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Devil Fish of the West Coast
by Damian Fagan
From this viewpoint at Cape Foulweather, Oregon, we watch the periodic "blows" of migrating gray whales (Eschrictius robustus). They surface, exhale, and take another breath before going back underwater. The heart-shaped spray rises from the double blowholes some 10 to 20 feet in the air, easy enough for us to see from this vantage point. These "coastal whales" tend to stay in shallower waters making them easy to watch from the shore.
What's in a Name?
Eschrictius honors the Danish zoologist Daniel F. Eschricht (1798-1863). The word robustus is Latin for "strong" or "oaken," which refers to the whale's size and strength. Early whalers called these whales "devil fish" because the females aggressively attacked to defend their calves that had been harpooned by the whalers.
Size and Shape
Adult gray whales are about the size of a school bus (40-45 feet long) and weigh between 30
and 40 tons. Females are a bit larger than males on average. Both adults and young lack a large dorsal fin. Instead they have a dorsal hump about two thirds of the way down their back, followed by a series of 6 - 12 "knuckles." As a whale surfaces and prepares to dive, these knuckles become visible. An adult's tail or fluke is 10 to 12 feet wide, pointed at the tips, and notched in the center.
Feeding Habits
Gray whales are mostly bottom feeders. Diving to the bottom, they roll their long tapered heads to one side and suck in a refrigerator-sized amount of sediments. With their giant tongue, the whales force the mud and water out of their mouths. Amphipods, mollusks, invertebrates and other crustaceans stick to the insides of the overlapping yellowish baleen. The whales then lick the food off the baleen with their tongue. Some whales feed on swarming schools of sardines, myscid shrimp, or crab larvae. Surprisingly, researchers can determine right- from left-lipped whales by the lack of barnacles on the side of the head that scraps along the ocean floor when feeding. Most gray whales are right-lipped.
The Long Migration
Gray whales migrate south from their summer grounds in the Bering and Chukchi Seas to the warm water lagoons and bays along Mexico's Baja peninsula and bays off the southern Mexico mainland states of Sonora and Sinoloa. Southbound whales tend to travel farther off-shore than the northbound migrating whales, but both can still be viewed from headlands along the West Coast of the United States. With a round-trip distance of 10,000 to 12,500 miles, the gray whale undertakes the longest annual migration of any mammal on Earth.
Moving constantly, the southbound whales travel 3-6 miles per hour and cover about 80 miles a day. Their wintering grounds are also their mating and birthing areas. Females give birth every other year and tend to locate in the quieter corners of the bays and lagoons where breeding activity is also taking place.
After their 12 - 13 month gestation (pregnancy), females give birth. Newborn gray whales are about 15 feet long and weigh between 1,100 and 1,500 pounds. The calves gain an amazing average of nine pounds per hour from nursing on their mother's milk, which is 50-60% fat. Nursing as the whales migrate northward, the calves need to add blubber for insulation before they reach their cold summer waters.
Journey North
The adult whales may not have eaten since leaving their summer grounds. In fact, they may have lost 30% of their body weight during their migrations and the winter season. Relying on fat reserves, they're ready to head north to eat.
Males, juveniles, and pregnant females are the first to leave their winter grounds. Small groups may travel together and since they travel close to shore, gray whales are easy to spot from coastal headlands. Later in the spring, the females and calves head north.
Not all of the gray whales travel up to the Arctic waters. Out of an estimated population of 18,000-20,000 about 200-400 whales remain off the coast from northern California to Vancouver Island, British Columbia during the summer. Often referred to as "resident" whales, these whales may spend the summer in this area, but not the year round.
As the whales migrate, whale-watching visitors to these wintering waters hope to encounter "friendlies." These gray whales seek out human contact and approach the small boats with no fear. The whales may rub against the boats, roll over and lift the boats on their bellies, or pull up alongside the boats and expect some head rubs. It's an amazing sight, since whalers in the 19th and early 20th century decimated whale populations in these very same waters.
References:
Darling, Jim. Gray Whales. Stillwater, MN: Voyageur Press, 1999.
Newell, Carrie. A Guide to Resident Gray Whales along the Oregon Coast. Eugene, OR: Nature Unlimited Ink Publishing, 2005.
Peterson, Brenda and Linda Hogan. Sightings: The Gray Whales' Mysterious Journey. Washington, D.C.: National Geographic Society, 2001.
Web sites:
http://www.learner.org/gwhale.html
http://www.noaa.gov/whales
http://oceanoasis.org/fieldguide/esch-rob.html
http://www.whalespoken.org
