The gray whale is distributed in an eastern North Pacific (North American) population and a critically endangered western North Pacific (Asian) population.
The gray whale has a dark slate-gray color and is covered by characteristic gray-white patterns, scars left by parasites which drop off in its cold feeding grounds. Individual whales are typically identified using photographs of their dorsal surface and matching the scars and patches associated with parasites that have fallen off the whale or are still attached.
North Atlantic populations were extirpated (perhaps by whaling) on the European coast before 500 AD and on the American coast around the late 17th to early 18th centuries. However, on May 8, 2010, a sighting of a gray whale was confirmed off the coast of Israel in the Mediterranean Sea, leading some scientists to think they might be repopulating old breeding grounds that have not been used for centuries. In May and June 2013 a gray whale was sighted off the coast of Namibia – the first confirmed in the Southern Hemisphere.
Gray whales measure from 4.9 m (16 ft) in length for newborns to 13–15 m (43–49 ft) for adults (females tend to be slightly larger than adult males). Newborns are a darker gray to black in color.
A mature gray whale can reach 40 t (44 short tons), with a typical range of 15–33 t (17–36 short tons).
The whale feeds mainly on benthic crustaceans, which it eats by turning on its side and scooping up sediments from the sea floor. It is classified as a baleen whale and has baleen, or whalebone, which acts like a sieve, to capture small sea animals, including amphipods taken in along with sand, water and other material.
Breeding behavior is complex and often involves three or more animals. Females show highly synchronized reproduction, undergoing oestrus in late November to early December.
The gestation period for gray whales is approximately 13,5 months. Similar to the narrow breeding season, most calves are born within a six-week time period in mid January. Females lactate for approximately seven months following birth, at which point calves are weaned and maternal care begins to decrease. The shallow lagoon waters in which gray whales reproduce are believed to protect the newborn from sharks and orcas. They lives between 55 and 70 years.
Estern population- each October, as the northern ice pushes southward, small groups of eastern gray whales in the eastern Pacific start a two- to three-month, 8,000–11,000 km (5,000–6,800 mi) trip south.
Western population- the current western gray whale population summers in the Sea of Okhotsk, mainly off Piltun Bay region at the northeastern coast of Sakhalin Island (Russian Federation).
Resident group- a population of about 200 gray whales stay along the eastern Pacific coast from Canada to California throughout the summer,
not making the farther trip to Alaskan waters.