Bird

Re-snagging the Goulburn River for improved Native Fish habitat

Wednesday 8 June, 2011
The Goulburn Broken CMA is reintroducing large woody habitat (or snags) in the Goulburn River between Murchison and Shepparton to increase native fish habitat. The snags will have no net impact on water flow and will enhance native fish habitat, thereby leading to a more sustainable native fish community, resulting in huge benefits for recreational fishers in our region.

The Goulburn Broken CMA is reintroducing large woody habitat (or snags) in the Goulburn River between Murchison and Shepparton to increase native fish habitat. The snags will have no net impact on water flow and will enhance native fish habitat, thereby leading to a more sustainable native fish community, resulting in huge benefits for recreational fishers in our region.

Snags are the branches, trunks and whole trees found in waterways resulting from trees on the river bank either falling in or dropping their branches.  Snags occur through the natural processes of flooding, bank erosion, wind or limb shedding and has been occurring for thousands of years. 

“Snags are the inland equivalent of coastal reefs and provide habitat for native fish and other animals such as tortoises and native water rats.  Native fish use them to shelter from fast currents and sunlight and take refuge from predation.  Native fish also use snags as feeding and spawning sites, and as nursery areas for juvenile fish,”  says Goulburn Broken CMA CEO, Mr Chris Norman.

Electrofishing studies carried out over a seven year period in the Goulburn River near Shepparton found almost twice as many fish at sites with a high density of snags compared to a site with a low density of snags .  Other fish surveys within the Murray Darling Basin have found that 80% of Murray Cod are found within 1 metre of a snag.

“In the past snags were removed from our river systems for boating safety, improved navigation reasons and to reduce the incidence of localised flooding.  This has been identified as a major reason for the loss of in-stream habitat in waterways, resulting in the decline of native fish populations.“ Removal of timber has been shown to increase the rates of erosion in many stretches of river, causing impacts on pubic assets and loss of both private and public land.”

Recently, a group of riverine ecologists from the Murray Darling Basin Authority estimated the native fish communities currently in the Basin to be about 10% of their levels before European settlement.

“Re-snagging is part of the solution to restore native fish habitat to our rivers.  Re snagging on its own, however, is unlikely to be the sole driver in native fish recovery in the Goulburn River. The key is to better manage our riparian zones by fencing to restrict stock access and protect native vegetation, and then revegetating degraded areas so
there will be a constant natural supply of snags in the future,” says Mr Norman.

Re-snagging will be carried out between Seymour and the Mitchellstown Bridge upstream of Nagambie when conditions allow, using funding provided by the Recreational Fishing Licence Grants Scheme. Snagging is seen as part of the medium-term solution to improve habitat for the next 20 years; in the long term revegetation programs will provide ongoing contribution to river health and fish populations.  

“This is  is a win-win situation for the Goulburn Broken CMA and local government, with fallen trees sourced from a number of locations across the catchment.  River Red Gum, Grey Box and Yellow Box trees that had fallen in local government managed parks, reserves and road sides due to storms and flooding will be used for the project.

Goulburn Broken CMA contractors also managed to source the larger portions (mainly the roots and trunks) of some large trees that were removed as part of the construction of the Nagambie Bypass,” says Mr Norman.

The snags are secured safely and positioned in a way that does not block the river channel. Each snag has been embedded with an electronic microchip to allow identification of the snag’s original position if any significant movement occurs during a flood.

The re-snagging project is part of the Goulburn Broken CMA’s Goulburn River Large Scale River Restoration Project funded by the Victorian State Government.  For more information please contact the Goulburn Broken CMA on 03 5820 1100. 

RELEASE ENDS

Photos available upon request.