[MARMAM] Recent paper on harbor seal foraging in the Salish Sea

Madelyn Voelker madelyn.voelker at gmail.com
Sun Oct 4 12:20:28 PDT 2020

Greetings MARMAM!

A recently published paper on harbor seal foraging in the Salish Sea is now
available at this link:

Voelker, MR, Schwarz, D, Thomas, A, Nelson, BW, Acevedo Gutierrez, A.
molecular barcoding of prey DNA reveals predictors of intrapopulation
feeding diversity in a marine predator. *Ecol Evol*. 2020; 00: 1– 19.


Predator–prey interactions are critical in understanding how communities
function. However, we need to describe intraspecific variation in diet to
accurately depict those interactions. Harbor seals (*Phoca vitulina*) are
an abundant marine predator that prey on species of conservation concern.
We estimated intrapopulation feeding diversity (variation in feeding habits
between individuals of the same species) of harbor seals in the Salish Sea.
Estimates of feeding diversity were examined relative to sex, month, and
location using a novel approach that combined molecular techniques,
repeated cross‐sectional sampling of scat, and a specialization metric
(within‐individual consistency in diet measured by the Proportional
Similarity Index ([image:
urn:x-wiley:20457758:media:ece36638:ece36638-math-0001])). Based on 1,083
scat samples collected from five haul‐out sites during four nonsequential
years, we quantified diet using metabarcoding techniques and determined the
sex of the scat depositor using a molecular assay. Results suggest that
intrapopulation feeding diversity was present. Specialization was high over
short periods (24–48 hr, [image:
urn:x-wiley:20457758:media:ece36638:ece36638-math-0002] = 0.392, 95%
CI = 0.013, R = 100,000) and variable in time and space. Females showed
more specialization than males, particularly during summer and fall.
Additionally, demersal and benthic prey species were correlated with more
specialized diets. The latter finding suggests that this type of prey
likely requires specific foraging strategies and that there are trade‐offs
between pelagic and benthic foraging styles for harbor seals. This
differential feeding on prey species, as well as between sexes of harbor
seals, indicates that predator–prey interactions in harbor seals are
complex and that each sex may have a different impact on species of
conservation concern. As such, describing intrapopulation feeding diversity
may unravel hitherto unknown complex predator–prey interactions in the

Please feel free to contact me with any questions regarding this work.


Madelyn Voelker
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