GRAY WHALE

Gray Whale (Eschrichtius robustus)

The Gray Whale is found in Arctic feeding grounds between April and November, and in Mexican breeding grounds from December to April. Between October and February the species migrates south, returning north again between February and July. This 'round trip' migration of 12-20,000km every year is believed to be the longest of any mammal.

Classification: Wilhelm Lilljeborg identified a sub-fossil in 1861, naming it Balaenoptera robusta. In the same decade, however, John Gray of the British Museum noted the differences between this species and the rorqual whales, and so placed it in a new genus, Eschrichtius, after the zoologist Daniel Eschricht.

Local Names: California Gray Whale, Devilfish, Mussel-Digger, Scrag Whale. The American spelling of 'Gray' is internationally accepted, and reflects the creature's body colour.

Description: This is a stocky but slender whale, with a small, narrow triangular head and pointed paddle-like flippers. Instead of a dorsal fin, there is a series of bumps called crenulations along the dorsal ridge. It is mottled grey in colour, with 2-4 throat grooves, and the skin is encrusted with patches of barnacles and whale lice. The Gray Whale is about 12-14m in length, with the largest recorded measuring in at 15m (females are generally larger than males). It weighs between 14-35 tonnes. There are about 280-360 yellow-white baleen plates per animal.

Recognition at Sea: The shape of the head, skin colour and lack of a dorsal fin should discern the Gray Whale from other large whales. The blow is vertical, between 3-4.5m in height, and - when viewed from in front or behind - has been described as 'heart-shaped'.

Habitat: This species is a coastal cetacean, usually seen over the continental shelf and in water less than 10m deep. Nearly all animals, during their migration, pass within 2km of the shoreline, and occasionally Gray Whales are encountered in deeper waters.

Food & Feeding: The Gray Whale is unique among all the cetaceans in that it is a bottom-feeder and rolls onto its side, sucking up sediment from the seabed. This sediment contains a number of bottom-dwelling organisms (mainly benthic amphipods) which are retained by the baleen whilst the water and silt are filtered out. The Gray Whale feeds in shallow waters, usually between 50-120m deep. During the peak feeding period, adults consume between 1-1.25 tonnes of food per day.

Behaviour: Gray Whales typically travel in small groups of around three, although up to 16 animals may travel together in close association. In breeding areas, groups of two (primarily mother/calf pairs) or three are most common, but in feeding grounds good conditions can lead to hundreds of whales congrating. Moans, whistles, growls, bongs, rumbles, clicks, chirps and rasps, as well as breaching and underwater exhalation, are the primary means of communication between individuals.

Longevity: Approximately 70 years.

Estimated Current Population: 22,000 animals. There were three populations of Gray Whale - East Pacific, West Pacific and Atlantic. The latter was hunted to extinction 300 years ago, and the West Pacific population has been so drastically reduced that it seems it will share the Atlantic's fate. The East Pacific population was once considered extinct but has recovered surprisingly well and is now a focal point for whale-watchers.

The Influence of Man: The Western Pacific stock of Gray Whales was probably not more than several thousand animals when commercial whaling began in the 1600s. By the time Korea took 1,500 animals between 1910-1933 through shorebased whaling, the population was almost extinct. The Eastern Pacific and Atlantic stock began to be exploited in 1846 by American whalers. About 11,000 whales were taken in 1874 off the coast of California alone. As the stock diminished, the whaling was reduced but factory ships slaughtered 1,000 animals between 1914 and 1946 (when the species was granted full protection). Between then and 1989 5,500 whales have been taken as part of the aboriginal hunt or by 'scientific' permit. One calf, named Gigi, was brought into captivity in the early 1970s but released after a year. In 1988 when four Gray Whales were entrapped by ice in Alaska help came from all over the globe, highlighting the importance of these special creatures. Kayaking with Gray Whales is now becoming a popular holiday experience, as Mark Carwardine explains in his book On The Trail Of The Whale.

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