SUNSET ON THE SHORES OF LOCH CARRON.
From a Photograph by Miss Alexandra Fraser.
To summarise the results of these experiments, it seems clear that in order to obtain the best results the following conditions should be fulfilled:
1. There must be a sufficient supply of the right kind of food for the fish in the loch in order that they may grow to a large size.
In order to attain this object, it is desirable that the loch should not be too high above the level of the sea. As Mr. Malloch says in the work to which I have already referred (p. 179): “Lochs over 1000 feet above sea-level, fed from snow from surrounding hills, produce little feeding until May, and owing to the cold fall off in September, thus giving the trout only four months of good feeding. On the other hand, lochs at or near sea-level produce good feeding in March, and continue to do so for three months more than their Highland brethren. It will be seen, then, that this extra time for feeding, when extended over the seven or eight years which constitute the life of a trout, easily accounts for the difference of size.” Moreover, as the same writer points out, in a loch which is very high above the sea-level, not only is the feeding-time shorter, but the food is much scarcer.
On the question of food supply it is worth while to recall the words of Mr. F. H. Halford:[34] “Food supply generally is ... chiefly dependent on the presence of the weeds in which the best forms of food for the fish are to be found.... It must not, however, be forgotten that, in Marryat’s terse words, ‘while floating food is caviare, sunk or mid-water food is beef to the fish.’ Hence, when engaged in his examination of the weeds and the animal life contained therein, the fisherman should remember that he can only expect well-fed, good-conditioned, healthy, and consequently game trout in a (loch) which contains a bountiful supply of crustaceans, such as fresh-water shrimps and mollusks such as snails of the genera Limnaea, Planorbis,” etc., etc.
Further, it is of the utmost importance that the number of fish in the loch should be regulated in such a way that the food supply may be sufficient to enable the fish to grow to a large size.
Where the fish cannot spawn effectively, and it is therefore necessary to renew the stock, experience alone can decide the number of fish which should be put into the loch every year. Spring is the best time to do this. The number of fish which should be put in will obviously depend chiefly upon the amount of food in the loch and the number of fish caught, and destroyed by their enemies, during the preceding year. In many lochs there are stones under which the small trout can find protection from the large ones, but where there is no protection it is worth while to put stones or small drain tiles round the edge of the loch.