| Summary: | Aerial surveys in Prince William Sound to document spring herring biomass have been conducted since the early 1970’s. This zip file contains geospatial files, xml files, and databases collected during aerial surveys to document Pacific herring biomass in the Prince William Sound Area, Alaska, 2008-2021. Because of interest in herring predators, additional effort has been placed on documenting numbers and locations of Steller sea lions, humpback whales, Orca whales, Dall porpoises, and marine bird aggregations associated with herring schools or spawn. Zip files containing geospatial files, xml files, and databases with marine mammal and marine bird sightings during aerial surveys are also included in this data package. Regular surveys are conducted mid-March to mid-May each year to coincide with spring Pacific herring spawning events. Two observers generally split the duties as follows: one observer collected data on the ESRI Arcpad application, and the second observer collected data on paper maps and photographed spawn, herring schools; and marine mammal or seabird observations. During a portion of 2020 surveys only one observer flew due to the COVID-19 pandemic. Measurements made during the survey include estimating the linear extent of milt, estimating the biomass of herring schools from surface area, estimating the number of individuals by species for marine mammals and birds, and the GPS survey routes made by the airplane.
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