23 September 2005

Australia: Test-tube sharks on the way?

Australian scientists are hoping to develop techniques that would allow them to produce 'test-tube' grey nurse sharks, in a bid to save the species from terminal decline.

The grey nurse, also known as the sand tiger shark, is a form of nurse shark unique to Australasia. Despite state protection that bans deliberate fishing of the shark, scientists at Melbourne Aquarium have warned that takes (accidental or otherwise) of the grey nurse are occurring at an unsustainable rate.

The shark has a lengthy reproduction cycle and produces just two pups. Numerous pups initially form in two wombs, but they turn on each other and go through a cannibalistic process. Just one survives in each womb, to be born after a year's gestation.

The scientists want to be able to save more embryos for development. They plan to catch females in the wild and scan them to check for the stage in pregnancy in which plenty of embryos are still alive.

When such a female is caught, its embryos will be removed either surgically or by flushing. They will be placed in artificial uterine solution and returned ashore for laboratory development.

Sounds simple! First, however, scientists need to develop the techniques necessary to carry out the removal of embryos, create workable artificial uterine conditions, and establish feeding patterns that will keep the embryos healthy as they grow.

Some 10 years have been earmarked for the developments, with a reported Aus $250,000 committed to the scheme by the Australian Government.

Source: www.divernet.com


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