Gray Whale

The Gray Whale is a large baleen whale known for having the longest migration of any mammal, traveling up to 20,000 km round trip annually. It inhabits shallow coastal waters of the North Pacific, feeding primarily on bottom-dwelling invertebrates. Remarkable for its mottled gray skin covered in barnacles and whale lice, it is one of the most ancient whale lineages, often called a 'living fossil.'

North Pacific Ocean, primarily along the coasts of North America (Mexico, USA, Canada, Alaska) and northeastern Asia (Russia, occasionally Japan and Korea)

Eastern Pacific population ranges from Baja California Mexico breeding lagoons north along the US and Canadian coast to feeding grounds in the Bering, Chukchi, and Beaufort Seas off Alaska and Siberia. A small remnant Western Pacific population feeds off Sakhalin Island, Russia, and winters near Japan and South Korea.

Altitude and depth

Primarily found in shallow waters from the surface to about 60-120 meters depth, rarely venturing into deep pelagic zones.

Seasonal movements

Undertakes one of the longest annual migrations of any mammal, traveling south in autumn/winter to warm breeding lagoons in Mexico and north in spring/summer to Arctic feeding grounds.

Shallow coastal waters, lagoons, and bays, particularly favoring nearshore continental shelf areas with soft sediment bottoms for benthic feeding.

Adaptations to its environment

Possesses a thick layer of blubber for insulation in cold Arctic waters, baleen plates for filter feeding on benthic invertebrates, and a flexible neck allowing it to root along the seafloor. Lacks a dorsal fin, instead having a dorsal hump and knuckles, an adaptation for maneuvering close to shallow bottoms.

Listed as Least Concern by IUCN overall due to recovery of the Eastern North Pacific population, though the Western North Pacific population remains Critically Endangered with only a few hundred individuals.

Estimated population

Eastern North Pacific population estimated at approximately 14,000-27,000 individuals (recently fluctuating due to mortality events), considered stable to slightly declining; Western Pacific population estimated at under 300 individuals and critically endangered.

Ship strikes, entanglement in fishing gear, habitat degradation from coastal development, oil and gas exploration noise, and climate change affecting Arctic prey availability.

Diseases and parasites

Commonly hosts external parasites such as barnacles (Cryptolepas rhachianecti) and whale lice (Cyamus scammoni); can also suffer from skin lesions, entanglement injuries, and occasional viral or bacterial infections.

Protected under the US Marine Mammal Protection Act and Endangered Species Act (partially), international moratorium on commercial whaling by IWC, protected breeding lagoons in Mexico (e.g., Ojo de Liebre Biosphere Reserve), and ongoing research/monitoring of Western population by Russian and international scientists.

Recommended actions

Continued protection of Mexican breeding lagoons, stricter shipping lane regulations to reduce strikes, expanded monitoring of Western Pacific population, and mitigation of industrial noise and oil exploration in critical habitats.

Mottled gray to grayish-black skin covered extensively with white patches from barnacles, whale lice, and scarring. The body is robust with a narrow, arched head, no dorsal fin (replaced by a dorsal hump and series of knuckles along the tail stock), and paddle-shaped pectoral fins.

Size

Adults typically measure 12-15 meters in length, with females slightly larger than males.

Weight

Adults weigh between 15,000-33,000 kg (15-33 tonnes).

Distinctive features

Distinguished from other baleen whales by its lack of a dorsal fin, heavily encrusted skin with barnacles and lice, and unique bottom-feeding behavior that leaves characteristic feeding pits on the seafloor.

Differences between males and females

Females are slightly larger than males on average, but there are no dramatic differences in coloration or other physical traits between sexes.

Generally solitary or found in small, loose groups of 2-3 individuals, though larger aggregations can form temporarily at feeding or breeding grounds.

When it is active

Diurnal and nocturnal activity patterns, with feeding and traveling occurring throughout day and night, particularly during migration.

Diet

Primarily benthic feeder, consuming amphipods, tube worms, and other small invertebrates found in seafloor sediments; occasionally feeds on planktonic crustaceans in the water column.

How it feeds and hunts

Uses a unique bottom-feeding technique, rolling onto its side and sucking sediment and prey from the seafloor, then filtering it through baleen plates to expel mud and water while retaining food.

Communication

Communicates through a variety of low-frequency moans, grunts, and pulses, as well as physical behaviors like breaching, spy-hopping, and tail slapping.

Interactions with other species

Killer whales (orcas) are the primary natural predators, especially targeting calves during migration; gray whales also host commensal species like barnacles and whale lice on their skin.

Role in its ecosystem

Plays an important ecological role as a bioturbator, disturbing and aerating seafloor sediments through feeding, which influences benthic community structure and nutrient cycling.

Breeding occurs primarily in winter in warm lagoons of Baja California; gestation lasts approximately 13-14 months, resulting in a single calf born in the same lagoons the following winter.

Raising the young

Calves are nursed and cared for exclusively by mothers for about 7-8 months, with strong mother-calf bonds observed during migration; mothers are notably protective in breeding lagoons.

Maturity and lifespan

Reaches sexual maturity around 6-12 years of age; lifespan in the wild is estimated at 55-70 years, with no significant captive population for comparison.

Classification

Class Mammalia > Order Cetartiodactyla (Cetacea) > Family Eschrichtiidae > Genus Eschrichtius > Species Eschrichtius robustus

Subspecies

No formally recognized subspecies, but two distinct population groups exist: the Eastern North Pacific population (migrating between Mexico and Arctic Alaska/Siberia) and the critically endangered Western North Pacific population (found near Sakhalin Island, Russia).

Scientific synonyms

Balaena gibbosa, Balaena robusta, Rhachianectes glaucus

Recent studies

Recent studies (2019-2023) have documented an Unusual Mortality Event in the Eastern Pacific population linked to changes in Arctic prey availability due to climate change, prompting increased monitoring of body condition and calving rates.

Genome and DNA

Diploid chromosome number is 44; genetic studies have been used to distinguish between the Eastern and Western Pacific populations, revealing limited gene flow between them.

Compared with similar species

Unlike rorquals (e.g., humpback or blue whales), gray whales lack a dorsal fin and throat grooves are fewer and shorter; they are more closely related to an ancient lineage and are the sole surviving member of family Eschrichtiidae.

Gray whales undertake the longest migration of any mammal, up to 20,000 km round trip annually. They are known for their curious and friendly behavior toward boats in Mexican lagoons, sometimes approaching closely to be touched by whale watchers.

Where and how to see it

Best observed during migration season (December-April) along the Pacific coast of North America, with prime viewing in breeding lagoons of Baja California, Mexico (e.g., Laguna San Ignacio) where whales often approach boats closely.

Risks to humans

No notable risk to humans; gray whales are generally docile and even curious toward boats, though caution is advised to avoid collisions or disturbing mother-calf pairs.

Human uses

Historically hunted extensively for oil, meat, and baleen by commercial whalers, nearly leading to extinction in the 19th and early 20th centuries; today primarily valued for ecotourism through whale watching in Mexico and along the US/Canadian coast.

Myths and legends

Indigenous peoples of the Pacific Northwest, such as the Makah and Chumash, have long traditions and legends involving gray whales, viewing them as important spiritual and subsistence resources; some coastal cultures considered them sacred beings connected to ancestral spirits.