Gray Whale (Juvenile)
Eschrichtius robustus

Physical Description

• Baleen whales, meaning instead of teeth they have thin filamentous plates in their mouths that help them filter plankton.
• Gray coloration with white patches that are mainly made of barnacles and sea lice.
• No dorsal (back) fin, instead a small hump about ⅔ of way down back and 6-12 knuckles down their backs.
• Adults weigh 33,000-88,000 pounds and grow to be 40-50 feet (longer than a school bus!).
• The females are usually slightly larger than the males.

Range

• Gray whales are found only in the Pacific Ocean.
• Gray whales used to spend every summer in the Bering Sea feeding. Now they mainly feed in the Chukchi Sea off of Alaska.
• Gray whales spend every winter in the waters of Baja California, Mexico to mate and give birth.

Habitat

• Gray whales stay near the continental shelf and are a coastal species.

Reproduction

• Gray whales migrate on a 10,000-mile round trip every year! They leave the food-rich Chukchi Sea in October, and swim to Baja, arriving in the warm water by January.
• Pregnant females give birth in January, and whales stay until March. They give birth and mate in the warm lagoons of Baja. Then they swim north again in April and May.
• Female gray whales usually give birth every 2-3 years, and are pregnant for 12 months.
• Newborn calves average 14-16 feet in length and are 2,000 pounds at birth.
• Calves are weaned at 8 months, once they are back in northern feeding grounds.

Diet

• They mainly eat amphipods in the mud at the seafloor.
• Also eat some krill and small fish at the surface.

Predators

• Killer whales prey on gray whale calves.
• Once gray whales are adults, killer whales cannot attack them.

Interesting Facts

• A gray whale can carry 400 pounds of barnacles and sea lice! 
• Gray whales were at the brink of extinction due to whaling in the 1900s, but in 1946 there was an international agreement to stop hunting them. The Atlantic population was hunted to extinction, but the Eastern North Pacific population was removed from the Endangered Species List in 1994. The Western North Pacific population is still endangered and only has about 200 whales.

You might have noticed that this gray whale is much smaller than 40-50 feet long. That’s because this is of a specific gray whale calf, JJ. The gray whale statue in the playground here at La Jolla Shores is 15 feet, the exact length that JJ the gray whale was when she was found in 1997, dehydrated, hypoglycemic, and near death in Marina del Rey. JJ was brought to SeaWorld San Diego to be nursed back to health. After fourteen months at SeaWorld, JJ was a healthy 19,000 pounds, was eating on her own, and was 31 feet long, the length of JJ the gray whale here on the map. She was ready to be released back into the wild, a true rehabilitation success story! 

To learn more about JJ the gray whale, click here. 

To hear a gray whale’s call and see videos of them swimming, visit Voices in the Sea, a collaboration between the Pacific Life Foundation and Scripps Institution of Oceanography. 

And come learn all about gray whales and their relatives at Birch Aquarium’s annual Whale Fest!

Scripps scientists are currently studying gray whale migration patterns, and are finding that they are migrating closer to shore, which could put them in more danger of ship strikes and entanglements.

Sources: National Park Service; Birch Aquarium at Scripps; The Marine Mammal Center; Voices in the Sea; CBS8; Regina Guazzo, Scripps Institution of Oceanography

Photo: Courtesy of SeaWorld