Longevity and Aging
- Walruses live up to 40 years.
- As a walrus ages, it periodically produces growth layer groups of dental material. Age can be estimated by examining a sliced section of a cheek tooth and counting these layers.
- Polar bears occasionally prey on walrus calves and probably eat dead walruses. Walruses are not a main part of the polar bears' diet.
- Killer whales may prey on walrus calves and injured adults.
- Walruses have been hunted commercially for their meat, skin, and ivory tusks by traders from Norway, Russia, Great Britain, Greenland, Canada, and the United States. Since the mid-1800s walrus populations have been severely depleted and allowed to recover three times. Researchers attribute this cycle of exploitation to a lack of communication and monitoring of harvests between the nations. Going largely unnoticed, many walrus populations were nearly wiped out before efforts were made to preserve them. Most walruses are hunted at sea.
- Indigenous Arctic peoples of the U.S., Canada, Greenland, and Russia subsistence hunt walruses for their meat, hide, ivory (from the tusks), and other raw materials.
- Walrus hunts are an important part of the culture and tradition of many indigenous Arctic cultures.
- The combined U.S. and Russian subsistence harvest of walruses has averaged about 7,334 walruses per year for the past 40 years.
- In Alaskan waters, subsistence take has significantly decreased to an average of 4,869 per year since the 1990's. Scientists estimate that, each year, an average of 42% of walruses that are struck by bullets are lost before they can be recovered by hunters. With this struck and lost percentage factored in, Alaskan walrus mortality due to hunting averages 5,794 walruses per year
Disease and Parasitism
Walruses are susceptible to a number of viruses, internal and external parasites, and to microbial infections of the skin and internal organs.
Intraspecific Causes of Death
- Many males die annually from injuries incurred while fighting during breeding seasons.
- Calves may be accidentally crushed by adults.