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Body condition of gray whales (Eschrichtius robustus) feeding on the Pacific Coast reflects local and basin-wide environmental drivers

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Akmajian, Adrianne M, Scordino, Jonathan J, Gearin, Patrick J, Gosho, Merrill·2021·J. Cetacean Res. Manage.
DOI 10.47536/jcrm.v22i1.223
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Abstract

A small subset of the Eastern North Pacific gray whale population does not make the full migration from wintering grounds in Mexico to feeding grounds in the Bering, Chukchi and Beaufort seas and instead feed along the Pacific Coast between northern California and northern British Columbia – this group is known as the Pacific Coast Feeding Group (PCFG). We evaluated the body condition of PCFG whales observed in northern Washington and along Vancouver Island to evaluate how body condition of gray whales changes within and between years. We found that PCFG gray whales improve body condition through the feeding season and at varying rates by year and that they have variability in their body condition at the start and end of each feeding season. The inclusion of environmental factors, particularly the Pacific Decadal Oscillation (lagged two years) and September kelp canopy cover along the Washington coast (lagged one year), drastically improved the ability of a multiple regression model to predict average whale body condition for a given year as compared to models without environmental factors included. A comparison of our findings to a previously published study on body condition of gray whales at Sakhalin Island, Russia highlight the differences of life history strategy between a group of whales with a long migration (Sakhalin whales) and those with a short migration. Whales feeding at Sakhalin Island gain body condition quicker and more predictably to a good body condition by the end of the feeding season than the whales we studied in the PCFG. Photogrammetry may be an effective method for monitoring the effects of climate change on PCFG gray whales.

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  • Body condition of Pacific Coast Feeding Group gray whales was found to be variable by year and improves through the feeding season, but not at the same rate every year.

    “Body condition was found to be variable by year and improves through the feeding season, but not at the same rate every year.”

    From Update on the status of gray whales since the 2020 Implementation Review (2024) · cites this paper as Akmajian et al., 2021

  • Accounting for environmental factors, particularly the Pacific Decadal Oscillation, significantly improved the ability of regression models to predict body condition in a given year.

    “Accounting for the impact of environmental factors, particularly the Pacific Decadal Oscillation, significantly improved the ability of regression models to predict body condition in a given year.”

    From Update on the status of gray whales since the 2020 Implementation Review (2024) · cites this paper as Akmajian et al., 2021

  • Kelp canopy cover is positively correlated with gray whale body condition in Washington.

    “Kelp canopy cover is positively correlated with gray whale body condition in Washington (Akmajian et al., 2021).”

    From Update on the status of gray whales since the 2020 Implementation Review (2024) · cites this paper as Akmajian et al., 2021

  • The rate of improvement in body condition during the feeding season was much greater for whales feeding at Sakhalin than PCFG whales, suggesting better quality or availability of prey at Sakhalin Island.

    “(2) the rate of improvement in body condition during the feeding season was much greater for whales feeding at Sakhalin than PCFG whales, suggesting better quality or availability of prey at Sakhalin Island.”

    From Update on the status of gray whales since the 2020 Implementation Review (2024) · cites this paper as Akmajian et al., 2021

  • The years of better and worse body condition were not the same for the Sakhalin and PCFG study areas.

    “Akmajian et al. (2021) compared their results to Bradford et al. (2012) and drew the following conclusions: (1) the years of better and worse body condition were not the same for the two study areas”

    From Update on the status of gray whales since the 2020 Implementation Review (2024) · cites this paper as Akmajian et al., 2021

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Cited by

Sorted by citations

Authors
Akmajian, A. M., Scordino, J. J., Gearin, P. J., & Gosho, M.
Affiliations
NOAA National Marine Fisheries Service (US)
ORCID
Akmajian, Adrianne M
Venue
J. Cetacean Res. Manage.
Publisher
International Whaling Commission
Published
2021-12-10
Volume
22
Issue
1
Pages
87-110
ISSN
  • 1561-073X (ISSN-L)
  • 2312-2706
  • 1561-0713
DOI
10.47536/jcrm.v22i1.223
OpenAlex
W4200270951
Cited by
16
References
0
Citations by year
2026: 1 · 2025: 2 · 2024: 8 · 2022: 4 · 2021: 1
FWCI
1.76
Type
journal article
Language
en
Open access
Licence
Locations
  • The journal of cetacean research and management. Special issue (publishedVersion, cc-by-nc)
  • NOAA Institutional Repository (submittedVersion, cc-by-nc)
Funders
  • National Oceanic and Atmospheric Administration
  • Pacific Islands Fisheries Science Center
Topics
  • Physical Sciences › Environmental Science › Ecology › Marine animal studies overview
  • Physical Sciences › Environmental Science › Global and Planetary Change › Marine and fisheries research
  • Physical Sciences › Environmental Science › Ecology › Wildlife Ecology and Conservation
Keywords
gray whale, body condition, feeding season, Pacific Decadal Oscillation, environmental drivers, migration strategies, photogrammetry, climate change, Northeast Pacific

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