photo: Greg O'Corry-Crowe
The beluga, or white whale (Delphinapterus leucas), is one of the most recognizable of cetaceans. A medium-sized member of the Ondontocetes, or toothed whales, belugas can grow to 2 tonnes in weight and over 16 feet in length. Known best for the pure white color of adult individuals and their diverse vocal repertoire, earning them the title of "canary of the sea", beluga whales are remarkable for many reasons. Highly social, belugas can form groups of as little as two or three individuals to herds that number in the thousands. They are supremely adapted to their arctic and sub-arctic environment. A thick layer of blubber and the presence of a tough dorsal ridge instead of a fin to name a few.
Beluga whales have a circumpolar distribution, and, worldwide, may number in the hundreds of thousands. However, some local populations are small, numbering in the low hundreds, while past commercial hunting lead to a loss of range. Beluga whales are an important resource for many native peoples throughout coastal Alaska and the Arctic and management objectives are concerned with maintaining the species range while ensuring beluga whales remain a sustainable subsistence resource.
Until recently, beluga whales were considered denizens primarily of the continental shelf waters that skirt the entire arctic, adapted to a life in these shallow, highly productive seas. It was also believed that their northerly movements were restricted by the permanent arctic ice cap. Recent research and documentation of Native knowledge has dramatically altered our views.
In collaboration with many institutions and agencies, including the Alaska Beluga Whale Committee and the Department of Fisheries and Oceans, Canada, we have conducted molecular genetic research on beluga whales throughout the Arctic for over a decade. Concentrating on belugas in the Bering, Chukchi and Beaufort Seas, and the Gulf of Alaska, the analysis of variation in multiple genetic markers has revealed much about the dispersal patterns, breeding behavior and social organization of this species. Analyses of variation within the maternally inherited mitochondrial genome (mtDNA) indicated that geographically separate summering groups were in fact demographically discrete sub-populations, and as such should be managed as separate stocks (O’Corry-Crowe et al., 1997, 2002). We were also able to reconstruct the migration routes of some of the large arctic stocks, revealing in one instance that the large sub-population of whales that summers in the eastern Beaufort Sea in Canada's far northwest, also spends part of the year in both Alaskan and Russian coastal waters.
We have also conducted satellite telemetry studies with a number of research groups in Alaska, Canada, Russia and Norway. Working from research vessels and remote field camps, this research involves catching belugas and attaching satellite-linked transmitters to their dorsal ridge. These tags, which communicate with polar orbiting satellites, have yielded a wealth of information about movement patterns and dive behavior. For example, belugas that summer along Alaska's Chukchi Sea coastline migrate hundreds of kilometers further north through the permanent polar ice cap and have been recorded making deep dives off the continental slope (Suydam et al., 2001; R.S. Suydam, unpubl.).
We have successfully combined the two disciplines of molecular genetics and satellite telemetry to reveal that the ecology of beluga whales in different regions differs greatly. Our findings have forced us to revise our ideas about this species greatly. These data are now being integrated with those of other scientific studies and with Traditional Ecological Knowledge to help us design better management strategies for this species.
O'Corry-Crowe GM, Suydam RS, Rosenberg A et al. (1997) Phylogeography, population structure and dispersal patterns of the beluga whale Delphinapterus leucas in the western Nearctic revealed by mitochondrial DNA. Molecular Ecology6, 955-970.
O'Corry-Crowe GM, Dizon AE, Suydam RS, Lowry LF. (2002). Molecular genetic studies of population structure and movement patterns in a migratory species: the beluga whales (Delphinapterus leucas), in the western Arctic. In Molecular and Cell Biology of Marine Mammals (C.J. Pfeiffer, ed.). Kreiger Publishing Co., Malabar. pp 53-64.
Suydam, R.S., Lowry, L.F., Frost, K.J., O'Corry-Crowe, G.M. and Pikok, D.Jr. (2001) Satellite tracking of eastern Chukchi Sea beluga whales in the Arctic ocean. Arctic, 54(3): 237-243.