Major fish kills that occurred in the summer of 2018-19 in the Darling River system (the Darling Barka), were of an unprecedented size and generated global concern. The event identified a gap in knowledge of the longer-term consequences of a changing climate for fish populations in the broader Barwon-Darling River system. As climate change predictions suggest a warmer and drier future, the drought conditions associated with the fish kills are likely to become more frequent and severe. There is an urgent need for increased understanding of how fish populations will respond to changes in climate and hydrology, and to identify and evaluate appropriate management responses.
This research focuses on modelling the meta-population dynamics of Golden perch (Maquaria ambigua), a native species significantly impacted by the fish kills in 2018-19 by implementing a spatially explicit model of annually varying waterholes in the Barwon-Darling River. Using field measurements of fish from reaches in the research area we model age-structured populations considering all life history stages and their response to annually varying waterhole hydrologic connectivity. This was to account for the effects of changes to annual carrying capacity in waterholes treating isolated pools during dry periods as components of the metapopulation model.
The models predict the population-level outcomes of increasing frequency and duration of low flows and cease-to-flows, including the likelihood and consequences of fish kills under future scenarios of climate and hydrology. Evaluations of water management scenarios (e.g., environmental flows, variations to flow rules) and other mitigation options influencing waterhole persistence are evaluated to assess differences in the effectiveness of alternate management responses to protect fish populations in the Barwon-Darling system.