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The Gray Whale - subfamily Eschrichtidae, is one of the most active of all large whales with spyhopping and breaching commonly observed. The Gray can grow to a length and weight of 15m (50ft) 30-35 tons for the female and 14m (46ft) 16 tons for the male. This whale is well known for the 19,500km (12,000 mile) round trip between its northern feeding grounds in the Beaufort, Bering and Chukchi seas and its southern breeding grounds in Baja California and off the Korean coast.The Gray is mottled over it's entire body including the flippers and tail flukes (though albino individuals are not uncommon). This grey body is covered with white, yellow or orange patches of barnacles and associated parasites (whale lice), particularly on top of the head, around the blowhole and on the anterior part of the back. The head is narrow and arched along the upper surface giving it a conical shape. It's mouth contains small hairs along the upper jaw with 130-180 relatively small baleen plates on each side.
Primarily a bottom feeder, the Gray will dive to 120m (395ft) deep, but prefers much shallower water. While feeding it stirs up clouds of mud from the seabed and from it's mouth during filtration. During this time the whale will mostly consume tubeworms and sessile polychaetes. While migrating the Gray will feed at the surface on small fish and shrimp-like mysids (Acanthomysis sculpta) but once the Arctic is reached it will consume it's main prey gammarid amphipods.
Three populations once existed. One in the North Atlantic was hunted to extinction around 1700; a Korean population in the Northwest Pacific was hunted until 1968 and is now rare; the third, a Californian population in the Northeast Pacific still exists in moderate numbers, 17,000 - 18,000 despite earlier over exploitation.
On June 16th, 1994 the U.S. Fish and Wildlife Service (FWS) removed the eastern North Pacific stock of Gray Whales (Eschrichtius robustus) from the U.S. List of Endangered and Threatened Wildlife. The decision was based upon a determination by the FWS and the National Marine Fisheries Service (NMFS) that the population had recovered to its pre-exploitation size.
Mexico set the precedent for Gray Whale habitat protection when the Whale Sanctuary in Laguna Ojo de Liebre, Baja California Sur was established by presidential decree. In 1988, the Vizcaino Biosphere Reserve was created to encompass two areas used by gray whales, Laguna Ojo de Liebre and Laguna San Ignacio. In addition to the establishment of protected areas for this cetacean, legislation prohibiting the harassment, capture, physical harm or killing of gray whales was also enacted in 1983 and 1991.
The Gray Whale can be observed in December to April in Mexico, with small numbers in British Columbia, Canada, Washington State, Oregon,and northern California. The main breeding lagoons in Mexico are Ojo de Liebre, Guerrero Negro, San Ignacio, Scammon's and the Magdalena Bay complex.
During April to November the whales inhabit their Arctic feeding grounds in the northern Bering Sea and southern Chukchi Sea.
Migrating gray whales have a predictable breathing pattern: a whale will blow 3 to 5 times, raise its flukes, then submerge for 3 to 5 minutes. It can stay submerged for about 15 minutes.
Sexual maturity in Grays occurs between 5 to 11 years old, or when they reach 11 to 12 metres in length, gestation is approximately 13 to 14 months. A newborn gray whale is usually 4.5 meters long and weighs roughly 450 kg.
Calving every two years on average, a females gives birth to a single calf. Mating and calving occur primarily in the lagoons off Baja California, Mexico. Calves nurse for about 8 months on milk containing 53% fat, human milk, by comparison, is only 2% fat. When the calves are weaned, they begin using their baleen to sieve food from the water.
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