Surveys of Steller sea lions (Eumetopias jubatus) in Alaska, June-July 2016-2025 : An update on the status and trend and comparisons of new analytical methods

Sweeney, Katie L.; Birkemeier, Burlyn; Warlick, Amanda J.; Luxa, Katie

doi:10.25923/7pbk-tb66

i

Surveys of Steller sea lions (Eumetopias jubatus) in Alaska, June-July 2016-2025 : An update on the status and trend and comparisons of new analytical methods

2026
By: Sweeney, Katie L. ; Birkemeier, Burlyn ; Warlick, Amanda J.
Series: NOAA technical memorandum NMFS-AFSC 516

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Personal Author:

Sweeney, Katie L. ; Birkemeier, Burlyn ; Warlick, Amanda J. ; Luxa, Katie
Corporate Authors:

Alaska Fisheries Science Center (U.S.) ; Marine Mammal Laboratory (U.S.) ; Cooperative Institute for Climate, Ocean, and Ecosystem Studies.
NOAA Program & Office:

NMFS (National Marine Fisheries Service) ; AFSC (Alaska Fisheries Science Center) ; CICOES (Cooperative Institute for Climate, Ocean and Ecosystem Studies)
Description:

From 2016 to 2025, the Alaska Fisheries Science Center’s Marine Mammal Laboratory (MML) conducted annual count surveys of Steller sea lions (Eumetopias jubatus) in June/July in Alaska. MML surveyed the endangered western distinct population segment (DPS) and Southeast Alaska (eastern DPS). Data collection included aerial imagery (crewed and uncrewed aircraft platforms), visual counts (ship, skiff, and crewed aircraft platforms), and land-based visual counts. Imagery was processed and counted via our traditional methods, and a new hybrid count workflow was introduced for counting 2024 imagery, which integrated artificial intelligence detection and classification. We used agTrend to model all raw count data to 2025 to produce estimated counts (an index of abundance)—and annual rates of change for 15- and 30-year periods. However, we restricted reporting to data through 2024; 2025 estimates were excluded due to high uncertainty from limited survey coverage, specifically the lack of count data east of Samalga Pass.
Series:

NOAA technical memorandum NMFS-AFSC 516
DOI:

https://doi.org/10.25923/7pbk-tb66
Publisher:

pdf
Document Type:

Technical Memorandum
Place as Subject:

Alaska
License:

https://creativecommons.org/publicdomain/zero/1.0/
Rights Information:

CC0 Public Domain
Compliance:

Submitted
Download URL:

https://repository.library.noaa.gov/view/noaa/73346/noaa_73346_DS1.pdf
File Type:

[PDF - 6.98 MB]
Collection(s):

NOAA Cooperative Institutes ; National Marine Fisheries Service (NMFS)
Main Document Checksum:

urn:sha-512:35fca8d752e0083a5f0258e3d121ea0a2180417858c9532d14b097be13be518ea91ec2bf0c23488278349e78e9448f953bc17a3f3a0243496899d729edd7e9f6

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