Gray Whale - Eschrichtius robustus

Taxonomy & Nomenclature

Scientific Name Eschrichtius robustus
Author (Lilljeborg, 1861)
Taxonomic Rank Species
Taxonomic # 180521
Common Names English: Gray Whale
Spanish: Ballena gris
English: grey whale
Current Standing valid
Taxonomic Parents Kingdom: Animalia
  Phylum: Chordata
    Subphylum: Vertebrata
      Class: Mammalia
        Subclass: Theria
          Infraclass: Eutheria
            Order: Cetacea
              Suborder: Mysticeti
                Family: Eschrichtiidae
                  Genus: Eschrichtius
Taxonomic Children
Synonyms (since 1950)
Taxonomic data is courtesy of the Integrated Taxonomic Information System (ITIS)
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Physical Description / Field Identification

Gray whales are easy to identify. They are intermediate in robustness between right whales and rorquals. Although young calves are dark charcoal gray, all other gray whales are brownish-gray to light gray. They are nearly covered with light blotches and white to orangish patches of whale lice and barnacles, especially on the head and tail. These patches of ectoparasites are very helpful in distinguishing this species. The upper jaw is moderately arched, and the head is acutely triangular in top view and slopes sharply downward in side view. The flippers are broad and paddle-shaped, with pointed tips. The flukes have smooth S-shaped trailing edges, with a deep median notch. There is a dorsal hump about two-thirds of the way back from the snout tip, followed by a series of 6-12 smaller "knuckles" on the dorsal ridge of the tail stock. There may be several (generally 2-5) short, but deep, creases on the throat that allow compression of the throat during feeding.

The mouth contains 130-180 pairs of yellowish baleen plates, with very coarse bristles. The blow is bushy, heart-shaped when viewed from ahead or behind, and rises less than 3-4 m.

At birth, gray whales are about 4.6-4.9 m long; adults are 11-15 m in length, with females slightly larger than males. Maximum body weight is over 35 tons.

Can be Confused With

Gray whales are unique in body shape and patterning, and there is usually no problem with identification. From a distance, however, they can sometimes be confused with right, bowhead, sperm, or humpback whales.

Distribution

Gray whales are migratory, found only in the North Pacific Ocean and adjacent seas. There are two populations, a large eastern Pacific stock and a very small, remnant western Pacific stock. They are primarily bottom feeders and are thus restricted to shallow continental shelf waters for feeding. In fact, they are the most coastal of all great whales, living much of their lives within a few tens of kilometers of shore (although they do feed great distances from shore on the shallow flats of the Bering and Chukchi seas). Gray whales stocks which previously occurred in the North Atlantic were wiped out by whalers in the seventeenth or eighteenth century.

Ecology and Behavior

Most groups are small, often with no more than three individuals, but gray whales do sometimes migrate in pods of up 16, and larger aggregations are common on the feeding and breeding grounds. Breaching, spy-hopping, and other aerial behaviors are common, especially during migration, and in and near the breeding lagoons of Baja California and mainland Mexico. The migration from winter breeding grounds in Mexico to summer feeding grounds in the Bering, Chukchi, and occasionally Beaufort, seas is witnessed by tens of thousands of people each year along the west coast of North America.

Breeding of eastern Pacific grays occurs in winter, in or near the Baja California breeding lagoons. The western gray whale’s breeding grounds are a mystery, although there is evidence that the southern coast of China was used in the past.

Feeding and Prey

Gray whales are suckers, using suction to take in food, water, and sediments – then expelling the water and sediment, while trapping they prey with their baleen plates. They feed primarily on swarming mysids, tube-dwelling amphipods, and polychaete tube worms in the northern parts of their range, but are also known to take red crabs, baitfish, and other food (crab larvae, mobile amphipods, herring eggs and larvae, cephalopods, and megalops) opportunistically or off the main feeding grounds.

Threats and Status

Gray whales were one of the first of the great whales species to be targeted by whalers. They are relatively large and slow-moving, and nearly their entire lives are spent in neashore areas, with easy access from the shoreline. In these respects, they were ideal targets, however gray whales can also be aggressive when attacked (earning them the nickname ‘devilfish’), and many whalers lost their lives at the hands of a thrashing gray whale. The North Atlantic population was wiped out by whalers, apparently some time in the 1700s.

Until recently, the western North Pacific (Korean-Okhotsk) stock was thought to have followed them into extirpation. However, a small remnant group (about 100 whales) was recently found to be spending its summers feeding off Sakhalin Island, Russia. It is not known if there are other such groups, but at least the population appears to be extant.

The eastern North Pacific (California-Chukchi) stock was twice reduced to near extinction in the last 150 years. Since its protection after World War II, the California gray whale has rebounded to numbers thought to be near pre-exploitation levels (about 26,600 in the late 1990s).

Currently, Gray whales are ‘Critically Endangered’ (IUCN – western Pacific stock), ‘Lower Risk/Conservation Dependent’ (IUCN – eastern Pacific stock) and the ‘Endangered’ (western North Pacific population, United States ESA). In 1994, the Gray whales in the eastern North Pacific were delisted from the United States ESA, but continue to be monitored as required.

Links

References

Barlow, J. 1994. Recent information on the status of large whales in California waters. NOAA Technical Memorandum NMFS SWFSC 203:1-27.

Jones, M.L. and S.L. Swartz. 2002. Gray whale Eschrichtius robustus. pp. 524-536 in W.F. Perrin, B. Wursig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.

Reeves, R.R. and E. Mitchell. 1988. Current status of the gray whale, Eschrichtius robustus. Canadian Field-Naturalist 102:369-390.

Rice, D.W., A.A. Wolman and H.W. Braham. 1984. The gray whale, Eschrichtius robustus. Marine Fisheries Review 46:7-14.

Weller, D.W., B. Würsig, A.L. Bradford, A.M. Burdin, S.A. Blokhin, H. Minakuchi and R.L. Brownell. 1999. Gray whales (Eschrichtius robustus) off Sakhalin Island, Russia Seasonal and annual patterns of occurrence. Marine Mammal Science 15:1208-1227.

Weller, D.W., A.M. Burdin, B. Würsig, B.L. Taylor and R.L. Brownell. 2002. The western gray whale a review of past exploitation, current status and potential threats. Journal of Cetacean Research and Management 4:7-12.

Wolman, A.A. 1985. Gray whale Eschrichtius robustus (Lilljeborg, 1861). pp. 67-90 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Vol. 3: Sirenians and the baleen whales. Academic Press.

ITIS TSN180521
Status - ESA, U.S. FWS -
    E (Western North Pacific)
Status - Red List, IUCN -
    CR (western)
    LC (Global or one of the sub regions)
    RE (Global or one of the sub regions)
#records (spatial)16,236
#records (non-spatial)0
#datasets49
Year1975 - 2015
Latitude24.62 - 72.34
Longitude-173.40 - 158.55
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