Commonwealth Environmental Water Office via Murray- Darling Freshwater Research Centre, $206,587.
Dr Paul Humphries, Dr Stacy Kopf, Luke McPhan and Institute Adjunct Dr Geoff Vietz
From 2017 to 2019 ILWS researchers, in collaboration with researchers from the Centre for Freshwater Ecosystems (formerly Murray-Darling Freshwater Research Centre) undertook research activities for the third and final phase of the Murray-Darling Basin Environmental Water Knowledge and Research (EWKR) project’s Fish theme. The theme’s main aim was to better understand the important factors affecting the recruitment of riverine fish and how these factors are influenced by water flows.
Photo : Dr Amina Price (CFE) and Dr Paul Humphries collecting samples in the Ovens River. Pic: Jessica Davison.
Building on the outcomes of the Conceptualisation of flow-recruitment relationships for riverine fisheries. Foundation activities for the Fish Theme of Environmental Water Knowledge Research (EWKR) project in 2016, the researchers carried out specific on-ground research activities to test some of the hypotheses to come out of the conceptual synthesis.
The Ovens River, in North-East Victoria, was used as a “test river” as it is relatively unimpacted by flow regulation. Twelve of its reaches were characterised in terms of their retention capacity. In summer 2017-2018 researchers collected zooplankton (which larval fish feed on) from within those reaches to determine if increasing retentiveness equates to more food. The following summer they undertook further monitoring to test another hypothesis which is that fish larvae settle in those reaches that are more retentive and more likely to provide more food.
The research conducted by the ILWS researchers is described in the Individual Research Activity Summaries detailed in the final report for the fish theme research. Activities they contributed to or led included:
A key finding of their research was that recruitment of native riverine fish in the Murray-Darling Basin operates at multiple spatial scales, from the patch scale within a river reach all the way up to the basin scale. Fish larvae interact with food, temperature and predators at small scales, which determines initial recruitment, but hydrological and hydraulic diversity and connectivity at much larger scales are critical for maintaining whole populations. Ensuring a diversity of flows and the habitat that is produced through the interplay of flow and the physical structure of rivers is key to maintaining recruitment in the suite of native species of riverine fishes.
Price, A., Balcombe, S., Humphries, P., King, A. & Zampatti, B., (2019) Murray‒Darling Basin Environmental Water Knowledge and Research Project — Fish Theme Research Report. Report prepared for the Department of the Environment and Energy, Commonwealth Environmental Water Office by La Trobe University, Centre for Freshwater, CFE Publication 223 June 2019 41p. [Appendices 203p.]
The research has provided a better understanding of the links between key water flow characteristics and potential fish responses which will assist water managers to develop environmental water regimes around the needs of native fish. The information may be used to improve predicting the outcomes of proposed water management regimes.
Dr Paul Humphries Email