Rare lamprey fish population increasing thanks to environmental water releases
Date posted: 24 August 2017
Hon Ian Hunter MLC
Minister for Water and the River Murray
Environmental water released to the Coorong and Murray Mouth this winter is helping populations of pouched lamprey, a rare and primitive fish, migrate upstream to spawn.
Around 100 gigalitres of environmental water was released at the Barrages during July and August to support native fish and bank vegetation across the Southern Connected Basin.
Pouched lampreys spend most of their adult life at sea but require freshwater systems to reproduce and grow. During the Millennium Drought, lamprey numbers declined because they were unable to migrate upstream to spawn.
Targeted winter environmental watering carried out annually since 2015 at the barrages and fishways have enabled lampreys to travel from the ocean and estuary into the freshwater environment of Lake Alexandrina, and then to the River Murray.
This year’s winter environmental watering is one of the largest managed winter releases. Lamprey monitoring has detected these fish moving through the Barrages, indicating that environmental water is providing conditions to facilitate migration.
Lamprey monitoring will continue until early September to better understand their migration upstream to their breeding grounds.
In addition to the benefits in the Goulburn and Murray rivers, the environmental water has provided freshwater to the Coorong estuary and ocean to encourage native lamprey migration.
The environmental water release also flushes salt from the river system to the ocean, improves water quality in the estuary and assists in maintaining an open Murray Mouth.
The environmental water has been made possible thanks to a collaborative effort between the South Australian and Victorian governments, the Commonwealth Environmental Water Office and Basin communities.
The lamprey monitoring is funded by the Murray-Darling Basin Authority and is carried out by the South Australian Research and Development Institute with support from the Department of Environment, Water and Natural Resources.
Quotes attributable to River Murray Minister Ian Hunter
Winter environmental water releases have been targeted since 2015 to provide freshwater cues at the Murray Mouth to attract lampreys and other native fish, such as the congolli.
We expect that this year’s monitoring will help determine whether the lamprey’s breeding grounds could be in one of the Victorian tributaries or even in local tributaries of Lake Alexandrina.
New fishways that were recently constructed at the barrages are proving popular with many species of native fish including pouched lampreys, in particular the dual vertical slot fishway at Mundoo barrage, which provides the most direct route from the Murray Mouth to Lake Alexandrina and the River Murray.
The winter releases demonstrate how environmental water holders use water to achieve multiple benefits throughout the river system.
This collaboration between environmental water holders, Victoria and South Australia shows that multiple ecological benefits can be achieved across the system by working together to deliver environmental water as part of the Murray-Darling Basin Plan.
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