Eastern Pacific Gray Whale
Gray whales are familiar to most of us because they travel close to shore during their annual migration between the lagoons of Baja California and the arctic seas where the majority go to feed. We are thrilled by the sight of their puffy blows and cheered by a glimpse of their tail flukes. Piedras Blancas is one of the best places along the California coast to watch for gray whales. You might see these barnacled beauties at any time from December through May, but your closest views will probably be in April and May when the mothers and calves are passing. The majority of the northbound mothers and calves pass between the 2 Piedras Blancas rocks and land. That makes the elephant seal viewing area prime whale watching turf!
Color: Gray whales are mottled gray in color. Scars from barnacles and scratches add to the distinctive patterns that help identify animals. They are host to barnacle clusters and orange "lice".
Shape: Gray whales have a narrow tapered head that is about 1/6 of their body length. They do not have a dorsal fin; instead they have a dorsal hump starting about 2/3 of the way down their back, followed by a series of 6-12 bumps, or “knuckles”. They have 2-7 creases, or pleats, under their throats that allow for expansion while feeding.
Weight and length: Gray whales are considered to be a medium sized baleen whale. Both sexes weigh between 30-40 tons. Calves weigh 1500-2000 pounds at birth. Females are around 41-46 feet in length and males are slightly smaller at 38-43 feet long. Calves are about 15 feet long at birth and by six months of age they are about 22 feet long.
Breathing and diving: All baleen whales have two blowholes, or nostrils at the top of the head. When viewed in windless conditions the blow of the gray whale is heart-shaped, about 10-15 feet high. It is mostly comprised of condensation created when the whale's vaporous breath meets the cool ocean air.
They typically breathe 3-5 times in a row, about 10-20 seconds apart, then dive for 3-7 minutes. They usually raise their flukes before a deep dive, so if you have the pleasure of seeing the flukes that mean you may not see the whale for while. Watch for the pattern and you may be able to judge where the whale will surface next. Most dives average 5 minutes but they can stay under water for 20 minutes.
Feeding: The majority of gray whales feed in the cold arctic waters of the Bering, Chukchi, and Beaufort Seas . They are unique among whales in that they are mostly bottom feeders. They dive to the bottom, roll over on their side (usually the right side), and suck up sediment containing amphipods (bottom-dwelling crustaceans about 1/3-1 inch long that are related to shrimp.) Gray whales suck up several cubic feet of sediment at one time leaving shallow, mouth-sized rectangular pits, about 7 feet long. One adult gray whale may eat about 67 tons of food during the 5 months they are feasting.
Not all feeding is done in the Arctic . Some feed opportunistically along the northward migration. Some have been observed using alternative feeding styles. They have been seen using the gulping method of feeding, in which quantities of water containing krill or small schooling fish are engulfed and the water expelled. Some grays have also been seen skimming food from the surface. Over 80 different prey species have been identified.
Migration: Gray whales make one of the longest round-trip migrations of any mammal, along 5,000-7,000 miles of coast. The Arctic seas provide seasonal abundance of food and the warmer waters off Baja provide a nurturing climate for giving birth. They feast from late spring to early fall, trying to put on as much blubber as possible to see them through the long migration when they will be eating little or nothing. They may actually save energy by leaving the cold waters when food is no longer available. The current thinking is that the grays may migrate to avoid orcas.
Making one of the longest migrations of any mammal, gray whales spend about half the year feasting and half the year fasting. From about May-October gray whales put on as much weight as possible. They will lose about 30% of their weight during the long migration.
Although the mothers and calves spend a lot of time in the lagoons the vast majority of the others are seen along the coast of Baja and off the mainland of Mexico.
Migrating gray whales follow a generally predictable calendar. The southbound migration occurs between October and February. Pregnant females lead the way - they are in a hurry. The adults of both sexes follow them. Juveniles bring up the rear of the parade; some of them don't even make it all the way to Baja before turning around and heading north.
The northbound migration takes place in two distinct pulses, or waves. The first pulse is comprised of newly impregnated females, adult males, and juveniles. The second pulse consists of mothers and calves, which remain in the Baja waters a month or two longer than the others so the calves can size and strength before embarking on the long journey north.
At Piedras Blancas we may see the first of the southbound grays in late November. The peak of southbound migration is usually mid-January. During February whales may be seen going in both directions!
The peak of the first group heading north past Piedras Blancas is usually during the first two weeks in March. The greatest numbers of mothers and calves is usually between mid-April and mid-May.
Grays usually travel within 2.5 miles of the shore, staying in water that is less than 300 feet deep, although at times they pass through deeper water. Their migratory path has undoubtedly evolved as a response to changes in the earth's climate. During the last ice age (18,000 years ago) they wouldn't have been able to access the rich amphipod beds of the arctic because of the Bering Land Bridge. As a whale that lives along the coast, the gray whale has had to adapt to changing conditions to survive.
Movement/Behavior: Gray whales move through the water using up and down movements of their flukes. They travel both night and day at speeds of 3-6 miles per hour, averaging 80-100 miles a day. It takes about 2 months to complete the migration. On the trip north they travel a little slower, especially the mothers and calves that stop to nurse and rest.
Gray whales engage in a variety of activities, including spyhopping and breaching. Spyhopping is when they thrust their heads 6-10 feet out of the water. It isn't known for certain why they do this, perhaps it is to look around, but the eyes are not always above the water. Breaching is the most spectacular behavior. As much as 3/4 of the body is propelled out of the water, then whale twists and re-enters the water on its side or back with a tremendous splash. Breaching usually occurs 2-3 times in a row but it can go on for a dozen times or more. It isn't known why they breach. Baby gray whales are seen breaching too. Although gray whales are very goal-oriented while they are travelling you may see some of these behaviors off Piedras Blancas.
One of the more remarkable gray whale behaviors has been the "friendly" activity exhibited by some whales in the lagoons. Some gray whales approach small boats allowing people to touch them. It is difficult to explain these behaviors; perhaps they are displays of curiosity or reflect a desire on the part of the whales for tactile interaction (gray whales like to rub on the ocean floor or against pilings.) Whatever the reason, these behaviors are all the more remarkable since whalers once referred to the gray whale as the "devilfish" because the females would so fiercely defend their calves.
Pods of 2-3 are common but larger groups of 18 or more have been seen. Although gray whales are not considered highly social they do exhibit very caring behaviors toward each other. They will attend a sick or injured whale and come to the aid of a live-stranded calf. Sometimes another female may accompany a mother and calf.
Sounds: Gray whales make a variety of sounds - grunts, rumbles, clicks, knocks and moans. Among the times they are most vocal is when they are gathered in small groups, when swimming with bottlenose dolphins, or on a collision course with boats or one another. They are very sensitive to sounds.
Reproduction: Courtship and mating occur during the southbound migration and in the waters off Baja. Most females give birth every other year or so, therefore, there are more males than females ready to mate. However, gray whale males are not aggressive. Courting triads are common, one female and two males, with the males taking turns. Large groups of breeding gray whales have also been observed. Because the males have large testes and produce a lot of sperm, biologists refer to "sperm competition" taking place. In other words, males compete by trying to wash away the other fellow's sperm rather than trying to achieve exclusive access. Gray whales are sexually mature at 5-11 years of age, or when 36-39 feet long.
Calves: Most births occur in the lagoons of Baja (Guerro Negro, Scammon's, San Ignacio, and Magdelana), but some calves are born en route and along the Baja coast. Calves are born as far north as Monterey Bay so you may see southbound calves! The pregnant females begin arriving at the lagoons around mid-December. Most calves are usually born between January 5 and February 15 after a 12-13 month gestation. Calves nurse on milk that is about 50% fat and gain about 60 pounds a day. The nipples are located within folds on either side of the genital slit. When the calf touches one of the folds, muscles push the nipple out and a stream of thick milk is directed into the calf's mouth. Calves drink about 50 gallons a day. The relationship between mother and calf is very tender. The mother supports the calf at the surface for the first few breaths. Within a few hours the calf can keep afloat and swim. There is a lot of touching and the baby rides on the mother's back when young. Calves gain strength and a layer of blubber before the long journey north. Calves are weaned at about 8 months.
Longevity: Gray whales may live around 50 years.
Predators: The orca is the main predator of the gray whale besides man. When orcas are around the gray whale goes into hiding, coming close to shore, hiding behind rocks or in kelp. Gray whales will also float near the surface, breathing lightly to avoid detection. Transient pods of ocras hunt in packs and savor the tongue and throat blubber of gray whales, often leaving the rest of the carcass. Calves are especially vulnerable. During the northward migration, gray whale mothers and calves travel very close to shore in an attempt to avoid detection by predators. Orcas have been seen off Piedras Blancas. Great white sharks scavenge carcasses and may kill small calves.
Status: The California gray whale has been near extinction twice. The first time was after the discovery of the calving lagoons in the 1850's. They made a brief recovery but the introduction of factory ships in the early 1900's again pushed them to the brink of extinction. Protected from commercial hunting since 1946, some hunting has been allowed for subsistence or for "research." They were listed as "endangered" under the US Endangered Species Act of 1969 and further protected in American waters by the Marine Mammal Protection Act of 1972. The Eastern Pacific gray whale was removed from the Endangered Species list in 1993 after estimated numbers exceeded 21,000.
Research: Point Piedras Blancas is the ideal location to take the official gray whale calf count. About 80% of the mothers and calves pass between the two Piedras Blancas rocks just south of the point, and land. The rest are not far offshore. The count takes place between mid-March and the end of May or first part of June.
The survey teams are under the direction of Wayne Perryman, from the Southwest Fisheries Science Center, La Jolla, California. Wayne has been collecting data on the number of gray whale calves passing Piedras Blancas since 1994. A complicated formula is used to convert the number of calves actually counted into the estimated total. (Numbers provided by Wayne Perryman, NMFS)
Obviously, there was a sharp drop in the number of calves during 1999-2001. In an article in Maine Mammal Science, January 2002, Perryman points to the correlation between years when the arctic ice breaks up late in the season and low calf production. Why is sea ice in the arctic a factor in gray whale calf production? The newly pregnant females are the first to return to the feeding grounds and they must be able to store enough fat to see them through the long winter migration, when they will be giving birth and lactating. The amount of pack ice influences the length of the feeding season. Presumably, if they are not able to store enough fat reserves, the fetus will be aborted.
Background photo by NOAA