Gray whales are mysticetes, or baleen whales. Gray whales are the only species in the family Eschrichtiidae. These large whales can grow to about 50 feet (15 m) long, and weigh approximately 80,000 pounds (35,000 kg). Females are slightly larger than males.
They have a mottled gray body, with small eyes located just above the corners of the mouth. Their“pectoral fins” (flippers) are broad, paddle-shaped, and pointed at the tips. Lacking a dorsal fin, they instead have a “dorsal hump” located about two-thirds of the way back on the body, and a series of 8-14 small bumps, known as “knuckles,” between the dorsal hump and the tail flukes. The tail flukes are more than 15 feet (3 m) wide, have S-shaped trailing edges, and a deep median notch.
Calves are born dark gray and lighten as they age to brownish-gray or light gray. All gray whales are mottled with lighter patches, and have barnacles and whale lice on their bodies, with higher concentrations found on the head and tail.
Gray whales are frequently observed traveling alone or in small, unstable groups, although large aggregations may be seen on feeding and breeding grounds. Similar to other baleen whales, long-term bonds between individuals are rare. Gray whales are bottom feeders, and suck sediment and the“benthic” amphipods that are their prey from the sea floor. To do this, they roll on their sides and swim slowly along, filtering their food through coarse baleen plates, of which they have 130-180 on each side of the upper jaw. In doing so, they often leave long trails of mud behind them, and “feeding pits” in the sea floor.
Gray whales become sexually mature between 6-12 years, at an average of 8 years old. After 12-13 months of gestation, females give birth to a single calf. Newborn calves are approximately 14-16 feet (4.5-5 m) long, and weigh about 2,000 pounds (920 kg). The average and maximum life span of gray whales is unknown, although one female was estimated at 75-80 years old after death (Jones and Swartz, 2002). The age of large whales in family Balaenopteridae can be estimated by counting the layers present in waxy ear plugs, which are formed in the auditory canal (Hohn 2002).
Killer whales (Orcinus orca) are the only non-human predator of gray whales.
ESA Endangered – Western North Pacific population
MMPA Depleted – Western North Pacific population
MMPA – All gray whales, like all marine mammals, are protected under the MMPA
Delisted from ESA – Eastern North Pacific population
CITES Appendix I – throughout its range
|80,000 pounds (35,000 kg)|
|50 feet (15 m) long|
|mottled gray body, with small eyes; they have a “dorsal hump” (not a dorsal fin) and a series of 8-14 small bumps, known as “knuckles”|
|unknown, but may be as long as 80 years; sexually mature at around 8 years old|
|bottom feeders, they eat “benthic” amphipods|
|traveling alone or in small, unstable groups|
Most of the Eastern North Pacific stock spends the summer feeding in the northern Bering and Chukchi Seas, but gray whales have also been reported feeding along the Pacific coast during the summer, in waters off of southeast Alaska, British Columbia, Washington, Oregon, and California. In the fall, gray whales migrate from their summer feeding grounds, heading south along the coast of North America to spend the winter in their breeding and calving areas off the coast of Baja California, Mexico. Calves are born in shallow lagoons and bays from early January to mid-February. From mid-February to May, the Eastern North Pacific stock of gray whales can be seen migrating northward with newborn calves along the West Coast of the U.S.
Photo-identification studies indicate that gray whales in this stock move widely within and between areas on the Pacific coast, are not always observed in the same area each year, and may have several year gaps between re-sightings in studied areas (Calambokidis and Quan 1999, Quan 2000, Calambokidis et al. 2002).
RELATIVE SPECIES: Humpback Whale
NEIGHBORING SPECIES: Sperm Whale, North Pacific Right Whale, Bowhead Whale all have similar distributions.
PREDATORS: Humans, Killer Whales
THREATS: Vessel collisions, fishing nets, habitat degradation, and noise disturbance from vessels.
DIET: Benthic amphipods
MANNER OF FEEDING: Filter through sediment in shallow waters.
BEHAVIOR: Very curious towards boats. Spyhopping and breaching. They travel alone or in small pods. Swim and dive in predictable patterns in one direction. They migrate longer than any whale (5,000 miles). When diving, their tail flukes are entirely exposed above the water.
REPRODUCTION: Many males will compete to mate with one female in warm waters during the winter months. Gestation lasts 12-13 months, however the calf doesn’t grow during the last month of gestation. The calf leaves the mother at 7-9 months.
LIFE SPAN: 40 years
Population Trends: Systematic counts of Eastern North Pacific gray whales migrating south along the central California coast have been conducted by shore-based observers at Granite Canyon most years since 1967. The most recent stock assessment reports with population estimates are available on our website.
In contrast, the Western North Pacific population remains highly depleted and its continued survival is questionable. This population is estimated to include fewer than 100 individuals.
Historical threats included primarily
- commercial whaling, which severely depleted both the eastern and western populations between the mid-1800s and early 1900s
Current threats include:
- collisions with vessels
- entanglement in fishing gear
- habitat degradation
- disturbance from ecotourism and whale watching
- disturbance from low-frequency noise
- possibility that illegal whaling or resumed legal whaling will remove animals at biologically unsustainable rates.
The eastern stock, due to their annual migration along the highly-populated coastline of the western U.S., as well as their concentration in limited winter and summer areas, may make them particularly vulnerable to:
- impacts from commercial/industrial development
- local catastrophic events
The Eastern North Pacific stock of gray whales was removed from the U.S. List of Endangered and Threatened Wildlife in 1994, based on evidence that they had recovered to near their estimated original population size and were not in danger of extinction throughout all or a significant portion of their range. In 1999, a review of the status of the Eastern North Pacific stock of gray whales [pdf] recommended the continuation of this stock’s classification as non-threatened. This determination was based on the continued growth of the population (at that time, rising at 2.5% annually and estimated at 26,600 individuals) and the lack of evidence of any imminent threats to the stock. We continue to monitor the abundance of the stock, especially as it approaches its carrying capacity.
All marine mammals, including gray whales, are protected under the Marine Mammal Protection Act of 1972, as amended. As of 1994, the Eastern North Pacific stock of gray whale is no longer listed as endangered under the Endangered Species Act of 1973.
The Western North Pacific stock of gray whales has not recovered. It is listed as “Endangered” under the ESA and “depleted” under the MMPA.
- Calambokidis, J., J. D. Darling, V. Deeke, P. Gearin, M. Gosho, W. Megill, C. M. Tombach, D. Goley, C. Toropova and B. Gisbourne. 2002. Abundance, range and movements of a feeding aggregation of gray whales (Eschrichtius robustus) from California and southeastern Alaska in 1998. J. Cetacean Res. Manage. 4(3):267-276.
- Calambokidis, J., and J. Quan. 1999. Photographic identification research on seasonal resident whales in Washington State. Unpubl. doc. submitted to the Workshop to Review the Status of the Eastern North Pacific Stock of Gray Whales, 16-17 March 1999, Seattle, WA.
- Hohn, A.A. 2002. Age Estimation. pp. 6-13. In: W.F. Perrin, B. Würsig, & H. Thewissen (eds.) Encyclopedia of Marine Mammals. Academic Press, San Diego, CA.
- Jones, M.L. and Swartz, S.L. 2002. Gray Whale. Pp. 524-536. In: W.F. Perrin, B. Würsig, & H. Thewissen (eds.) Encyclopedia of Marine Mammals. Academic Press, San Diego, CA.
- Quan, J. 2000. Summer resident gray whales of Washington State : Policy, biological and management implications of Makah whaling. MS. Thesis. School of Marine Affairs, University of Washington. Seattle, WA.
- Knopf, Alfred A. Guide to Marine Mammals of the World.Random House. 2002
- Gray whales make one of the longest annual migrations of any mammal: they travel about 10,000 miles (16,000 km) round trip!
- Gray whales were once called “devil fish” because of their violent reactions when harpooned by whalers.
- Gray whales are known for their curiosity toward boats and are the focus of whale watching and ecotourism along the southern portion of their migration.
- Most commonly observed during whale watching tours.
- They are covered in barnacles, and sea lice especially on the head. They have no dorsal fin, unlike other baleen whales.
- Once called “devil fish” due to their violent reactions to commercial whalers.They are protected from commercial whaling, however are still hunted by the native Chukotka people of Washington.