THE Murray Darling Basin is surely Australia's greatest ecological disaster.

About 80 per cent of the average natural flow is being diverted, primarily for irrigation.

However, as low as the Murray River and its tributaries might be, extensive stocking of Murray cod and yellowbelly has kept a quality fishery.

Sadly, the same cannot be said for the once-mighty Snowy River in Gippsland and its Australian bass population.

The Snowy suffers the indignity of siltation and other problems because its flow has been stemmed by Lake Jindabyne.

During 2003, Victoria's Marine and Freshwater Research Institute spent about six months catching, tagging and releasing bass in the Snowy with the aim of determining their movements and breeding patterns.

Preliminary results indicated that few small bass were present in the river, with the population dominated by large individuals 30-50cm-plus and about 15 or 16 years old.

Initial field sampling indicated spawning, successful larval development and/or migration did not occur in 2002.

The data showed successful recruitment for Australian bass in the Snowy River was episodic. The last good year was 1987.

This year the migration patterns of the bass are again under scrutiny and there has been work repairing the habitat in the river.

Victoria's Minister for Responsible Fisheries Joe Helper said the latest fish tracking research showed adult bass could move with ease across the sand slug, a 16km stretch of shallows, north of Orbost.

To track the bass, scientists from the Fisheries Research Branch at Snobs Creek implanted fish with acoustic tags that could be detected by data loggers placed along the length of the Snowy River.

Fisheries Victoria acting executive director Anthony Hurst said the approach revealed many adult bass travelled extensive distances, moving upstream at speeds averaging more than 3km/h.

Although extensive movements were recorded year-round, Mr Hurst said scientists found significant migrations to the lower reaches of the catchment during late winter and spring.

The research found that as water temperatures increased in spring, bass moved away from the ocean to waters higher in the catchment.

Mr Hurst said although bass moved throughout the day and night, they preferred staying close to woody snags and boulders during daylight hours.

However, after dusk, they were shown to move into the deeper waters along the Snowy.

The second project, the Snowy River Estuary Fish Habitat Improvement Project, has involved the placement of 138 logs around First and Second islands and along the banks of the Snowy estuary, 2km northwest of Marlo.

East Gippsland Catchment Management Authority's Jasmine Butler said the 8m logs, secured to piles driven into the riverbed, would quickly become colonised by invertebrates and crustaceans, providing an improved food source for both juvenile and adult fish.

The Snowy and its estuaries support populations of black bream, luderick, Australian bass and estuary perch.

Installation of the submerged logs will provide food and improve shelter for these species.

The reality is that to fix the problem and boost fish stocks the river needs water, which has to be released from NSW.

Ten years ago the NSW, Victorian, and federal governments signed off on a $425 million agreement to save the Snowy by guaranteeing minimum environmental flows.

It was a waste of money. Research is fine, but we also need outcomes.