Gray whales average 46 to 50 feet in length and can weigh nearly 40 tons. Females are generally larger than males. Grays have two blowholes on top of their heads. Instead of a dorsal fin, these creatures have a low hump on their back followed by six to 12 knobs/knuckles along the top of the tail area.

Gray whales derive their names from their mottled gray color. A number of parasites attach themselves to grays and discolor their skin. Patches of white, yellow, or orange barnacles and whale lice cover these whales. Some have hosted up to 100 pounds of barnacles.

Habitat & Diet

Gray whales inhabit the coastal waters of the North Pacific Ocean and migrate annually from Alaska to Mexico. The whales spend their summers feeding in the Bering Sea near Alaska. In the fall they travel down the Pacific Coast to their winter breeding and calving grounds off Baja California, Mexico.

As bottom feeders, gray whales forage the ocean floor for food. They mainly suck small invertebrates and crustaceans out of the sand and mud, and filter food through their baleen plates. Grays can consume up to a ton of food and 1 million calories per day.

Social Organization

Gray whales are mainly solitary creatures. During migration they sometimes travel in pairs and trios, however, they do not develop stable groups. Mothers and calves form the only known stable bond, which disappears at weaning.

Reproduction

At eight years of age, gray whales reach sexual maturity. They court or mate either during migration or in and around breeding lagoons. Females give birth to a single calf about every two years. Gestation takes 13 to 14 months. Mothers nurse their young for six to seven months.

Threats to Gray Whales

Once exploited by whalers to the brink of extinction, gray whales dramatically rebounded to near original population levels. Sustained protection of the Endangered Species Act, Marine Mammal Protection Act, and the Convention on International Trade in Endangered Species of Wild Fauna and Flora helped save this species. Grays were removed from the endangered species list in 1994.

Though protection from whaling has enabled the population to recover, human induced threats still exist. For example, whales get entangled in fishing gear, salmon set nets, and crab pot lines. In addition, large ships occasionally collide with gray whales, leading to injury or death; and smaller ships harass these whales, disturbing swimming patterns or displacing calves from their mothers.

Other possible threats include the sound made by oil and gas exploration activities. The loud pulsing noises occur at frequencies that overlap gray whale calling frequencies, potentially interfering with socialization, reproductive behavior, and communication between whales.