An artificial uterus, designed to give live birth to sharks, rests in the lab of the Port Stephens Fisheries Institute, in the New South Wales. It’s an atypical maternity ward.

The uterus, a series of tanks, tubes and fluid-exchange systems, is a proof-of-concept for now. But one day it could boost the dwindling numbers of the grey nurse shark.

Nick Otway, a fisheries biologist, was charged with devising a plan to breed this threatened shark with a bizarre reproductive cycle. In a paper published in Zoo Biology, Sept. 8, he and his colleague Megan Ellis, report they have done just that.

Grey...