Salmonia; Or, Days of Fly Fishing / In a series of conversations. With some account of the habits of fishes belonging to the genus Salmo

by Sir Humphry Davy

Hal.—Certainly not. There are as many fish to be taken perhaps in the Spring fishing; but in this deep river they are seldom in good season till the May-fly has been on, and a fortnight hence they will be still better than even now. In September there may be good fish taken here; but the autumnal flies are less plentiful in this river than the spring flies.

Phys.—Pray tell me what are the species of fly which take in these two seasons.

Hal.—You know that trout spawn or deposit their ova and seminal fluid in the end of the autumn or beginning of winter, from the middle of November till the beginning of January, their maturity depending upon the temperature of the season, their quantity of food, &c. For some time (a month or six weeks) before they are prepared for the sexual function, or that of re-production, they become less fat, particularly the females; the large quantity of eggs and their size probably affecting the health of the animal, and compressing generally the vital organs in the abdomen. They are at least six weeks or two months after they have spawned before they recover their flesh: and the time when these fish are at the worst is likewise the worst time for fly-fishing, both on account of the cold weather and because there are fewer flies on the water than at any other season. Even in December and January there are a few small gnats or water-flies on the water in the middle of the day, in bright days, or when there is sunshine. These are generally black, and they escape the influence of the frost by the effects of light on their black bodies, and probably by the extreme rapidity of the motions of their fluids, and generally of their organs. They are found only at the surface of the water, where the temperature must be above the freezing point. In February a few double-winged water-flies which swim down the stream are usually found in the middle of the day,—such as the willow-fly; and the cow-dung-fly is sometimes carried on the water by winds. In March there are several flies found on most rivers. The grannam or green-tail-fly, with a wing like a moth, comes on generally morning and evening, from five till eight o’clock, A. M. in mild weather in the end of March and through April. Then there are the blue and the brown, both Ephemeræ, which come on, the first in dark days, the second in bright days; these flies, when well imitated, are very destructive to fish. The first is a small fly with a palish-yellow body, and slender beautiful wings, which rest on the back as it floats down the water. The second, called the cob in Wales, is three or four times as large, and has brown wings, which likewise protrude from the back, and its wings are shaded like those of a partridge, brown and yellow brown. These three kinds of flies lay their eggs in the water, which produce larvæ that remain in the state of worms, feeding and breathing in the water till they are prepared for their metamorphosis and quit the bottoms of the rivers, and the mud and stones, for the surface, and the light and air. The brown fly usually disappears before the end of April, likewise the grannam; but of the blue dun, there is a succession of different tints, or species, or varieties, which appear in the middle of the day all the summer and autumn long. These are the principal flies on the Wandle—the best and clearest stream near London. In early spring these flies have dark olive bodies; in the end of April and the beginning of May they are found yellow; and in the summer they become cinnamon-coloured; and again, as the winter approaches, gain a darker hue. I do not, however, mean to say that they are the same flies, but more probably successive generations of Ephemeræ of the same species.

The excess of heat seems equally unfavourable, as the excess of cold, to the existence of the smaller species of water-insects, which, during the intensity of sunshine, seldom appear in summer, but rise morning and evening only. The blue dun has in June and July a yellow body, and there is a water-fly which in the evening is generally found before the moths appear, called the red-spinner. Towards the end of August, the Ephemeræ appear again in the middle of the day: a very pale small Ephemera, which is of the same colour as that which is seen in some rivers in the beginning of July. In September and October this kind of fly is found with an olive body, and it becomes darker in October, and paler in November. There are two other flies which appear in the end of September, and continue during October if the weather be mild: a large yellow fly with a fleshy body and wings like a moth; and a small fly with four wings, with a dark or claret-coloured body, that when it falls on the water has its wings like the great yellow fly, flat on its back. This, or a claret-bodied fly, very similar in character, may be likewise found in March or April, on some waters. In this river I have often caught many large trout in April and the beginning of May, with the blue dun, having the yellow body; and in the upper part of the stream below St. Albans, and between that and Watford, I have sometimes, even as early as April, caught fish in good condition: but the true season for the Colne is the season of the May-fly. The same may be said of most of the large English rivers containing large trouts, and abounding in May-fly;—such as the Test and the Kennet; the one running by Stockbridge, the other by Hungerford. But in the Wandle at Carshalton and Beddington, the May-fly is not found; and the little blues are the constant, and when well imitated, killing flies on this water; to which may be joined a dark alder-fly, and a red evening fly. In the Avon, at Ringwood and Fordingbridge, the May-fly is likewise a killing fly; but as this is a grayling river, the other flies, particularly the grannam and blue and brown, are good in spring, and the alder-fly or pale blue later, and the blue dun in September and October, and even November. In the streams in the mountainous parts of Britain, the spring and autumnal flies are by far the most killing. The Usk was formerly a very productive trout stream, and the fish being well-fed by the worms washed down by the winter floods, were often in good season, cutting red, in March, and the beginning of April: and at this season the blues and browns, particularly when the water was a little stained after a small flood, afforded the angler good sport. In Herefordshire and Derbyshire, where trout and grayling are often found together, the same periods are generally best for angling; but in the Dove, Lathkill, and Wye, with the natural May-fly, many fish may be taken; and in old times, in peculiarly windy days, or high and troubled water, even the artificial May-fly, according to Cotton, was very killing.

Poiet.—I have heard various accounts of the excellent fishing in some of the great lakes in Ireland. Can you tell us any thing on the subject, and if the same flies may be used in that island?

Hal.—I have been several times in Ireland, but never at this season, which is considered as best for lake-fishing. I have heard that in some of the lakes in Westmeath, very large trout, and great quantities may be taken in the beginning of June, with the very flies we have been using this day. Wind is necessary; and a good angler sometimes takes in a day, or rather formerly took, from ten to twelve fish, which weighed from 3 to 10lbs., and which occasionally were even larger. In the summer after June, and in the autumn, the only seasons when I have fished in Ireland, I have seldom taken any large trout; but in the river Boyle, late in October, after a flood, I once had some sport with these fish, that were running up the river from Lock Key to spawn. I caught one day two above 3lbs. that took a large reddish-brown fly of the same kind as a salmon fly; and I saw some taken that weighed 5lbs., and heard of one that equalled 9lbs. These fish were in good season, even at this late period, and had no spots, but were coloured red and brown—mottled like tortoise-shell, only with smaller bars. I have in July, likewise, fished in Loch Con, near Ballina, and Loch Melvin, near Ballyshannon. In Loch Con, the party caught many small good trout, that cut red; and in the other I caught a very few trout only, but as many of them were gillaroo or gizzard trout as common trout.

Poiet.—This must have been an interesting kind of fishing. In what does the gillaroo differ from the trout?

Hal.—In appearance very little, except that they have more red spots, and a yellow or golden-coloured belly and fins, and are generally a broader and thicker fish; but internally they have a different organization, possessing a large thick muscular stomach, which has been improperly compared to a fowl’s, and which generally contains a quantity of small shell-fish of three or four kinds: and though in those I caught the stomachs were full of these shell-fish, yet they rose greedily at the fly.

Poiet.—Are they not common trout which have gained the habit of feeding on shell-fish?

Hal.—If so, they have been altered in a succession of generations. The common trouts of this lake have stomachs like other trouts, which never, as far as my experience has gone, contain shell-fish; but of the gillaroo trout, I have caught with a fly some not longer than my finger, which have had as perfect a hard stomach as the larger ones, with the coats as thick in proportion, and the same shells within; so that this animal is at least now a distinct species, and is a sort of link between the trout and char, which has a stomach of the same kind with the gillaroo, but not quite so thick, and which feeds at the bottom in the same way. I have often looked in the lakes abroad for gillaroo trout, and never found one. In a small lake at the foot of the Crest of the Brenner, above 4000 feet above the level of the sea, I once caught some trout, which, from their thickness and red spots, I suspected were gillaroo, but on opening the stomach I found I was mistaken; it had no particular thickness, and was filled with grasshoppers: but there were char, which fed on shell-fish, in the same lake.