Читать книгу Essays in Natural History and Agriculture - Garnett Thomas - Страница 5

In addition to the objections which I have offered to the seeming doubt of Dr. Fleming, whether Salmon enter rivers for any other purpose besides propagation, the following have come to mind; and though they do not apply to the Salmon, they confirm me in the opinion that there are reasons, of which we know nothing, for fish ascending rivers, which are not at all connected with propagation. One is the habit of what is here called streaming. In the winter the fish not engaged in spawning (I speak of Trout, Grayling, Chub, Dace, &c.) leave the streams and go into deep water; either because the water is warmer there, or because they there find more food; and it is well known to fly-fishers that they do not catch many fish in the streams if they begin early, say in February. It is proverbial here that fish begin to stream when the great grey, or what is called in other districts the devil or dule crook, and in March brown or brown drake, comes upon the water; and I have seen Trout by scores leaping at a weir in the beginning of May, whether in search of food or an instinct implanted in them to keep all parts equally stocked with them, I do not know; but it has certainly nothing to do with their spawning. Is it presumptuous to suppose that God in His providence has implanted this instinct in Salmon for our good, that we might have a supply of excellent food, which without this would be in a great measure unattainable? Whether this is the true cause, and the only one, I am unable to determine; but this is the effect produced, and in the absence of other reasons it is, in my opinion, one that ought to be admitted. Another reason why fish ascend rivers is their impatience of heat. I speak now more particularly of Grayling; if the weather is very hot at the end of May or the beginning of June, the Grayling in the Wharfe (they are almost unknown in this part of the Ribble) ascend the mill streams by hundreds, and go up the wheel races as far as they can get, and stay there until the stoppage of the wheels (many a ducking have I had in pursuit of them), when they are obliged to beat a retreat, and this often proves a disastrous one to many of them. The ascent of young Eels by millions, and the ascent of the Flounder, are neither of them connected with the propagation of their kind, and though I cannot say for what purposes they do ascend, I am, I think, justified in doubting assertions which seem to have nothing to support them but the positive manner in which they are made.

The Salmon Par is neither a Hybrid nor a distinct species of the genus Salmo, but a state of the common Salmon. The author of "Wild Sports of the West" says of the Par, as I have noted previously, "That it has very much the appearance of a Hybrid between the Salmon and the Trout, and (in a note) that the natural history of this fish is doubtful. Some conjecture that it is a Hybrid between the Salmon and Trout, because it is only found in rivers which are frequented by Salmon. Others think it a cross breed between the sea Trout and river Trout," and then he speaks of this "hybridous diminutive," as if he thought one of these opinions was correct. That the Par is not the result of a cross between a sea Trout and a river Trout, is proved by the fact that there are no sea Trouts in the Wharfe, the Par (admitting it to be a distinct species, which I do not), the Salmon, and common Trout being the only kinds of Salmonidae which are found in that river, at least where I am acquainted with it. If the Par be the result of a cross between the Salmon and the Trout, what becomes of it in the spring, and where are all the Par, which were so abundant in October, gone to in April? Did they migrate to the sea, the shoals would be met with by somebody; and did they stay in the river they would be caught at one time or other. However, as it is well known that neither of these cases is ever realized, we must suppose another, which I have already done in my former communication. In fact, in angling in the beginning of March, fish are often caught which would puzzle the most experienced fisherman to determine whether they are Par or Smolts, especially after they have been caught some time; and in a large number caught at that time there are all the intermediate shades of appearance between the perfect Par and the real blue Smolt.

CLITHEROE, May 29th, 1834.

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CLITHEROE, March 18th, 1846.