Corryong Fishing Comeback (with a bit of help)

“Not again!” That was my first thought as the news came through in late December 2019. A lightning strike fire, which had been burning ominously in Burrowa-Pine Mountain National Park, had apparently exploded in hot northerly winds and torn down towards Corryong and surrounding townships. Hadn’t north-east Victoria had its share of bushfires?

When the fires were finally out in February, with all the destruction, it seemed almost frivolous to be worried about the fishing. Yet the Corryong district was known for some of the finest trout and cod opportunities in Victoria, and I wasn’t the only one wondering how these species had been affected. The members of Corryong Angling Club, who were seeing firsthand the effects of the fire (and in particular damaging post-fire run-off) on key waterways like the Nariel, Cudgewa and Thowgla creeks, were turning their thoughts to a way back for the fish and the fishing.

Through observing fishery recovery following events like the Alpine fires in 2003, the Great Divide North and South fires in 2007, and the Black Saturday fires in 2009, I suspected the situation probably wasn’t as bleak as it first appeared. Still, the Corryong fires saw many groups and individuals motivated to do something to hasten the recovery of the local streams and the fish. With the smoke barely gone, a number of plans swung into action.

Nariel Creek, May 2020. Starting to recover, but some help would be nice! (P. Weigall pic)

Habitat Recovery

The science is clear: the single biggest boost you can provide to just about any freshwater fishery, is to improve the living conditions for the residents. It’s common sense: give fish places where they can hide, rest, and feed efficiently; provide decent water (flows, quality and the right temperatures), and then add good habitat for the food they eat, and fish will thrive.

Conversely, take those things away, and no amount of intervention with things like stocking or even angler take, is going to make much of a difference. Of course, catch regulations and stocking can often play a valuable role in fishery management generally. But there’s no point in stocking fish into water that’s uninhabitable, and no point placing catch restrictions on fish that aren’t present in the first place.

This is what bushfire damage does. Ironically, it often isn’t fire itself which kills the fish, it’s the effect of heavy rain afterwards on the suddenly-denuded and ash-blanketed landscape. The runoff chokes gills and smothers streambeds. Meanwhile, without living vegetation, the bare banks erode easily and cooling shade from trees is gone. Any fish that are left, or which subsequently return, are faced with a bleak environment.

After the bushfires are out, when it rains on bare ground and ash, the problems for fish are only beginning. (P. Weigall pic)

Habitat repairers talk about the homogeneous stream-bed that’s often found in the aftermath of fires, with finer sediment and collapsed stream banks resulting in a broad, featureless channel. Nowhere for fish to avoid predators or current, and few opportunities for their aquatic or terrestrial food sources to re-establish.

Given time, fire-affected streams can often recover on their own. However, on high-value angling streams, time is precious. This is where targeted habitat repair has kicked in on the Cudgewa, Thowgla, and in particular, the Nariel. With a major funding investment from the Victorian State Government, a collaboration between the North-east Catchment Management Authority (NECMA), the Australian Trout Foundation (ATF), the Corryong Angling Club and local farmers, has resulted in some remarkable habitat work.

Thanks to a new fishway further downstream, cod from the Murray River can now access this very fishy stretch of the Cudgewa Creek.

Instream, a weir blocking native fish migration on the Cudgewa has been modified by creating a rock-ramp fishway; while on the Nariel and Thowgla, structures to provide fish habitat, reduce erosion and encourage revegetation, have been installed. On the banks, tree-planting is hurrying up the return of shade, bank stabilisation and helping terrestrial fish food come back.

Structural work like this on the Nariel offers big benefits to cod, trout and other river residents initially left homeless after fires.

Stocking trial

When wild trout fisheries are depleted by droughts or fires, stocking would seem, on the face of it, to be one solution to recovering stocks. Unfortunately for quick fixes though, the science hasn’t been very promising. Globally, stocking has often proven to be ineffective in restoring decent wild trout fishing. Locally, extensive research through Victoria’s own Wild Trout Fishery Management Program, found that stocking thousands of yearling brown trout into Victoria’s wild trout streams provided a negligible return. (Surveys over three years recaptured only 17 brown trout from 15,000 stocked.)

Even so, one thing that hadn’t been tried was stocking with very small wild fish. So, at the instigation of local anglers and the ATF, and with the cooperation of NSW Fisheries and the Victorian Fisheries Authority, 25,000 wild-sourced brown trout ova were collected from Gaden Hatchery on the Thredbo River, then hatched at Snobs Creek Hatchery. These fry were subsequently stocked in November 2020 at a number of sites on the Nariel Creek once conditions for trout survival had begun to improve. (The nearby Thowgla Creek was deliberately NOT stocked to provide a comparison point for wild trout regeneration without this kind of human assistance.)

Landing one of several Nariel brown trout with local angler Neal Bennetts on the net. DNA tests will eventually tell whether trout like this were stocked as fry, or are wild-bred fish. (Great fun either way.)

The fate of these trout is being well monitored.  Since the fires, Arthur Rylah Institute staff have been busily surveying the Nariel, Thowgla and Cudgewa to track cod, trout and fish recovery generally. Because the Gaden trout had their DNA signature recorded prior to release, a very small dorsal fin sample from each Nariel brown trout surveyed will be DNA tested, enabling researchers to determine which surveyed trout are from the Gaden stocking, and which are entirely wild-bred.

The Fishing

As for the Corryong district fishing itself, I can vouch that it’s coming along nicely! During a trip to the area a few weeks ago to discuss and explore the bushfire recovery work, I managed to do a fair bit of sampling myself with a fly rod; some of it in the company of local angler and advocate Neal Bennetts. NECMA’s Andrew Briggs showed us around, and all our fishing was in the vicinity of the stream rehabilitation work.

Selecting a Hot Dot PTN. Nymphs were good on the day, though hopper patterns rose quite a few fish despite the rain.

The whole experience was beautifully photographed (as you can see) by David Anderson. We caught – and of course missed – plenty of trout on both the Nariel and the Thowgla, where Neal was unlucky to drop a ripper brown on a hopper pattern. While there was some talk of ‘camera shy’ trout, ultimately, a respectable number turned out to be willing to pose …

Thowgla brownie on a hopper in the rain. Definitely a wild trout, and a bushfire survivor – but no doubt helped on its journey by NECMA habitat work.

The most memorable moment for me was arriving at some just-completed log work on the Nariel, which we all agreed would probably be devoid of trout for the moment, given the very recent disturbance by a lot of heavy machinery and Hi-Viz! Still, it was deemed a good photo opportunity, so I dutifully fished up the edge of the structure with my now trusty hopper pattern and hot dot PTN nymph… and caught a nice fat brownie right in the middle of the new work.

The power of habitat: the machinery has barely left, and this trout has moved back in.

We were all delighted to see a trout back so soon, and I re-fished exactly the same water as David sent his drone up for some more footage. Bang! Almost in the identical spot, I got another – the only double for the day. If that doesn’t say something about the value of habitat repair, I don’t know what does.

…and another fish, perfectly timed for a drone’s eye view.

The Future

Besides the direct benefits to Corryong’s local streams, all the work reported on above will have broader value when it comes to our fishery management response to future fires.

Post-fire gold.

While we might wish otherwise, sooner or later bushfires will impact valued fisheries somewhere, and the lessons from Corryong will help us respond better… including whether or not stocking with small wild trout has value. Stay tuned.