2025 Aerial Surveys of Steller Sea Lions in the Aleutian Islands, Alaska

Who is conducting the research?

Scientists from NOAA Fisheries’ Alaska Fisheries Science Center (AFSC), in collaboration with NOAA’s Office of Marine and Aviation Operations, will be conducting the research.

What is the research objective?

Alaska Fisheries Science Center scientists will conduct aerial surveys aboard a NOAA Twin Otter aircraft (tail number N56RF) to collect high-resolution imagery of the endangered western Distinct Population Segment of the Steller sea lion. Survey imagery will be used to count adults, juveniles, and pups.

Where is the research being conducted?

Aerial survey operations will be based in Adak and Dutch Harbor, Alaska to target known Steller sea lion sites in the eastern and central Aleutian Islands regions.

Why are the data important? How will data be used?

The Alaska Fisheries Science Center has conducted aerial surveys of Steller sea lions since the 1970s. Annual surveys are vital to monitoring the population and assessing trends over time. Surveys of the western Distinct Population Segment are especially important as this population is listed as endangered under the Endangered Species Act. Counts collected from imagery will be used to update regional count estimates, population trends, and are reported to stakeholders.

Due to weather and survey logistics, the central Aleutian Islands region has not had a comprehensive survey since 2018. Collecting more data in this region is vital towards a better understanding of trends west of SamalgaPass, which have oscillated between decreasing and stable in previous survey years. The eastern Aleutian Islands region is the second priority area to survey.