Migration of Blue Whales

Why do they migrate and what threats do they face during their migration?

Blue Whales and Why They Migrate

Blue whales (Balaenoptera musculus) are the great giants of the sea, weighing up to 200 tons and measuring up to 100 feet long  [1] . These endangered mammals can live between 80 to 90 years! Their diet mainly comprise of krill (small crustaceans) and can eat up to 4 tons of krill a day  [1] .

Watch a blue whale eat some krill!

Blue whales migrate seasonally for food and to find places for calving and nursing  [2] . Summer is when the production of zooplankton (krill included) is at its highest, so they would travel to the poles in the spring to make it for peak production and leave for the equator by early winter  [2] . Some groups travel shorter distances while others would anually travel between the poles and the equator  [2] .

Blue whale reported sightings along Pacific Coast. These sightings are along the migration path for blue whales!

Current Threats to Blue Whales

Blue whales are currently on the endangered species list  [1]  . Although the population of blue whales is still recovering from aggressive hunting in the 1900s for whale oil that nearly drove blue whales to extinction, human activities are the reasons why their population recovery is slow  [1]  .

A reoccurring threat that blue whales face during their migration journey is being struck by vessels. Shipping ports and shipping paths have grown exponentially which means there is overlap between the paths of shipping vessels and blue whales. The map below shows a visualization of this overlap along the Pacific Coast.

Distribution of blue whale sightings compared to the ports, shipping zones, and zones that vessels are told avoid on the Pacific coast.

Other threats to blue whales include  [3] :

  • Getting caught in fishing gear
  • Ocean noise
  • Habitat degradation
  • Pollution
  • Climate change

Despite these threats that they currently face, there have been huge conservation efforts to protect the blue whales! From laws to new technology to address these threats, there is still hope for the blue whale population to bounce back.

What can I do?

After reading through, you may have questions of how you can help and whether your efforts would be enough. Spoiler alert: there are many ways to help and every little bit helps towards conservation efforts to protect the blue whales!


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