Vulnerability of the endangered Maugean Skate population to degraded environmental conditions in Macquarie Harbour

Maugean Skate (Zearaja maugeana) are only known from two isolated estuarine systems located on the west coast of Tasmania, representing one of most restricted distributions of any elasmobranch. There is, however, uncertainty about the continued persistence of the species in one of these estuaries (Bathurst Harbour), suggesting that Macquarie Harbour may now represent the sole remaining habitat for the species. The species is listed as Endangered under the Threatened Species Protection Act (Tas) and the Environmental Protection and Biodiversity Conservation Act (Comm) and, apart from protected status, is without a recovery plan or management strategy. The physicochemical conditions in Macquarie Harbour have changed markedly since European settlement, influenced by anthropogenic activities in and around the estuary (e.g. mining, forestry, hydro-electricity generation, and marine farming operations) as well as the more general effects of climate change. Of recent concern, has been a marked decline in dissolved oxygen (DO) conditions in Macquarie Harbour which are likely to have a significant impact on many resident species, including the Maugean Skate. In the absence of population dispersal or mixing outside of Macquarie Harbour, any longer-term changes to DO conditions in the harbour are likely to result in changes to ecological assemblages inhabiting this unique estuarine system. The current study describes the vulnerability of the Maugean Skate, across all its life history stages, to a range of environmental stressors. The ability to monitor population status and population responses of the Maugean Skate to any changes in environmental conditions will be critical in assessing the need for further conservation management action.