Marine Biology
Migratory patterns

Gray Whale Migration of the Gray Whale Orcas Killer Whale Western Coast Predators



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Migratory patterns
Jose Juan Gutierrez's image for:
"Gray Whale Migration of the Gray Whale Orcas Killer Whale Western Coast Predators"
Caption: Migratory patterns
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Image by: Chris huh
© GNU Free Documentation License, Version 1.2 http://commons.wikimedia.org/wiki/File:Gray_whale_size.svg

Gray whales spend the summer season feeding in the cold waters of the north, and then in October, as the northern ice starts to form southward, they begin to move in small groups and along the Western coast of Canada and the United States, until their arrival to the warmer waters of the south in B.C.

During the month of October of each year, small groups of gray whales begin their annual migration from the cold waters of the Bering and Chukchi seas in Alaska to the warmer waters in the gulf of Baja California, Mexico. This migration takes from two to three months, and it covers up to 6,000 miles (10,000 kilometers).

Travelling night and day along the Western Pacific U.S. coast, at an average speed of 5 miles (8 km.) per hour; they can cover 85 miles (136 km.) of distance a day. By the end of December and early January, they begin to reach their destination at the lagoons: “Laguna Ojo de Libre; San Ignacio and Magdalena.”

The first whales to arrive are the pregnant mothers, who look for the protection, which these shallow waters can provide to their new born calves, (babies) from their natural predators: “killer Whales (Orcas).” Between February and March the majority of the population of Gray whales has arrived in the lagoons.

While in the lagoons, the pregnant whales begin to give birth to the new calves (babies) and mating among males and females initiates. The gestation period requires about one year, and females reproduce biannually. The calf can measure about 4 meters (13 ft) in length. . It is possible that the shallow lagoon waters could act as a protection barrier to keep the newborn calves from the attack of the killer whale (Orca).

From February to March, the males and single females begin to abandon the lagoons. The pregnant whales and nursing mothers are next in the departure. Some mothers could take some time before deciding to leave, making sure that their calves (babies) are ready for the journey, and this could extend well into May.

Once they leave the shallow waters in the Baja peninsula, and on their way north, they have to face their natural predator, when they swim across open waters in the Monterrey Bay, where the calves are the obvious target of the killer whales (Orcas).

Gray whales can grow to about 52 feet (16 m) long, weight 40 tons and they usually live from 50-60 years. During their migration of thousands of miles, they feed occasionally from Benthic Crustaceans, however, depending entirely on the fat reserves that were obtained during their stay in the northern waters.

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More about this author: Jose Juan Gutierrez

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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://www.learner.org/jnorth/tm/gwhale/MigrationRoute_Map2008.html
  • InfoBoxCallToAction ActionArrowhttp://www.learner.org/jnorth/tm/gwhale/Nurseries.html
  • InfoBoxCallToAction ActionArrowhttp://www.learner.org/jnorth/tm/gwhale/SouthboundBabies.html