NFRS — Lower Darling Demonstration Reach

Why the Lower Darling?

The Lower Darling River is significant for native fish in the Murray-Darling Basin. Iconic species such as Golden perch, Murray cod, Silver perch and Freshwater catfish, as well as a number of important small-bodied native fish species, live in this special river. The Darling River supports the breeding and recruitment (growth and survival) of fish, with Golden perch adults, for example, spawning upstream so that larvae and young fish drift downstream. As they drift they grow, so by the time they reach the Menindee Lakes, there are juveniles and adults able to repopulate, both in an upstream and downstream direction. Recent science demonstrates that Golden perch in the Murray system (from Echuca down to the Lower Lakes in South Australia) are often those that began life in the Darling River.

The Lower Darling River Murray cod population is particularly important for the recovery of adjacent populations in the mid and lower Murray River system that in recent years, have suffered severe declines with blackwater fish deaths across thousands of river kilometres.

Golden perch. Photo credit: Finterest

Big Murray cod. Photo credit: Jamin Forbes

Recovering the Lower Darling

NSW Department of Primary Industry, in collaboration with other State and Commonwealth agencies and organisations, are now looking at management actions to protect and recover native fish populations in the short term (2019-20), as well as when conditions improve. These actions include:

Short term:

Water quality and fish monitoring
Creation of artificially aerated refuge areas in the Lower Darling
Relocation of fish from diminishing pools to better quality waterbodies

The results so far...

Round 1 of fish community sampling occurred within the Fish Death Reach and a Control Reach in June 2019. The primary objectives of this sampling were to: 1) examine the status of the remnant fish population, and; 2) investigate the impact of the 2018/19 fish deaths on the fish community with comparison against an unaffected river reach.
To monitor short-term change in the fish community post the fish death event, a second round of fish community sampling was conducted within the Fish Death Reach in October 2019. The second round of sampling was not conducted within the Control Reach as monitoring results would have been confounded by the removal of fish during fish rescues.
Preliminary analyses indicate a positive short-term change in the fish community between July and October 2019 after the fish death events.
Continued significant decline was observed in Australian smelt and common carp. However short term recovery was observed in the abundances of carp gudgeon and freshwater prawn; two short-lived, opportunistic, non-flow dependent recruiters.

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Long term:

Increasing restocking efforts
Improving fish passage through the region
Rehabilitating aquatic habitat at priority reaches of the river
Working with other state and federal agencies
Engaging and building capacity with local communities, to deliver further management actions to support the movement, breeding and recruitment of native fish

An aerated refuge area in the Lower Darling. Photo credit: NSW DPI

Karoola Refuge Pool with Iain Ellis. Photo credit: NSW DPI

Working with community:

There will be a number of activities with key stakeholders relationships in the Lower Darling region to provide on-ground coordination and information sharing across fisheries-related activities:

A “Fish, Flows and Cultural outcomes for the Lower Darling River “program will also be established so that Aboriginal voices are heard in water management activities and decision making. This will involve working with local Barkindji representatives so that they can inform future water management activities and decision making. This program is intended to align with the development of a “Healthy Country Program” by the Barkandji Native Title Group Aboriginal Corporation. Read the paper they produced here.

Freshwater dreaming - catfish. By Sam Assan

Iain Ellis at the Menindee information session. Photo credit: NSW DPI

A community workshop was held in Menindee in late November 2019 to kick off on-ground engagement. It is hoped that more events like this one will provide a channel for more effective public engagement and local knowledge to be incorporated into research activities. It will also assist researchers and managers to dispel misinformation associated with particular topics and addressing wider community issues/concerns.

A citizen science project involving local people, including anglers and Aboriginal community members, will enable changes in the fish community to be tracked through time by locals. This will need cross-collaboration between researchers and scientists, which should boost understanding of fish and flow relationships, as well as ecological processes such as hydraulic variability, thermal stratification and oxygen depletion (linking to our aeration efforts to mitigate hypoxia in 2019-20).

Out and about with the locals. Photo credit: NSW DPI

Adding water into the river via the Jamesville pump. Photo credit: NSW DPI

Training in the use of monitoring equipment and data collection through photo-point monitoring will be provided so that community members can create photo point time series, or use photo diaries to document changes in their river, ideally pre and post drought recovery. Water quality units will also be made available for use by community members so that water quality data relating to assessing the effectiveness of aeration units Fisheries and the MDBA have installed in 2019-20 can be gathered.