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

Funded Activity Summary

The physio-chemical conditions in Macquarie Harbour have changed markedly since European settlement and the general decline in DO since 2009, which occurred at the same time as the rapid expansion of marine farming operations, is likely to have had a significant impact on many resident species, including the endangered Maugean Skate. Given the species poor ability to cope with low DO, any reductions in bottom DO concentrations are expected to directly influence the distribution of the skate, highlighting the need to better understand the oxygen demands of the species. Current generation acoustic tags capable of measuring DO and activity in the field, which when combined with laboratory studies, represent methods to examine tolerance and responses to varying levels of DO. Bottom DO also has implications for the development and survival of skate eggs. Limited information suggests that eggs are deposited at depths of > 20 m where they are likely to be increasingly exposed to low DO concentrations. An understanding of the relationships between environmental conditions and the development and survival of embryos, coupled with the depths in which eggs are deposited, has particular relevance to assessing the implications of changing environmental conditions on future recruitment and productivity of the Maugean Skate population.

Furthermore, the ability to monitor the status of this population, especially given the rate and extent of recent environmental changes in Macquarie Harbour is critical to assess its future viability. Tracking size composition, including data from previous studies, has the potential to provide a baseline against which reduced recruitment (if linked to the changed environmental conditions) could be detected.

The maintenance of best environmental practices by the aquaculture industry supported by effective monitoring and environmental management policies represent essential requirements if industry and Maugean Skate populations are to coexist.



Objectives:
1. Determine the distribution of Maugean skate eggs within Macquarie Harbour, with particular reference to depth and bottom DO.
2. Examine the relationship between environmental conditions and survival and viability of Maugean skate eggs.
3. Determine what DO levels Maugean skate experience in Macquarie Harbour, particularly when in deeper waters.
4. Determine the physiological costs of the DO levels Maugean skate are exposed to in Macquarie Harbour.
5. Assess the potential of using the size composition of Maugean Skate catches as an indicator of population change, in particular recruitment variability
6. Assess the implications of declining DO concentrations in Macquarie Harbour on the future viability of the Maugean Skate population.

Funded Activity Details

Start Date: 01-04-2017

End Date: 31-07-2020

Funding Scheme: Funding Scheme not available

Funding Amount: $421,129.00

Funder: Fisheries Research and Development Corporation

Research Topics

ANZSRC Field of Research (FoR)

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ANZSRC Socio-Economic Objective (SEO)

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Other Keywords

Biology | Ecosystem | Physiology | Remote Sensing

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