The blue whale is the largest animal known to have lived – larger than any dinosaur or currently living animal. It can grow up to 33 m long (27 m long in the northeast Pacific) and weigh up to 150,000 kg. Despite its large size, the blue whale feeds almost exclusively on krill. Blue whales in the northeast Pacific are thought to spend their summers feeding off the coast of the U.S. and Canada, and their winters in the tropical and subtropical waters off of Mexico and Central America. The presence of mother and calf pairs off the Gulf of California from December to March suggests that blue whales may breed and calve in the winter, though no breeding ground has been identified and their mating habits are not known. Their lifespan is also not known.
There are 3 blue whale subspecies – the Northern Hemisphere blue whale, Antarctic blue whale, and pygmy blue whale. The populations in the eastern Pacific and the western and central Pacific are separate. Blue whales are widely distributed in most oceans, and can be found near the coast and far offshore. Their calls are some of the lowest frequency sounds produced by any animal, and can travel 100s or even 1000s of kilometres. These long range low frequency calls may allow solitary and widely dispersed blue whales to contact with one another.
Blue whale populations were depleted significantly by commercial whaling. They have no known predators, although they may occasionally be attacked by orcas. Threats to the blue whale include vessel strikes, entanglement in fishing gear, ocean noise, pollution and climate change.
|
Call Types |
Description |
Duration (seconds) |
Frequency Range |
Source Level (dB with reference to 1 micropascal) |
|---|---|---|---|---|
|
Long pulses, buzzes, rasps |
Multi-part calls |
10 to 30 |
15Hz to 40Hz |
155 to 188 |
Mysticeti
Mysticetes are some of the largest animals on Earth, and they eat some of the smallest animals in the ocean. Instead of teeth, mysticetes have flexible, hairy keratin plates called baleen. They take large gulps of water and filter it through their baleen, eating the plankton, krill and small fish left behind. They were heavily hunted in the 17th to 20th centuries for oil, and their baleen had many uses, including collar stiffeners and corset stays. Many mysticetes are migratory. 7 of the 15 Mysticeti species inhabit the eastern North Pacific. Some mysticete species may be threatened by climate change, because some species depend heavily on plankton as a food source; plankton abundance and distribution is affected by changes to the ocean associated with climate change.
Ocean Networks Canada has recorded the following Mysticete species:
- Humpback Whale
- Grey Whale
- Fin Whale
- Blue Whale
