A new estimate of adult population size for Australia’s eastern Grey Nurse Shark drew on widespread genetic sampling and forensic exploration of family trees.

Grey nurse sharks are found across tropical and temperate regions of the North and South Atlantic, Indian and western Pacific oceans, to depths of at least 230 metres. Internationally, they are listed as Vulnerable on the International Union for Conservation of Nature Red List of Threatened Species.

Australia has distinct eastern and western populations, each inhabiting an approximate 2700 kilometre stretch of coastal waters. The eastern population ranges from central Queensland to at least the New South Wales/Victoria border and the western population ranges from Western Australia’s North West Shelf to at least Cocklebiddy in the Great Australian Bight. The eastern population is listed as Critically Endangered under the Australian Environment Protection and Biodiversity Conservation Act 1999.

Objective 1 of the 2014 national recovery plan for the Grey Nurse Shark is to: Develop and apply quantitative monitoring of the population status (distribution and abundance) and potential recovery of the Grey Nurse Shark in Australian waters.

Previous population estimates for Grey Nurse Shark in 2009 and 2010 relied on photo identification, but this technique can have challenges relating to covering the full geographic range of the population, and the accuracy of matching the sharks’ spot markings.

This CSIRO-led project, funded by the National Environmental Science Program Marine Biodiversity Hub, built on data collections and analytical techniques developed in a suite of related projects completed under this partnership.