| A western North Pacific gray whale spyhops off Sakhalin Is., Russia. This project will help characterize potential genetic differences between PCFG and other gray whale populations like the ENP and WNP. Image credit: Craig Hayslip. |
PI: Dr. Daniel Palacios, Whale Habitat, Ecology, and Telemetry Lab (WHET Lab)
Collaborators: Dr. Scott Baker and Debbie Steel, Cetacean Conservation and Genomics Lab (CCGL)
For further information please contact project PI Daniel Palacios.
The gray whales we call “summer residents” along the Oregon coast are part of a small population of around 230 animals (Calambokidis et al. 2020) known as the “Pacific Coast Feeding Group” (PCFG). During winter months these PCFG gray whales migrate south to the warm lagoons in Baja California, Mexico, to breed and calve. But in summer months they end their northbound migration in the Pacific Northwest, where they feed in shallow waters from northern California to Southeast Alaska (Lagerquist et al. 2019), while the larger population, known as Eastern North Pacific (ENP) gray whales and most recently estimated at about 14,500 animals in the 2022/2023 season (Eguchi et al. 2023), continues their migration to the Arctic. Yet a third group of around 200 animals and known as the Western North Pacific (WNP) population feeds off the Russian coast in the Sea of Okhotsk (Mate et al. 2015). While structure of and relationships between these three populations is complex and continues to be revised (Lang et al. 2022), one of the main outstanding questions about PCFG gray whales is whether their population is genetically differentiated and demographically independent from both the ENP and WNP gray whale populations, which could warrant separate management status (International Whaling Commission 2012, Weller et al. 2013). A recent study has shown that gray whales of the PCFG population are significantly smaller than whales of the ENP population (Bierlich et al. 2023).
In the autumn months between 2009 and 2013, we deployed satellite tags on 35 PCFG gray whales off central Oregon and northern California to track their movements over long periods of time. The tags provided a wealth of new information about the movements of PCFG whales (Mate 2013, Mate et al. 2014, Lagerquist et al. 2019). For 25 of the tagged whales, we also obtained a small sample of skin and blubber tissue using a biopsy dart for various analyses. In April 2022, we received funding from MMI's Oregon Gray Whale License Plate Program to construct genetic profiles for the 25 archived skin samples, with the goal of helping refine our understanding of the movements and migratory strategies of the tagged whales using genetics and photo-identification resight information. In this page we provide an overview of the project and its main results.
In collaboration with the Cetacean Conservation and Genomics Lab (CCGL), the goal of this project is to generate complete genetic profiles for the 25 tagged PCFG gray whales for which we have archived skin samples. The genetic profile consists of: (a) sex identification; (b) mitochondrial DNA haplotype, defined by 522 base pairs from LeDuc et al. (2002); and (c) microsatellite genotypes for individual identification and parentage analysis (maternity or paternity), following genomic methods consistent with those implemented by Lang et al. (2022) on WNP and ENP samples. Combined with tagging data, we can refine the question of population differentiation and also ask, for example, whether genetic relationships reflect how different individuals move and where they spend most of their time.
This DNA register, although initially just for the 25 tagging samples, is anticipated to grow and become a valuable resource as samples of PCFG gray whales continue to be submitted to CCGL. The DNA register will be available to the scientific community, particularly within the PCFG Consortium. Ultimately, this new knowledge will provide another line of evidence for helping refine our understanding and possible designation of this subpopulation as a differentiated stock, which could have significant management and conservation implications.
As of December 2022, all 25 samples have been genetically sexed (12 females and 13 males), and we have obtained the mitochondrial DNA (mtDNA) haplotype for 23 of them. We hope to re-run the two samples that did not initially yield a haplotype in January 2023.
A mtDNA haplotype is an identifying marker that is maternally inherited, so within a population, whales with the same haplotype are more closely related than those with different haplotypes. To learn more about the spatial and temporal patterns of movement of the tagged PCFG whales, we have generated the set of two maps below, showing animations of the tracks of the tagged animals colored by their individual mtDNA haplotype.
Genotyping the microsatellite loci is also underway, and we look forward to providing another project update as soon as we have new results.
The animation on the left shows the tracks of 10 of the satellite-tagged having haplotypes from A to H, representing six unique mtDNA haplotypes.
Among these whales are well-known individuals off the Oregon coast, including "Rat", "Boomerang", "Moby Dick", "Stamp", and "Harry". Immediately after tagging, the two whales with the same A haplotype (both male) appeared to feed in the same general area south of HMSC, with one ultimately migrating south to Baja California for the winter, where its tag deployment ended. The other whale (Rat) actually never migrated to the breeding lagoons, even though it was tracked for over a year!
Animation created by WHET Lab member Michaela Kratofil.
The animation on the left shows the tracks of 11 of the satellite-tagged having haplotypes from K to T, representing six unique mtDNA haplotypes.
This indicates that of the 23 samples analyzed so far, 12 have a unique haplotype, which is a high diversity.
Animation created by WHET Lab member Michaela Kratofil.
FUNDING
The tissue samples were collected during tagging activities sponsored by ONR, IWC, IUCN, Navy Fleet Command, Exxon Neftgas, and private donors to the Marine Mammal Institute Endowment. This project is funded by the Marine Mammal Institute's Oregon Gray Whale License Plate Program. We deeply appreciate the support of the Oregonians who purchased or renewed their Coastal Playground license plate!
REFERENCES
Bierlich, K. C., Kane, A., Hildebrand, L., Bird, C. N., Ajo, A. F., Stewart, J. D., Hewitt, J., Hildebrand, I., Sumich, J. & Torres, L. G. (2023). Downsized: gray whales using an alternative foraging ground have smaller morphology. Biology Letters, 19(8), 20230043. https://doi.org/10.1098/rsbl.2023.0043.
Calambokidis, J., Laake, J. & Perez, A. (2020). Updated analysis of abundance and population structure of seasonal gray whales in the Pacific Northwest, 1996-2017. Paper SC/A17/GW/05SC/68B/ASI01 presented to the International Whaling Commission Scientific Committee Annual Meeting, 12–24 May 2020, virtual. 73pp.
Eguchi, T., A. R. Lang, and D. W. Weller (2023). Abundance of eastern North Pacific gray whales 2022/2023. U.S. Department of Commerce, NOAA Technical Memorandum NMFS-SWFSC-680. https://doi.org/10.25923/n10e-bm23.
International Whaling Commission. (2012). Report of the Scientific Committee. Journal of Cetacean Research and Management (Suppl.) 13.
Lagerquist, B.A., D.M. Palacios, M.H. Winsor, L.M. Irvine, T.M. Follett, and B.R. Mate. (2019). Feeding home ranges of Pacific Coast Feeding Group gray whales. Journal of Wildlife Management 83(4):925-937. https://doi.org/10.1002/jwmg.21642.
Lang, A. R., Weller, D. W., Burdin, A. M., Robertson, K., Sychenko, O., Urbán, J., Martínez-Aguilar, S., Pease, V. L., LeDuc, R. G., Litovka, D. I., Burkanov, V. N., & Brownell, R. L. (2022). Population structure of North Pacific gray whales in light of trans-Pacific movements. Marine Mammal Science 38(2):433-468. https://doi.org/10.1111/mms.12875.
LeDuc, R. G., Weller, D. W., Hyde, J., Burdin, A. M., Rosel, P. E., Brownell, R. L. J., Würsig, B., & Dizon, A. E. (2002). Genetic differences between western and eastern gray whales (Eschrichtius robustus). Journal of Cetacean Research and Management, 4(1): 1–5. https://doi.org/10.47536/jcrm.v4i1.860.
Mate, B. (2013). Offshore Gray Whale Satellite Tagging in the Pacific Northwest. Prepared for Commander, U.S. Pacific Fleet, Pearl Harbor, Hawaii. Submitted to Naval Facilities Engineering Command Northwest (NAVFAC NW), Silverdale, WA 98315-1101, under Contract # N62470-10-D-3011, issued to HDR Inc., San Diego, California 92123. 18 June 2013.
Mate, B. R., Ilyashenko, V. Y., Bradford, A. L., Vertyankin, V. V., Tsidulko, G. A., Rozhnov, V. V., & Irvine, L. M. (2015). Critically endangered western gray whales migrate to the eastern North Pacific. Biology Letters 11(4), 20150071. https://doi.org/10.1098/rsbl.2015.0071.
Mate, B., L. Irvine, and T. Follett. (2014). Offshore Gray Whale Satellite Tagging in the Northwest Training Range Complex (NWTRC). Prepared for Commander, U.S. Pacific Fleet, Pearl Harbor, Hawaii. Submitted to Naval Facilities Engineering Command Northwest (NAVFAC NW), Silverdale, WA 98315-1101, under Contract # N62470-10-D-3011, issued to HDR Inc., San Diego, California 92123. June 2014.
Stewart, J.D. and D.W. Weller. (2021). Abundance of eastern North Pacific gray whales 2019/2020. U.S. Department of Commerce, NOAA Technical Memorandum NMFS-SWFSC-639. https://doi.org/10.25923/bmam-pe91.
Weller, D.W., S. Bettridge, R.L. Brownell Jr., J.L. Laake, J.E. Moore, P.E. Rosel, B.L. Taylor, and P.R. Wade. (2013). Report of the National Marine Fisheries Service Gray Whale Stock Identification Workshop. U.S. Dep. Commer., NOAA Tech. Memo. NOAA-TM-NMFS-SWFSC-507. https://repository.library.noaa.gov/view/noaa/4463.
Background image credit: Craig Hayslip
