[MARMAM] New Publication: Gray Seal Isotopic Niches

Keith Hernandez keith.hernandez2011 at gmail.com
Thu Oct 31 14:15:32 PDT 2019

Hello MARMAM community,

On behalf of my co-authors, I am excited to announce our new publication
regarding the isotopic niches of gray seals in the Canadian Journal of
Zoology. The abstract is provided below.

Although it is often assumed that individuals in generalist populations are
equivalent, recent research indicates that individual dietary
specialization can be common in marine predators. Gray seals (*Halichoerus
grypus* (Fabricius, 1791)) were considered locally extinct in United States
waters by 1958 but have since recolonized the region. Although considered
generalists, less is known about gray seal foraging ecology in the United
States. To address this, we used carbon and nitrogen stable isotope
analyses to investigate the foraging niches of adult gray seals in
Massachusetts, USA. We examined skin, fur, and blood components to
investigate seasonal variability and individual consistency in foraging
niches, and serially sampled vibrissae to quantify the degree of individual
foraging specialization in this population. Our results suggest that seals
shift from coastal foraging habitats before molt to offshore habitats after
molt, with a coincident shift from higher to lower trophic-level prey.
Adult gray seals also exhibited individual consistency in foraging niches
independent of population-level shifts and reflect a generalist population
composed of individual foraging specialists. These findings serve as a
baseline for subsequent research on gray seals in United States waters that
could help to determine the mechanisms which promote individual
specialization in this population.

The paper can be found at this URL: https://doi.org/10.1139/cjz-2019-0032 .
If you cannot access the paper, please feel free to email me at
keith.hernandez2011 at gmail.com.

Keith M. Hernandez, MS
PhD Candidate, Marine & Coastal Trophic Ecology Lab
1243 Energy, Coast & Environment Building
Louisiana State University
Baton Rouge, LA 70803
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