Gray Whale Migration

Here’s a timely excerpt from the Cabrillo Reference Manual (E-binder) about the gray whale migration.  Enjoy!

Gray Whale Migration – Witness the Annual Winter Journey

Each winter, the Pacific gray whales pass by the western overlooks of Cabrillo National Monument. After spending the summer feeding in the food-rich waters of the Arctic, the whales swim south along the coast to the bays of Baja California, where they mate and nurse their young. Along the way, they pass Point Loma and Cabrillo National Monument, where you can witness their annual winter journey.

Interesting Whale Facts

  • Adult Pacific gray whales are 30 to 50 feet long and weigh from 20 to 40 tons.
  • Baby gray whales average 15 feet in length and weigh about a ton.
  • A mother gray whale’s milk is more than 50% fat.
  • Gray whales live 20 to 40 years on average, and some live 60 years. They reach sexual maturity at eight years.
  • Gray whales make a series of grunts, clicks and low rumbles to navigate and communicate among themselves. They don’t ‘sing’ elaborate songs like humpback whales.
  • Instead of teeth, gray whales have long sheets of baleen (made of the same material as your fingernails) hanging from the roofs of their mouths. They use these comb-like sheets to filter food from the water.
  • Gray whales eat tiny animals called amphipods. Millions of amphipods live in the muddy Arctic seafloor. Lying on its side, a gray whale slurps up mouthfuls of mud and water, then filters out the amphipods through its baleen.
  • A gray whale’s skin is dark gray. But it is mottled with scars and patches of light-colored barnacles growing on its back. Each whale has its own distinctive pattern of barnacles and scars, and scientists use these patterns to identify individual whales.
  • Gray whales have six to 12 knobs, or bumps, along the tops of their tail ridges instead of a fin like some other whales.
  • Killer whales, large sharks, and people are the gray whales’ only known predators.
  • Gray whales were nearly hunted to extinction in the 19th century.
  • Gray whales have been protected from exploitation by the International Whaling Commission since 1946. As a result, current populations are considered close to their pre-exploitation numbers.

Gray whale vs. man

A Gray Whale’s Year

When gray whales appear off our coast in December, they are nearing the end of a long journey from Arctic waters to the lagoons of Baja California. It’s one leg of a round-trip migration of nearly 12, 000 miles—the longest of any mammal:

Summer: Gray whales summer in the waters off Alaska and Siberia. The Arctic seas produce tons of amphipods that are the staple of a gray whale’s diet. Feasting on this bounty, the whales build up a layer of blubber that serves as insulation and as a food reserve. In late September, grays begin the southern migration. Except for an occasional meal along the way, they won’t eat again until they return the following summer.

Fall: Migrating whales arrive along the Oregon and northern California coasts in late November and early December. Most pass San Diego in late December, January and February.

Winter: Grays mate and give birth in the warm, shallow lagoons of Baja California from January through March. A cow mates one year, then returns to give birth the next.

Spring: In late February, some grays begin swimming north. Cows with calves are the last to leave the lagoons, remaining until March or April.

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