After the Apocalypse

Sitting on top of Mount Hotham David could see the horizon in all directions. As far as the eye could see, 1.3 million hectares had been burnt. In places the fire had been so hot it had split boulders and burnt every living thing to the water line, in others the tops of the trees were still intact although the leaves were brown. It had been the understorey that had burned.

Some streams still had some green foliage along the edges but others were bare and the trees were skeletonised sticks where fire had been so hot as to consume the green branches of the tops of trees.

The EPA provided us with a photo of a tidal wave of sludge that was passing down the Ovens River after the first rain fell after the fire. This thick sludge of ash and mud was the consistency of custard. That same weekend it claimed the life of a volunteer fire fighter who drowned when her vehicle was washed over a river crossing. The survival of any fish or other gill-breathing organisms was doomed.

The heat generated by the fires raised the oxygen losses and water temperatures killing most of the inhabitants of the streams. Assuming the life expectancy of fish is five years (some live longer) this means that five-year classes of fish have been lost to the fire in affected streams. From tiny fingerlings to three pounders, all sizes have been lost.

Some fish have survived. It is a fact that a few fish managed to make it through. Retreating to cold spots in the river bed or wherever they could reach spring fed water that remained cool enough to keep them alive as the fire raged around them.

Some fish are now being recruited from dams and storages where the urge to spawn will bring them back into some of the fire affected streams. Nevertheless the losses have been a significant blow to the populations of fish that had already been adversely affected by prolonged drought.

A five-year generational gap exists in the fishery. Natural recruitment will be low, as erosion, siltation and the suffocation of spawning beds by ash will prevent good natural recruitment for at least two years until the scouring effect of winter floods cleans the gravels and silts to allow recovery.

The release of alkalinity by the ash will first have a caustic effect on our generally acidic streams neutralising and finally creating a burst of growth in the macrophytes (waterplants) and the macro invertebrates (insect) populations. Abundance will return with the recycling of nutrient from the fires back into the environment.

Trees and plants are re-colonising the ash beds and exposed soils and binding them together with new growth. Unfortunately this takes time for recovery to take effect. It may be two or three years.

What of the effect on our human population? Like the wild life that survived the fire many of them have been profoundly affected. Tourism has died. Positive efforts are being made to try to revive confidence but many businesses in the fire ravaged areas will not survive.

The state Government has allocated $2 MIL for immediate relief but four shires in the fire-affected regions have lost a total of $121 MIL of economic activity as a result. This will need much time to address.

My concern is to address the fish populations first. Then economic recovery will follow more quickly. The loss of five year classes of fish can be addressed by a restocking process of yearlings. These will thrive in the developing, nutrient rich environment and plus the gaps caused the fire in the first year of low recruitment.

If governments were to provide this restocking program it would short-circuit the drawn out recovery process. A positive message that they were proactively intervening to assist the recovery would inspire the return of recreational anglers to our streams and help repair damaged rural economies.

After all, when you are travelling on a fishing trip and you buy a burger in Bairnsdale and fill up with fuel in Maffra or pop into the blue duck for a beer, you are having a profound effect on the recovery of recreational angling tourism in the regional areas of Victoria.

~ Geoff Hall