Gray whale

 

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Classification:

Global Population

Description and Natural History

Physical Description
Gray whales are not as stocky as right and bowhead whales but are more robust than sei, fin, Bryde's and minke whales. The head is triangular when seen from the top, looking down, and the upper jaw is slightly arched when compared to right and bowhead whale jaw lines. The flippers are broad and paddle-shaped. The gray whale, like the different right whales, lacks a dorsal fin but does have a dorsal hump about two-thirds of the way down the back, followed by a series of smaller "knuckles" down the tail stock.

They grow to between 11 and 15 meters (36 - 49 feet) in length and weigh a maximum of 35 tonnes (77,161 pounds). As their name suggests, adults are brown-gray to light gray. They are covered with light blotches and white or orange patches of whale lice and barnacles.

Calves are born dark gray in color and are four to five meters (13 - 16 feet) in length and weigh up to 500 kilograms (1,102 pounds). Calves are weaned at about seven months.

Natural History
Gray whales inhabit shallow continental shelf waters and are predominantly a coastal species. There are two stocks of North Pacific gray whales; the Northeast Pacific (eastern) or California stock, and the Northwest Pacific (western), otherwise known as the Korean or Asian stock.

The Northwest Pacific stock was hunted to near extinction and remains severely depleted with as few as 50 reproductive individuals. The primary calving and mating grounds of this remnant population are suspected to be in the coastal waters of the South China Sea, with summer feeding grounds in the Okhotsk Sea off the northeastern coast of Sakhalin Island, Russia.

The Northeast Pacific stock calves in the lagoons of Baja California, Mexico, before undertaking a migration of up to 18,000 kilometers (11,184 miles) to summer feeding grounds in the Bering, Chukchi and Beaufort Seas.

A population of gray whales inhabiting the North Atlantic was hunted to extinction as early as the 17th century.

Gray whales feed in shallow shelf waters or near offshore banks. The feeding strategy of the gray whale differs from other baleen whales. They lean to one side and stir up the bottom, sucking up mostly mysids and amphipods, but also red crabs, baitfish and other food when available. Clouds of muddy water can sometimes be seen when gray whales are feeding.

In 1973, the Northeast Pacific stock of gray whales was listed under the U.S. Endangered Species Act (ESA). In 1994, this stock was removed from the list when the population was estimated at 22,000 individuals. Pre-exploitation population size for both stocks in the North Pacific has been estimated at about 30,000 individuals. The western stock probably numbered between 1,000 and 1,500 animals in 1900 but was virtually exterminated by 1933.

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Status of the Species

Status
The Northeast Pacific stock was downlisted from Endangered under the U.S. Endangered Species Act in 1994. It is currently listed as Lower Risk (Conservation Dependent) by the International Union for the Conservation of Nature and Natural Resources (IUCN). The geographically distinct Northwest Pacific stock of gray whales is listed as Critically Endangered by the International Union for the Conservation of Nature and Natural Resources (IUCN).

Threats to the Species
The Northeast Pacific stock is affected by habitat degradation and loss, especially in the development of critical calving grounds in Mexico.

Current threats to the remnant Northwest Pacific stock include an undetermined level of hunting, incidental take in Chinese fisheries, nearshore industrial and shipping activity, possible ship strikes, offshore oil and gas development including seismic testing, drilling, ship and air traffic, and oil spills. Habitat damage from drilling and dredging, habitat exclusion due to noise pollution, and the impact of the above on prey communities may also be threats to this population.

Gray whales are also affected by industrial development and noise pollution. Chemical contamination is also a concern.

Hunting: Gray whales were hunted by aboriginal peoples for hundreds of years. Commercial whaling of the Northwest Pacific stock, mostly for oil, began during the seventeenth century and ended in 1933 with the economic (if not biological) extinction of the stock.

After 1937, the gray whale gained protection from hunting by Norwegians, Americans and nationals of other signatory states under the International Agreement for the Regulation of Whaling. This agreement did not protect grays from non-signatory whaling countries such as Japan and the Soviet Union, nor from scientific collections by Canada (in 1953) and the United States (1959-1970). Although protected since 1946 by the IWC, individuals from this stock were taken until 1966 and possibly until 1980. One whale was taken illegally in 1996 off the coast of Japan.

International Trade
No legal trade.

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Authors and Sources

Sources
American Cetacean Society. 1996. Fact Sheets. http://www.acsonline.org/factpack/graywhl.htm

Anonymous. 2001. Draft environmental assessment on issuing a quota to the Makah Indian tribe for a subsistence hunt on gray whales for the years 2001 and 2002. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service. 64pp.

CITES. 2001. http://www.cites.org.

IUCN. 2001. The 2000 IUCN Red List of Threatened Species. http://www.redlist.org.

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