Marine Biology

The Migratory Cycle of Pacific Great White Sharks



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With almighty cavernous mouths filled with row upon row of jagged teeth, great white sharks are the most feared predatory fish in the world. This species is scientifically known as Carcharodon carcharias, which incidentally derives from the Greek for serrated tooth. These massive sharks, of which the females are the largest, can grow to 7 meters in length and weigh up to 2,100 kg. In fact, great whites are the world’s biggest fish.

Due to media portrayal, the great white is one of the most dreaded species in existence. Obviously it is not advisable to swim in close proximity; nevertheless humans are not the favored prey. Great whites prefer to feed on seals, sea lions, dolphins and other species of shark.

Up until 2002 it was widely believed that Pacific great whites remained relatively close to the coast. However, a nature study conducted by six marine scientists from three Californian universities has proven otherwise.

Using a tagging system it was discovered that great whites sometimes migrate for thousands of miles. In essence, Pacific great whites are for much of the time pelagic in that they prefer to live deep in the ocean as opposed to coastal areas.

Each winter the great whites travel to the middle of the Pacific ocean. Some even swim out to as far as Hawaii. The males leave this area during the months of June and July and then travel to the central and northern coasts of California.

Pacific great whites mate in the waters of Guadalupe Island, Mexico and then journey deep into the Pacific. Males complete a one year migration cycle and the females undertake a two year tour. The female migration exists in four stages, the first being the gestation stage. The gestation period lasts for 18 months and 15.5 of these are spent offshore. It is for this reason that great whites exist in Hawaiian waters throughout the year, although the numbers are greater during the winter.

The second stage of the female migration is referred to as the pupping phase. The sharks make a two month journey along the Mexican coast at sometime between the months of April and August until they reach Baja, California where they give birth. However, this area is unsafe for great whites due to commercial fishing, and unbeknown to the females they leave their pups in great danger.

The females then travel back to Guadalupe Island and this is known as the pre-aggregation phase. Throughout this time they avoid the males. During the mating phase, a variety of injuries have been seen on both male and female sharks. It is currently unclear whether this is due to males fighting in order to claim females, or for food, or both. Nevertheless it appears to be the reason why the females steer clear of the males until they are ready to reproduce.

The aggregation phase comes into effect when the females finally return to Guadalupe Island. It takes place between late September and early October. This proves that Pacific great white sharks are philopatric in that they return to the same place to mate. They remain in the waters of Guadalupe Island for little more than four months until the migration cycle is repeated.

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More about this author: Caroline Fynn

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  • InfoBoxCallToAction ActionArrowhttp://www.honolulumagazine.com/Honolulu-Magazine/February-2013/Great-white-sharks-in-Hawaii-More-likely-than-you-think/
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