Gray whales undertake one of the greatest migrations of any mammal with a round trip of 14,500 to 21,000 km (9,000 to 13,000 miles) every year while losing up to a third of their body weight as they fast along the way. They can be found in the shallow waters along the entire west coast and can easily be seen from land. It’s common to see them breach, fluke, spy hop, flipper wave, and tail wave throughout the year.
- U.S. Endangered Species Act (ESA) – Delisted, Eastern North Pacific population
- U.S. Marine Mammal Protection Act (MMPA) – Protected
- International Union for the Conservation of Nature (IUCN) – Least Concern
Gray whales are dark gray overlaid with mottled white, yellow, and even orange due to scarring by ectoparasites like barnacles and lice. They are stout, muscular animals in comparison to other baleen whales with a blunt, narrow, and triangular shaped head with no throat pleats. They are easily identifiable with no dorsal fin; instead, it has a series of 6 to 12 bumps (peduncles) along its back that are visible as the whale arches its back before it dives. Their flippers are broad and paddle-like, and their flukes are scalloped with a deep notch in the middle. When it surfaces, its blow is straight up, short, broad, and bushy. Gray whales are 12 to17 m (42 to 55 feet), with females being larger than males and weigh an average of 27,000 to 36,000 kg (30 to 40 tons).
Distribution and migration
They range from the Beaufort and Chukchi Seas in Alaska to Baja California and mainland Mexico. In the north, they spend May to October at their feeding grounds where there is abundant food. Pregnant females are the first to head south to calving grounds, followed by non-pregnant females, males and juveniles. Females give birth in the lagoons and bays of western Baja California or the southern waters of the Gulf of California. The northward migration can begin as early as December and lasts through September, with newly pregnant females leading the way followed by males, juveniles, and lastly by females with their new calves. With such a prolonged northward and southward migration, people can often see gray whales going in either direction. In addition, some whales do not migrate as far north as Alaska, but spend their summer feeding at various locations along the way, including the west coast marine sanctuaries.
Gray whales stick to shallow depths from 3 to122 m (10 to 400 feet) and feed over soft bottom substrates of mud or sand.
Feeding style and diet
Invertebrates in or just above the mud make up a majority of the diet, and gray whales will plow the sea floor in search for them. They also skim the surface of the water to eat schooling fish or krill. The diet also includes copepods, amphipods, worms, mysid shrimp, krill, larval crab, red crabs, and small schooling fish such as anchovy.
Other common species found on the west coast
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.