Important information about the use of intermediate fly lines in fly fishing on rivers and streams.
I like to write this topic, because I myself very often and successfully use intermediate fly lines when fly fishing on the river. Let's look at the benefits and advantages of using these slow-sinking lines. First of all, you have to say what an intermediate line is. It is practically a sinking line that has a sinking rate of less than 3 inches per second. The widespread theory that the intermediate line hangs at some depth in the water column is nonsense. Even these fly lines are still sinking, but more or less slowly.
Intermediate lines are mainly the domain of still water fly fishing, but let's talk about when and how to use these fly lines on rivers. I would probably divide the whole chapter into three main topics, namely streamer fishing, fishing with a wet fly and a nymphing. There is probably no other method to fly fish effectively with intermediate fly lines, and if so, only in some special situations.
Reason 1: Streamer Fishing
Intermediate fly lines are probably most associated with the topic of streamer fishing. In the same way, classic sinking fly lines are associated with this method of fly fishing. So how to choose the right sink rate of the line to be maximally effective? The main selection factor is two things - speed of the current and the depth of the water column. Nothing more is needed. Of course, if there is a situation where fish for some reason attack streamers on the surface, then the situation changes, but we assume the standard phenomenon of streamer fishing near the river bottom.
We always fish with the streamer downstream. Some might argue, but in the case of a well-executed downstream fishing, we will always be more successful. So how do we find out which fly line we choose? It is therefore necessary to take into account the two factors already mentioned above. The faster the current, the more sinking rate is needed and the same is valid for the water depth. When streamer fishing downstream, we create an arc on the line, which is desirable. If you fish the streamer on a slow flow even though it is deep, and you use a sink line that is too fast sinking, then you will have to pull the fly quickly so that it does not catch at the bottom, and you will not give the line time to create just the desired arc. Therefore, in addition to the correctly selected sinking rate of the line, it is necessary to choose the right casting angle to the opposite bank. In the event of a slow stream, we can stand further from the bank and sometimes throw perpendicular to the opposite bank, while fishing in a fast stream it is necessary to wade closer to the other river bank and cast more downstream so that the line after casting forms an arc, but not so large and fast that the fly line does not have time to sink to the required depth. We will therefore use the intermediate fly line if we are streamer fishing in shallower water or in slower-flowing sections. So much for the use of intermediate fly lines in streamer fly fishing in general.
Reason 2: Wet Fly Fishing with low AFTMA lines
However, my favorite use of intermediate fly lines is for wet fly fishing in AFTMA 3. Today, manufacturers now produce these light AFTMAs, so it is not a problem to get them. Fly fishing with wet flies is a very old method and also very effective, especially when fishing for chubs but also for trouts. When wet fishing, we cast similarly to streamer method, i.e. obliquely (at an angle) to the opposite bank downstream. Commonly and most often this style is fished with a floating fly line, but with the floating line we need to solve several problems. On the one hand, we encounter greater loss of fish, which is caused by worse contact with the fish during the strike, when the fish picks up the fly and the arch on our line, which is on the surface, does not maintain this shape, begins to straighten and thus somehow and we do not have contact with the fish before the whole fly line is aligned. This is solved by a light intermediate line, which remains submerged during the strike, and we hook the fish through an arc, which, however, does not tend to level on the surface and stays in shape for a little longer than the fish calms down after the strike and thus keeps it nicely in contact during the first phase of fighting with fish. Then it is slowly cut and leveled. The loss of fish will therefore be significantly reduced.
The second big advantage is the presentation of wet flies. It has been tested that the success of a wet fly increases significantly when it hits the surface sharply and is immediately set in motion. The worst thing is when we cast the line lightly and do not straighten the whole rig, so after the fly will remain motionless for a while. It is precisely for this noticable "splash" that it is ideal to use the weight of the intermediate fly line, with which it is much easier to slap the water with a fly, and in addition it is also easier to level the entire rig after the cast. However, it is not appropriate to use intermediate fly line, for example, in the summer months, when it is hot and, for example, chubs are feeding in very shallow water, then we would be too deep with flies.
The third big advantage when fishing with an intermediate fly line is the position of the flies in the column. During active fishing, slow sinking intermediates get our flies only slightly below the surface, which is often enough for chub and trout to take the fly with confidence. If these fish are not active enough, then we often see only "rides" behind our flies, but without a strike. It is usually a matter of colder or worse weather or during the rain. In good activity, chubs especially like flies when they make arrows on the surface, when they are just below the surface, and this is a desirable phenomenon. I do not want to say that the use of an intermediate fly line for wet fishing is a panacea, but it is a very good choice.
Reason 3: Nymphing
The intermediate fly line can also be used on the river in combination with nymphs. This use is not common, but in extreme cases it can bear fruit. It is usually fished in deep pools on large rivers where it is not possible to wade. They are cast slightly obliquely downstream and the nymphs are let out below us, where they are slowly pulled back by figure of eight retrieve. We often catch graylings in this way, which like to gather just below us, where we practically feed them with our feet that release the food from the river bottom. So when there is no advice on the big river, this method is a good way to get the nymphs to the fish and somehow reasonably present them.