A diversity of Daly River flows sustains diverse freshwater fish

27 August 2019

Maintaining water flows in Australia’s northern rivers is essential to conserve the diversity of freshwater fishes and the health of barramundi populations, new Hub research shows.

The research on environmental flows in the NT’s Daly River, led by Associate Professor Alison King from Charles Darwin University, found that dry-season flows are necessary to maintain fish habitat and food webs in this tropical river – flows may be threatened by increasing demands for water extraction by agriculture and mining.

Researchers found that maintaining the variation in water depth and velocity along the river during the dry season is essential to retaining a diversity of fish habitats: from the deep, snag-bottomed pools favoured by larger fish to the rocky riffles favoured by small-bodied species. The river’s shallow, fast-flowing sections – most vulnerable to reductions in water levels – are critical nurseries and refuges for many smaller fish species. Many fish species in the Daly spawn all year round, not just during the wet season when water levels are highest; and some prefer the low water levels of the dry season.

And then big fish eat little fish. The abundance of barramundi in the Daly is strongly influenced by river flows and the availability of prey species. Barramundi that migrate to freshwater sections of the river grow 25% faster than those that remain in estuarine habitats, most likely owing to the greater productivity of the freshwater habitats. Maintaining year-round habitat and spawning opportunities for the small fish species eaten by barramundi is critical in sustaining healthy populations of this culturally and commercially important species.

sooty diagram

Recent Hub News

  • Nov 27, 2020


    16-year collaboration wins two Territory Natural Resource Management Awards We’re honoured to have won not one but TWO Territory NRM […]

  • Nov 25, 2020

    Setting standards for mine-site rehabilitation

    Ants and other animals key to tracking rehabilitation Studying ants and other animals is helping scientists in Australia’s north to […]

  • Nov 19, 2020

    Machine learning helps to map gamba grass from space

    Researchers from CSIRO, Charles Darwin University and The University of Western Australia have developed a machine-learning approach that reliably detects […]

  • fsdf
View more Hub news

North Australia News

Our Northern Hub Newsletter highlights what's going on in our research projects across northern Australia. It includes latest findings, what's coming up and what this all means for sustainable development and land and water management in the region.

Latest eNewsletters

Stay Informed

Want to know more about Hub activities and the development of northern Australia? Stay informed of activities, research, publications, events and more through the Hub Newsletter.

Subscribe to our mailing list

* indicates required