Blue Whale vs. Gray Whale
The blue whale is the largest animal known to have lived on Earth, a long, slender whale of the open ocean that feeds almost entirely on krill. The gray whale is much smaller, at about 49 feet. It is a mottled, barnacled whale that feeds on the sea floor in shallow coastal water. Both spend the winter in the waters of Baja California Sur, which is why a trip here can include both: gray whales in the Pacific lagoons, and blue whales in the Sea of Cortez.
The species facts on this page come from NOAA Fisheries’ profiles of both whales. For more on the Gray Whales of San Ignacio Lagoon and the work to protect them, see our gray whale conservation and research guide.
At a glance
| Blue whale | Gray whale | |
|---|---|---|
| Scientific name | Balaenoptera musculus | Eschrichtius robustus |
| Maximum length | Up to about 110 feet (Antarctic); up to about 90 feet in the North Pacific | About 49 feet |
| Weight | Up to 330,000 pounds (Antarctic); over 100,000 pounds in the North Pacific | About 90,000 pounds |
| Shape and color | Long and slender; mottled blue-gray, light blue under water | Mottled gray with lighter patches, barnacles, and whale lice |
| Food | Krill, almost exclusively | Small invertebrates such as amphipods, filtered from the sea floor |
| Range | All oceans except the Arctic | North Pacific only |
| Winter in Baja | Sea of Cortez, where mothers with young calves are regularly seen December to March | Pacific lagoons and bays, where calves are born from early January to mid-February |
| Status (U.S.) | Endangered | Eastern population recovered, removed from the endangered list in 1994; western population endangered |
| Lifespan | Estimated 80 to 90 years | Unknown; one female was estimated at 75 to 80 years |
Size
NOAA describes blue whales as the largest animals ever to live on our planet. In the North Pacific and North Atlantic they grow to about 90 feet and more than 100,000 pounds, and Antarctic blue whales can reach about 110 feet and more than 330,000 pounds.
Gray whales grow to about 49 feet and approximately 90,000 pounds, with females slightly larger than males. A newborn gray whale calf is already 14 to 16 feet long and weighs about 2,000 pounds.
How to tell them apart
A gray whale’s body is mottled gray, with lighter patches all over it. It carries barnacles and whale lice, most thickly on the head and tail. It has no dorsal fin. Instead, a low dorsal hump sits about two-thirds of the way back, followed by a row of 6 to 12 small bumps called “knuckles” leading toward the tail. Its tail flukes are nearly 10 feet wide. Calves are born dark gray and lighten as they grow.
A blue whale is long and slender, and its mottled blue-gray skin looks light blue under water, which is where the name comes from. The pattern of mottling varies from whale to whale, and researchers use it to identify individuals.
What they eat, and how
Both are baleen whales, which means they filter food through plates of baleen that hang from the upper jaw instead of catching it with teeth. The two species use their baleen in very different ways.
Gray whales feed on the bottom. They roll onto their sides and swim slowly along the sea floor, sucking in sediment and filtering out small invertebrates such as amphipods through 130 to 180 coarse baleen plates on each side of the jaw. They often leave trails of mud and feeding pits behind them.
Blue whales feed almost entirely on krill, small shrimp-like animals. A blue whale swims at a school of krill with its mouth open, and the pleated skin of its throat expands to hold the water it takes in. It then closes its mouth and pushes the water out with its tongue, and the baleen keeps the krill inside. The biggest blue whales may eat up to 6 tons of krill a day.
Where they live and migrate
Blue whales are found in every ocean except the Arctic. They generally spend summers feeding in polar waters and migrate toward the equator as winter arrives, following their food. NOAA notes that eastern North Pacific blue whales are believed to spend winters off Mexico and Central America, and that blue whales with young calves are regularly seen in the Gulf of California, the Sea of Cortez, from December through March. Scientists believe the gulf is an important calving and nursing area for them.
Gray whales live only in the North Pacific, in two populations. The eastern population spends the summer feeding mainly in the Bering and Chukchi seas and migrates south along the coast of North America each fall to its wintering and calving areas off Baja California. Its round trip of about 10,000 miles, and in some cases more than 14,000, is one of the longest annual migrations of any mammal. Calves are born during the migration or in the shallow lagoons and bays of Mexico from early January to mid-February.
At San Ignacio Lagoon, Gray Whales are typically present from mid-January through early April. Our scheduled departures run from early February through late March, and flexible self-arrival stays are offered from January 25 to February 12 and from March 24 to April 4.
Calves and life history
Gray whales reach maturity at 6 to 12 years, most often at 8 to 9. A female carries her calf for 12 to 13 months and gives birth to a single calf.
Less is known about blue whales. The best available science suggests a pregnancy of about 10 to 12 months, most births and mating in winter, and a calf every 2 to 3 years. Blue whales are also among the loudest animals on the planet, and under the right conditions their calls may be heard by other whales up to 1,000 miles away.
Conservation status
Both species were heavily reduced by commercial whaling, and whaling brought both Pacific gray whale populations close to extinction. Blue whales remain listed as endangered under the U.S. Endangered Species Act, although NOAA reports that their numbers are increasing globally. Vessel strikes and entanglement in fishing gear are their main threats today.
The eastern population of gray whales, the one that winters in Baja, recovered and was removed from the endangered list in 1994. The western population, found mainly along the coast of eastern Asia, remains endangered, with fewer than 300 whales estimated.
Seeing both whales in Baja
Our 7-Day and 8-Day Big Whale trips are built around this overlap. Each itinerary combines time at Campo Cortez on San Ignacio Lagoon with sea safaris in Loreto Bay National Park on the Sea of Cortez. Depending on the departure, it includes four to seven Gray Whale watches at the lagoon, and the order of the lagoon and Loreto portions varies. The safaris search for Blue Whales, along with Humpback Whales, Fin Whales, dolphins, sea lions, and seabirds.
At the lagoon, NOAA notes that gray whales are known for their curiosity toward boats in some places, and at San Ignacio some whales choose to approach the pangas. In the Sea of Cortez, the search itself is part of the day, and blue whale movements change from year to year, so no sighting can be guaranteed. You can read more about the Sea of Cortez side on our Explore Loreto page.
Frequently asked questions
Is a blue whale bigger than a gray whale?
Yes, by a wide margin. A North Pacific blue whale can reach about 90 feet, while a gray whale grows to about 49 feet.
Do blue whales and gray whales eat the same food?
No. Blue whales eat krill in open water, and gray whales filter small invertebrates from the sea floor.
Can you see blue whales at San Ignacio Lagoon?
San Ignacio Lagoon is a Gray Whale calving lagoon. Blue whales are found in the Sea of Cortez, which is why our Big Whale trips pair the lagoon with sea safaris from Loreto.
Are gray whales endangered?
The eastern population that winters in Baja was removed from the U.S. endangered list in 1994. The small western population remains endangered.
Sources
- NOAA Fisheries, Blue Whale, species profile.
- NOAA Fisheries, Gray Whale, species profile.
Planning a trip
If you would like to see both whales on one trip, compare the Big Whale departures on the 2027 trip calendar, or call 877-506-0557 or email info@bajaecotours.com, and we will help you choose the dates that suit you.