Salmon, the common name of the soft-rayed fishes of the genus salmo (Cuv.). The old genus salmo of Artedi and Linnaeus has been subdivided into the three principal families of salmonidoe, characini, and scopelidoe, of which only the first concerns us here; this, besides the salmon and trout, includes the smelt, cape-lin (mallotus), grayling, whitefish, and others. The genus salmo has the cheeks or whole head covered with scaleless integument, and the rest of the body with cycloid, thin, small scales; there is an adipose fin on the back near the tail, over the anal, and the dorsal is over the ventrals; the branchiostegal rays vary from 12 to 19, and there is a false gill on the inner side of the operculum; the edge of the upper jaw is formed by the maxillaries as well as the premaxillaries; the air bladder is always present, large and simple, opening into the pharynx; the intestinal canal is short, with numerous pyloric caeca; the ovaries form closed sacs without oviducts, and the eggs enter the cavity of the abdomen, whence they pass out by an opening behind the anus.
The names salmon and trout have been applied in the most indefinite and contrary manner, by different authors and in both hemispheres, to the fishes of this genus; those by almost universal consent called salmon will be alluded to here, leaving for the article Trout the brighter spotted and usually smaller and fresh-water species. According to Prof. Rasch of Norway, many so-called species of the salmonidoe produce fertile offspring inter se; the spawn of the true salmon fecundated by the common trout has been known to produce 40 per cent. of a well shaped prolific brood; showing either that hybrids are not sterile, or that the limits of the species cannot be defined. Even the genus as restricted by Cuvier has been subdivided into three by Valenciennes according to the distribution of the vomerine teeth; in salmo (Val.) there are strong conical teeth in both jaws and a small group at the end of the vomer; the palate bones and the sides of the tongue are also armed with teeth; in fario (Val.), including the salmon trout, there is in addition a single mesial line of teeth on the vomer; and in salar (Val.) the vomer has two rows of teeth.
Species called salmon and species called trout are found in each of these subdivisions, but the last two contain chiefly those called salmon trout and trout. The salmons are of great importance to man as an article of food, and are the most esteemed of any fresh-water fish; the number of men and the amount of capital employed in this fishery are very great; their flesh is eaten fresh, salted, smoked, dried, and pickled. The species, which are numerous, inhabit the sea and fresh waters, some migrating from the ocean to rivers at the breeding season; they spawn in shallow streams, both sexes assisting in forming the bed; they are found in the northern waters of Europe, Asia, and America, even in small streams, in the cold water of the arctic zone, and as high as the regions of perpetual snow; none have been found in South America, the East Indies, or Africa. They are unmistakably alluded to by Pliny and Ausonius. - At the head of the true salmons, or those having the body of the vomer smooth, stands the common salmon (S. salmo, Val.; S. salar of authors). In this the head is large, the gape wide and well furnished with teeth; the gill openings are very large, and consequently death very soon takes place out of the water; the abdominal outline is much more curved than the dorsal; the snout pointed, and the body rather slender and fusiform; the form is elegant, and the movements are rapid and vigorous.
The color is slaty blue on the back, darkest on the head, duller and slightly silvery on the sides, and beneath pearly silvery white; there are numerous black spots above the lateral line; the dorsal, pectorals, and caudal are dusky, the anal white, and the ventrals white externally and dusky internally; the gill covers are rounded posteriorly, and the tail is nearly square in the adult, but forked in the young; the scales are delicate, and sunk in the thick and fatty skin. As seen in the markets they are generally not more than 3 ft. long, though they attain a much greater size. From the northern seas they enter the rivers when swollen by the rains and more or less turbid and deep, remaining for a time in the brackish estuaries; they are probably able to detect the mixture of the waters through the nostrils, which are freely supplied with nervous filaments; they ascend during the flood, at the rate of 15 to 25 m. a day, resting in pools when the water is unfit for their progress; the females ascend before the males.
Having attained the requisite height, as the cold weather comes on they take measures to deposit their spawn; at this time the female becomes very large, and her silvery tints dull gray; the male becomes thinner on the back, the nose longer, the under jaw turns up in a strong hook which enters a hollow in the nose, and the colors become brown and red. A furrow, 6 to 9 in. deep, is excavated in the bottom, principally by the female; in this the spawn is deposited, impregnated, and covered with gravel by the fish. The spawning process consumes from 8 to 12 days, and at the end of it the fish are very much emaciated, the scales are cast off, and they retire to some quiet place to regain their strength; in this condition they are called kelts, and are unfit for food. The eggs remain covered by the gravel all winter beneath the ice, and begin to be hatched by the end of March or commencement of April; experiments prove that the eggs are hatched in 114 days when the temperature of the water is at 36° F., in 101 at 43°, and in 90 at 45°. The young come out from the gravel when about an inch long; these are called parr, and remain a year in fresh water; when 4 to 6 in. long they receive the name of smolts, and are greenish gray above and silvery below, with very deciduous and delicate scales, in which state they descend to the sea; after about two months' sojourn there they ascend the rivers again, weighing 2 1/2 to 4 lbs., and are then called grilse; they spawn during the winter, and then are entitled to the name of salmon; descending and returning the following season, they weigh 10 to 15 lbs., and may go on increasing to 60 or 70 lbs.; but now a salmon of 30 lbs. is considered very large, as from the injudicious methods of fishing both in Europe and this country most are caught in the condition of grilse or younger.
According to Dr. Davy, the eggs retain their vitality for many hours in the air, if moist and cold (even to 32° F.), but not more than an hour if dry and at ordinary temperatures; both the ova and young fish will bear a heat of 80° or 85° in water for a short time, but die in water above 84° or 85°; they perish also in salt or brackish water. In their descent to the sea they generally remain for a time in brackish water, getting rid of their fresh-water parasites (crustaceans which attach themselves to their gills), and they do the same thing before they ascend the rivers, which frees them from marine parasites. This species is very extensively distributed in northern Europe and America, being found in Great Britain, the Orkneys, France, Belgium, Holland, Germany, Russia, Denmark, Sweden, Norway, and Iceland, getting access from the English channel and the northern seas by the Tweed, Tay, Severn, Loire, Rhine, Elbe, etc.; it does not occur in rivers falling into the Mediterranean, and does not come below the 45th parallel of latitude; in North America it frequents the rivers of Labrador, Canada, Newfoundland, Nova Scotia, New England, and those of New York communicating with the St. Lawrence, ascending even to Lake Ontario. Salmon can live without access to the sea, as is seen in Sebago and other landlocked lakes of Maine, but they are of inferior size and quality.
It is well known that the salmon has the power of swimming with great velocity, of stemming rapid rivers, and of jumping over dams and waterfalls of considerable height; they have been known to spring 14 ft. out of water, and to describe a curve of at least 20 ft. in order to surmount a cascade; if not successful at first they persevere till they succeed, unless the obstruction be insurmountable; these efforts they are able to make by their powerful and active muscles, and especially by the strong and fleshy tail. Ascending the rivers from June to September, their shoals are attended by porpoises, seals, and carnivorous fish, which find them an easy prey; it is popularly believed that they return to the river in which they were hatched, which in their immense numbers would be likely to happen to some, but more unlikely, as the fact proves, to the greater portion. The salmon is very voracious, and grows rapidly; in the sea it feeds principally on small fishes, especially the sand eel (ammodytes), crustaceans, the ova of echinoderms, etc.; it is believed that it eats very little while in fresh water from its thin appearance, but the emaciation would be sufficiently accounted for by the waste incidental to the breeding season.
In the sea salmon very rarely bite at a hook, but in rivers and estuaries they will rise to artificial flies. For an interesting account of salmon fly fishing the reader is referred to Sir Humphry Davy's "Salmonia, or the Days of Fly Fishing." They are speared by the American Indians, and also in the Scottish rivers. Where salmon fishing is pursued as a business, they are taken in nets, usually in gill nets, stretched across the mouths of the rivers. Many hundred salmon of good size are often taken at a single haul of a seine, and some of the English fisheries furnish annually more than 200,000; the fisheries of Scotland and Norway are also very profitable. Rivers are let out to sportsmen with the exclusive right of fishing for salmon; the streams of the British provinces in America are frequently thus disposed of both to native and foreign anglers. The river Thames was once celebrated for its salmon, but its stream is now too impure to invite them to enter. The Merrimack river in Massachusetts formerly swarmed with salmon weighing from 9 to 12 lbs., but the numerous dams and manufacturing establishments have driven them away, and the northern markets are now supplied from the Kennebec river and the British provinces, and from the Pacific coast.
The salmon enters the rivers of Nova Scotia in the latter part of April, the rivers emptying into the bay of Fundy a month later, and those emptying into the gulf of St. Lawrence in June; the females arrive first, and the males about a month after, and the grilse ascend during July and August. They spawn late in autumn, most of them returning to the sea before the rivers are frozen over, but some remaining in fresh water all winter and going to the sea in the spring; the ova are cast when the water is at most at 42° F., in shallow, pure, and rapid streams. Among the noted rivers for fly fishing are the Gold and St. Mary's in Nova Scotia, and the S. W. Miramichi and Nepisiguit in New Brunswick. The flesh is exceedingly delicate, and of a tint of pink which has received therefrom the name of salmon-colored; the delicacy of the flesh is no doubt due to the ova of echinoderms and crustaceans which form their chief food, and the intensity of the red color seems to be in proportion to the quantity of the gam-marinae (minute amphipod crustaceans) which they devour. As with all fish which swim near the surface, it should be eaten when fresh, as the flavor is rapidly lost after death.
The salmon is one of the fish to which the attention of pisciculturists has been directed, from the ease with which artificial fecundation is effected, the successful results obtained, and the value as food. In the Penobscot river in November, 1871, the Russian method of fecundation, that of carefully keeping the eggs and milt from water until they have come in contact, was practised with such success that 96 per cent. of the eggs were fecundated, a very much larger proportion than in the natural operation; 70,000 eggs from 10 females, thus fertilized, were sent in December to other parts of Maine, Massachusetts, and Connecticut. From the ninth annual report of the commissioners of fisheries of Massachusetts, for the year ending Jan. 1, 1875, it appears that their chief work consisted in hatching the eggs and planting the young of the California and Maine salmon; a few landlocked salmon from Sebec were also distributed to different parts of the state. Salmon eggs have also been carried from Scotland to New Zealand. - The S. hamatus (Cuv.), regarded by Bloch and other naturalists as the old male of the preceding species, has the back reddish gray, the sides brighter, and lower parts dull white; there are black spots above the lateral line, and some red markings, and the fins are bordered with blackish; the lower jaw in both sexes and in the young has a terminal hook turned upward and received in a depression near the union of the intermaxillaries; the mouth is very large from the elongation of the jaws, and is armed with strong teeth.
The true salmon enters the rivers in summer, but this species ascends between October and the end of February, so that the two are not found together except at the end of the fishing season; the flesh is lighter colored and drier than in S. salar, and is hence less esteemed; it is found in the rivers of western Europe, but a specimen so named by Agassiz was caught in 1860 in the Merrimack river, showing that species which generally leave their arctic retreats for the European shore sometimes descend on the American coast. In the S. hucho (Val.), the salmon of the Danube, the body is longer and rounder than in the common salmon; it is grayish approaching to violet on the back, silvery white on the sides and below, the head and dorsals with a greenish tint, and the other fins yellowish; above the lateral line are black spots, smallest in the largest fish; as in other salmons, the young have seven or eight dark vertical bands on the body, which disappear with age; it attains a weight of 80 or 40 lbs., and is not found in the rivers opening into the Baltic; the flesh is white, but softer and less agreeable than in the common species; the spawning season is in June. For other species of old world salmon, see Cuvier and Valenciennes's Histoire naturelle des pois-sons, vol. xxi.
Among the American species the arctic salmon (S. Rossii, Rich.) deserves mention; it grows to a length of 2 or 3 ft., and has a more slender form than the common salmon; the color above is brownish green, the sides pearly gray with bright red dots near the lateral line, and red below; the under jaw is considerably the longer; the scales small, and separated from each other by smooth skin; it is found in the arctic seas and in the rivers therewith communicating so abundantly, that over 3,000 were taken at a single haul of a net during one of the expeditions of Sir John Richardson. Many other species of the arctic seas, on the E. and W. coasts of North America, are described and figured in Richardson's "Fauna Boreali-Americana," and many since his time have been described from the Columbia river and its tributaries, and from the rivers of the N. W. coast. (See "Report of United States Commission of Fish and Fisheries," by Prof. Baird, part ii., 1875).
Common Salmon (Salmo salar).
Salmon One Year Old.