150 
National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
@ established in 1881 «< 
Spencer F. Baird 
First U.S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Abstract—Pacific salmon (Oncorhyn- 
chus spp.) are important to the ecology, 
economy, and cultures of the Pacific 
Northwest. Many populations of Pacific 
salmon in the Pacific Northwest are 
declining because of poor marine sur- 
vival. We evaluated the role of Steller 
(Eumetopias jubatus) and California 
(Zalophus californianus) sea lions as 
predators of Pacific salmon. Roughly, 
half of the 1330 metric tons (t) of 
Pacific salmon eaten by Steller sea 
lions per year and of the 1220 t of 
Pacific salmon eaten by California sea 
lions per year in northwest Washington 
during 2010-2013 were coho salmon 
(O. kisutch). The response of Steller and 
California sea lions to the large run of 
pink salmon (O. gorbuscha) in 2011 
was less than expected. Sea lions of 
these species rarely ate large (roughly 
>50 cm in total length) Chinook salmon 
(O. tshawytscha), indicating that they 
have limited direct competition for prey 
with the southern resident distinct pop- 
ulation segment of killer whales (Orc- 
inus orca). Combined, California and 
Steller sea lions in northwest Washing- 
ton consumed a mass of coho salmon 
similar to that landed by commercial 
fisheries in Washington State. More 
work on modeling the effect of the 
predation by California and Steller 
sea lions on salmon populations, par- 
ticularly for coho salmon, is needed to 
better evaluate the conservation and 
productivity of Pacific salmon. 
Manuscript submitted 21 December 2021. 
Manuscript accepted 27 April 2022. 
Fish. Bull. 120:150-161 (2022). 
Online publication date: 19 May 2022. 
doi: 10.7755/FB.120.2.5 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Consumption of Pacific salmon (Oncorhynchus 
spp.) by California sea lions (Zalophus californianus) 
and Steller sea lions (Eumetopias jubatus) 
in northwest Washington during 2010-2013 
Jonathan J. Scordino (contact author)! 
Cydni Marshall? 
Adrianne M. Akmajian? 
Daniel Shay” 
Randall James? 
Email address for contact author: jonathan.scordino@makah.com 
" Marine Mammal Program 
Makah Fisheries Management, Makah Tribe 
150 Resort Drive 
Neah Bay, Washington 98357 
? Institute of Science and Technology 
North Central High School 
1600 North Howard Street 
Spokane, Washington 99205 
Pacific salmon (Oncorhynchus spp.) are 
keystone species in the ecology (Willson 
and Halupka, 1995; Lincoln et al., 
2020), economy (Amberson et al., 2016), 
and cultures (Butler and Campbell, 
2004; Amberson et al., 2016; Korzow 
Richter et al., 2020; Atlas et al., 2021) 
of the Pacific Northwest. These species 
are taken by many predators (Willson 
and Halupka, 1995; Lincoln et al., 2020) 
throughout their life cycle and are 
important because they deliver marine- 
derived nutrients to freshwater (Zhang 
et al., 2003) and terrestrial ecosystems 
(Schindler et al., 2003; Walsh et al., 
2020). 
Many stocks of Pacific salmon along 
the West Coast of the United States are 
currently imperiled, and their import- 
ant role in Pacific Northwest ecosys- 
tems is threatened (O’Higgins, 2015). 
Results from recent research indicate 
that the marine life phase of Pacific 
salmon plays a more important role in 
salmon population dynamics than had 
been previously recognized (Sobocinski 
et al., 2021; Welch et al., 2021). During 
3 Marine Ecology Program 
Makah Fisheries Management, Makah Tribe 
150 Resort Drive 
Neah Bay, Washington 98357 
the marine life phase, survival of species 
of Pacific salmon is affected by climatic 
conditions (Mueter et al., 2005; Crozier 
et al., 2021), interspecific and intra- 
specific competition with other Pacific 
salmon (Ruggerone and Nielsen, 2004; 
Kendall et al., 2020), and predators 
(Chasco et al., 2017a; Seitz et al., 2019; 
Sherker et al., 2021). Across the North 
Pacific Ocean, Pacific salmon are becom- 
ing smaller and are more frequently 
spawning at younger ages (Ohlberger 
et al., 2018; Losee et al., 2019), reducing 
their reproductive potential (Ohlberger 
et al., 2020; Oke et al., 2020). Manishin 
et al. (2021) found that these changes 
observed in the demographic structure 
of Chinook salmon (O. tshawytscha) 
could be attributed to recent increases 
in the mortality rate of salmon in the 
life stage after their first winter in the 
ocean and suggested that high preda- 
tion rates could be a major factor in 
mortality. More research is needed to 
improve our understanding of where 
and when predation of Pacific salmon 
occurs, particularly for recovery efforts 
