Mackenzie Canals Mega trout

After moving across the ditch three years ago, my wife Kristina and I have embraced this highly accessible man-made fishery with open arms.

Strange, was my first impression. Slightly familiar – water and fish – but also very foreign. However, there wasn’t much time to take it all in as on my second cast I was hooked up! More about that later…

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The fishery has a very similar feel to an Australian tailrace, aquaduct or water race fishery – something you might find connected to power generation or irrigation system back home.

This fishery was no means an overnight success. The hydro power scheme here has been operating since the late 1970s and you can bet your backsides that the fishing has been better than good from the mid-1980s onwards. But it’s Twizel, Canterbury – in the South Island – and (thankfully) things move at a nice, slow pace here. So yes, they’ve been catching fish in the canals almost forever and they’ve almost always been big, but never as big as they are now!

 

Fish food

Let me set the scene for you. The canal system runs for just under 50km and contains five power generation stations, half a dozen or more salmon pens (salmon farms) and five large bodies of water, namely Lake Tekapo, Lake Pukaki, Lake Ohau, Lake Ruataniwha and Lake Benmore.

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The system carries water that starts it life on the snowy peaks of the MacKenzie Basin, which includes the iconic Mt Cook. The pristine water is super-oxygenated and largely unaffected by agriculture. As for the striking blue colour, that’s caused by glacial flour (fine particles of rock sediment), which also supplies some nutrients.

So, the water in these canals is a superb environment for aquatic life, and while it’s a totally man-made structure, nature has stepped in to make something awesome out of it!

People used to think the trout caught in the canal system grew to enormous sizes because of excess feed that escapes the caged Quinnat salmon Oncorhynchus tshawytscha in the salmon farms. But when an 8km section of canal was drained for maintenance, it became clear there was more to it.

The canals have been in operation since 1977 and for many years were considered lifeless. But with constant flow and stable water temperature, the nutrient-rich water grew a staggering amount of plant and animal life, which in turn fed the trout.

This is no ordinary food supply. Without floods, temperature fluctuations or changes in water quality, it is a 24/7 natural fish food factory. And you know what happens when you drop a trout into that sort of environment – you grow monsters!

One of the main drivers for trout growing to epic proportions is the bully, a native forage fish that thrives in the canal environment. Bullies are everywhere.

But since trout and salmon are lazy, you’ll always find them hanging around fish farms, along with most of the anglers! But the cool thing is, fish grow faster feeding on natural food than they do feeding exclusively on salmon pellets. Strange but true!

This, of course, doesn’t take away from the fact that free-ranging salmon are used to being fed on pellets (they are farm escapees) and are also schooling fish, so it makes sense that most of them are found near or under the salmon pens.

 

The angle

There are people far more qualified than me to talk about Twizel canal fishing. After all, I’ve only been fishing them for three years, on and off. So all I can do is share my own thought processes when attacking this system – other people fish differently and also enjoy success, but this is what I do.

 

Soft baits

Soft baiting really did change the way people think about fishing in New Zealand. In the North Island it totally revolutionised snapper fishing and you could say that the same is happening in the South Island for popular species like blue cod and trout.

But soft baiting isn’t just the new kid on the block that everyone wants to be seen with, it actually works better than other methods because of what soft baits bring to the table. Soft baits are a perfect fit for canal fishing.

The average canal depth is around six metres and widths vary from 40m to 100m. Taking into account a relatively constant water flow and the canal’s uniform nature, the least amount of flow is found right on the bottom, with even less on the inside edges of the corners and behind small build-ups of sediment and weed where pressure waves form.

One sure thing about trout: if they can sit still and eat all the food they need, then that’s what they’ll do! So, if you’re a trout, you want to find the best position with the most food and swim as little as possible.

Finding these areas is not always easy since canals are largely featureless. But right on the bottom and on the edges have the slowest flow, so this is where I start.

My thinking was to get my soft bait to the bottom as quickly as possible and then keep it there, putting it in front of more fish for longer. This worked really well the first few times I went fishing because it was later in the season (June-July). Everything was frozen and people were turning on their electric heaters and using power.

The winter demand for power helps keep the turbines running at full speed, creating heavy water flow. Generating power = water flow = fish holding tight on the bottom where the flow is less.

 

The drift

Drifting soft baits has been apart of the North American fishing scene for decades. This technique employs a fixed weight and a soft bait. If you can imagine a fixed sinker bait fishing rig, you be in the ball park.

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There are two main ways this rig is set. It’s commonly known as a drift rig.

Essentially you have a lead weight, either at the bottom with a short dropper 1 to 1.5 metres up the line, or a sinker on a dropper with the soft bait 1 to 1.5 metres further down the line. Either way, the sinker can be pulled off or snapped off the rig while your hook remains attached to the line.

This is achieved by attaching the sinker to your rig with a section of lighter line or fixing the weights so they can be pulled off (split-shot or drop-shot sinkers can do this).

The baits commonly used with this technique in the canals are egg patterns, but two and three-inch PowerBait minnows can also get results.

Fishing extremely lightweight jig heads can get you the same type of drift and similar results if worked properly – weights like 1/24, 1/36, 1/40 and 1/50 of an ounce. With all drift rigs, the name of the game is to drift them – don’t impart any action. It’s a ‘dead drift’ technique.

So once you have your rig in the water and find you can walk with it, you should! The canals allow this to happen very easily because of their design.

Keeping close to the bottom is key and walking with your rig 45 to 70 degrees downstream is the go.

 

Gear list

You don’t need to be a super guru to catch a monster, but having the right gear can help. Here’s a checklist of things you’ll need:

  • Spin rod from 6 to 8 foot (1.8 to 2.44m) in length with a suitable reel that has a ‘good’ drag (you’ll need it).
  • Main line should be braid, somewhere between 3 and 6 pound, with a 4, 6 or 8-pound fluorocarbon leader.
  • Soft baits in minnow patterns from 2 to 4-inch and a selection of egg patterns  Glo-bug flies, soft plastic or Gulp/PowerBait.
  • Waders or gumboots and very warm clothing.
  • The biggest net you can find!

 

Twizel in the middle of the year often has highs of just 1 or 2 degrees with lows of minus 6-12, so I’m not joking when I say bring warm clothes. Also keep in mind that the entire system has didymo in it and anything that has come in contact with the water will need to be thoroughly cleaned with detergent.

This area that has so much potential and is already growing some of the largest trout in the world. It’s a truly outstanding place that we need to look after if we don’t want to lose it forever.

 

   This article is reproduced with permission of   
New Zealand Fishing News

August 2018 - Adam Royter
Re-publishing elsewhere is prohibited

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