(Lilljeborg, 1861) - Gray whale
Gray whales are easy to identify. They are intermediate in robustness between right whales and rorquals. 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 to 12 smaller “knuckles” on the dorsal ridge of the tail stock. There maybe several (generally 2 to 5) short, but deep, creases on the throat that allow compression of the throat during feeding.
Although young calves are dark charcoal grey, all other gray whales are brownish grey to light grey. 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 mouth contains 130 to 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 to 4 m.
Can be confused with
Gray whales are unique in body shape and patterning, and thereis usually little problem with identification. From a distance, however, they can sometimes be confused with right, bowhead, sperm, or humpback whales.
At birth, gray whales are about 4.5 to 5 m long; adults are 11 to 15 m in length. Maximum body weight is over 35 t.
Gray whales are found only in the North Pacific Ocean and adjacent seas. Gray whales are 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 kilometres of shore (although they do feed great distances from shore on the shallow flats of the Bering and Chukchi seas). Gray whale stocks which previously occurred in the North Atlantic were wiped out by whalers in the seventeenth or eighteenth century.
Biology and Behaviour
Most groups are small, often with no more than 3 individuals, but gray whales do sometimes migrate in pods of up to 16, and larger aggregations are common on the feeding and breeding grounds. Breaching, spy-hopping, and other aerial behaviours 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 occurs in winter, during migration, and in or near the Baja California breeding lagoons. Gray whales feed primarily on swarming mysids and tube-dwelling amphipods in the northern parts of their range, but are also known to take red crabs, baitfish, and other food opportunistically.
The North Atlantic stock was apparently wiped-out by whalers in the 18th century. A western North Pacific (Korean) stock may also have been extirpated in the mid 20th century; its continued existence as a small remnant is still debated. The eastern North Pacific (California-Chukotka) stock nearly suffered the same fate twice, once in the late 1800s and again in the early 1900s. Both times, a respite in commercial whaling allowed the population to recover. About 170 to 200 from this latter stock are killed annually under special permit by commercial whalers on behalf of Soviet aborigines, and one or a few are taken in some years by Alaskan Eskimos. Since receiving IWC protection in 1946 and the end of research harvests in the late 1960s, this population has increased, and now apparently equals or exceeds pre-exploitation numbers.