Resource managers need to know how many porpoises there are, where they are, and how their populations are changing. Because harbor porpoise are small, inconspicuous, and rarely active at the surface, and also often travel alone, collecting these data is challenging. Our scientists use various methods to assess harbor porpoise populations and present the data in annual stock assessment reports.
Aerial and Vessel Surveys
Aerial and vessel surveys collect data used to estimate harbor porpoise abundance for stock assessments. We also use vessel surveys to collect data for special research, including a study of temporal changes in abundance of harbor porpoise (Phocoena phocoena) inhabiting the inland waters of Southeast Alaska spanning 22 years.
Our scientists have used passive acoustic monitoring (listening to underwater sounds) to monitor the year-round presence of harbor porpoises in some habitats. By combining these data with fishery trawl transects we can assess fish and invertebrate diversity and identify potential harbor porpoise prey.
Environmental DNA Research
We are using environmental DNA techniques to understand population structure within inland waters of Southeast Alaska, an area where bycatch may be impacting one of the Alaskan harbor porpoise populations: A Little Bit of Seawater Is Helping Scientists Study Elusive Harbor Porpoise off the Coast of Alaska.
Drawing on Archaeological and Local Knowledge
Little is known about harbor porpoise in Cook Inlet, Alaska, and no long-term studies of porpoise have been done there. We summarized occurrence of harbor porpoise over time from archaeological data, anecdotal reports, and systematic surveys to increase our understanding of porpoise found in this region.