Dall's and Harbor Porpoise Survey Data, Prince William Sound, Alaska: 2007-2008, 2011-2015, and 2017-2025, Gulf Watch Alaska Pelagic Component

These data are part of the Gulf Watch Alaska (GWA) Pelagic component, which is a long-term ecosystem monitoring program of the Exxon Valdez Oil Spill Trustee Council for the marine ecosystem affected by the 1989 oil spill. As part of a larger study of humpback whale (Megaptera novaeangliae) impact to Pacific herring (Clupea pallasi) populations in Prince William Sound (PWS), Dall's porpoise (Phocoenoides dalli) and Harbor porpoise (Phocoena phocoena) observations were recorded during boat-based whale surveys. Pacific herring in PWS have been classified as "not-recovered" by the Exxon Valdez Oil Spill Trustee Council (EVOSTC). Predation by marine mammals has been cited as a factor in the failure of this population to rebound. Following protocols established during the winters of 2007/08 and 2008/09 (EVOSTC project PJ090804), the seasonal trends and abundance of humpback whales in PWS were examined. During these surveys, incidental observations of porpoise were also recorded. The dataset is a single comma-separated values (csv) file containing the date, time, location, number, and behavior of porpoise observed during humpback whale surveys in Prince William Sound, Alaska from 2007-2008, 2011-2015, and 2017-2025.