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.