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The Gray Whale Migration in California and Beyond

By Amanda Townsel

The California coast is an outstanding place to see gray whales, Eschrichtius robustus, during their annual migration between feeding and breeding areas. Thanks to a moratorium on whaling and other multinational protections, the Eastern Pacific population of the gray whale is thriving with around 26,000 individuals, and a Red List status of Least Concern.

These charismatic marine mammals can reach 40-50 feet in length and weigh more than 36 tons (72,000 pounds) when fully grown. Gray whales are true to their name, and are dark gray in color with blotchy white patches. The white patches are variations in pigmentation, scars and even barnacles and whale lice. The latter two can contribute up to 400 pounds to the whale’s weight!

A gray whale breaches near Half Moon Bay, CA. © Rhys Watkin

Annual Gray Whale Migration: A Guide to the Seasons

Every year the whales undertake the longest migrations of any mammal, traveling 12,000 miles round-trip from their feeding grounds in the Arctic to calve and breed in the Baja lagoons, and then back again. That is about the same as traveling across the United States from San Francisco, California to Washington D.C., 3 times!

Summer (approx. May - September) | Arctic Feeding Grounds: Gray whales spend their summers feeding in the nutrient rich waters of the Arctic, though some whales are seen further south during this time, even in California. Gray whales feed on small animals (usually amphipods) that live in the seafloor sediment. Like people, gray whales show left and right side preference! While eating, gray whales move along the seafloor on their side, using their baleen to sift their food from the sediment. Side preference can be determined by looking at the whale's head—the side with fewer barnacles and some evidence of scraping on the skin is their preferred side.

September - October | Southward Migration: Gray whales begin to leave their Arctic feeding grounds in September, migrating south along the coastline to breed and calve in Baja California, Mexico. Gray whales travel at approximately 5 miles per hour and average about 75 miles a day.

Late December | Arrival to Baja California: Adult females and males begin to arrive in the lagoons of Baja California. There are four lagoons in Baja that the whales inhabit. Pregnant females (carrying calves conceived a year earlier) are coming here to give birth in the sheltered, warm waters where they can nurse their calves and help them develop strength for the journey back north. Adult male and non-pregnant female whales also make the journey to Baja's lagoons in order to mate.

January - March | Baja's Lagoons & the California Coast: January through March is an ideal time to see migrating gray whales along the California coast, with whales traveling both northward and southward. This is also the time during which gray whales arrive in Baja. Most whales arrive to Baja's lagoons during January and February, and by mid-March the majority of the population has reached the lagoons where they will mate and calve.

Most gray whale calves are born in January, as well as during the end of December and start of February. Newborn gray whale calves are about 15 feet long and weigh 1,500 lbs. During this time, the mother and calf pairs are known for their curious and "friendly" behavior, whereby they actively seek out interaction with whale watchers (e.g. "petting").

February - late April | Northward Migration: Gray whales leave Baja's lagoons to migrate back north starting at the beginning of February and continuing through April. This is an excellent time to see migrating gray whales along the California coast, with large numbers of whales traveling northward. Female whales with newborn calves are the last to depart to the lagoons in order to give the calves as much time as possible to grow. These mother-calf pairs tend to stay close to the coast throughout their migration, and will be looking to avoid predators, especially killer whales and great white sharks. Gray whale calves will nurse for approximately seven months and will stay by their mom's side for up to nine months.

Gray whales migrate annually along the California coast. © Rhys Watkin

Witness the Gray Whale Migration in California

Led by Oceanic Society's local wildlife experts, our 3-hour whale watching tours from Half Moon Bay let you experience the gray whale’s annual migration. These gray whale watching tours run weekends between January to March, which means you may see both south- and northbound whales!

Gray whale flukes are more rounded than those of humpback whales. © Rhys Watkin

How to Spot & Identify Gray Whales

Beyond their coloration, there are a few distinguishing characteristics that can help you identify gray whales along the California coast.

Blow or spout: Like other baleen whales, gray whales have two blowholes. When they breathe out, the spray (also called the 'blow') sometimes takes the shape of a heart. Keep an eye out for these distinct puffs on the horizon!

Flukes: Gray whale flukes are rounder than the well-known humpback flukes, with a distinct heart-shape.

Distinctive Dorsum (Back): Gray whales do not have a dorsal fin. Instead they have a low hump and have a knobby/bumpy appearance.

Breaching Behavior: Though not quite as acrobatic as the humpback whale, gray whales will emerge from the water and land in a giant splash, a behavior known as breaching.

California sea lions are visible year round on the California coast. © Rhys Watkin

Other California Marine Life to See on Whale Watching Trips

In addition to gray whales, there is some other wildlife you may spot on our Half Moon Bay whale watching trips.

Year-round: Harbor seals, California sea lions, and pelicans hang out near Half Moon Bay year-round and, very rarely, sea otters make an appearance. You may also spot Risso’s dolphins, common dolphins, or Pacific white-sided dolphins.

January: Open ocean birds like murres and auklets seek a reprieve in calmer waters along the coast and elephant seal breeding season has begun at Año Nuevo State Park.

March - early April: Humpback whales can be spotted in Half Moon Bay from. Humpbacks are almost black in color, with white markings along their underside, fins, and flukes (tail). Their flukes are wide with an uneven end, and their pectoral fins are long - almost one-third of their body length.

Naturalist Susan Sherman briefs Oceanic Society guests. © Rhys Watkin

Your Trip Supports Ocean Conservation

Oceanic Society is a 501(c)(3) non-profit organization dedicated to ocean conservation. Your participation in our whale watching trips helps fund our global ocean conservation programs and local programs including the Captain Roger Thomas Scholarship Fund, which gives whale watching experiences to groups and individuals in the San Francisco Bay Area that otherwise might not have the opportunity to do so. Moreover, we use our whale watching cruises as an opportunity to collect photographic identification data on whales, which we share with a network of researchers throughout the eastern Pacific. For more information, see our Half Moon Bay Gray Whale Watching page.

Author

Amanda Townsel is an Oceanic Society communications strategist, copywriter, and community coordinator. Amanda earned a Bachelor’s in Psychology from the University of San Diego and a Master’s in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. She is an avid traveler with a professional career that includes diving, marine ecotourism research, and strategic communications for conservation organizations.

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