A womb with a different view: one step towards an ex situ grey nurse shark breeding program
The critically endangered grey nurse shark (Carcharias taurus) off the east coast of Australia is in a very precarious position and facing extinction because of past and present fishing-related interactions. The sharks own bizarre reproductive biology involving intra-uterine cannibalism followed by oviphagy results in only two pups (one in each uterus) being born biennially after 9 12 months of gestation. In August 2005, NSW DPI commenced a long-term research program aimed at developing the knowledge and techniques to bypass the intra-uterine cannibalistic stage and enable the propagation of grey nurse sharks in an artificial uterus. This paper provides an overview of this multi-faceted research program and then concentrates on the some of the results obtained for our model species the dwarf ornate wobbegong shark (Orectolobus ornatus). These wobbegongs are easily maintained, feed, mate and pup in captivity. The results of studies involving intensive field sampling, biochemistry and ultrasonography are described and important aspects of their reproductive cycle and uterine fluid composition are highlighted. We then describe the design, construction and operation of an artificial uterus. Finally, we present results arising from our successful, world-first test of the artificial uterus. This experiment involved the harvesting and transfer (in September 2007) of 6 six late-stage wobbegong embryos (3 males, 3 females) into the artificial uterus and we summarise their subsequent development, a somewhat different birth and then their growth in captivity over the ensuing months.