The Natural Trout Stream Paradox

The paragraph below appeared in my email inbox recently, advertising a fishing film festival.

“Gin-Clear Media’s Backcountry: South Island is the feature film of the festival. The South Island [of New Zealand] has vast tracts of some of the most intact, undisturbed natural areas left on our planet—these last truly wild places deliver beauty and isolation in spades but it is the allure of giant trout in crystal clear water that draws anglers from around the globe to this treasured land.”

A prime example of south island back country from Lee's last trip
A prime example of south island back country from Lee’s last trip

What struck me the first time I read this were the words ‘intact’, ‘undisturbed’, ‘natural’ and ‘wild’.  New Zealand’s south island back country is all of these things.  It is steep, remote, rocky, isolated and free from the influences of man and development.  Except that giant trout are not ‘natural’ or ‘wild’ in these landscapes. They have been added. And only very recently.  And since that time the delicate balance of these river ecosystems has been greatly ‘disturbed’.

 In a continent that split off from its nearest neighbour 85 million years ago, New Zealand has been slowly evolving its own unique species of trees, shrubs and grasses. In the absence of any land-based predators, many of the birds lost the need to fly and started walking.  The fish started to change too. Because New Zealand is steep and there are so many waterfalls along the rivers, some of the freshwater fish developed the ability to ‘climb’ up rocks.  All of these are amazingly cool traits.  And even after all this time New Zealand still only has a tiny number of native fish, less than 40. By comparison Australia has 280.

The flip side is that a lot of these cool fish are in big trouble. In particular the non-migratory smaller fish (Galaxias). The huge trout NZ is famous for need to eat a lot to grow to this size and maintain condition.  It doesn’t take a rocket scientist to work out that any small fish that strays too close to a trout lie will quickly become the next meal.  Watch a big trout burst out from behind a mid-stream rock and you quickly appreciate that they are superb hunting machines. Similar to Australia, trout are only part of the story behind the decline of native fish. Land clearing, sedimentation, dam walls and water extraction all play a part. But the back country of the south island has virtually none of these things (neither do many of the alpine and sub-alpine streams in Australia). It is still natural, intact and wild. And yet research like this tells us that pretty much anywhere trout grow bigger than 15cm, the native fish disappear.

Koranga Trout feature image NZ Graz
A New Zealand rainbow trout

Now the purpose of this post is not to start a ‘kill all the bad trout’ campaign. I’ve been to New Zealand and hiked up into the back country and caught some magnificent trout. Five rainbows of 4 to 5 pounds each in one day is something that I will remember for a long time.  So is the moment when one those trout was plucked off the bank as I landed it (no net) by a long-finned eel that must have been six foot long.  You can read the full post here if you wish. Trout and salmon have been breeding freely in New Zealand since their introduction in the 1800’s. To try to ‘get rid of them’ would be a hugely expensive and time consuming task – not to mention, unpopular.

Koranga Graz Trout NZ

No, the purpose of this post is to make us anglers think about what we are talking about when we describe ‘wild’, ‘natural’ and ‘undisturbed’ places.  To me these are the places where the trees, shrubs and grasses are the same ones that have been there for millions of years. The insects, frogs and birds are the ones that evolved to feed and breed in the vegetation. A natural and intact place is one where the fish, whether they be a species of Perch, Cod, Trout or Salmon, have been eating those insects, frogs and smaller fish in balance forever.  As the influence of man spreads across the world, these places are exceedingly rare. The paradox is that many of the last truly natural places are under threat due to the historical and ongoing practice of introducing just a handful of different fish, particularly trout and salmon.  In my mind, that is a little disturbed. What do you think …

Graham

For the record, I have nothing against Gin Clear Media, they produce and show some truly spectacular fishing films and place an enormous emphasis on enjoying and protecting our waterways. I’ve been to the RISE film festival the last two or three years and will probably go again this year. Screening times and trailers can be found here. Although to be honest, I find the anglers and film maker’s incredible passion for both the conservation of natural rivers AND introduced fish species perplexing … even paradoxical.

flickandflyjournal.com

Hamish Webb, Dan Firth, Graham Fifield and Lee Georgeson have been fishing the south-east Australian region since 1987. Since then they’ve become avid sportfishermen who are constantly looking for new ways to challenge themselves. They are all scientists and conservationists who are passionate about the long-term sustainability of the ecosystem in which they live. They promote understanding and appreciation of the complex socio-political, economic and environmental issues surrounding fish, fishing and fisheries, while never losing sight of the various motivations that keep them coming back. In English, that means they love all things fishing and have a damn good time on the water, and that’s all that really counts in the end!

2 thoughts on “The Natural Trout Stream Paradox

  • August 24, 2015 at 9:54 am
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    Well said.

    At least two rigorous scientific studies have shown it IS introduced trout, and not habitat degradation, that is the main cause of galaxias decline/disappearance in New Zealand.

    Townsend and Crowl (1991) deliberately designed a multi-factorial study that included catchment condition and habitat degradation as factors, so the impact of them could be separated out from the impact of trout.

    Their study clearly showed that trout, not habitat degradation, was the main predictor of galaxias presence or absence in streams.

    From memory, a very recent study found similar results — saw it recently but can’t remember the details. A bit of googling would find it. For a start, it would definitely have Townsend and Crowl (1991) in its reference list.

    As for Australia, well, we’ve said it before, but the upland rivers and streams in the southern Murray-Darling Basin actually DID have large sporting native fish (i.e. trout cod and Macquarie perch) to very high altitudes, that WERE catchable on fly, and DID fight as hard, or harder, than introduced trout. The introduction of trout was not out of necessity, but out of cultural cringe and the ugly devaluing and denigration of superior native fish. The evidence from Trueman’s oral histories (2007, 2011) and the wealth of historical newspaper articles, some of which I’ve collated, show how abundant upland native fish once were in upland streams. Their disappearance from, effectively, all of these upland streams is not just due to habitat degradation and dams. It is due to filling of these streams with introduce predatory trout, and the constant restocking of these streams with trout, including after big bushfire/ash-fish-kills. Many of the upland streams that upland native fish have died out of are in superb condition and there are no other explanatory factors. There are shades of the NZ contradiction that you refer to in the practice of Australian trout fishermen (and fishery managers) glibly blaming “habitat degradation” for the disappearance of trout cod and Macquarie perch from upland streams in the southern MDB … and in the same breath then waxing lyrically about the pristine “trout streams” they’ve just been fishing — in the southern MDB!!!

    Anyway, as you say, no-one is pushing for trout eradication in Australia or NZ, or even major changes to their distribution.

    But a bit of balance, sanity and reason is needed.

    Currently we have introduced trout dominating every single sizeable upland river and stream in SE Australia, while upland native fish are close to extinction, with not a single upland river or stream reserved for them. (It is probably not possible to produce a completely trout-free upland river for upland native fish, but we could at least produce a stream where trout numbers have been suppressed as low as possible.) Fishermen have no upland native fisheries in their rightful upland stream habitats. And NSW and Victorian Fisheries still release introduced predatory trout into endangered Macquarie perch habitats, and still pretend this is no problem. (This is particularly low and irresponsible behaviour.)

    Methinks we need some changes.

    Simon

    Colin R. Townsend and Todd A. Crowl (1991). Fragmented population structure in a native New Zealand fish:
    an effect of introduced brown trout? Oikos 61: 347-354.

    Reply
  • Pingback: A deeper look at “wild” places (and is stocking threatened native fish outside their range a good idea?) | Flick and Fly Journal

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