GEO119 Pacific Walrus: Odobenus Rosmarus Divergens

Pacific walrus (Odobenus rosmarus divergens)
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Pacific walrus (Odobenus rosmarus divergens)
Pacific walrus (Odobenus rosmarus divergens) is a marine mammal, endemic to the continental shelf waters of Bering and Chukchi seas. Their distribution relies heavily on the water depth as well as the sea ice characteristics. Pacific walrus is a keystone species and therefore plays a significant ecological role in its habitat. They are the primary consumers in the benthic community and control the nutrient flux within the benthic zone. It is difficult to establish the actual population of the walrus due to their habitats which are remote and difficult to access and for the fact that they spend most of their time underwater. However, researchers have estimated their populations over the past two centuries based on their distribution, actual census as well as the level of harvest.
The population trend of this mammal has been fluctuating according to the various researches done from the 1700s, with the declines occurring from the 1800s. The most recent research conducted by the former Soviet Union together with the US states an estimated population of 200,000 individuals. The Pacific walrus population has over the years been affected by natural factors such as predation, disease, and parasites, stamping during stampedes, the sex ratio among other natural factors. However, the observed decline in population that is likely to persist in the future can be attributed to both direct and indirect human impacts.
Over the years, there has been subsistence hunting of walrus by the native communities in Alaska and Russia. The intensity of hunting increased in the mid-1800s with the introduction of commercial hunting of walrus oil, hides, and ivory. The hunters have introduced new hunting methods such as shooting with rifles, which frequently kill the easily available females leaving this mammal population in danger. Overexploitation as a direct human impact is likely to be a possible threat to the future population of the Pacific walrus. The overexploitation has not only been for commercial purposes, but also for recreation, education and research purposes.
Direct human disturbance of the Pacific walrus habitats is another factor that is likely to threaten their population in the future, as it interferes with their mating and foraging ground. This may be through oil spill...