THE LOCH PROBLEM For some twelve years I have been trying experiments on lochs on my ground in the North of Scotland, and have written what follows mainly because I hope and believe that the result of these experiments may prove useful to some of those who love trout-fishing as I do, and have the means at hand, possibly without fully realising their opportunities, of increasing their sport and that of their friends. I have spent much labour and a good deal of money in attempting to improve the fishing in various lochs. In some cases these efforts have proved useless; in others the labour and money expended in stocking the lochs and increasing the food supply have been altogether out of proportion to the results obtained, but in one case, and one case only, the results have been phenomenal, not only in my own experience, but also in that of my keeper, who, like myself, has all his life been keenly interested in and familiar with trout-fishing in the North. In the case of those lochs where no good result has been achieved, I have at least learnt something from my failure. The loch upon which I experimented with such wonderful results must have been a veritable larder of food for the trout when I put them into it, for there was a large quantity of water lizards, leeches, frogs, and above all, fresh-water shrimps; there were also various kinds of insect life, water beetles, notably the coch-y-bundhu, and a smaller beetle with a silver body which moves with a swift darting movement. It is impossible for the trout to spawn effectively, as there is no burn coming into or going out of the loch and no water continually moving over a shingly bottom. The loch is not more than six acres in extent, and is about 500 feet above the level of the sea. At the time, just thirteen years ago, when I began to put fish into it, there were no fish in it, and so far as I know there never had been any, except some years ago when a few trout were put in, but these had no doubt been caught or died long before I began my experiments. I am also quite certain, for the reasons already mentioned, that they had left no descendants. Every year, in May or June, about 2½ acres of the loch are covered with a common kind of rush, the “Horse-tail,” _Equisetum maximum_, and about one-quarter of an acre with grass, which, I believe, is a species of _Scirpus_. In the rushes and round them are patches of a kind of surface weed which is common in Highland lochs, and which, as every fly-fisher in the Highlands knows, is a great danger to him. This weed, the scientific name of which is, I am told, _Potamogeton polygonifolius_, covers an area of some 20 square yards. Lastly, and most important of all, there is in the loch a considerable quantity of the well-known Water Milfoil or shrimp-weed, _Myriophyllum verticillatum_, which in this water produced quantities of fresh-water shrimp. [Illustration: AN AUTUMN DAY, LOCH CARRON--LOOKING WEST.