Trout holding in rivers are often difficult to find.
It’s common to fish two or three pools with no sign of fish, when we know that fish are in the river, especially when we read the results of Fish & Game drift dives, or see the results of other anglers’ efforts on the same river.
An important factor is that fish find some pools much more attractive to hold in than others; depending on the fish population numbers and respective sizes, the weaker/smaller fish may be forced to reside in the less favourable pools. However, usually the populations are not that high, and it’s normal for some pools to hold two, three or more significant fish, while those in between are empty or only support a few tiddlers. This phenomenon is clearly noticeable, especially on larger rivers such as the Tongariro, at least when the fish are not actively moving through.
Highly productive pools are often just stumbled upon, but anglers can observe a few signs to get a good idea of whether or not fish are likely to be present in a pool. If you want to go catching, instead of fishing, it’s obviously more productive to just fish the likely pools than to work your way along a river casting into every pool, run, nook and cranny. This is an advantage that regular anglers of a river have over those who only fish the water a few times each season; they know exactly which pools are likely to hold fish.
During hot weather, trout regularly use pools when resting. They move into faster broken water to feed, because there will be more food and oxygen available, but when they want to rest they find a position in a deep, cool pool with adequate cover.
In some cases, depending on food levels and fish population, there are positions available that will provide all the necessary requirements; prime positions such as these are taken by the largest, strongest trout. Other pools can be so large and have such a gentle flow that fish must patrol the pool when feeding.
Visually spotting trout is the most common way of working out if they are present in a pool, but the best pools will not allow anglers to see resting fish, primarily because they are so deep. Overhanging vegetation and undercut banks are commonly used, and if a river has deep pockets of water, trout will take advantage of them. They are ideally looking for water over 2.5 metres deep and up to about four metres in depth. Pools of this depth inevitably have the length and breadth to reduce the bottom current to a comfortable flow, and they often hold several large fish comfortably. What’s more, a certain amount of food will drop into the depths of the pool as a bonus to its residents. This level of homeliness can make even the most wary trout a little more blasé.
The deep pool provides the angler with a few advantages, too: the slow water flow means there is usually a build-up of sand on the bottom, and any rocks breaking through the sand are smooth and unlikely to impede a fly. Also,the depth is too great for inconvenient weed to be a problem.
When looking for likely deep pools, check out any big areas of water with a relatively smooth surface. If the water is clear, you will be able to spot the deeper section; otherwise, you can usually work out where it is, especially if it’s safe to wade. Try to work out the length and width; sometimes you can get an idea of the depth, but it can be deceiving.
Pools like this have been the domain of the skilled spin angler up until recently; even with little current flow, getting a fly down to the bottom had been impossible. Nowadays, with decent sinking leaders and tungsten-bead flies, it’s not such a problem – although that’s not too say it’s easy either.
I prefer to use a fast-sinking line and fish downstream, sometimes resorting to a ridiculously heavy 400-grain shooting head. Even with a heavy line, the key to getting strikes is waiting twice as long as you think it takes for the fly to get to the bottom. Even in the quietest of pools, trout holding in deep water do not appear to be spooked by a clumsy cast, and usually fail to notice the presence of an angler at the top of the pool.
Unless you have managed to scope out the hole well, so you know its exact whereabouts and dimensions, you will have to estimate its position. Stand as close to the head as you think is safe, and cast downstream, beyond where you think the tail is. I usually cast on a bit of an angle (depending on the current flow) in the hope that the line will sink down to the edge of the pool, reducing its impact on the residents, before swinging across in the gentle current to lie directly downstream of my feet. If there is no current, it doesn’t matter whether or not you cast directly downstream or at an angle; if there is some current you may want to feed out a few more metres of line, depending on the length of the pool, to increase the length of the retrieve. Once you have made the cast, remember to wait before starting the retrieve.
The best flies are Woolly Bugger variations. I like the Thin Mint Tungsten, but there are a number of flies sporting heavy tungsten beads and thin bodies with marabou tails that will also perform well.
Many anglers have a lot of success retrieving Booby flies through deep, quiet pools, and the characteristics of the pattern are perfect for this environment. A floating Booby on a short leader no more than 300mm long, attached to a fast-sinking line, will attract fish when retrieved slowly and haltingly.
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by John Murphy - 2011
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Originally published in New Zealand Fishing News