Whale Alert – West Coast

Whale Alert – West Coast

Humpback whale

Megaptera novaeangliae

Humpback whales are known for their alluring songs, extraordinary feats of agility, long migrations, and for their original style of feeding.  They are the most acrobatic of all the large whales and will often breach, spy hop, lob tail, flipper wave, and tail wave.  A breach can even become a full summersault with several breaches following in quick succession.

Conservation status

Appearance

One distinguishing characteristic of the humpback whale are its wing-like pectoral fins that are long, narrow, and about one third of its body length.  They have knoblike bumps called tubercles that are located along the front edge of the pectoral fin and also on the lower lip and rostrum.  There is a single ridge that runs from the blowhole to the snout and 14-35 throat pleats that extend to the navel.  Its dorsal fin can be rounded or slightly bent and the tail is wide and scalloped with a serrated rear edge.  The blow is moderate to low at 3 m (10 feet) and can appear V– or heart-shaped.  Its back is black to dark gray with an underside that can be pale white to mottled to all black.  They range from 12 – 13 m (39 – 42 feet) and weigh 30,000 kg (33 tons), with females being larger.

Distribution and migration

Humpback whales are found in all the world’s oceans and undertake one of the largest migrations of any mammal.  There are three separate populations in the Pacific Ocean that are distinguished by their winter to spring migrations.  The eastern north Pacific stock migrate from Washington to Baja, the central north Pacific stock from Alaska and British Columbia to Hawaii, and the western north Pacific stock from the Bering Sea to Japan and the Philippines.  Each of these three populations occur in the California Current; however, the eastern north Pacific stock is dominant, spending spring, summer, and fall feeding in coastal waters from Washington to California.  This population spends time off Mexico and Costa Rica at its calving grounds in the winter.  As they head north for the summer to their primary feeding grounds in Alaska, pregnant females, non-pregnant females, and males lead the way, followed by females with young.  Some individuals may linger in California if food is sufficient; however, they are mostly present from April to October.  Then in the fall, they begin the southward migration back from feeding grounds led by females with weaned but dependent calves, followed by juveniles, then adult males, and finally pregnant females.  Migration routes may lead over deep waters with some individuals traveling across the Pacific to Hawaii or further north to Glacier Bay and the Bearing Sea in Alaska.

Habitat

Humpback whales are associated with areas of high productivity and prey concentration; these include the shallow continental shelf and shelfbreak, islands such as the Channel Islands, offshore banks and seamounts like Cordell Bank, and reefs.  In their winter calving grounds, they prefer waters of 200 m (656 feet) deep or less with a temperature of 21 degrees C (70 degrees F) or warmer.

Feeding style and diet

Humpback whales feed almost continuously from May to October, but less at their winter calving grounds.  They feed by gulping prey in the water column as well as bottom-feed, so their diet consists of a wide range of invertebrates and fish.  Their main prey item is schooling fish like anchovies, sardines, herring, juvenile salmon, pollock, sandlance, and mackerel, but they will also eat krill and occasionally copepods, pteropods, and cephalopods.

Other common species found on the west coast

Blue whale     Fin whale    Minke whale     Gray whale     Killer whale

Learn more

Want to learn more about whales along the west coast? 
Check out the Field Guide to MARINE MAMMALS of the Pacific Coast, a California Natural History Guide by Sarah G. Allen, Joe Mortenson, and Sophie Webb.