Publication (Media): Snags: Our Rivers’ Coral Reefs

Publication Type:	Media Release
Publication Name:	Snags: Our Rivers’ Coral Reefs

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Nicol, Simon (2000) Snags: Our Rivers’ Coral Reefs - Apr 27 2000, CRCFE, Canberra - Media Release.

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Snags: Our Rivers’ Coral Reefs

Snags are trees and branches that fall into and lodge in a river and are an essential part of a river’s ecology.

A program to replace the all-important snag is saving the habitats of many species of fish and invertebrates in the Mighty River Murray.

The tide of opinion has turned since 1858, when people removed snags from rivers to protect the hulls of boats. The practice continued until as late as two decades ago, when the community began to understand the importance of snags to our river habitats and commenced snag-replacement programs to repair our waterways.

The Department of Natural Resources and the Environment Victoria (DNRE) through the Cooperative Research Centre for Freshwater Ecology in Canberra has received $540,000 Natural Heritage Trust funding over two years from the Murray Darling 2001 Fish Rehabilitation Program to investigate the effectiveness of re-snagging for the rehabilitation of native fish populations in the Murray River.

The project focuses on one river section between Yarrawonga and Cobram, and once complete will also suggest ways in which re-snagging can be successful on a broader scale.

Project co-ordinator Simon Nicol, says the study is in its second year, with initial results suggesting increased numbers of fish in the area.

“Our team has replaced 300 snags at 20 sites along the Murray. The locals have been enormously supportive of our project. Individuals have volunteered use of their land for snag storage, whilst local councils have lent their support with equipment to harvest and move the logs.

“A council bulldozer has been very effective for moving logs - many with a heavy root mass - into the river. The sheer weight of the logs drags the root mass to the stream bed, and no further handling is needed, ”Mr Nicol said..

Dr. John Koehn an aquatic biologist with the project states that “to most people, especially boating operators and enthusiasts, encountering a snag on a relaxing river jaunt spells possible disaster. What they often don’t know is that snags support more aquatic organisms than any other part of the stream, and without them, many species of fish, birds and insects simply die”.

“While sometimes bothersome to people, snags are also an essential ingredient in the recipe for river health, providing roosting sites for birds, turtles and platypus, and protection and food for native fish, invertebrates, insects, fungi and algae,” Dr Koehn said.

“The Murray Cod, for instance, uses snags for shelter in fast-flowing streams, and as resting points as they journey hundreds of kilometres to spawn. Also the Golden Perch is known to use the pools formed at the base of snags for shade and shelter from predators.

“River Blackfish lay their eggs in cracks and hollows on a snag’s surface. Numbers of these fish species are dwindling, and our studies have shown that the removal of snags is almost certainly linked to this decline.”

Snags also helped create and maintain the shape of rivers and streams and removing them caused erosion, downstream flooding and re-shaping of the river-bed.

Dr Koehn said he expected the full benefits of re-snagging to be evident within a year.

Captions:
Re-snagging in progress in the river Murray between Yarrawonga and Cobram
Snags provide important habitat for water birds such as these Ibis

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