More frequent and longer cease to flow conditions in the Murray–Darling Basin place significant pressure on the health of waterways, including native fish populations, aquatic habitat, and water quality. The Northern Basin contains stronghold areas for species that are listed as threatened under NSW and federal legislation, including important populations of Murray Cod, Silver Perch, Freshwater Catfish, Olive Perchlet, and Purple Spotted Gudgeon. Additionally, there is a growing awareness that fish populations are connected at a regional scale, increasing the importance of flows that link the Northern Basin to improve the health of the system, and protect the resilience of native fish populations especially during extreme events, such as droughts.
The historical Northern Connectivity Event occurred during autumn 2018 in response to extended cease to flow conditions in the Barwon–Darling River during early 2018. This significant and unprecedented event involved the active management of approximately 23 GL of water for the environment along the entire length of the Barwon–Darling River and major tributaries of the Northern Murray–Darling Basin, including the Border Rivers and Gwydir, to protect native fish populations by maintaining refuge habitat, and improving water quality, productivity, and longitudinal connectivity.
Monitoring of the Northern Connectivity Event was undertaken to determine native fish community composition, condition, and movement responses in the Barwon–Darling, with sampling completed on the Barwon-Darling downstream of Louth before and after the flow event, as well as the establishment of an intensive acoustic array between Louth and Tilpa. The event-based monitoring will greatly enhance knowledge of the resilience and responses of native fish communities in the Barwon–Darling River, especially during dry periods and resumption of flow events that will provide greater confidence in setting objectives and achieving outcomes for native fish from management of water for the environment.