Folders: ROOT > ScienceBase Catalog > Alaska Science Center (ASC) > walrus ( Show direct descendants )
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This data package contains digital images, survey location logs and a summary tabulation from carcass survey conducted at walrus haulouts in Alaska. A summary of image collection times is provided as a tabular file. The images are considered sensitive. They are archived at the U.S. Geological Survey, Alaska Science Center (a USGS Trusted Digital Repository). At this time, only this metadata record describing the data, an image inventory table, and a satellite (GNSS) log are publicly accessible.
Sea ice loss represents a stressor to the Pacific walrus (Odobenus rosmarus divergens), which feeds on benthic macroinvertebrates in the Bering and Chukchi seas. However, no studies have examined the effects of sea ice on foraging walrus space use patterns. Thus, we examined walrus foraging resource selection as a function of proximity to resting substrates and prey biomass with a matched use-availability design. We quantified biomass of 17 benthic taxa, which included amphipods, bivalves, polychaete, sand dollars, tunicates, and sipunculids. We included covariates for distance to sea ice and distance to land, and systematically developed a series of candidate models to examine interactions among benthic prey biomass...
Categories: Data
We summarize available information on Pacific walrus haulouts from available reports, interviews with coastal residents and aviators, and personal observations of the authors. We provide this in the form of a georeferenced database that may be queried and displayed with standard geographic information system and database management software. The database contains 150 records of Pacific walrus haulouts, with a summary of basic characteristics on maximum haulout size, age-sex composition, season of use, and decade of most recent use. Citations to reports are provided as a bibliographic database.
Categories: Data;
Types: ArcGIS REST Map Service,
ArcGIS Service Definition,
Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Alaska,
Arctic,
Arctic Ocean,
Beaufort Sea,
Bering Sea,
This dataset consists of the complete set of aerial imagery and data from walrus haulouts collected by unoccupied aerial system (UAS) surveys near Pt. Lay, Alaska, during the autumns of 2018 and 2019. The data include: 1) georeferenced digital aerial imagery and flight logs from UAS surveys, and 2) orthoimages derived from the aerial imagery and flight logs by standardized structure from motion algorithms.
This dataset is comprised of three tables showing the reaction of walruses hauled out on sea ice of the Chukchi Sea to overflights by rotary wing Unoccupied Aircraft Systems (UAS). Data include behavior of walruses before, during, and after overflights, and environmental conditions during flights.
This dataset contains measurements of oxygen consumption and carbon dioxide production of 3 adult female walruses (Odobenus rosmarus divergens) while resting, swimming, and diving at the Oceanografic Aquarium in Valencia, Spain. Oxygen consumption and carbon dioxide production was measured for walruses breathing under a respiratory dome while resting at the water surface, under a respiratory dome after swimming and diving, and via breath by breath respirometry using a pneumotachometer when hauled out.
State-space models offer researchers an objective approach to modeling complex animal location datasets, and state-space model behavior classifications are often assumed to have a link to animal behavior. We evaluated the behavioral classification accuracy of a Bayesian state-space model in Pacific walruses using Argos satellite tags outfitted with sensors to detect animal behavior in real time. To compare these real behaviors to modeled behaviors, we fit a two-state discrete-time continuous-space Bayesian state-space model to data from 306 Pacific walruses tagged in the Chukchi Sea. We matched predicted locations and behaviors from the state-space model (resident, transient behavior) to true animal behavior (foraging,...
Categories: Data
An animal’s energetic costs are dependent on the amount of time it allocates to various behavioral activities. For Arctic pinnipeds, the time allocated to active and resting behaviors could change with future reductions in sea ice cover and longer periods of open water. The Pacific walrus (Odobenus rosmarus divergens) is a large Arctic pinniped that rests on sea ice or land between foraging trips to feed on the seafloor. This dataset contains behavioral data collected from 216 radio-tagged adult female walruses instrumented in the Chukchi Sea (2008–2014) that formed the basis of a Bayesian generalized linear mixed effects model that investigated probability that a walrus was in water foraging, in water not foraging,...
Categories: Data
This data release comprises 3 datasets used to develop forecasts of autumn body condition for adult female Pacific walruses in the Chukchi Sea during mid and late century time periods. The activity dataset contains daily telemetry records for 218 adult female walruses tracked for periods of 7 to 104 days during 2008-2014, in the Chukchi Sea. Records include the number of hours the walrus was in the water, number of hours the walrus was foraging, study area region where the walrus was located, depths of the foraging locations, and the proportion of the region covered by sea ice. The movement dataset contains telemetry records for 94 of these walruses, giving the dates they moved from one region to another, and the...
This dataset provides walrus haulout group outlines, systematic grids cast over the outlines, and digitized points at the centroids of the individual walruses identified inside a randomly selected subset of grid cells. These data are based on visual interpretation of imagery from 26 aerial surveys by an Unoccupied Aerial System (UAS) operated by the U.S. Geological Survey, Alaska Science Center over large groups of walruses resting onshore near Point Lay, Alaska during the autumns of 2018 and 2019. These walrus group outlines, grid cells and digitized walrus points were collected as part of an effort to estimate the number of walruses in the Northeast Chukchi Sea during the autumn of 2018 and 2019.
The Pacific walrus (Odobenus rosmarus divergens) feeds on benthic invertebrates on the continental shelf of the Chukchi and Bering seas and rests on sea ice between foraging trips. With climate warming, ice-free periods in the Chukchi Sea have increased and are projected to increase in frequency and duration. We radio-tracked walruses to estimate areas of walrus foraging and occupancy in the Chukchi Sea during June–November of 2008–2011, years when sea ice was sparse over the continental shelf. The earlier and more extensive sea ice retreat in June–September and delayed freeze-up of sea ice in October and November, allowed walruses to arrive earlier, occupy slightly more northern areas, and stay later in the...
Categories: Data;
Types: Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Pacific Walrus,
Walrus,
behavior,
satellite tracking,
telemetry
This data release includes two summary geospatial rasters in GeoTIFF format indicating the seasonal Pacific walrus distribution apparent from from ARGOS location tracking obtained from the temporary attachment of ARGOS transmitter tags to Pacific walruses between 1987 and 2015. We deployed tags on walruses at locations in the eastern and northern Bering Sea, the eastern Chukchi Sea, and southern coast of the western Chukchi Sea. We estimated daily locations and characterized seasonal distributions (May-November and December-April) across the Pacific Arctic on a coarse grid (50km resolution).
This data set describes nucleotide sequence data derived from 18S ribosomal DNA amplified in two fragments. A total of 87 feces from Pacific walrus and 57 marine invertebrates were examined for this study. Samples were collected from the Bering Sea and Chukchi Sea, Alaska. Samples used in the study originated from feces or muscle samples collected in the field from ice floes or benthic van Veen grab samples.
This dataset contains lab-measured percent lipid and fatty acid composition data from Pacific walruses harvested in waters near Saint Lawrence Island. Each row indicates data from a single layer from a blubber core sample collected from one body site (flank, rump, or sternum) from one walrus harvested by Native Alaskans during the spring walrus hunts of 2007 - 2010. Blubber cores were divided into two roughly equal depths (inner and outer) and individually characterized. Results are proportion lipid content of the sub-sample mass and proportional abundance of each fatty acid of total fatty acids identified in the sub-sample on a wet-weight basis. Some samples were found to be inadequate due to lack of anatomical...
These data were used to evaluate effects of vessel exposure on Pacific walrus (Odobenus rosmarus divergens) behaviors. We obtained >120,000 hours of location and behavior (foraging, in-water not foraging, hauled out) data from 218 satellite-tagged walruses and linked them to vessel locations from the marine Automated Information System. This yielded 206 vessel-exposed walrus telemetry hours for comparison to unexposed hours which we used to assess if vessel exposure altered walrus behavior.
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