Grays, Humpbacks, and Blues (Oh My!)

By Audrey Evans, Education Specialist

While the number of gray whales sighted this season has reached 424, we have also been seeing an increasing number of other baleen whales as well. To date we have seen 14 humpback whales and 2 blue whales for the 2015-16 season. While not uncommon off our coast, both species are not frequently spotted from the Marietta in winter. To give some perspective, during our regular whale watching season (which spans December through April each year), we spotted 11 humpback whales last season and only 2 the year before. Blue whales were an even more uncommon sight as we didn’t see any last season and only one the season before.

In the case of humpback whales, they are similar to gray whales in that feeding and breeding drives migration. Like the gray whales, most northern hemisphere humpbacks feed in summer months in northern latitudes and breed in warmer tropical or subtropical waters during winter. Instead of being strictly coastal migrators like gray whales, north Pacific humpbacks may cross thousands of miles of open ocean to breed in Hawaii, Mexico, or Japan. Humpbacks are found throughout the world’s oceans and in both northern and southern hemisphere. Gray whales are found only in the northern hemisphere Pacific ocean.

Blue whale off San Diego (July 2012).

Blue whales occur much more offshore than gray whales. Though a number of blue whales can increasingly be found in recent years off the San Diego coast in summer, it is much more rare to see them here in winter. In summer blue whales feed on large aggregations of krill which they filter out of the water column using their baleen. Like other baleen whales, blue whales migrate between summer and winter but research suggests some populations stay in one place year-round. Blue whale migration is not as well understood and distribution appears to be driven by food requirements. We find them in areas where krill can be highly concentrated.

Some stats from our whale watching archives: 

Blue whales: 

  • 0 in 2014/2015
  • 1 in 2013/2014
  • 5 in 2012/2013
  • 0 in 2011/2012

Humpback whales: 

  • 11 in 2014/2015
  • 2 in 2013/2014
  • 18 in 2012/2013
  • 13 in 2011/2012

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Scripps Institution of Oceanography UC San Diego