The bowhead whale is a large whale found in the Artic, and the largest population, the Bering-Chukchi-Beaufort Seas (BCBS) stock, migrates between the eastern Beaufort Sea-Amudsen Gulf in summer and the Bering Sea in the winter. The population of this stock is estimated to be 8,200 and is gradually recovering from commercial hunting pressures in the late 1800's and early 1900's at an annual 3.2% rate of population increase (1). A number of anthropogenic factors have probably played a role in the decline of the bowhead whale population and may be having an impact on its recovery.
However, studying bowhead whale reproductive systems is complicated by the absence of any bowhead whale experimental models. At the start of this project, the only bowhead-specific experimental model was a cell line from bowhead kidney. Cell lines from bowhead ovary and testis did not exist. Thus, it was not possible to directly study the effects of contaminants on bowhead reproductive organs.
To create the cell lines needed to build an experimental model, each fall the Wise Laboratory makes a trek to Barrow for several weeks of field work collecting tissues and developing new cell lines. This work is possible because of many collaborators and cooperators who allow the Laboratory to attend the fall hunts of bowhead whales conducted by the natives. The hunters have been kind enough to provide the Laboratory with tissue samples from the organs of a number of individual whales that have now been developed into cell lines. Using these cell lines, investigations can be done that will allow study of the effects of contaminants on bowhead testis and ovaries.
Bowhead whales are considered perhaps the best animal to compare with right whales, a species that is severely endangered (see ), because they are more closely related to each other than they are to any other marine mammal (2, 3). Thus these studies have important implications for right whales as well.
With the data obtained from these efforts, we will be able to determine: 1) which classes of contaminants damage the reproductive organs of bowhead whales; 2) the sensitivity of reproductive organs compared to somatic tissues (lung and skin); and 3) how bowhead cells compare to right whale cells. Furthermore, this proposal investigates cell lines from animals of different age classes (adult and sub-adult), different genders and multiple individuals from both species.
This work will help us to begin to understand the intra-species differences (age, sex and individual) in the response to the genetic effects of environmental contaminants by using cell lines from each animal. We will also look at the differences between reproductive and somatic tissues.
This study will greatly enhance our knowledge of the physiology and toxicology of the right whale. Moreover, it will create tools (cell lines) that can serve as right whale-specific models, which can be used by other investigators to better understand additional aspects of right whale genetics, physiology, immunology and biochemistry, as well as investigations into the effects of other contaminants and infectious agents.
Cell lines have been created from 20 bowhead whales and immortalization of these cells is progressing. The first banded karyotype for bowhead whale has been established, which will help identify individuals genetically as well as possibly suggest abnormalities that might impair reproduction or offspring success.
Preliminary experiments have been conducted determining the cytotoxic effects of several contaminants. There are clear patterns that the cytotoxicity varies by organ with some organs much more sensitive than others. In addition, a preliminary risk assessment list has been started that indicates that antifouling agents are more toxic than anticorrosives, which are more toxic than mercury, which is more toxic than radionuclides. These preliminary data are being confirmed and evaluations of flame retardants and PAHs are currently being started.
- Raftery, AE, and Zeh, JE. Estimating Bowhead Whale Population Size and Rate of Increase from the 1993 Census. Journal of the American Statistical Association 93: 1-13, 1998.
- McLeod, S.A., Whimore, Jr., F.C., Barnes, L.G. "Evolutionary Relationships and Classification" in The Bowhead Whale, Burns J.J., Montague, J.J., and Cowles, C.J. (eds.). Allen Press, Inc. Lawrence Kansas.
- Rice, D., Marine Mammals of the World - Systematics and Distribution, Special Publication Number 4, The Society of Marine Mammalogy, 1998.
Wise, Sr. J.P., Wise, S.S, Kraus, S. Shaffiey, F., Grau, M., Li Chen, T., Perkins, C., Thompson, W.D., Zheng, T., Zhang, Y., Romano, T., and O’Hara, T. Hexavalent Chromium Is Cytotoxic and Genotoxic to the North Atlantic Right Whale (Eubalaena glacialis) Lung and Testes Fibroblasts. Mutation Research. 650: 30-38, 2008.
The Wise Laboratory is assisted in this work by an important number of collaborators and cooperators. In particular, the following prominent scientists and their teams provide significant support and input:
Dr. Scott Kraus is Vice President of Research at the New England Aquarium. He also operates the research field station in Lubec, Maine. He provides expert advice and guidance on North Atlantic right whales and access to samples.
Dr. Tracy Romano is the Vice President of Research and Veterinary Services, Mystic Aquarium & Institute for Exploration. She provides expert advice and guidance on the immune system in marine mammals.
Dr. Todd O'Hara is a researcher with the Institute of Arctic Biology at the University of Alaska, Fairbanks. He provides expert advice and guidance on bowhead whales and helps with access to the field station in Barrow, Alaska.
Dr. Yawei Zhang is an Assistant Professor of Epidemiology and Public Health at Yale University. She provides expert advice and guidance on the statistical analysis and epidemiological design of marine mammal studies.
Dr. Tongzhang Zheng is Professor of Epidemiology and Public Health and Head of the Environmental Health Sciences Division at Yale University. He provides expert advice and guidance on the statistical analysis and epidemiological design of marine mammal studies.
This work was generously supported by grant number NA03NMF4720478, "The Genetic Effects of Environmental Contaminants on the Reproductive Systems of the North Atlantic Right Whale (Eubalaena glacialis)" from the National Marine Fisheries Service of the National Oceanic and Atmospheric Administration and by the Maine Center for Toxicology and Environmental Health.