The 'really wild’ loch trout show huge variations in both size and coloration. From the angling standpoint, though some fish stocks have remained untouched by human hand, it does not necessarily follow that huge fat trout are sitting there just waiting for your fly. - Many anglers ask why it is that they can catch glorious deep set golden specimens in one loch yet in a neighbouring loch only a short step away, the trout are all small with large heads and skinny bodies. - Genetics will play a part in this however the quality of habitat is equally important. Where they live, where they spawn and what they eat, dictates how our indigenous trout will develop. Understanding these vital factors will assist the trout angler greatly in making an adroit selection from our myriad of fishing waters.

The more lochs you fish the more you will understand the significance of sussing out the resident trout’s habitat prior to starting to fish. Though random angling can sometimes work, there are so many lochs on offer especially in Northern climes, its easy to guess wrongly and bungle your angling day. To alleviate the guesswork, when first approaching `new’ waters you should look for aquatic features which break up the uniformity of the loch surface. These can take the form of promontories and bays, in and outflowing burns, islands, weed beds, skerries, boulders, shelves and drop-offs. Such characteristics harbour vital sources of food and shelter for the wild trout, basically the more of these features there are the more likelihood of the loch supplying good trout.

The depth of the loch and its degree of exposure also plays a significant part. In deep glacial lochs, brown trout tend to hug the edges away from the cold sterile centre. Often they will be found in only a few feet of water as they forage amongst the boulders for caddis, midge larvae and nymph. Food supply is critical in such waters and trout territories are much more defined in a few specific areas of the water. Do not be deterred from trying the bigger lochs however, no matter how intimidating they might look. Think micro environments rather than a great windblown expanse of loch and concentrate your fishing efforts at any shallower and/or more sheltered points. I recently had my eyes opened on the so called `poor’ trout of Loch Ness, one of the longest and most wave lashed lochs in Scotland. An evening drift tight to the shore in a shallower corner near busy Fort Augustus produced a succession of glorious butter fat trout of over the pound, so don’t let those first impressions of vast horizons fool you!

In lochs which are uniformly shallow the trout can spread out more to forage throughout the loch and you can therefore afford to drift over apparently open water with more confidence. Keep the objective of hitting those trout territories in mind however, for example drift across the mouth of a bay from one promontory to another or out to cover the edges of mid water weed beds. Incidentally, where weeds appear in the centre of a loch for no apparent reason, they are usually growing over an underwater spring. Thus when lochs are described as being `spring fed’ the presence of the weed beds gives away the exact location of mineral rich springs. Of all the trout holding areas in smaller lochs, these weed beds are the most important. Here many invertebrates flourish in comparative safety and where there is plenty of food there will always be eager trout.

The quality and size of loch trout you catch will be further influenced by the quality of natural feeding available and the number of trout competing for it. Initially you can judge something of the productiveness a loch by looking at its immediate environment. Lochs ringed with white stones (Gaelic `Clachan Geala’) are often limestone in nature. However, mineral rich deposits can exist in many forms around lochs. That yellowy white calciferous mud known in Caithness as marl, greatly increases the fertility of any water as do the hard limestone rocks resembling granite commonly found at Eribol and Assynt. Lochs which have bases of ancient calcium bearing shell sand such as the Badenloch system in central Sutherland can also be exceptionally fertile. This shell sand, left behind from a retreating ice cap, makes for unusual ‘machair lochs’ miles inland not dissimilar in character to those waters of the Outer Isles. Also remember that pockets of fertility enhancing limestone do not just exist in the far north, Scotland has calcium enriched deposits dotted across its landscape from Loch Awe in Argyll right up to the Shetland Isles. Be cautious too in judging books by their covers as many apparently barren peaty hill lochs actually harbour excellent food supplies for trout with mayfly, caddis, shrimp and snail all present in abundance. Such initially uninspiring waters are often enriched by a hidden underlay of limestone.

If you really want to examine the quality of natural feeding, there is no substitute for turning over weed and gravel along the shoreline and brushing the undergrowth a few times to see what flutters up. Remember many natural hatches in Scotland are often misunderstood. Frequently mayfly, sedge and some olives hatch later in the year than do their southern counterparts. For example our mayfly rarely appear in number until mid June but then we enjoy far more sustained hatches than those in the South with mayfly still appearing in late August. Even when a lochs natural feeding is profuse, size of trout can vary according to the productivity of spawning sites. Too many trout competing for a finite amount of food is always counterproductive.

Water quality is also vital but I would err on the side of caution in placing too much emphasis on the pH of a loch. Wild trout flourish in clean well oxygenated water and can survive in most waters from slightly acidic through neutral to fairly alkaline. While it is true alkaline waters harbour better quality nourishment for trout particularly freshwater shrimp, neutral to marginally acidic waters can also be very productive. Relying on a pH analysis of the loch is not normally enough to make a sound judgement of its fishing qualities, you should also take the aforementioned factors into account. Clarity of water can sometimes mean some exceptional trout present, there is a saying in my neck of the woods `the clearer the water the bigger the trout’ however I would again qualify this by urging you to look at availability of food, total resident fish numbers and the quality of shelter/safe retreats for the trout. Note water which is `stirred’ by high winds i.e. carrying a lot of suspended sediments, will often appear unproductive in terms of trout angling. You will sometimes hear lochs described rather unkindly as `dour peat pits’ where trout rise only infrequently and are rarely seen on the surface. More often than not these waters are highly exposed lochs where gales whip up a fine layer of peat from the loch base giving the whole water a mirky unfishable appearance. In such conditions it is rare to connect with a trout, not because they are not there, but rather the fish have great difficulty in seeing your fly. Unless you land your offering bang on the trout’s nose he rarely takes in `dirty’ water, however thus afflicted lochs should never be dismissed outright because of sediment action. Visit them after a spell of calm warm weather when the fine peat layer has settled back on to the loch base and the story will be very different.

Though its important to think about the lochs features, fish characteristics, natural feeding and depth of the water and its pH, it is equally important not to get too clinical about it all. The fun is in the finding out. With Scotland’s wild trout season again upon us, where will you go?…….

Lesley Crawford

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