California gray whales are gliding through Central Coast waters on their 5,000 to 6,000 mile trek from their feeding grounds around Alaska's Bering Sea south to where they rest, breed and give birth in warmer Mexico.
The end of January was the peak of their southward migration although they're still coming and soon they'll be heading back our way on their return trip north.
Since December, groups of up to 10 have been spotted at the edge of the Monterey Bay Submarine Canyon while individuals or pairs have been seen closer to shore. They're best observed from a boat piloted by an experienced whale watching captain and crew.
"Seeing these animals is something that everyone should experience," said Kenny Stagnaro, owner and skipper of the vessel Velocity, which frequently passes in and out of the Santa Cruz harbor channel for whale watching trips. "They are truly amazing creatures."
Their southern destinations are warm Baja California waters where females give birth, then nurse and nurture their young. They include but aren't limited to Laguna San Ignacio, Laguna Guerrero Negro, Laguna Ojo de Liebre and Magdalena Bay.
Mating usually occurs there but it can also happen during their migration south. The gestation period of the gray whale is about a year. Calves are born live at around 15 feet long and 1,500 pounds. They put on weight and grow as they nurse on mother's milk, more than half of which is fat.
Around the middle of February, the California gray whales head north for summer feeding off Alaska. They primarily feed on a small crustacean called amphipod macrocephela which is nourished by algae that drops from sea ice in the Bering and Chukchi seas. They'll also eat smaller amphipods, which look like a kind of shrimp under a microscope. If they need nourishment during their migration they forage in the mud, sand and silt at ocean's bottom, unlike other baleen whales that skim the surface or gulp food in the water column.
The best period for viewing the northward migration is February through May. This leg of their journey tends to be more social and leisurely than the southbound trip. Mothers and calves can be spotted in April and May, and sometimes they travel close enough to shore that they can be seen from high points along the coast.
Their coastal highway gets very busy in both directions as the southern and northern migrations coincide during February, although the southbound whales travel further offshore than the northbound ones do.
They travel from a sea with a water temperature of 38 degrees to lagoons that are 70 degrees. When they leave Alaska they can have 6 to 8 inches of blubber to sustain them on journey. By the time they return they have just 2-3 inches of blubber left. Mothers need more, said Stagnaro, to nurse their young on the trip north.
Their population is a little more than 20,000, an increase from previous years. At maturity, they can be up to 50 feet long and weight up to 40 tons. Some whales can live to be 80 years old.
Observers remark that gray whales are less charismatic than others. That may be true while they are here, but they become animated while feeding off Alaska. While some can be friendly to humans in Baja California, the whales are not as approachable during mating and birthing.
Because the sea off California is their thoroughfare and not a café or playground, grays do not display the personality here that Orcas or Humpbacks do. But their speed and force is constant, said Stagnaro, so finding and following them is easier. "They are very majestic to watch, especially when they breech," he says.
If you get a chance, go check them out. There's plenty of time left.
Dan Haifley is executive director of O'Neill Sea Odyssey. He can be reached at email@example.com.