Alaska Harbor Seal Aerial Survey Units

Aerial surveys of coastal Alaska are the primary method for estimating abundance of harbor seals. A particular challenge associated with aerial surveys of harbor seals is maintaining consistent spatial representation of haulout locations. In some cases, seals aggregate into a single large grouping at a particular area. In other cases, seals aggregate into several smaller groups spread over a particular area. To establish geo-spatial consistency, the Alaska Fisheries Science Center developed coastal survey units (spatial polygons) throughout the distriubtion of harbor seals in Alaska. Each survey unit was designed to be approximately 10-15 kilometers in coastal length, to faciliate efficient aerial surveys, and to aggregate known harbor seal haulout locations. Each survey unit was assigned a unique alphanumeric identifier and the spatial data are provided in the geographic (epsg:4326) coordinate reference system. The survey units form the spatial foundation for estimation of harbor seal abundance and trend.

This geospatial dataset describes the survey units used for coastal aerial surveys of harbor seals in Alaska

London, J.M., K.M. Yano, E.L. Richmond, R. Montgomery, J.M. Ver Hoef, and P.L. Boveng (2015): Aerial Survey Units for Harbor Seals in Coastal Alaska. Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration. --doi:TBD, contact authors for updated citation details--

objectid: integer unique identifier

polyid: alphanumeric identifier for each survey unit

stockid: numeric identifier for the population stock

stockname: common name for the population stock

geom: geographic object (polygon)

While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

Acknowledge NOAA/NMFS/AFSC as the source from which these data were obtained in any publications and/or other representations of these data. Communication and collaboration with dataset authors is strongly encouraged prior to use.

The data set is in the process of being archived with the NOAA National Centers for Environmental Information. Once the archival process is complete and verified, the data set will be publicly available.

The data set is in the process of being archived with the NOAA National Centers for Environmental Information. Once the archival process is complete and verified, the data set will be publicly available.

User must read and fully comprehend the metadata prior to use. Applications or inferences derived from the data should be carefully considered for accuracy. While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty. Acknowledge NOAA/NMFS/AFSC or the specified citation as the source from which these data were obtained in any publications and/or other representations of these data. Communication and collaboration with dataset authors is strongly encouraged.

no metadata access constraints

Metadata are subject to revision at any time and information within the metadata record should not be cited without author consent. While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

Authoritative data are housed within a PostgreSQL/PostGIS database within AFSC and provided to the public via an ESRI ArcGIS Server at the Alaska Fisheries Science Center.

Survey unit boundaries are evaluated annually to insure all harbor seal habitat within Alaska is incorporated. Feedback from aerial survey observers and, in some cases, telemetry studies informs this evaluation.

not automatically processed

IT Security and Contingency Plan for the system establishes procedures and applies to the functions, operations, and resources necessary to recover and restore data as hosted in the Western Regional Support Center in Seattle, Washington, following a disruption.

The aerial survey units (polygons) were derived from a multi-stage effort that combined historical knowledge of harbor seal haul-outs, typical aerial survey routes and techniques, and detailed coastline maps. Each unit was designed to be approximately 10-15 km in coastline length and 1-2 km in width. The units were designed such that an aircraft surveying obliquely would be within a unit boundary under typical survey conditions. Additionally, the survey unit boundaries were optimized to limit the number of known haul-out locations near the boundary.