The gray whale (Eschrichtius robustus) is the official marine mammal for the U.S. state of California. There were once three stocks of gray whales — one in the Atlantic Ocean, long extinct; one in the western Pacific; and a third in the eastern Pacific.

The species makes well-documented seasonal migrations up and down the state's coast and beyond, from the warm, shallow waters of Mexico to the nutrient-rich waters of the U.S. state of Alaska. During their 19,300-kilometer (12,000-mile) journey, gray whales are often spotted from shore, making them a favorite of whale-watching companies. They are easily identified by their dark gray color, lumpy back, heart-shaped spout and absent dorsal fin. They grow up to 15 meters (49 feet) long.

Gray whales are known to feed on a variety of species. They specialize in bottom feeding, focusing on amphipods — small, shrimp-like organisms that live in tube structures in mud. They also ingest other mud-dwelling invertebrates, including tube worms and mollusks.

To feed on these creatures, whales suck in water and mud and separate food morsels using their broom-like baleen plates. They then push the excess water and mud back into the ocean by using their tongue to scrape food from the baleen.

As bottom feeders, gray whales prefer shallow waters and therefore migrate near the coast. Mothers birth one calf at a time, nursing them in the warm, shallow waters near Baja California, Mexico.

Unfortunately, some of these characteristics of gray whales nearly led to their demise.

Alisa Schulman-Janiger is the gray whale census director for the Los Angeles, California, chapter of the American Cetacean Society. She says the hunting of gray whales in Baja California lagoons during the late 1800s and early 1900s was devastating.

"The single biggest thing is that gray whales were targeted in their nursing lagoons," she says. "So the whalers would go into the lagoons and kill the pregnant mothers, the nursing mothers, and the calves would die also." Eastern Pacific gray whales were hunted to near extinction in the mid-1800s and again in the early 1900s. Their blubber produced oil used for lamps. The animals were easily accessible to whalers because they remained close to the coast. The species became overhunted in Southern California and Mexico. As populations rebounded in the 1920s, whalers used "floating factories" to process the whales out at sea.

Today, Pacific gray whales are protected by international organizations and several government agencies. The International Whaling Commission (IWC) was established in 1946, to regulate whaling throughout the world's oceans. Gray whales received protections from the IWC in 1947. In the United States, the animals are further protected by the Marine Mammal Protection Act and Endangered Species Act. Mexico transformed some of Baja California's major breeding and nursing lagoons into a protected refuge zone.

Limited whaling is still practiced by Indigenous peoples in Alaska, Canada, and Mexico. There have also been some reports of illegal whaling by nations that do not accept IWC treaties.

After being near extinction in the 1950s, the gray whale population in the eastern Pacific has rebounded to an estimated 19,000 animals, considered to be a healthy stock. In 1994, the gray whale was "de-listed," or removed from the Endangered Species List.

Unfortunately, gray whales in the western Pacific, vulnerable to whalers from Japan and Russia, have not fared as well — their population remains at just under 100 animals.