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Whatsapp Rainbow Trout are not native to Australian waters, however there are wild populations which are supplemented annually by fish raised in hatcheries.

Generations of anglers in south-eastern Australia have enjoyed waterways well stocked with trout. Yet both rainbow and brown trout are introduced species: breeding them to stock waterways may be detrimental to native fish and lead to a vicious cycle of re-stocking. James Bennett investigates.

In south-eastern Australia, the most sought-after freshwater fish is the trout—but fishers have a problem.

‘Over the last two years, rainbow trout numbers just collapsed,’ fly fisherman Steve Samuels told Off Track, sitting beside his favourite fishing spot, Lake Eucumbene in the Snowy Mountains.

‘We started stocking Lake Eucumbene with rainbow trout in the year 2000, about four years after that that the fishing went absolutely gangbusters.

We put 150,000 fish in this lake and we’ve been doing it since year 2000—that would indicate to me that we’re getting things more right than wrong. To suddenly change that to 300,000 might make the fishery collapse.

‘That went for seven to eight years, then over the last two years we saw the collapse again even though we are stocking.’

Some ecologists believe the fish shouldn’t be there at all, because trout can drive away or out-compete native species like golden or Macquarie perch, and smaller galaxids at higher altitudes.

Although he’s not advocating the de-stocking of trout, Professor Ross Taylor, a freshwater ecologist at the Australian National University in Canberra, said their impact on native species has been well documented.

‘In Australia, where we’re very heavily stocking some waterways, that means we get quite a dramatic effect on native fish biomass,’ he said.

‘[But] there isn’t a question here of saying, “lets eradicate trout,” it’s not realistic and I don’t think there’s a social mandate to do it.’

The brown trout was first introduced to Australia 151 years ago.

‘It’s controversial, there are a lot of people that would say they wish it never happened,’ Steve Samuels acknowledged. ‘But we also brought out lots of other things that are a lot worse for the environment.

‘We brought out foxes and the starlings, rabbits, pigs, goats and even sheep and cattle and horses, even ourselves—as Anglo-Saxon people were all imports into this country and we’ve all had our impact.’

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Whatsapp Fishing guide and author Philip Weigall with a brown trout fresh off the line.

Samuels is the president of the Monaro Acclimatisation Society in southern New South Wales, one of many such societies set up in Australia during the early years of white settlement which aimed to establish more homely surroundings for the early pioneers.

‘The acclimatisation society was about trying to make Australia a little bit more like home, a little bit more like England, and in the 1800s you can understand that, it was a long way from home,’ he explained.

‘Good, bad or indifferent, we have these fish in the lake and what we at the Monaro Acclimatisation Society try to do is to make sure that we manage the fishery.

‘A lot of people have a downer on trout, we love them, of course, we think they’re a good sport fish.’

Philip Weigall, a fishing writer and guide, can’t help but agree.

‘There’s just, there’s something about them. I mean, obviously they’re pretty, but you could say that about a lot of fish,’ he said, casting a fly line into Tantangara Reservoir in the Snowy Mountains.

‘A very important part of it [is] they just happen to like to live in beautiful places, they like mountains, they like clear water, all the things I guess that we associate with beauty.’

How the first fish arrived is a story in itself: 151 years ago, a ship by the name of the Norfolk docked in Melbourne from England, carrying a most unusual cargo.

In her hold lay boxes and boxes of live trout and salmon eggs.

The ova had survived the three-month journey from England, carefully sandwiched between layers of damp moss and ice.

The eggs unloaded in Melbourne would perish, but the remainder, carried further south to Tasmania, would hatch into the first Australian-born brown trout.

They were supplemented several years later by rainbow trout, originally from North America, but brought to Australia via New Zealand.

Related: Why the allure of fishing has little to do with fish

Both species are still being bred and released into lakes and rivers today.

Gary Caldwell, the assistant manager at the New South Wales Department of Primary Industries’ Gadens Hatchery at Jindabyne lists the facility’s annual output: ‘Between 300,000 and 500,000 browns, upwards of a million rainbows depending on survival rates, 100,000 brook trout and 200,000 to 250,000 Atlantic salmon.’

Staff at the facility harvest eggs from trout that move up the Thredbo River to spawn each autumn. They’re then fertilised and nurtured through a series of tanks and ponds before release.

The work is paid for by the revenue fishery authorities derive from selling recreational fishing licenses.

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Whatsapp Fly fishing has drawn generations of fishers to the wild spots of Australia, like Thredbo River.

In the United States, fisherman-turned-author Anders Halverson has argued that requiring fishery managers to be self-sustaining drives them to pursue aggressive stocking policies designed to drive license sales and thus income.

‘The idea is to get [trout] in there and then tell people where they are so that they go catch them and bring them out again,’ he said.

Halverson’s book, An Entirely Synthetic Fish, documents mankind’s efforts to spread rainbow trout around the world.

According to Halverson, fish stocking had been pursued with such vigour in parts of the US that it has actually made fishing worse.

‘If you stock hatchery fish on top of wild fish, you end up having fewer of either,’ he said.

‘They chase the wild fish out of their holds and after a month or two the stocked fish die, but only after they’ve also caused the death of many of the wild fish, because they’ve chased them out and caused them to burn too much energy.

‘You can guess what happens then—this is a big economic driver in many places—everybody complains there’s no fish in the rivers so its a cycle, a spiral: you stock even more fish, people say, “Come stock our river again, were out of fish,” and so it drives this cycle where wild fish are driven down, down, down and you might have been better not stocking anything at all in many cases.’

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Whatsapp Fly fishers practice their craft at Lake Eucumbene.

When trout catches dwindle, which anecdotally they have done across south-eastern Australia, grumblings of protest don’t take long to build into something much louder.

Widespread reports of fewer fish in New South Wales and Victoria in recent seasons have prompted renewed debate about the best way to manage fisheries.

Steve Samuels said any decline had a big impact on business in town like Lake Eucumbene, which are sustained in large part by fishing tourism.

‘The majority of anglers that fish this lake probably come from Victoria, Melbourne right up through to Sale, Sydney and the ACT, they saddle up for a decent trip, so if the fish aren’t here, they stop coming they find other places to go and fish.

‘We’ve seen it over the last two years when the rainbow trout weren’t here in numbers that were keeping anglers happy, they find somewhere else.’

That much is acknowledged by authorities.

‘It’s a very important fishery; it is of enormously important for social and economic reasons,’ NSW Department of Fisheries inland manager Cameron Westaway said.

Steve Samuels said there is empirical evidence for the success of stocking programs.

‘We know they’re effective because there’s trout there,’ he said of existing efforts.

‘A lot of the streams we stock have been noted trout streams for well over 100 years.

‘They’re streams that anglers go to today and anglers fish and they see trout and they catch trout and they’ve been doing that for 100 years, so we know that the trout survive.’

However, Samuels also said he’s wary of pursuing what might be seen as the easy option—stocking more fish in places like Lake Eucumbene.

‘When you haven’t got enough of something you tend to want more, and so you put more in, but I’m very guarded against doing it,’ he said.

‘We put 150,000 fish in this lake and we’ve been doing it since year 2000—that would indicate to me that we’re getting things more right than wrong. To suddenly change that to 300,000 might make the fishery collapse.’

Samuels is pushing for more research to understand exactly what is happening to trout numbers.

So too is Philip Weigall, who favours allowing fish to spawn and breed naturally where possible.

‘Let’s be clear about it—stocking is not all bad, there definitely are stocked trout waters in Australia and some of them are very, very good,’ he said.

‘I’m always at pains to point out that stocked is not some sort of second rate “not-really-real, not really fun”.

‘However, all the international research and what research has been done in Australia shows that if you have the capacity for trout to spawn and breed on their own there’s no better way of populating recreational trout fisheries.

Related: A tale of two fish

Amongst the fishing community, however, that is a contentious view.

Mr Weigall acknowledges that his ‘nature is best’ philosophy worries some.

‘It does, because it’s a really difficult thing to explain to people, and understandably so. To the typical guy who goes out fishing a few times a year, not a trout bum like me who devotes their life to it, if there’s not enough trout, the logical solution would seem to be “put more in”.

Scientists working for the NSW government have also told Off Track that existing research cannot adequately explain recent poor seasons.

Cameron Westaway, the NSW Department of Fisheries inland manager, admitted that the paucity of reliable information was due to limited fishery management funds.

‘We’d always like to do more research, but within reasonable cost constraints,’ he said.

‘We’re looking forward to trying to develop some research that will better guide us in how we maintain and enhance, and keep it a great fishery.

At present, a percentage of the fish stocked in Lake Eucumbene have a fin clipped so they can be identified. That doesn’t always allow researchers to accurately determine the age of a fish, though.

Off Track has also been told that resource constraints mean researchers are rarely able to catch enough spawning fish for a reliable sample size.

Fish released into Lake Jindabyne have wire tags implanted into them.

These tags confirm that a fish came from the hatchery, but if authorities want to verify its age, it must be killed to read the information contained.

The paucity of reliable consistent information has seen Victoria commit significant resources to learning more about how fish survive in rivers across the state’s north-east, including Philip Weigall’s old stomping ground, the Delatite river.

In that river, eight acoustic receivers, together with temperature gauges, have been set up to record the movements of 100 tagged trout, in a bid to work out what impact water temperature has on the fish

Victoria’s trout project is seen as a benchmark in evaluating many of the myths and theories that surround good and bad fishing seasons.

Scientists there are one year into a three-year study that will aim to answer seemingly simple questions: Is there actually a decline in wild trout populations? What is the impact of water temperature? Does fish stocking help?

In an effort to distinguish stocked from wild fish, scientists will add a naturally occurring barium isotope to the eggs of hatchery fish as they’re fertilised which will colour the earbone inside their head.

The trial, conducted at Lake Eildon, will allow scientists to assess the interaction between fish in the lake and the rivers which surround it.

The fish will still need to be killed to assess their origin, but the technique is more cost-effective and can be applied en-masse, unlike clipping or tagging.

As for New South Wales, Cameron Westaway told Off Track a survey is being designed that will assess the lakes’ ecosystems, with a focus on understanding the lifecycles and fluctuations in the number of insects, smaller fish and other creatures which make up the trout diet.

‘We also need to get a handle on catches, we need some sort of creel survey that tells us what anglers are catching,’ Westaway said.

‘To do a Rolls-Royce model can be very expensive, so we need to work with anglers and universities and others to try and get cost-effective research happening.

‘You can’t just jump in, because you’ll get it wrong.’

Trout fisheries caught on the fly Listen to the full episode of Off Track to hear more of this fishy tale.

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