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Students Ask and Experts Answer

Life Cycle


Q. How long does a gray whale live?
A. The maximum lifespan of a gray whale is unknown, but estimated at 40 to 80 years. There was a report of a large female that was estimated to be about 75-80 years old when she was killed.


Q. At what age do gray whales mate and breed?
A. Gray whales reach sexual maturity somewhere between 6 and 12 years of age, or when they reach 36-39 feet (11-12 m) in length. Adult gray whale males and females do not stay together after mating.

Q. How long is a gray whale's pregnancy?
A.
Gestation is 12-13 months. After mating during southward migration or in the lagoons, the newly pregnant female returns to the arctic feeding waters on spring's northward migration. All summer and into early autumn she feasts for herself and her unborn baby. Then she migrates south in late fall or early winter to the nursery lagoons in Mexico, where most of the births take place. (Each year, several calves are born along the southern part of the migration route. San A female usually has one calf every two years.

Q. What do newborn calves look like?

Photo Keith Jones

A. Newborns are dark gray to black, although some may have distinctive white markings. A calf weighs about 1,500 -2,000 pounds (680-920 kg) and is about 15-16 feet (4.56-4.9 m) long at birth. Newborns are fondly called "pickleheads" because the dimples in their skin resemble the dimples on a pickle!

Q. What do baby gray whales eat?
A.
Whales are mammals, so calves nurse on their mothers' milk. They nurse for around 7 to 9 months. They will drink about 50 gallons of mother's milk each day as they grow a thick layer of blubber for the northward migration to colder waters. Whale milk is rich—about 53% fat. Such rich milk helps them gain weight faster. (Human milk is about 2% fat.)

Q. Where are the baby grays born?
A.
Mating and calving both occur mainly in the lagoons of Baja California, Mexico. The shallow, warm, sheltered lagoons are ideal nurseries. However, a few births are always reported during the southward migration, too.

Q. What makes the lagoons such good nurseries?
A.
The shallow lagoons are safe from hungry orcas. The warm water probably helps the calves stay warm until they can gain blubber. The salty water may make it easier for the babies to nurse because it makes the babies more buoyant.

Q. Why do mothers and calves stay in the shallow lagoons for 2-3 months?
A.
This time allows the calves to build up a thick layer of blubber. They need blubber for energy to swim during the northward migration. Blubber keeps them warm as they reach the colder waters.

Q. Are whales good mothers?
A.
Yes! Mom-and-calf pairs share a tender bond, in human terms. Mothers are very protective of their calves. They earned the name "Devilfish" from early whalers in the lagoons because of their violence towards whalers who killed their babies.

Q. Whales are mammals, so what happens when a baby whale is born underwater?

A.
A mother supports her calf at the surface for its first few breaths of air. She buoys up the baby with her own back and flukes so it can breathe air.

Q. When are gray whale calves born?
A.
Calves are usually born from late December to early February in the warm, shallow lagoons of Baja California, Mexico. More than half of the births usually occur in Laguna Ojo de Liebre. Also, each year a few births take place in the open ocean during the journey south to Mexico.

Q. How big are baby gray whales when they're born?
A.
Calves average about 15 feet long at birth and weigh around 1500 pounds. A calf weighs about 1,500 -2,000 pounds (680-920 kg) and is about 15-16 feet (4.56-4.9 m) long at birth. Calves may gain 60 to 70 pounds each day on their mother's fat-rich milk. They reach 18 to 19 feet in length in their first 3 months of life.

Q. Can baby whales swim right away?
A.
Within three hours of birth, a calf can keep itself afloat and swim on a steady course. A calf may rest on its mother's back or fins until it becomes a stronger swimmer.

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