Grey Nurse Sharks Get Artificial Uterus

June 23, 2009

Release from: Australian Associated Press

An Australian fisheries biologist has come up with a novel way to stop endangered grey nurse shark pups eating their siblings in the womb - an artificial uterus.

Grey nurse shark embryos compete for nutrition within the mother's two uteruses, with the strong ones gobbling up their weaker kin.

New South Wales Port Stephens Fisheries Institute biologist Nick Otway said overfishing had endangered the species and the cannibalistic embryos made it difficult for numbers to rebound.

"The last shark standing in each womb devours any unfertilised eggs during a year-long gestation, after which the mother gives birth to the two pups,'' he said.

"The shark's long pregnancy and low birth rate, along with people killing it because they mistakenly assume it is a man-eater, have knocked its numbers down to just a few thousand worldwide.

"Caretakers have had trouble keeping pups born in captivity alive, producing only nine sharks in 20 years.''

He is hoping to fix the problem after a successful trial of acrylic wombs in "birthing'' wobbegong sharks, which develop in a similar way to the grey nurse.

In the trial, 10-month old embryos from a wobbegong were put into fake wombs in a special tank and bathed in a solution similar to that which would be in the mother shark's uterus.

He and his team will experiment on younger wobbegong embryos before trying to replicate the intrauterine solution of a grey nurse and breed pups.

He said the fake womb could potentially increase a grey nurse's brood to 20.

Otway said he could adapt the device for biologically similar species, but he isn't keen to experiment with artificial human uteruses.

"That might be possible, but I don't want to get into it because of the ethical issues,'' he said.

"I'll stick with sharks."