, Volume 188, Issue 1, pp 263–275 | Cite as

Temporal records of diet diversity dynamics in individual adult female Steller sea lion (Eumetopias jubatus) vibrissae

  • A. C. Doll
  • B. D. Taras
  • C. A. Stricker
  • L. D. Rea
  • T. M. O’Hara
  • A. P. Cyr
  • S. McDermott
  • T. M. Loomis
  • B. S. Fadely
  • M. B. Wunder
Community ecology – original research


Detailed information on the nutrition of free-ranging mammals contributes to the understanding of life history requirements, yet is often quite limited temporally for most species. Reliable dietary inferences can be made by analyzing the stable carbon (C) and nitrogen (N) isotopic values (δ13C and δ15N) of some consumer tissues; exactly which tissue is utilized dictates the inferential scope. Steller sea lion (SSL) vibrissae are grown continuously without shedding and thus provide a continuous multi-year record of dietary consumption. We applied a novel kernel density approach to compare the δ13C and δ15N values along the length of SSL vibrissae with δ13C and δ15N distributions of potential prey species. This resulted in time-series of proportion estimates of dietary consumption for individual SSL. Substantial overlap in δ13C and δ15N distributions for prey species prevented a discrete species-scale assessment of SSL diets; however, a post hoc correlational analysis of diet proportion estimates revealed grouping by trophic level. Our findings suggest that adult female SSL diets in the western and central Aleutian Islands shift significantly according to season: diets contain a higher proportion of lower trophic level species (Pacific Ocean perch, northern rockfish, Atka mackerel and walleye pollock) in the summer, whereas in the winter SSL consume a much more diverse diet which includes a greater proportion of higher trophic level species (arrowtooth flounder, Kamchatka flounder, darkfin sculpin, Pacific cod, Pacific octopus, rock sole, snailfish, and yellow Irish lord).


Stable isotope Carbon Nitrogen Trophic Kernel density 



We would like to thank the field teams of the Alaska Department of Fish and Game (ADF&G) and the Marine Mammal Laboratory (MML) for collection of vibrissae from adult female Steller sea lions and the vessel crew of the R/V Norseman II for their support of this project. Analysis of stable isotopes in vibrissae was funded by NOAA through NA13NMF4720041 to ADF&G. We would like to thank Ocean Peace Inc. for their donation and shipment of fish samples to UAF, subsampled from their commercial fishery in the Aleutian Islands in 2013 and 2014. Prey stable isotope analysis was sponsored by the Cooperative Institute for Alaska Research with funds from the National Oceanic and Atmospheric Administration under cooperative agreement NA13OAR4320056 with the University of Alaska (LDR and TMO). Additional funding for analysis of prey was provided through an INBRE Undergraduate Summer Research Award to G. Johnson. We thank ADF&G for providing salary support and supplies for initial fish sampling, and the WTL for providing storage, sample processing facilities and equipment for chemical analyses. We thank E. Audette, M. Campbell, L. Correa, E. Decker, Z. Goeden, A. Grimes, J. Harley, G. Johnson, S. Kennedy and for assistance with subsampling tissues and the Alaska Stable Isotope Facility at UAF for analysis. We also thank A. Parnell for consultations regarding the adaptation of Bayesian SIMMs for time series diet modeling. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Steller sea lion vibrissae were collected under authority of MMPA permit #14326 and 18528 to MML and #14325 to ADF&G, and under ACUC protocols A-NW2010-4 and A-NW2013-2 to MML, 2010-14R to ADF&G, and 594759-2 to LDR. Collection of Atka mackerel and Pacific cod in NMFS Fisheries Management Area 543 was permitted under NOAA Letter of Acknowledgment (LOA): 2013-01.

Author contribution statement

LDR, CAS and MBW originally formulated the idea and developed methodology with ACD and BDT; LDR, BSF and TMO organized fieldwork and sample collection; ACD and BDT collaborated in data analysis model development, and ACD and BDT wrote the manuscript; all other authors provided editorial advice.

Supplementary material

442_2018_4173_MOESM1_ESM.pdf (2 mb)
Supplementary material 1 (PDF 2026 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • A. C. Doll
    • 1
  • B. D. Taras
    • 2
  • C. A. Stricker
    • 3
  • L. D. Rea
    • 2
    • 4
  • T. M. O’Hara
    • 5
  • A. P. Cyr
    • 6
  • S. McDermott
    • 7
  • T. M. Loomis
    • 8
  • B. S. Fadely
    • 9
  • M. B. Wunder
    • 1
  1. 1.Department of Integrative BiologyUniversity of Colorado-DenverDenverUSA
  2. 2.Alaska Department of Fish and Game, Division of Wildlife ConservationFairbanksUSA
  3. 3.US Geological Survey, Fort Collins Science CenterDenverUSA
  4. 4.Institute of Northern EngineeringUniversity of Alaska FairbanksFairbanksUSA
  5. 5.Department of Veterinary MedicineUniversity of Alaska FairbanksFairbanksUSA
  6. 6.College of Fisheries and Ocean SciencesUniversity of Alaska FairbanksFairbanksUSA
  7. 7.Alaska Fisheries Science CenterNational Marine Fisheries Service, NOAASeattleUSA
  8. 8.Ocean Peace IncAnchorageUSA
  9. 9.Marine Mammal Laboratory, Alaska Fisheries Science CenterNational Marine Fisheries Service, NOAASeattleUSA

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