Of all our river-fish, no two are more opposite in looks than the lordly Salmon and the humble, squirming Eel. They also differ very greatly in their egg-laying habits. The Eel leaves the river and spawns—that is, lays eggs—far out at sea, and never in the river. The Salmon leaves the sea, and spawns far up the river, and never in the sea. Even at the cost of its own life the Eel must go out to sea, and the Salmon must come up-river, for the duties of egg-laying.
The sea is a rich dining-room, full of all kinds of good food. And it is there that those splendid Salmon you see in the fishmonger's shop became so plump. We do not know where the Salmon wanders in the wide sea. He may go far away, he may stop near our shores. But we do know that the young herrings, the juicy shrimps, and all the other titbits he eats make him grow like magic. Yet, when Nature calls him, he leaves it all behind, forgets to eat, and turns his head up the river-mouth. Let us share his journey, and see what happens.
It is early autumn when our Salmon shoots with great speed up the river. This is his first journey up there, but he will not be content until he reaches the shallows, perhaps one hundred miles or, more up-stream. How does he find his way? What guides him, and why does he go? The only answer is that he feels he must go; that he obeys that wonderful, strange guide we call Instinct.
The perils of the journey are great. Miles and miles of nets are spread to catch the Salmon, and thousands are caught in that way. There are many other dangers, including the anglers with their glittering "flies." Our Salmon does not care to eat on his travels. But he may snatch at the "fly" or prawn which is drawn in front of his nose. If he escapes the fishermen, he comes to other dangers. Weirs and rapids and waterfalls bar his path. But something tells him to go up-stream, so he tries with all his might to jump over the obstacles. He darts through the rushing water, and high in the air, with all the strength of his powerful body. If he is beaten back he tries again and again, until at last, with a splendid leap, he gains the top, and rushes on in safety.
The Salmon makes his Leap
After resting here and there, our Salmon journeys on, and in time he finds himself near the right spot. The river is here about two feet deep; and the clear, sparkling water glides Swiftly over a bed of stones. These are the "spawning beds," and our Salmon goes no farther.
But, though his dangerous travels are over for the time, his hardships are before him. Many other Salmon have run up to the spawning beds from the sea; some are hen-fish, some cock-fish, as the female and male Salmon are called. The hen-salmon, with a swirl of body and tail, makes a place for her eggs in the gravel. Then, having laid some, she goes a little way up-stream, and lays more. The eggs are heavier than water, and so they sink and are soon covered over.
While this is going on the cock-salmon are fighting and driving one another about. They are rivals, and they fight fiercely, sometimes wounding one another. They have terrible teeth, and the lower jaw at this time is curved into an ugly hook. At last the busy scene of fighting and splashing and egg-laying is over. Then the hen-salmon rest in the deep pools before going back, to the sea to feed ravenously and regain strength. But the cock-salmon remain to guard the spawning bed for a week or more, and most of them die soon after.
Now we will follow the fortunes of the precious eggs. Each hen-fish has laid from 8,000 to 20,000, according to her size. What a vast army of them lie under the gravel! But Salmon eggs are a dainty dish, and every water-bird, many insects, fish and other creatures hasten to have eggs for dinner. Also, as it is now winter-time, there are floods which sweep the eggs away. The lucky ones remain for three months. Then from each one a little creature emerges, wriggles up through the gravel, and rests for six weeks or so. It is quite helpless, with no nest or parent to guard it, and it cannot eat. But it does not starve, for Nature has provided it with a queer kind of "feeding-bottle." The yolk of the egg still holds to its little body, and from this it obtains all the food it needs.
Well, the "feeding-bottle" is empty and gone, so the baby Salmon eats tiny insects. Spring has come, and the river begins to "wake up," and you might see the little Salmon ever so busy darting after flies or grubs of any sort. It is a beautiful baby, olive-brown above, pure white below, with spots and upright stripes along its sides. For many years nobody knew whose baby it was! It has a name of its own—Parr. The Salmon's life is like a book with many chapters, and in each chapter the Salmon has a different name, as you will see.
By the next Spring our little Parr is four inches long. He is now over a year old, and stays where he is for . still another year. Then he feels the call of the sea. He becomes silvery in colour, and in this lovely "sea-jacket" off he goes to the ocean. With his new coat the baby Salmon takes a new name—he is no longer a Parr, but a Smolt, six inches long and a few ounces in weight.
We lose him as soon as he leaves the river, and find him again when he returns to the river to spawn. But no longer is he the little silvery Smolt! Some young Salmon spend one year in the sea, and some two, three, or four years. And in that time they grow enormously.
We will suppose that our Smolt spends one-and-a-half years under the ocean wave. He has escaped seals and otters and nets, and has fed so well that he now weighs nearly eight pounds! He is a lovely shining fish, strong and plump, yet as swift as an arrow. In this chapter of his life we must call him a Grilse. As we have seen, he has a long journey, a long fast, and a hard time when he reaches the spawning beds. So the Grilse will need every ounce of his strength and fat to face the ordeal! He leaves the sea, and, strange to say, runs up the very same river in which he was born!
If you ask how the Grilse finds this particular river, no one can tell you. You may also wonder how we know so much about him. Well, for many years Salmon have been watched very closely. For instance, in one river of Scotland over 5,000 little Smolts were caught and marked in a certain way. They were then put back to continue their journey to the sea. Numbers of these fish were caught again in the same river, some after one year, others after two or three years, had passed. Some of these little Smolts had grown into great Salmon of from thirty to forty pounds' weight But they had returned to their own river to spawn.
Another very strange thing was discovered! As you know, the Salmon's silvery scales are arranged like the tiles on a roof. As the fish grows, of course its coat of scales must grow too. If you make a roof larger, you add more tiles. But the growing Salmon does not add more scales, so the old scales must grow as the fish grows. Perhaps you know how a tree increases, ring by ring each year. Well, the fish-scale also increases like that, by adding tiny rings of growth.
Life of a Salmon as Shown by the Scales—Scale from fish magnified twenty-five times. This Salmon spent two years in fresh water as a Parr, then two years in the sea, and returned to fresh water, probably to spawn, in the beginning of its fifth year.
By counting these rings it is possible to say how many years the fish has lived. But it was also found, after many thousands of scales had been examined, that the rings told the whole story of the Salmon's life. Thus from one scale we know how long the fish stayed in the river before it went to sea, and how long it spent in the sea before it came back to the river. Those who have studied the scales can read on them every chapter in the story of the Monarch of the River!