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Annual California Sea Otter Census: 2018 Census Summary Shapefile

Dates

Publication Date
Start Date
2018-04-26
End Date
2018-05-24

Citation

Hatfield, B.B., Yee, J.L., Kenner, M.C., Tomoleoni, J.A., and Tinker, M.T., 2018, Annual California sea otter census—2018 spring census summary: U.S. Geological Survey data release, https://doi.org/10.5066/P98012HE.

Summary

The GIS shapefile "Census summary of southern sea otter 2018" provides a standardized tool for examining spatial patterns in abundance and demographic trends of the southern sea otter (Enhydra lutris nereis), based on data collected during the spring 2018 range-wide census. The USGS spring range-wide sea otter census has been undertaken each year since 1982, using consistent methodology involving both ground-based and aerial-based counts. The spring census provides the primary basis for gauging population trends by State and Federal management agencies. This Shape file includes a series of summary statistics derived from the raw census data, including sea otter density (otters per square km of habitat), linear density (otters per km [...]

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Attached Files

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Shapefile: Census_sum_2018.zip
Census_sum_2018.prj 428 Bytes
Census_sum_2018.shp 646.4 KB
Census_sum_2018.shx 15.62 KB
Census_sum_2018.dbf 1.01 MB

Purpose

The range-wide census is conducted to monitor trends in abundance of the southern sea otter, and thus provide State and Federal resource agencies with the information they need for effective management. Because the censuses represent uncorrected total counts (rather than sample-based surveys), they cannot be considered as accurate estimates of true population abundance. Instead, these data represent a valuable time-series of index counts, and provide the means of assessing spatial and temporal trends in relative abundance. The 3-year running average of the spring counts have been identified as the best index of trends and status of the population, because these averages decrease the influence of year-to-year sampling variance. The 3-year average counts are used by the US Fish and Wildlife Service in its listing determinations (de-listing or up-listing) for this legally threatened population.

Map

Spatial Services

ScienceBase WMS

ScienceBase WFS

Communities

  • USGS Western Ecological Research Center

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Additional Information

Shapefile Extension

boundingBox
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maxX-120.27277220980577
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