Geographic range:
Nearctic, Neotropical: The area of distribution of the gray whale
corresponds today to shallow coastal waters from Bering and Chukchi
Seas down south along the Pacific coast on Northern America to Baja
California, Mexico. In the past the species lived also in Northern
Atlantic and western north Pacific. Atlantic population became extinct
due to over -hunting and western north Pacific population has almost
been depleted.
Physical characteristics: Adult gray
whales reach around 14 m of length and weigh about 30 - 40 tons. Females
are slightly larger than males. The body, like in all marine mammals,
is stream like. The head is narrow and tapered with upper jaw arched
in profile and slightly overlapping the lower jaw. Little depressions
are present on the rostrum. Each carries one stiff hair. There are
2-5 grooves on the ventral throat, each up to 1.5 m in length.
Overall body color is gray with conspicuous patches and white mottling
on dark background. Skin usually displays many scratches. Newborn
calves are dark gray to black, although some may have distinctive
white markings.
Dorsal fin is lacking completely, only prominent dorsal hump is present
followed by a series of 6-12 knuckles along the dorsal ridge that
extend to the fluke. Pectoral fins are paddle shaped and pointed at
the tips. The fluke is deeply notched in the center.
Food habits: Gray whales are bottom
feeders. Their principal food items are small crustaceans such as
amphipods, and tube worms found in bottom sediments. Feeding takes
place primarily during the summer months.
Reproduction: Gray whales become
sexually mature at 5-11 years of age, or when they reach 11-12 m in
length. Gestation takes 12-13 months. Newborn calves weigh over 500
kg and reach up to 4.5 m in length. Calves are fed milk with high
content of fat for 8 months and stay together with the mother for
2 or more years. Mating and calving both occur primarily in the lagoons
of Baja California, Mexico, although both have been observed during
the migration.
Behavior: Gray whales undergo the
longest migrations known in mammals. The round trip from their northern
feeding grounds to wintering calving and mating grounds, and back
sums up to 22 000 km. In October, the whales begin to leave their
feeding grounds in the Bering and Chukchi Seas and head south for
their mating and calving lagoons in Baja California, Mexico, where
they stay for about 2 - 3 months. Northward and and southwards migrations
take around the same time each. Some individual gray whales are known
to stay permanently in the Straits of Juan de Fuca between the State
of Washington and Vancouver Island, Canada and possibly off the central
California coast.
Habitat: Shallow coastal oceanic waters.
Conservation: Over -hunting drove
the populations of gray whales to the edge of extinction. The species
was given partial protection in 1937 and full protection in 1947 by
the International Whaling Commission (IWC). Since that time the eastern
North Pacific gray whale population has made a remarkable recovery
and now numbers between 19,000 and 23,000, probably close to their
original population size. |
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