2022 Results Of Steller Sea Lion Surveys In Alaska
The Marine Mammal Laboratory (MML) conducted aerial surveys to photograph and
count Steller sea lion (Eumetopias jubatus) pups (~1 month old) and non-pups (adults and
juveniles ≥ 1 year old)... (AFSC/MML/AEP 2016) in Alaska in June-July 2022.
The Alaska Fisheries Science Center’s Marine Mammal Laboratory (MML) conducts annual aerial-, boat-, and land-based surveys at known terrestrial rookery and haulout sites in Alaska to collect visual counts and high-resolution imagery from which Steller sea lions are counted. In 2022, MML survey teams collected counts from 97 sites in the Aleutian Islands regions and one site in the western Gulf of Alaska region. We used a newly updated agTrend model that is more precise to model all raw count data through 2022 to estimate counts (as an index of abundance) and annual rates of change. Non-pups and pups in the western DPS of Alaska increased 1.05 and 0.50% y-1, respectively, between 2007 and 2022; however, there was high variability among regions. Non-pups and pups in the western Aleutian Islands region continued to decline, along with pups in the neighboring central Aleutian Islands region. Non-pups in the central Aleutian Islands region plateaued, however more data is needed from the eastern portion of this region. Regions east of Samalga Pass (western DPS) began to increase in the early 2000s; however, pup production slowed or plateaued in the early 2010s, with subsequent non-pup plateauing or declines starting in the late 2010s for all regions. Southeast Alaska (eastern DPS) non-pups and pups increased 2.08 and 2.51% y-1, respectively, between 1992 and 2022. Declines in non-pup counts since 2019 were preceded by plateaued pup counts in the late 2000s. As signs of recovery have slowed or ceased altogether in the western DPS, and Southeast Alaska appears to be declining in recent years, it is evident Steller sea lion populations in Alaska remain sensitive and regular surveys are critically important to monitoring regional variability, especially as environmental anomalies (i.e., heatwaves in the North Pacific Ocean) occur with greater frequency and magnitude.