Watch: Trout in Taupo
The brown and rainbow trout that run through this river, the most fished in the country, are cunning.
But they'd have to be more than that to pick one of his stealthily-cast flies apart from any other little river morsel.
Because he is on the river all year round in his business, Taupo Trout Guide, he quickly learns how changes in the pools, typically from floods, alter the lies of the trout runs.
Cicada Pool, backed by a crumbling white cliff whose rock layers tell of a constantly changing landscape, is one of a cluster of fishing havens in the Tongariro's dynamic middle section.
There are curious names like Silly Pool, Cattle Rustlers Pool, Major Jones Pool and Breakfast Pool.
In winter spawning runs, vast numbers of trout battle their way far upstream to the multitude of spawning beds in the Tongariro's tributaries.
Between April and June, they congregate around the river mouths in preparation, before the great run begins around July.
The resulting bounty makes the Tongariro one of the world's premier fly fishing destinations.
For foreign anglers, a trophy fish might be 2kg; on the Tongariro, it's at least double.
Large runs, triggered by rain and cooler water temperatures, can number in the thousands, and the fishing is best when the river starts to clear after a heavy fall.
But the chill means the catch has to be earned.
Being the first angler at a pool early in the morning often comes with air so freezing it can ice up the eye of the rod. You'd be foolish to enter the waters in anything lighter than warm, thick, neoprene waders.
The trout, hugging the bottom as they head upriver, aren't gazing up so much for bugs blown from the trees, demanding skilfully placed flies to snag their attention.
In recent years, the spawning run has been so spread out the fishing has still been excellent in November.
But as spring gives way to summer, many fishers look to the shores of Lake Taupo for large trout, drawn into the shallow water as they chase smelt.
But this morning, Christmas has managed to hook a trout within just half an hour.
While it's one thing for an angler to cast a line well enough to attract a fish, it's another to know what to do when seeing the indicator at the head of the line jerk.
Sometimes the trout will take the line so hard that just lifting the rod will grasp them. At other times, the hook might be so poorly set that just a slight yank will lose the fish.
Brown trout, increasingly being found in the river over summer, are clever enough to know that making deep, slow runs might well peel the line off and get them out of trouble.
But rainbows, more easily tempted to move off their stations at the sight of an easy snack, tend to fight and thrash around. This naturally never ends well for them.
Whatever Christmas had hooked, it's managed to break free. Lucky fish.
The way he casts and mends his line, constantly flicking it forward in a wide loop with one hand and hauling it in with the other, has been perfected over a lifetime and can't be taught easily.
It's not uncommon for less skilled anglers to flip or roll a cast so badly that they hook themselves in the ear or neck.
Mastering a cast is all about timing. In golf, a sport so often compared to fly fishing, a clean drive comes from knowing where to hit the sweet spot of the club face, and it's no different here.
In low water conditions, like today, the fly has to meet the water without any trace of the line to spook the fish.
Christmas is experienced enough to choose from a wide range of casts; sometimes he might send the line 30m off into the head of a pool, but in tighter situations, he might only dispatch two rod-lengths.
He was ably schooled by his father, Colin, who had learned the art from an uncle in England.
As a Taradale boy, much of Andrew Christmas' boyhood was spent on the banks of Hawkes Bay's shallow, meandering rivers: the Esk, the Ngaruroro, the Tutaekuri, the Mohaka.
Each summer, his family would holiday around Taupo, and it's where he ended up after saving money from commercial diving at fish farms in Australia.
"I think this is my 10th year as a guide," he tells us.
"It's about being able to get outside. I'd never be able to be locked up i n an office or a factory or anything like that."
Kiwis, he reckons, are spoiled to have one of the world's top trout fishing locations in their own backyard. Pick up any international fishing guide and you'll find it.
American author Zane Grey, who popularised fly fishing and described New Zealand as an "angler's El Dorado", loved the Tongariro particularly.
Christmas often guides anglers who come from as far as Canada, the US and Britain and are so determined not to squander fishing time they'll even skip the quintessential Tongariro experience of smoking their catch on the riverside.
But today, that's our lunch plan. The floor of the smoker has been filled a centimetre thick with manuka chips, which after 15 minutes in the box will have added their earthy aroma to the classic brown sugar and salt marinade on the trout fillet.
"It's a hot smoke," Christmas says, "and it's fantastic on cream cheese and crackers".
We tuck in, ripping pink pieces of the trout off and washing them down with a light white wine.
Just being able to hook a trout, then smoke it on the river amid the quiet of nature, reflects much of the beauty of fly fishing. Author Izaak Walton called it "the contemplative man's recreation".
To Christmas, it's skilful sport, a peaceful sport, a friendly sport. "It's definitely not like catching a marlin, or filling the bin full of snapper. It's about being outdoors, and enjoying the day," he says.
"If you are fly fisherman, everyone respects that everyone's out in the wilderness for the [same] reason ... they are doing the thing that they love."
And, in this picture of placidity, they're doing it here.
Trout, marinated and smoked
1 Gut and clean the trout, cut off the head and tail, then butterfly it by cutting it lengthways from the front down one side of the backbone.
2 Rub brown sugar generously into the meat, add salt, and leave to soak in the fridge for at least one night.
3 Light a dish of methylated spirits and scatter manuka sawdust in the bottom of the smoker, creating a base 1cm deep.
4 Rinse the trout of sugar and salt, place it on the smoker rack, and cover it with a sheet of tinfoil.
5 Place the lid over the smoker then position it over the methylated spirits.
Cook for 15 minutes without lifting the lid.
6 Once cooked, take out the bones then serve on crackers and cream cheese.
The series
Monday: A snapper safari in a mussel town
Yesterday: Hangi the Rotorua way
Today: Smoking on the Tongariro
Tomorrow: The barbecue capital of New Zealand
Friday: Kaimoana on the coast.
