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Shrinking waters a concern
  |  First Published: May 2007



For some time now the drought and its effect on trout fisheries has been a dominant topic of conversation in our part of the world.

To date most of the talk has been about the rivers which, by and large, no longer exist. Anglers have simply had to live with the fact that for four or five years most of the trout streams have been dry or so short of water that the trout have died.

The only exceptions have been some of the higher-country streams where there has been enough seasonal snowmelt and rain, or prolonged drainage from alpine bogs and springs, to keep some flow.

In rivers such as the Thredbo, Snowy, Eucumbene, Goodradigbee and Murrumbidgee, connected to large storage dams, some trout have survived by migrating to and from the larger waterways as conditions dictate or allow.

Most of the other rivers are dead or have been invaded by carp, which can survive the low flows, high temperatures, low oxygen levels and poor food that typify most of the waterways.

Unfortunately, restocking of selected streams with trout fingerlings from the hatcheries has not been a success. There simply isn't enough water for the fish to survive so things are looking pretty grim.

As if that wasn't bad enough, attention is shifting to the Snowy Mountains lakes. In the past these storages have been thought of as invulnerable. They are large, deep, snow-fed every year and have lower evaporation rates because of their high altitude. They are the permanent, ‘untouchable’ waterways, the last bastions of good trout fishing on mainland Australia. Recently we are starting to rethink that.

Lake Jindabyne, for example, fed mainly by the supposedly mighty Snowy and Thredbo rivers, has dropped to 46% capacity. Islands and other structures unseen for some time have started to emerge. The bare lake edges and muddy shores indicate how fast the level is dropping.

It’s not yet short of water and, in fact, is fishing well and is considered the most healthy of the highland lakes but there is still concern about the low level for this time of year.

Tantangara Dam, one of highest trout lakes and fed by the Murrumbidgee River, is at 5.5% – too low even to drain down the tunnel to Eucumbene and play its usual top-up role. It's only a small lake and at this level is not much more than a large puddle but it carries a huge population of trout, mostly smaller browns, and it must be increasingly difficult for the trout to survive in a healthy state under these conditions.

EUCUMBENE

The big worry, though, is Lake Eucumbene. The largest and oldest of the Snowy lakes has been the showpiece for trout fishing since it was constructed in 1959. It is a huge waterway, fed by numerous creeks and especially the Eucumbene River.

It takes in a major proportion of the mountain snowmelt each year and runoff from a high rainfall over a large catchment. When full, it carries more than 10 times the amount of water in Sydney Harbour.

It is the premier trout fishery of mainland Australia and one of the most productive freshwater fisheries in the Southern Hemisphere.

After six or seven years of below-average rain and winter snow, it's in a tough position. It has fallen to just 17% of capacity, the lowest been since it was constructed and lower even than the previous record of 18% in 1983.

What's worse is that the level is still falling and there is no official statement on how low it will fall before we can expect any respite from Winter rains or snow.

The official version is that water releases will continue. Australia needs hydro-electric power and irrigation water, provided in part by water from Eucumbene. Drainage will continue until we hit some magical level where all activity will stop but we don't know what that level is. The impact on the fishery has been significant.

Firstly, there is a matter of aesthetics. The lake surrounds look awful. Vast expanses of baked mud, clay, silt and rock, the boring view sometimes broken by dead trees, exposed pastoral fences or the forlorn foundations of the Old Adaminaby township that was moved or drowned when the lake was developed.

Vast dust and sandstorms sweep across the terrain every time the wind blows and these can be awesome in their strength when an alpine gale erupts.

Then there is access. As the water retreats it leaves behind vast areas of mud, silt and soft clay that takes months to dry and until then represents a hazard to vehicles. Hundreds have become bogged in recent years and it may cost up to $500 for a commercial tow-truck to come out from a nearby town.

Boat launching has been increasingly difficult, to the point where many anglers don't try any more, although to their credit, local groups have organised relatively safe launching. Foot access, too, has been a problem. Walking to the lake edge has been arduous because of distance or boggy terrain. At the water's edge the bottom is soft and unpredictable. Make a false move and you sink to your waist in the sticky mud. Wading to fish is simply out of the question.

RAINBOWS SUFFER

The fish, too, are suffering. The browns aren't doing too badly; they stick mostly to the deeper water where it is cooler and has a better oxygen supply. They also dine pretty well on yabbies and any small fish and mostly are in good condition with firm, well-coloured flesh pleasant to eat.

The rainbows are doing it tough. They don't like yabbies much, which is a pity because that's almost all there is. They have to survive on such meagre fare as Daphnia (water fleas) and what few snails and aquatic insects remain.

Very few terrestrial insects, which normally would provide a large part of the rainbow's diet, make it to the lake. They are way back in the grass and trees in the distant hinterland, too far away to walk, fly or crawl to the water. The drought has significantly reduced the numbers of terrestrial insects that might otherwise be available.

So the rainbows are starving. They can be caught quite easily, using PowerBait, scrub worms, bardi grubs or lure or fly fished along the shore. The huge numbers of fish being taken are another matter for concern but they are in poor condition. Most are thin, shrunken, with pale flesh and empty stomachs. Most have an unattractive taste and really are not worth eating.

So if this situation is going to improve, we need rain or snow and lots of it. I have no faith in El Nino, El Nina or any other Spanish rainfall nonsense but if you know a decent rain dance, get out and give it a try. If your neighbours think you are mad, tell them I said it was worth a try. We'll try anything at the moment.

NATIVES RESTLESS

As if to compensate for the poor situation at Eucumbene, fishing for the native fish in the lower lakes around Canberra has been excellent.

The urban lakes and Googong Dam have been clear enough for good lure as well as bait fishing because of lack of inflow from rain.

All have yielded good-sized golden perch up to 6kg on spinnerbaits and deep-divers and there have been some excellent Murray cod of all sizes from around 30cm to specimens topping 30kg. Most of the fish have been caught and released, demonstrating the care and concern anglers have for these superb sportfish.

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