Note (return) — NATURAL HISTORY OF SALMON AND SEA-TROUT.

We agree with Mr Young in thinking that the preceding facts, viewed in connexion with Mr Shaw's prior observations, entitle us to say, that we are now well acquainted with the history and habits of the salmon, and its usual rate of growth from the ovum to the adult state. The young are hatched after a period which admits of considerable range, according to the temperature of the season, or the modifying character of special localities.21 They usually burst the capsule of the egg in 90 to 100 days after deposition, but they still continue for a considerable time beneath the gravel, with the yelk or vitelline portion of the egg adhering to the body; and from this appendage, which Mr Shaw likens to a red currant, they probably derive their sole nourishment for several weeks. But though the lapse of 140 or even 150 days from the period of deposition is frequently required to perfect the form of these little fishes, which even then measure scarcely more than an inch in length, their subsequent growth is still extremely slow; and the silvery aspect of the smolt is seldom assumed till after the expiry of a couple of years. The great mass of these smolts descend to the sea during the months of April and May,—the varying range of the spawning and hatching season carrying with it a somewhat corresponding range in the assumption of the first signal change, and the consequent movement to the sea. They return under the greatly enlarged form of grilse, as already stated, and these grilse spawn that same season in common with the salmon, and then both the one and the other re-descend into the sea in the course of the winter or ensuing spring. They all return again to the rivers sooner or later, in accordance, as we believe, with the time they had previously left it after spawning, early or late. The grilse have now become salmon by the time of their second ascent from the sea; and no further change takes place in their character or attributes, except that such as survive the snares of the fishermen, the wily chambers of the cruives, the angler's gaudy hook, or the poacher's spear, continue to increase in size from year to year. Such, however, is now the perfection of our fisheries, and the facilities for conveying this princely species even from our northern rivers, and the "distant islands of the sea," to the luxurious cities of more populous districts, that we greatly doubt if any salmon ever attains a good old age, or is allowed to die a natural death. We are not possessed of sufficient data from which to judge either of their natural term of life, or of their ultimate increase of size. They are occasionally, though rarely, killed in Britain of the weight of forty and even fifty pounds. In the comparatively unfished rivers of Scandinavia large salmon are much more frequent, although the largest we ever heard of was an English fish which came into the possession of Mr Groves, of Bond Street. It was a female, and weighed eighty-three pounds. In the year 1841, Mr Young marked a few spawned salmon along with his grilse, employing as a distinctive mark copper wire instead of brass. One of these, weighing twelve pounds, was marked on the 4th of March, and was recaptured on returning from the sea on the 10th of July, weighing eighteen pounds. But as we know not whether it made its way to the sea immediately after being marked, we cannot accurately infer the rate of increase. It probably becomes slower every year, after the assumption of the adult state. Why the salmon of one river should greatly exceed the average weight of those of another into which it flows, is a problem which we cannot solve. The fact, for example, of the river Shin flowing from a large lake, with a course of only a few miles, into the Oykel, although it accounts for its being an early river, owing to the receptive depth, and consequently higher temperature of its great nursing mother, Loch Shin, in no way, so far at least as we can see, explains the great size of the Shin fish, which are taken in scores of twenty pounds' weight. They have little or nothing to do with the loch itself, haunting habitually the brawling stream, and spawning in the shallower fords, at some distance up, but still below the great basin;22 and there are no physical peculiarities which in any way distinguish the Shin from many other lake born northern rivers, where salmon do not average half the size.