Riverine Larval Fish Assemblages Change Between Years with DIfferent Flow Conditons

What is it about?

Different fish respond differently to flow conditions in Australian temperate rivers. Hydrologic conditions in Australia temperate rivers are less predictable than tropical rivers, and therefore fish have evolved a range of life history strategies to adapt to these boom and bust cycles. Human induced changes to these systems have reduced the frequency and duration of major overbank flows, the timing, magnitude and frequency of ecologically important within-channel flows. This study examines larval fish assemblages between years and explores hydrological and environmental preferences based on evidence of larval collections. We suggest groupings of fish based on spawning characteristics and species response to hydrology (low – medium flow spawners, high flow spawners or seasonal spawners). The results suggests that a range of conditions (low flows and overbank flows) are required to maintain a diverse and abundant native fish fauna in the lower River Murray. This reinforces the need to provide targeted environmental water in heavily regulated rivers, aimed towards reinstating important components of the flow regime and restoring the health of the rivers, floodplains and fish communities

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Why is it important?

Restoring a more natural flow regime to modified rivers is integral to maintain and potentially restore declining fish populations. The challenges in heavily regulated river systems are vast, but a combination of environmental water allocations and active river management has the potential to provide a flow regime more reminiscent of natural conditions. This reinforces the need to provide targeted environmental water in heavily regulated rivers, aimed towards reinstating important components of the flow regime and restoring the health of the rivers, floodplains and fish communities