Gray Whales

Description

Gray Whales (Eschrichtius robustus) are baleen whales. Adult gray whale length is 39-46 feet, with the largest recorded measuring a little longer than 49 feet. Weight is 15-39 tons. A gray whale can live approximately 70 years.

Gray whales are divided into two discrete populations, one on either side of the North Pacific Ocean. The eastern population migrates along the West Coast of North America between winter calving grounds along Baja California, Mexico, and summer feeding grounds in the Bering and Chukchi Seas between Alaska and Russia. The eastern population has made perhaps the most complete recovery of any large whale population depleted by commercial whaling. The annual migration of some gray whales back and forth between calving and breeding grounds can exceed 10,000 miles, making it the longest annual migration of any mammal. The western population occurs along the Asian coast, where it migrates between summer feeding grounds off Sakhalin Island, Russia (about 500 miles north of the Japanese island of Hokkaido), and winter calving grounds at an unknown location suspected to be in the South China Sea. In contrast to the eastern population it remains one of the most critically endangered populations of any large whale numbers perhaps by 100 animals.

Diet

Gray whales feed in shallow waters, usually 150-400 feet deep. Adults can consume 1-1 tons of food per day during peak feeding periods.

Behaviour

The gray whale is unique among cetaceans as a bottom-feeder that rolls onto its side, sucking up sediment from the seabed. Bottom-dwelling organisms live in this sediment, and stay in the baleen as water and silt are filtered out.

A gray whale's blow is up to 15 feet high, and each blow is visible for about 5 seconds. When warm, moist air exhaled from the animals' lungs, meets the cool air at the ocean surface, it creates the bushy column we call a blow, or spout. Anticipate that the whale will dive for 3 to 6 minutes, then surface for 3 to 5 blows in row, 30 to 50 seconds apart, before diving deep for 3 to 6 minutes again.

Before making a long, deep dive, a gray whale often displays its 12 foot wide fan shaped flukes, or tail. The weight of the tail above the whale's body helps the whale to dive deep. The gray whale normally swims about 5 miles per hour about the speed of a child on a bicycle. The flukes have no bones and connect to the body and tail muscles by banks of tendons.

Gray whales occasionally hurl themselves out of the water and plunge back in with a tremendous splash! This is called a whale breach. Scientist do not know why gray whales do this, but it is very exciting sight to see! Sometimes other whales in the area will copy this behavior, so keep your eyes open

Current population numbers for the western North Atlantic stock are unknown but are estimated at over 250,000 animals. Most recent population estimates show increases in abundance in Canada and the United States, although the population in the Gulf of the St. Lawrence appears to be declining. Within U.S. waters, gray seals have been seen pupping in increasing numbers on isolated islands off the Maine coast, Nantucket-Vineyard Sound, outer Cape Cod, and on Muskeget Island. In 2002, more than 1,000 pups were born on Muskeget Island.

A reliable estimate for the eastern Atlantic stock is not available, though the population may be nearly equivalent to the western Atlantic stock. The majority of gray seals in this stock are located in the waters of Great Britain where the population is estimated to be between 117,000 and 171,000 at the start of the breeding season (excluding pups). The next largest eastern Atlantic population is in Iceland, estimated at 11,600 animals. While localized populations might differ, this stock is thought to be increasing overall.

Scientists estimate the Baltic Sea stock at over 22,000 gray seals, up from only 1,500-2,000 a few decades before. Although this population is growing, it is still a fraction of the historic population estimated at 88,000-100,000 animals.