1. Fish screened in an Australian first
Australia’s first conical fish exclusion screen has been installed on a regulator, in the Cohuna Weir pool, Gunbower Creek, north central Victoria. Conical fish screens were used because they work well in shallow water and have been proven to protect fish from entrainment and impingement in diversion pools, rivers and channels. The screens have minimal impact on water intake and are self-cleaning to prevent debris build-up. Each year hundreds of thousands of native fish and larvae are lost from the Gunbower Creek and the Murray River system as fish move into irrigation channels. Once in irrigation channels, the fish are lost to the natural system forever, having a negative impact on breeding and population numbers of native fish. More information: Cohuna Irrigation Diversion Screen Project – AWMA or watch the installation process:
2. Hotels for a different sort of fish
After 6 months in the water, new ‘Seahorse hotels’, resembling cages made of chicken wire, are being colonised by seahorses. Researchers have observed 20 or so adult and juvenile Seahorses living on the hotels in areas where had recently been none of these fish. The Seahorse population in Port Stephens, on the NSW central coast, was once prolific, but several large East Coast Low storms shifted large volumes of sand in the port, smothering the seahorse habitat of soft corals and sponges and resulting in a 90 per cent decline in population in just a three-year period. Seahorses rely on their habitat to camouflage themselves from predators and as a holdfast to prevent being washed away.
3. Returning the Cann River to health
The Cann River, in Victoria’s East Gippsland region, is remembered by locals as being filled with fallen branches, lots of trees on the banks and plenty of little islands in the middle of the river. This all changed with river ‘improvement’ works in the 1950s and 1960s, followed by a significant flood in 1971 which effectively stripped the river valley clean. Local landholders have been working ever since to return the river to health and to a state where the impact of floods is minimised. An important part of this has been fencing to keep stock off the river and giving native vegetation the chance to regenerate along the river’s banks. This has helped reed beds to form and over time longer and deeper pools of water have begun to re-establish. The river is becoming ‘choked up’ again, slowing it down and stabilising the riverbed.
“The river is back to where it was when I was a child. I can’t remember it looking as healthy as it is [now] …” says one local farmer.
Read more here http://www.egcma.com.au/news/ or watch the video below:
4. Tilapia vigilance appears to be paying off
Monitoring using eDNA across Queensland’s Fitzroy Basin has not found any indications of infestations of the highly invasive Tilapia. eDNA techniques analyse water samples for traces of fish DNA which can be used to identify the presence of individual species within a catchment. The broader community has been on alert since fears where raised that the pest had spread into the region’s waterways from the one known infestation in Yeppen Lagoon. Infestations are usually caused by people moving the fish between waterways or using them as bait. However, widespread floods across the Basin in 2017 raised the possibility that this pest had spread.
In the Burdekin, in Queenland Dry Tropics, there are waterholes and cane irrigation recycle pits full of nothing but Tilapia. An ongoing trial is exploring the use of Traditional Knowledge to remove the fish. The technique involves adding a native plant product to the water, which briefly lowers oxygen levels, without having any other impact on water quality and enables the Tilapia to be removed when they come to the surface. This should give native species such as Rainbow Fish, Spangled Perch, Sleepy Cod and Barramundi a chance to re-establish.
5. Taking out willows leaves more water for fish
Research has confirmed the long-held suspicion that water can potentially be returned to creeks and streams if riverine infestations of the Salix willow species are removed. The researchers found that in-stream willows account for more lost water than would be lost with the equivalent density of native species or if there were no vegetation but only open water. In cool temperate and semi-arid climates, each hectare of willow canopy removed provides an average net water saving of between 3.9 – 5.5 ML a year. In one 25km^2 study area, the removal of 10.4 ha of Willow canopy from within river channels will potentially return 41ML per year to the environment.
6. Mapping the water use of Traditional owners
The strong, ongoing connection that Aboriginal people have with Country and its water has been documented in the first maps that record Aboriginal cultural activities based on land and water values in the northern rivers of the Murray–Darling Basin. The maps, which have been given to the Euahlayi Nation and other Traditional owners, record more than 26,000 locations for fishing, hunting, ceremonies, harvesting plants, as well as burial mounds and sacred areas of deep spiritual significance. The mapped area includes the Barwon, Narran, Culgoa and Balonne rivers, from Brewarrina in northern New South Wales to St George in Queensland.
For more information, read more here: https://www.mdba.gov.au/media/mr/traditional-owners-map-land-water-use-northern-murray-darling
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