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The Pacific Gray Whale

by Jim Knight


Class: Mammalia
Order: Cetacea
Suborder: Mysticeti
Family: Eschrichtiidae
Genus: Eschrichtius
Species: Eschrichitius robustus

The only member of the family Eschrichtiidae , the pacific gray whale is one of the smaller mysticete, or baleen whales, to roam the seas. Adults measure 45-46 feet (13.7-14 m) with the female adult being slightly bigger. Both sexes weigh 30-40 tons (27,200-36,300 kg.). The Pacific Gray migrates along the eastern Pacific shallow coastal waters starting from the Bering and Chukchi Seas in Alaska in October and ending in their mating and calving lagoons in San Ignacio, Mexico 2-3 months later. The entire journey averages 10-14,000 miles (16-22,500km) round-trip and is one of the longest of all mammalian migrations on earth. The average speed is about five miles an hour (8 kmh) and travel 90-100 miles a day.

As recently as May, 2000, the Mitsubishi Corp. was planning to build a massive salt plant in the San Ignacio lagoon which would have wiped out the last breeding ground for this majestic titan. It took a public outcry of more than a million letters, the opposition of numerous environmental groups including the Natural Resources Defense Council, a group of world-renowned scientists, including nine Nobel laureates, and the United Nations World Heritage Committee, before Mitsubishi would abandon their plan. It was one of the most important environmental victories not only for the whale, but for the world.

The Pacific Gray used to find safe haven for breeding and raising young in many harbors up and down the pacific coast. Right in the Los Angeles basin, the Ballona Wetlands years ago was one of those breeding sites. Think what we could have had right in our own back yard if we had preserved this lagoon!

One fellow mammalian species, man, has turned most of these natural lagoons into commercial harbors and, now, the pacific gray has only the nursery sites left in Baja Mexico. The Pacific gray was almost hunted to extinction in the 1850’s after the discovery of the calving lagoons, and again in the 1900’s with the introduction of ‘floating factories”. In 1937 they were given partial protection and in 1947 full protection by the International Whaling Commission (IWC). Since that time, the eastern North Pacific gray whale has made a remarkable recovery and now numbers as much as 23.000, probably close to their original population size. Other gray whales were not as lucky. The north Atlantic gray was hunted to extinction and the Korean, or western north Pacific stock is now very depleted also possibly from over-hunting.

Gray whales have a streamlined body, with a narrow tapered head. The upper jaw (rostrum) is arched in profile, almost like a smile, and slightly overlaps the lower jaw. There are 2-5 grooves 5 feet (1.5 m) in length on the ventral throat (below the lower jaw). The gray whale received its name from the gray patches and white mottling on its dark skin. The skin has many scratches, scattered patches of white barnacles and orange whale lice. Occasionally one can see the Orca (killer whale) teeth scares on their flukes if it has been lucky enough to escaped a deadly attack.

The gray whale has no dorsal (top) fin. About 2/3 of the way back on the top of its body is a prominent dorsal hump followed by a series of 6-12 knuckles along this dorsal ridge that extend to the fluke, or tail. The fluke is about 10-12 feet (3.7m) across, pointed at the tips and deeply notched in the center.

It does have a small flipper for guidance, but the propulsion system is this large fluke. The fluke is horizontal, unlike fish species which have vertical tails. There are small pelvic and femur bones buried within the whale’s body and one theory asserts that this giant walked on land with four legs millions of years ago. Maybe their adaptation to marine life saved them from the cataclysmic devastation when the great asteroid eradicated the terrestrial dinosaurs.

The whale has no sense of smell. The outer ears, which in land mammals help collect the sound, have entirely disappeared. The ear openings are only the size of a knitting needle. Water, unlike air, is a very good medium for carrying sound and this might explain the small ears. It also might be the reason for other methods of communication such as breeching or sounds made within the throat.

One behavior pattern that makes up most of the whale sightings off our coast is when the whale prepares for a deep dive and thrusts it fluke into the air.
The second sighting is when it comes back to the surface and exhales a misty, heart shaped jet of vapor up to 10 feet (3.7m) through its blow spout. This is not water. Whales breathe air just like man. When it dives, it holds that air in its lungs with its spout closed. The air in its lungs becomes heated and full of water vapor. Then, when it rises to the surface and "blows" out this hot, moist air, it condenses and forms this column of cloudy vapor.

Other sighting phenomenon are spyhopping (when the whale raises their head above water) and, the more rare, breaching (when the whale leaps entirely out of the water and falls back into a resounding splash). Spyhopping may be a way of looking around, a courtship behavior, or an aid to swallowing food. Breaching may be a courtship, communication behavior, to get rid of parasites or just for fun. No one, even the scientists, knows for sure. Since they are bottom feeders, gray whales have developed a rythmic breathing pattern. Before taking a deep dive (usually lasting about 5-8 minutes), they will take a series of three to eight short, shallow dives of less than a minute each to store up oxygen and expel carbon dioxide. As a general rule one short dive for every minute spent in a deep dive.

Gray whales reach sexual maturity at 5-11 years of age, or when they reach 36-39 feet (11-12 m) in length.. Courtship and mating behavior is complex, and frequently involve 3 or more whales of mixed sexes. Mating and calving, on rare occasions, have been observed during migration. The pregnant females (about half of the adult females) leave the arctic waters first. The other half of the females, traveling in groups, or pods, will mate during the migration or in the lagoons giving birth the following year. ( Gestation takes 12-13 months). Once the pacific gray arrives in their mating and birthing lagoon of San Ignacio, it remains for 2-3 months giving the calves an opportunity to build up a thick layer of blubber to sustain them for the northbound migration and keep them warm in those northern colder waters. Females bear a single calf at intervals of 2 or more years. Calves, on the average, weigh 1,200 pounds (550kg) and are 15 feet (4.5 m) at birth. They nurse 7-8 months on milk that is 53% fat (human milk is 2% fat). The males attain almost three-quarters of their body length (28 feet, or 8.5 m) by the first year, females almost two-thirds of their body length (30 feet, or 9 m). The growth rate slows the second year, but whales continue to grow for about 30 years. It is said they can live as much as 100 years.

The northbound journey takes another 2-3 months and one can see the calves close to their mothers traveling near shore. The mothers can be very protective of their calves with very violent defensive behavior and earned the name “Devilfish” from the early whalers who hunted them in the lagoons.

Once back in the cold northern arctic waters of the Bering and Chukchi seas, they feed in the summer months on small crustaceans such as amphipods and tube worms found in bottom sediments. As a baleen whale, the whale dives to the bottom, rolls on its side and filters nutrient rich sediments through a series of 130-180 fringed overlapping plates hanging from each side of the upper jaw. These plates consist a fingernail-like material called keratin that frays out into fine hairs on the ends inside the mouth next to the tongue. As it closes its mouth, water and sediments are filtered through the baleen plates, trapping the food and is swallowed. All baleen whales have small throats compared to Odontoceti, or toothed whales because their food consists of these smaller organisms.

One of the best places in the Los Angeles area to watch these magnificent giants is at the Palos Verdes Point Vicente Interpretive Center, located at the end of Hawthorne Blvd. along Palos Verdes Dr. South in Rancho Palos Verdes. Currently the center is closed, but it is hoped that it will reopen for next years migration. Whalewatch, a group of volunteers sponsored by the Cetacean Society and the Cabrillo Marine Museum, take an annual census of the whale migration.

Thanks to the American Cetacean Society for much of the information for this article. For more information, their address is: P.O. Box 1391, San Pedro, CA 90731-1391. Phone: 310/548-6279. Email: ACS@POBOX.COM.

Suggested Readings:
GRAY WHALES, by David G. and Alan Baldridge, 1991

MARINE MAMMALS OF SOUTHERN CALIFORNIA by Anita Daugherty, Ca Dept. of Fish and Game, 1979

MARINE MAMMALS OF EASTERN NORTH PACIFIC AND ARCTIC WATERS, by John E. Hayning, 1986