Reuters recently reported on a long-term effort by Australian scientists to use artificial insemination and growing fetuses in test tubes to save the endangered grey nurse shark.
The grey nurse shark is apparently a docile marine creature that used to be plentiful off the eastern coast of Australia. Today, however, there are only an estimated 500 grey nurse sharks left there.
According to Reuters, the grey nurse shark was inaccurately blamed for a number of shark attacks and ruthlessly hunted until the 1960s. Unfortunately the species has never recovered.
Part of the problem is the species’ reproductive system which has evolved to include intrauterine cannibalism. According to Reuters,
. . . grey nurse embryo pups develop a jaw and razor-sharp teeth very early in their development and cannibalize siblings in the womb.
The sharks have two wombs in which a dominant pup will consume its siblings, leaving only two surviving pups every two years when the shark breeds.
In order to increase the odds of the grey nurse shark surviving off the coast of Australia, researchers there are working on methods to artificially inseminate the grey nurse sharks in captivity. In July the Melbourne Aquarium began an experiment artificially inseminating a seven-gill shark. if that experiment is successful, the same technique could be applied to the grey nurse shark.
But that doesn’t solve the problem of the intrauterine cannibalism. According to Reuters, another group of Australian researchers has come up with an even more radical plan — inseminate and grow grey nurse shark embryos in test tubes.
Reuters quoted New South Whales state fisheries biologist Nick Otway as saying,
Once the embryos have developed to a certain size (10 cm) they actually have a fully functional set of jaws and teeth, then they swim around and cannibalize their siblings. We have to bypass this cannibalistic phase. Once the animal gets through that stage it fends for itself. It just swims around the womb eating, we just have to feed it.
All these techniques pioneered with animal research being turned around and used to help save endangered species.
Scientists to breed test-tube sharks. Reuters, July 28, 2005.
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