The fin whale is the second largest animal on Earth, next to the blue whale. Fin whales can be up to 27m long and weigh up to 80,000kg, though fin whales in the Northern Hemisphere are slightly smaller. They can live for 100 years or more. Fin whales live in all oceans, with preference for temperate and polar latitudes. Most fin whales appear to be migratory, spending the spring and summer in feeding in higher latitudes and travelling to lower latitudes. A few non-migratory populations of fin whales exist, such as those in the Gulf of California and the Mediterranean Sea. Fin whales in the northern and southern hemispheres do not spend the same months nearer the equator, and so do not interact. Their colouration is asymmetrical; the left side of their lower jaw is dark while the right side is light. This unique asymmetry is reversed on their tongues. Fin whales are usually seen in social groups of 2-10 individuals, and may be seen in groups numbering nearly 250 individuals during migrations and near feeding grounds. Despite this, long term bonds between individuals seem to be rare.

Fin whales are very fast. They can cruise at 37kmph, and sprint up to 40kmph. Their speed, along with their low numbers and preference for offshore waters, makes them difficult to study. No mating grounds have been found, and it is possible that they do not have specific mating grounds. They appear to mate from November to January. Migratory fin whales give birth in tropical and subtropical areas in midwinter. They are capable of interbreeding with blue whales, and fin-blue whale hybrids have been documented.

Predators of fin whales include humans and orcas. They were hunted nearly to extinction by humans in the 20th century, and are the most reported as struck by vessels of the large whale species. Their threats include entanglement, climate change, overfishing, habitat degradation, high power sonar, vessel strikes and anthropogenic noise.

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 17^th to 20^th 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