[MARMAM] New Publication

John M. akjohnm at gmail.com
Mon Mar 13 09:42:15 PDT 2023


Publication Announcement:  Changes in the overwintering diet of Steller sea
lions (*Eumetopias jubatus*) in relation to the 2014 – 2016 northeast
Pacific marine heatwave (Maniscalco, J. M.)

Open Access:  Changes in the overwintering diet of Steller sea lions
(Eumetopias jubatus) in relation to the 2014 – 2016 northeast Pacific
marine heatwave - ScienceDirect
<https://www.sciencedirect.com/science/article/pii/S2351989423000628?via%3Dihub>

Understanding variation in the diets of endangered species during critical
time periods in their annual cycle is of utmost importance because of the
effects that diet can have on vital rates and population trends. This may
be especially true for Endangered Steller sea lions during the winter
months when prey can be difficult to find, and many adult females are both
lactating and pregnant. This study aimed to examine changes in the
overwintering diet of Steller sea lions across an extreme climatic event,
the northeast Pacific marine heatwave (PMH) that adversely affected this
species and broadly impacted many others throughout the trophic spectrum.
Diet analysis was conducted from scat samples using hard part remains and
qPCR methods. Prior to the peak impact of the PMH, Steller sea lions fed
predominantly on epipelagic and mesopelagic fishes such as capelin, walleye
pollock and Pacific cod. Following the warm-water peak, capelin was
strongly reduced in their diet, and diet diversity increased with greater
presence of demersal and benthic prey such as skates, lumpsuckers,
snailfish, and polychaetes. These results suggest that sea lions were
having a difficult time finding their preferred prey, spending time
searching deeper to find alternative prey with poorer energy content
following the peak impact of the PMH. These changes in diet corresponded
with fewer pups being born and a reduction in overall sea lion numbers in
the study area, providing evidence that overwintering prey fields may have
a substantial impact on population health.

-- 
*John M. Maniscalco, Ph.D.*
Senior Research Scientist, Alaska SeaLife Center
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