Tracked Great White Shark May Be Pregnant

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Justine Alford

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433 Tracked Great White Shark May Be Pregnant
Robert Snow, Ocearch. Image- Lydia, shortly before her tag was attached.

A great white shark that has been tagged by a group of scientists at OCEARCH, a non-profit organisation that carries out research on sharks and other apex predators, is thought to possibly be pregnant. Leader of the expedition, Chris Fischer, thinks that the shark, named Lydia, is probably headed for birthing grounds in the Mediterranean sea. Lydia was tagged last year near Jacksonville, Florida, and has since traveled around a whopping 20,000 miles. You can track her movements at the OCEARCH page.

Interestingly, Lydia is traversing the Atlantic, crossing the Mid-Atlantic ridge last weekend. It is becoming apparent that sharks are dwelling in temperatures once thought to be too cold. Lydia is the first shark to be tracked crossing the Atlantic. Fischer told the BBC that he believes "it's possible for Lydia to make it to the UK". Although there have been reported sightings in British water in the past, it is uncertain as to whether these were indeed great whites. 


The great white shark (Carcharadon carcharias) is a species of shark found in coastal and offshore waters which have a temperature range of between approximately 12 and 24 degrees Celsius. These sharks are apex predators; they have no natural predators of their own, and prey on a variety of animals including seals and smaller shark species. Female great whites are larger than males, and may reach up to 5 meters in length. 

There is no direct evidence that Lydia is pregnant, but Fischer recently told the the BBC that he guesses she is pregnant, and is heading to the white white shark birthing grounds. This is very exciting, because very little is in fact known about shark pregnancy. Male sharks have reproductive organs called claspers; these are used to deliver the shark sperm which comes inside a shelled packet. The body of the female will eventually break this down, impregnating the female, although it's unknown how long this takes. Great white sharks are ovoviviparous; the eggs develop and hatch inside the mother until birth. It's believed that during the mating process, the male shark will bite the female in order to help keep the sharks in the right place.

Tagging can be a fairly distressing process; the shark is sometimes removed from the water in order to secure the tag. Some types of tags can be attached whilst the shark is still in the water, but these tags do not stay on the shark for extended periods, meaning they can only be tracked for shorter periods of time. Tags can also induce fouling of the dorsal fin over time. There are both costs and benefits to the process that need to be weighed up - thanks to tagging, our knowledge and understanding of these creatures has increased many times over. The more we understand of them, the easier it will be to protect them. Many shark species are vulnerable to extinction.