Dr. John Maniscalco, who has been studying Steller sea lions at the ASLC for over 20 years, recently attended a virtual annual meeting of Steller sea lion research permit holders and presented plans for ASLC’s Steller sea lion research and some new findings in our ongoing studies.
This meeting was attended by representatives from National Marine Fisheries Service, Alaska Department of Fish & Game, Canadian Department of Fisheries and Oceans among several other organizations and universities ranging from California through Alaska, and Russia. This meeting is a great example of people coming together from all over the world to protect and conserve an endangered population of marine mammals!
At the meeting, Dr. Maniscalco shared new findings from the Chiswell Island Steller Sea Lion Project, which included optimistic improvements in Steller sea lion survival and reproductive rates in the three most recent years, as well as an interesting new discovery that could adversely impact the population for years to come.
The increase in survival and reproductive rates over the past three years is promising news, as this western population of Steller sea lions was listed as Endangered under the U.S. Endangered Species Act in 1997 following a major population decline.
The ASLC has been monitoring this population since that decline and has seen a general increase in the population from 1998 through 2015. The peak impact of the Northeast Pacific warm water anomaly occurred during the winter of 2015 and into 2016, and the Chiswell team began to see significant declines in pups and adults in the summer of 2016. Our team believes that changes in food availability likely played some role in the decline (click here to read more about the Chiswell team’s previous publication about this data).
However, we have also discovered that there is an apparent delay in the age at primiparity (meaning the age the females first give birth) for the female Steller sea lions born close to the peak of the 2014-2016 Northeast Pacific warm water anomaly.
Females that were born prior to the warm water anomaly were giving birth at an average of 5.5 years of age compared to 6.7 years of age for those that were born in 2016 [see figure below].
We’re not sure what this means for the future years of this population, but it could limit lifetime reproductive success and continue to adversely impact the population for years to come.
As we gear up for another year of monitoring this endangered population of Steller sea lions pupping at Chiswell Island, we’re reminded how important multi-year monitoring projects like this one are.
We would not be able to see the long-term changes in populations and the effects on this incredible ecosystem as a whole.
Be sure you’re following the ASLC on Facebook, Instagram, and YouTube to get weekly updates from the Chiswell Island Steller Sea Lion Monitoring Team this summer. We can’t wait to share some of the exciting moments our team gets to capture with the remote video monitoring season at the ASLC!
