Links between Gulf rivers and coastal productivity

The Mitchell, Gilbert and Flinders rivers flow into the southern Gulf of Carpentaria, supporting healthy ecosystems and nationally significant wetlands as well as important recreational and commercial fisheries. Banana prawns, barramundi and other important fishery species use estuarine ecosystems at different points throughout their life cycle. The Queensland State Government has also identified these river systems as catchments where irrigated agriculture is already occurring or likely to occur.

Specifically, water managers needed to know which flow characteristics of the rivers earmarked for future development are most important for the region’s plants and animals so they can make informed management decisions. This project has provided important new information about why freshwater flows in the Gulf estuaries and floodplains are essential for banana prawn and barramundi fisheries and the broader estuarine ecosystem, and modelled the potential scale of the impact of water extraction on the fisheries.

This project:

  • quantified end-of-river nutrient concentrations and loads from wet season flows
  • measured coastal/estuarine primary productivity in the three different Gulf estuaries
  • quantified densities and size structure of juvenile banana prawns in the estuaries
  • modelled how changes in flow may affect banana prawn catch
  • determined how flows affect growth rates of barramundi and their use of the river systems
  • quantified the economic impacts of changes to flows on the commercial barramundi fishery and the Northern Prawn Fishery in the Gulf of Carpentaria
  • identified areas and periods of floodplain inundation using remote sensing and used this to estimate potential floodplain primary productivity.

Gulf rivers map

Location of the three study rivers in north Queensland.

  • Glenn Halliday with a southern Gulf of Carpentaria barramundi. Photo courtesy of Carpentaria Barra and Sport Fishing Charters.
  • Field work in the Gulf of Carpentaria, photo Stephen Faggotter.
  • The researchers will use banana prawns, which have a well understood life cycle, as an indicator species. Photo: Matthew Whittle.
  • Field work in the Gulf of Carpentaria, photo Stephen Faggotter.
  • Field work in the Gulf of Carpentaria, photo Stephen Faggotter.
  • Mitchell River in the Gulf of Carpentaria, photo Stephen Faggotter.
  • Field work in the Gulf of Carpentaria, photo Stephen Faggotter.
  • Gilbert River in the Gulf of Carpentaria, photo Stephen Faggotter.
  • Mitchell River in the Gulf of Carpentaria, photo Stephen Faggotter.
  • Flinders River in the Gulf of Carpentaria, photo Stephen Faggotter.
  • Gilbert River in the Gulf of Carpentaria, photo Stephen Faggotter.
  • Flinders River in the Gulf of Carpentaria, photo Stephen Faggotter.
  • Water covering floodplain near Norman River in the Gulf of Carpentaria, photo Michele Burford
  • Norman River in the Gulf of Carpentaria with floodwaters draining off floodplain, photo Michele Burford
  • Barramundi, photo NAER Hub
  • Norman River flooding near Normanton, photo Michele Burford
  • Norman River flooding across road near the town of Normanton in 2011, photo Michele Burford
  • Water draining off saltflats into Norman River in the Gulf of Carpentaria during flood, photo Michele Burford

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