"Mayday mayday mayday", the millennium ark is sinking!

Despite exceptional advances in ensuring the health and well-being of animals in human care, zoos of the twenty-first century are ill-prepared and overwhelmed by the sheer number of species requiring conservation support. Furthermore, small population management paradigms have failed to achieve the demographic and genetic targets required to sustain most endangered species in human care. Predictions made in the 1980s regarding the potential of a "millennium ark"-aided by the use of assisted reproductive technologies (ARTs)-for saving species have proven to be wildly over-optimistic. ARTs continue to be touted as a panacea for saving endangered species and even for resurrecting extinct ones. And yet, while the first successful interspecies embryo transfer in a wildlife species occurred 30 years ago, there still is not a single example of embryo-based technologies being used to consistently manage a conservation-reliant species. The limited contribution of ARTs to species conservation to date principally stems from the lack of knowledge of species biology, as well as inadequate facilities, space, expertise, and funding needed for their successful application. ARTs could and should be an important tool in our conservation toolbox, but we cannot fall into the trap of believing that we can "assist" or clone our way out of the present biodiversity crisis. Reproductive technologists overstate the potential of ARTs for saving endangered species, zoos overestimate their ability to sustain genetically and demographically viable captive populations with existing resources, and conservationists underestimate their need for zoos in the face of failing efforts to sustain species in nature. Unless all parties concerned-reproductive technologists, zoo biologists and conservationists-adopt parallel efforts to sustain wild populations and places, zoos risk becoming living museums exhibiting relic species that no longer exist in nature.