For insights into the likely effect of this year’s bushfires on our trout, Philip reviews some past events.

2019 started badly for many trout fishing areas in south-eastern Australia. After a decent December in terms of rainfall and temperature, January brought a ‘flash drought’ with very little rain, and maximum temperatures up to 5C above average. Then came the almost inevitable bushfires, mainly started by lightning, and in that sense, virtually unavoidable. Tasmania was hit particularly hard, but the mainland trout areas certainly didn’t escape, particularly Gippsland in Victoria.

To state the bleeding obvious, bushfires are bad and if I never saw another one, I’d be happy. Sadly, that’s not going to happen. However one bright note is, I’ve learnt over the years that the impact on our trout waters is usually much less than I once feared. As we wonder what the fishing will be like following the latest fires, my diaries provide an interesting, even unexpected record.

Alpine Fires 2003

In terms of scale of destruction of trout fishing areas, these were the worst fires of my lifetime. Started by multiple lightning strikes in early January 2003, the fires burnt through hundreds of thousands of hectares of the best trout country in the Victorian Alps and the Snowy Mountains, before rain finally extinguished them in March.

Despite the grim reports, in late February, Felix Borenstein (now owner of Owen River Lodge) and I could stand the cabin fever no longer and drove up into the mountains. To our pleasant surprise, on the Ovens and Kiewa rivers, it was pretty much business as usual (clear, 19C water on the Ovens; clear and 20C on the Kiewa). We had good fishing despite the ominously blackened ranges in the middle distance.

Then we took the Bogong High Plains Road and reality gradually hit. At first, the drive up to Falls Creek wasn’t too confronting, because much of the fire on that side of the mountain hadn’t been too hot. (It’s worth remembering that fire intensity can have a big impact on outcomes, and large scale fires always have substantial variations in damage within the fire zone). In fact, some gullies and stream-sides had hardly been touched and we even managed some enjoyable fishing on both branches of the East Kiewa River above Lake Guy.

Rocky Valley Reservoir itself, on top of the High Plains, was, as expected, mostly unscathed. The heath and snowgrass was burnt here and there, but the alpine climate and open plains had evidently taken the sting out of the fire. Rocky Valley fished as well as it usually does for mostly small trout.

Then the next day, we took the road into the Mitta Valley and the further we descended, the more blasted the landscape. Barely halfway down the mountain, the country had been incinerated – black sticks in grey and white ash stretched as far east as the eye could see. Not a single distant ridgeline showed any green. Road signs and posts were burnt and there was not a bird or animal to be seen.

Descending the last few steep switchbacks to the Omeo Highway, the Mitta Mitta River came into view; an incongruous ribbon of water in the seared landscape… yet we immediately saw a rise! With rods rigged, Felix and I fished up the 18C river with Wulffs and bead-head nymphs. The diary records that we saw plenty of rises in the quieter pools, but caught most of our fish in the runs; browns to 1½ pounds. I don’t need the diary to remind me of the 3 pounder that Felix missed, nor the sambar deer lying dead by the river, seemingly unscathed, or the lone wallaby we startled on a tussock island. It was a sad, surreal few hours, but we saw with our own eyes that the river and the trout had survived.

The rivers weren’t out of danger yet though. Heavy rain over the following months produced major ash runoff events, something I’d previously been told kill all aquatic life. On the Indi River, I collected a bottle of water so turbid, you couldn’t see through it. Yet the trout survived and I’ve kept that bottle as a reminder of what trout can tolerate.

Extensive monitoring of the Indi ash runoff events right through 2003 offered some insight into how the fish managed. Despite turbidity readings being off the charts, these run-off events were brief in duration and significantly, dissolved oxygen levels never dropped below 6ppm; comfortably above trout survival thresholds.

By late summer and early autumn 2004, my diary entries were recording a series of successful trout fishing trips to the Indi, upper Mitta and other fire-affected streams like the East Kiewa and Nariel. A common note at the end of each entry was simply, ‘Back to normal.’

As an interesting postscript, I had good fishing at Lake Jindabyne in June 2004, and visited Gaden Hatchery to write an article about the annual Thredbo River fish trap monitoring and stripping, which occurs as trout run up from the lake to spawn. The fish being stripped looked unusually big and sure enough, when the numbers were crunched later, they showed that the average size was 2kg; the largest in years and nearly double the average of the previous two years. It’s notable that this peak came soon after the Thredbo and Snowy had poured bushfire run-off into the lake.

Black Saturday 2009

If the 2003 Alpine Fires are remembered for their sheer size, the February 2009 Black Saturday fires, just north of Melbourne, are infamous for their savagery. Given the loss of life and property, it seemed almost petty to worry about the welfare of the local trout streams. But finally, Max and I took a deep breath and on 17 April 2010, headed to the Steavenson River.

Scarcely a year after the fires, the Steavenson valley was in recovery, with green grass everywhere following generous summer rains. Even the tree-ferns were coming back and numerous houses were being rebuilt under the gentle autumn sun. The crowded black sticks on the surrounding mountainsides were a reminder though of what the Steavenson catchment had been subjected to.

The river itself looked good; maybe a fraction more discoloured than usual, but the runs at least were silt-free. There were no rises, so when a nice trout took my Royal Wulff in the very first little pool I fished, I was equally surprised and delighted.

What followed was possibly the best fishing I’ve had on the Steavo – before or since. Max and I landed 16 trout in a few hours – nothing exceptional numbers-wise, but the size was remarkable, with trout from 1-2lb making up the majority. Had these fish too benefitted from the nutrient boost following the fires?

Northern Grampians Fires 2014 

Lightning strikes in January 2014 started fires that burned for weeks in the northern Grampians, including virtually the entire catchment and surrounds of Lake Wartook, one of my favourite places in Victoria. Once the fires were extinguished, the next problem was access – all roads into the area were closed.

Finally, in late June 2014 the roads reopened, and a few days later, Andrew and I headed straight to Wartook. As I’ve become used to after these events, the landscape was almost unrecognisable. The fire had clearly been a very hot one: the 20 metre long plastic pontoon jutting out into the water at the boat ramp had been reduced to an unrecognisable lump of melted plastic.

Yet the weirdest thing was being able to walk anywhere through the forest around the lake at will. Usually, above the high water mark, Wartook’s shores are an impenetrable wall of scrub, but this was gone, with only the blackened eucalypt trunks intact.

My diary that day records very clear water, at 9.5C temperature. The lake was at 46% of capacity and calm under patchy mist and cloud. Past experience with fire-affected lakes suggested the Wartook trout would be fine. Still, it was good to catch a 3 pound brown, and spot a few smelters and swirls.

However, it was two return trips with Max – first in mid-August and then mid-September 2014 – which persuaded me the trout were more than just ‘fine’. By that point, heavy rain had fallen over the Wartook catchment, and the lake had nearly doubled in volume to 87% and then 88%. On both trips, the water was slightly less clear than in June, but what really stood out was the size and condition of the trout. Besides plenty of ‘regular’ Wartook 2 and 3 pounders, we landed four fish between 5 and 6 pounds. Normally, we might have been happy to catch a couple of fish this size in a whole season, not four in two trips.

Coupled with the excellent condition of all the trout caught on those August and September trips, I wondered if the extra nutrients from ash run-off had given the lake a boost? Obviously, the sample size was too small to draw hard conclusions, but in the years since, I’ve noticed our catches return to the more typical ‘pre fires’ range, with the trout in good but not great condition, and 5 pound plus fish rare once again. It seems that at the very least, the 2014 fires did no harm to Wartook.

Conclusions

In my decades of fishing records, I can’t find an example of a trout lake being negatively affected by fires. Yet there’s no doubt that, very occasionally, fires can be devastating to trout streams. My old farmer mate Tom from the upper Murray, recalls an ash run-off event on the Indi from his childhood, when the water became so putrid, even the freshwater crays marched out onto the banks in their hundreds. And in more recent times, structural damage to rivers like the Wellington and Suggan Buggan from post-fire flash floods, has taken many years to heal.

Still, history shows us that the vast majority of fire-affected streams continue to produce fishing with scarcely a blip, or are back to full strength within a year or two. And to reinforce the above, for lakes, I’m yet to fish one anywhere after bushfires, that’s not at least as good if not better than beforehand.

Yes, bushfires are something we’d be better off without, but if your favourite trout water was caught up in the latest fires, don’t be too quick to write its obituary.