Longevity & Causes of Death

Baleen Whales

Longevity & Causes Of Death

Longevity

  1. Longevity for most baleen whales is unknown. Some researchers have estimated that blue whales may live 30 to 90 years, fin whales may live 90 to 100 years, and sei whales may live as long as 60 years.

Aging Studies

  1. Research on baleen whale aging is ongoing. The absence of teeth (which can be used to approximate age in toothed whales and many other mammals) makes age estimation difficult.
  2. Researchers are analyzing growth patterns on baleen plates and on the waxy ear plug of baleen whales in an effort to find a reliable method for estimating age.

Predators

  1. Killer whales prey on baleen whales. Working together, a group of killer whales can successfully attack a baleen whale much larger than themselves.
    • A 1985 study in one particular region near the Antarctic suggests that minke whales make up 85% of the killer whales' diet there.
    • Teeth scars on some baleen whales' flippers and flukes are evidence of killer whale attacks.
  2. Large sharks may prey on some baleen whales, particularly those that are ill, injured, or very young.
  3. The small (38 cm, or 15 in.) cookiecutter sharks use suction to attach themselves to whales, then they carve out a circular core of flesh with their large triangular teeth.

Commercial Whaling

  1. The commercial whaling industry began to expand in the 12th century.
    • Whale oil was used for lighting, heating, and lubrication; as a base for the manufacture of soaps and paints; and in processing textiles and rope.
    • Baleen was used to make corset stays, umbrella ribs, fishing rods, buggy whips, carriage springs, skirt hoops, brushes, and nets.
  2. Early whaling efforts focused on species of the right whale family.
    • The right whale family was so named because whalers considered these whales the "right" whales to harvest. Whales in this family were best for harvesting because have immense amounts of blubber and long baleen; they are slow swimmers; they are coastal species; and their bodies float when dead.
    • As the right whales became overhunted, the whaling industry sought out more numerous species to harvest.
  3. Whaling methods and equipment improved in the 19th and 20th centuries.
    • Improved weapons and boats made it possible for whalers to hunt faster species such as humpback, blue and fin whales.
    • Modern harpoons, explosives, and factory-type processing ships made whaling more efficient and resulting in greater numbers of whales killed.
    • Demand for whale oil and baleen decreased because alternatives were available, but demand for whale meat increased.
    • By the 1960s, blue whales were nearly extinct, and fin whales had also been overhunted. Whalers turned their attention to sei whales. When sei whales became severely depleted in the 1970s, minke and Bryde's whales became target species. All the larger species had become depleted due to overhunting.
    • For the most part, commercial whaling ended by the 1980s, but most whale populations have yet to recover.

Indigenous And Small-Scale Whaling

  1. Indigenous peoples from various coastal areas hunt some species of baleen whales for subsistence. For instance, people in coastal arctic villages hunt small numbers of bowhead whales, minke whales, and gray whales.

Environmental Hazards

  1. Baleen whales may be harmed by entanglement in fishing gear, heavy boat traffic, pollution, and competition with humans for food resources.
  2. Baleen whales in polar areas may become entrapped in ice.

Disease

  1. As in any animal population, a variety of diseases can be responsible for baleen whale deaths.