied is made regarding the display or utility of the data for other purposes or 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. JPG, PNG, SHP, CSV Tabular data in CSV format; geospatial data in SHP formats; digital images in JPG and PNG format; FGDC metadata in XML and HTML formats. https://doi.org/10.5066/P9CSM0KN None 20251208 U.S. Geological Survey, Alaska Science Center Mailing and Physical

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Anchorage Alaska 99508 USA 907-786-7000 gs-ak_asc_datamanagers@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata (CSDGM) FGDC-STD-001.1-1999