This record provides an overview of the NESP Marine and Coastal Hub emerging priorities study - "Application of environmental DNA to survey Bathurst Harbour Tasmania for the endangered Maugean skate". For specific data outputs from this project, please see child records associated with this metadata. -------------------- The Maugean skate (Zearaja maugeana) is listed as Endangered under Tasmania’s Threatened Species Protection Act and the Commonwealth Environmental Protection and Biodiversity Conservation Act 1999. Its known population is small (~3,000 individuals, Macquarie Harbour, 2016) and highly restricted, having only been recorded in two isolated estuaries: Bathurst Harbour and Macquarie Harbour in south-western/western Tasmania. This constitutes one of the most limited distributions of any known extant elasmobranch. Although the skate was first discovered in Bathurst Harbour, most knowledge of the species stems from the Macquarie Harbour population. Only four individuals have been reported in Bathurst Harbour, with the last reported sighting in 1992. Environmental conditions in Macquarie Harbour have changed markedly since then due to anthropogenic activities in and around the estuary including historical mining, hydro-electric generation and alteration of natural river flows, and marine fish farming. Previous research has shown clear signs of population stress and evidence of detrimental impacts of degraded environmental conditions on the Maugean Skate in Macquarie Harbour. Understanding the potential population status of the Maugean Skate in Bathurst Harbour will assist in determining conservation actions. This study used Environmental (e) DNA to determine the presence/absence of the endangered Maugean skate (Zearaja maugeana) in Bathurst Harbour, strengthening the evidence base for effective conservation plans and specific recovery actions. Outputs • Maugean skate eDNA sampling data and inferred species distribution (presence/absence) [dataset] • Final Project Report, including a short summary of recommendations for policy makers of key findings [written]

This record provides an overview of the NESP Marine and Coastal Hub Research Plan 2023 project "Delineation and estimation of the Maugean skate population in Macquarie Harbour, Tasmania". For specific data outputs from this project, please see child records associated with this metadata. -------------------- The endangered Maugean skate is now only found in Macquarie Harbour, which has a long history of environmental degradation, and recent research suggests that the population may be declining. However, our current abundance estimation tools are inadequate to determine population status and a new method is needed. This project will use next generation genetic sequencing and novel imaging survey tools to delineate and estimate the size of the Macquarie Harbour Maugean skate population to inform conservation strategies. There is also a need to investigate the evolutionary potential of the Maugean skate to adapt to the changing environmental conditions. This research will address these needs by examining the skate's genetic diversity and fine-scale population structure using whole genome typing, and developing a high-resolution dataset of genome-wide single nucleotide polymorphisms. This genetic approach will help inform adaptive management strategies, such as captive breeding, and enhance our ability to detect differentiated lineages with adaptive potential. Outputs • Tissue sampling results and genome-wide population genetic structure [dataset] • Adaptive resolution imaging sonar (ARIS) and lidar water column scanning [dataset] • Final project report [written]

This record provides an overview of the NESP Marine and Coastal Hub Research Plan 2024 Emerging Priorities project "Modelling adult abundance and habitat distribution of Maugean skate". For specific data outputs from this project, please see child records associated with this metadata. -------------------- The Maugean skate (Zearaja maugeana) is listed as Endangered under Tasmania’s Threatened Species Protection Act and the Commonwealth Environmental Protection and Biodiversity Conservation Act 1999. Its known population is small (~3,000 individuals, Macquarie Harbour, 2016) and highly restricted, having only been recorded in two isolated estuaries: Bathurst Harbour and Macquarie Harbour in south-western/western Tasmania. This constitutes one of the most limited distributions of any known extant elasmobranch. A Roadmap of Agreed Actions has been published by the Maugean skate recovery team. In this document, the recovery team agreed that Close Kin Mark Recapture (CKMR) be investigated as a priority action for determining historical abundance of the species in the harbour, and potentially as a complimentary monitoring tool going forward. The Commonwealth’s 2023 Conservation Advice for the Maugean skate has also identified this as a priority action. The CKMR method has been developed and operationalised for various finfish and elasmobranch species. The method uses next-generation sequencing methods to inform on the prevalence of closely related individuals (parent-offspring/half-siblings) within a set of sampled animals. This data is fed into statistical models of the population in order to obtain estimates of abundance of the breeding adults, adult survival rate, and given sufficiently informative data, population trend. CKMR will provide crucial independent estimates of the size of the Maugean skate spawning population in the Macquarie Harbour. This will be of significance for conservation decision processes which are ongoing and in determining monitoring options in the future. A secondary component of this project is to model the critical habitat distributions of the species. Maugean skate are thought to be impacted by low dissolved oxygen (DO2) in Macquarie Harbour. This is influenced by combinations of exogenous factors (industrial usage, manipulation of flow regimes from riverine inputs) and climatic / weather forcing events. Remediation trials involving the addition of DO2 are underway to determine if low DO2 conditions may be ameliorated using anthropogenic supplementation. However, a crucial missing element required to guide this process, is the linking of biophysical models of the harbour to observations of the conditions observed to be selected by the skate. This component of the project will combine synoptic biophysical predictions of the harbour with telemetry data from tagged Maugean skates which details the skates' selected temperature, depth and O2 conditions. These two information sources will be combined via habitat selection models - previously used to model habitat preferences of other species (e.g. Southern bluefin tuna) - to predict whether remediation, climate or other factors are likely to impact on the availability of selected skate habitat. Initial potential habitat maps will be generated for a hindcast period (2017-18), and for a forecast period based on models currently under development that simulate recent and evolving water quality in near-real time. This will enable recent and evolving maps of suitable skate habitats. Simulated habitat maps will be assessed against the known collective knowledge of skate habitat to identify critical habitat areas within Macquarie Harbour and inform future spatial and temporal sampling strategies. Outputs • High-quality DNA sequences of Maugean skate [sequencing data] • Hindcast maps (2017-18) of potential Maugean skate occupation [spatial data] • Recent and forecast (evolving) maps of potential Maugean skate occupation under different management scenarios [spatial data] • Estimates of spawning stock abundance of the Maugean skate from CKMR analysis [data contained in written report] • Final project report [written]

The Maugean Skate Zearaja maugeana is a micro-endemic species known from only two isolated estuaries, Bathurst and Macquarie Harbours in southwestern/western Tasmania. This constitutes one of the most limited distributions of any known extant elasmobranch. As a result, the species is listed as ‘Endangered’ under the Threatened Species Protection Act (Tasmania) and the Environmental Protection and Biodiversity Conservation Act (Commonwealth). Even though it was first discovered in Bathurst Harbour, most of what is known about the species comes from the Macquarie Harbour population. Only four individuals have ever been reported in Bathurst Harbour, with the last known sighting occurring in 1992. This study used environmental DNA (eDNA) to determine the presence/absence of the Maugean skate in Bathurst Harbour on the southwest coast of Tasmania. Water samples were collected from the seafloor in Bathurst Harbour in November 2021 and February 2022, and in Macquarie Harbour (control samples) in December 2021. Samples were filtered using a self-preserving eDNA sampling system. Following each survey DNA from the samples was extracted and analysed through qPCR amplification. Mitochondrial primer pairs from two gene regions were used to detect the presence of Maugean skate DNA in the samples. Where possible, positive detections were sequenced, and their identity verified.