Window on Nature
By Lowell & Kaye Christie, F47246
January 2003
It’s wintertime, and time to go whale watching along the West Coast. Although many whale species call the Pacific Ocean home, the gray whale (Eschrichtius robutus) is the obvious choice to write about, even though it isn’t the largest, smallest, fastest, or strangest whale in the ocean. What makes it special is that it is the species you’re most likely to see.
Gray whales do more traveling than any other whale species, migrating up and down the Pacific coastline between Alaska and Mexico. Unlike humans, gray whales aren’t very creative in their travels. Each year they follow the same route south to their winter home in Baja California, Mexico, and take the same route north for their summer feeding frenzy in the Bering and Chukchi seas. These icy waters north and west of Alaska teem with the morsels that make up their diet.
Unlike killer whales, gray whales are filter feeders. Instead of teeth, they have a series of fringed plates called baleen that hang downward on either side of their upper jaws. The inner margins of the plates have coarse bristles made of the same material as our fingernails. A gray whale feeds mainly on the bottom of the ocean by lying on its side and sucking the bottom sediment into its mouth. Then, when the whale ejects the water through its mouth, most of the small invertebrates are trapped on the baleen, while sediment and other particles are expelled through the baleen fringes.
Gray whales eat mostly amphipods (tiny crustaceans). Surprisingly, these whales don’t have to cover much distance to get enough food to slake their appetites; scientists have measured concentrations of 12,000 to 20,000 amphipods per square yard in whale feeding areas. It’s estimated that the daily intake of one whale is approximately 2,600 pounds of food. Thus, in five months spent in Alaskan waters, a single whale can down approximately 390,000 pounds of those little creatures. Now that’s an appetite.
During their northern feeding, gray whales become so fat that they carry along a 10-inch to 12-inch layer of blubber when they begin to migrate south. Once migration begins, they do very little feeding until they head north again the following spring.
The fact that gray whales migrate so close to shore made it very convenient for whale hunters to bring the species close to extinction. (The gray whale is believed to be extinct in the Atlantic Ocean.) Pacific gray whales would certainly be gone as well, had the species not been designated endangered. Their protection, however, has led to a comeback, and now there are an estimated 17,500 of these whales living in the eastern Pacific Ocean.
Obviously, naturalists can’t count every whale, but they’re doing their best. Since 1967, gray whales have been systematically counted along the Pacific Coast nearly every year. At first the count steadily increased, but during the last several years it’s leveled off and even decreased somewhat. Has the dropoff been caused by polluted water or harassment from small whale-watching boats? No explanation has been made, but naturalists and watchers are looking for clues to help stabilize whale numbers.
The kind of whale watching we do isn’t likely to threaten these majestic creatures. We follow a few unspoken rules, starting with “Watch, but don’t harass.” Should we decide to take a boat trip, we try to get a recommendation from a ranger or naturalist. And you can bet that if we are on a trip where whales are harassed, we will report it to the National Marine Fisheries Service, which is responsible for implementing the Marine Mammal Protection Act.
Since gray whales don’t migrate en masse, the opportunities for a sighting can last for several months. We count ourselves lucky to have seen gray whales a number of times and in a number of places. (Check out this month’s “Baker’s Dozen” column for suggestions about great viewing sites.)
We’ve had great sightings while looking over the edge of a bluff and even while walking on a sandy beach. We certainly wouldn’t discourage anyone from embarking on a whale watching cruise, however. We toured out of San Diego harbor on a huge sailing ship. It was an exciting adventure on a spectacular day. Despite a bout of seasickness, Kaye admits it was worth feeling a little queasy for the opportunity see whales going through all the motions that we had merely read about or seen on television.
Should you only get a glimpse of a gray whale before it dives, keep watching, because it may quickly surface again. However, gray whales can disappear for 30 minutes underwater before popping up for air. Water 500 feet deep isn’t beyond a gray whale’s reach, and it takes time to go down that far before surfacing. At the opposite end of the spectrum, gray whales can swim in relatively shallow water without running aground. We witnessed this while rockhopping along the California coastline. Only in our dreams did we ever expect to see a gray whale swimming along so close to shore — but sure enough, there it was. A whale calf deftly made its way through a rocky area near the tide pools we were exploring until it reached open water. We were so excited that Lowell forgot to take any pictures.
Sometimes whales “breach” as they come to the surface after a dive. They thrust their enormous bodies partially out of the water, and when they fall back at an angle you can see a big splash and hear a very loud crashing noise. Sadly, too many times we’ve heard the crash rather than seeing it. Scientists theorize that the purpose of breaching may be to clean off some of the barnacles and whale lice that cling to the whale’s skin. It also may aid in communicating with other gray whales.
“Spyhopping” is another gray whale activity you don’t want to miss. Though this trick isn’t noisy, you’ll be suitably impressed as the whale pokes its head as much as 10 feet out of the water and slowly pivots in a circle. Presumably it does this to look around, but at what? Is it looking for predators? Orienting itself to the coastline? Watching the tourists?
A gray whale breathes air at the surface of the water through two blowholes located near the top of its head. The spout of condensation and water that blasts from the spout rises 10 to 15 feet into the air and can be heard half a mile away.
Since you won’t see a gray whale in a zoo or aquarium, and you never hope to see one stranded on the beach, here’s an idea of their size. At birth, a calf is about the length of a camper van — approximately 15 feet long and weighing between 2,000 to 3,000 pounds. They grow very rapidly on their mother’s milk (it’s more than 50 percent fat). By the time a calf is weaned it will have nearly doubled in size to 28 feet by the end of summer. That would make it about the size of a type C motorhome.
Once weaned and on its own, a gray whale’s growth rate slows dramatically. At age eight a young whale will be sexually mature. Still, it continues to grow at a slow rate. Its length won’t max out until it reaches the age of 40. Then it will measure 45 to 50 feet long and weigh between 30 to 40 tons. Thus, many adult gray whales are longer than the longest type A motorhome.
Finally, here’s a brief and touching story we heard from someone who had a close encounter with a gray whale. Typically, fully grown adult whales are hard to get close to. But some years ago we spoke to a woman who had done just that on a field trip to the lagoons of Baja California, Mexico. Her eyes misted with tears as she said that one whale was “friendly,” meaning it intentionally came into physical contact with humans. She said stroking that whale was almost as moving as the day she