Meanwhile the eggs remain buried in the gravel for about four months. At the end of that time the little fishes hatch out, and immediately hide themselves for about a fortnight under a rock or a large stone. You would never know what they were if you were to see them, for they look much more like tadpoles than fishes; and each has a little bag of nourishment underneath its body on which it lives. When this is exhausted they leave their retreat and feed upon small insects, growing very rapidly, until in about a month's time they are four inches long. They are now called parr and have a row of dark stripes upon their sides, and in this condition they remain for at least a year. Their color then changes, the stripes disappearing, and the whole body becoming covered with bright silvery scales.
The little fishes are now known as smolts, and, like their parents; they make their way down the river and pass into the sea. There they remain until the autumn, when they ascend the river again. By this time they have grown considerably, weighing perhaps five or six pounds, and are called grilse. And it is not until they have visited the sea again in the following year that they are termed salmon.
When salmon are ascending a river and come to a waterfall, they climb it by leaping into the air and so springing into the stream above the fall, trying over and over again until they succeed. When the fall is too high to be climbed in this way, the owners of the river often make a kind of water staircase by the side of it, so that the fishes can leap up one stair at a time. This is called a salmon-ladder.
North Pacific Salmon
Now this description would not at all fit the case of the salmon which live in the North Pacific and ascend the rivers of California, British Columbia, and Alaska, and of Siberia and Japan on the other side of the ocean. These are the salmon which supply the whole country, and many other countries, with their pink flesh, boiled, and sealed in cans, so that it may be sent long distances and kept many months without spoiling. Every spring and summer, at different times according to the locality and the species—there are five kinds of importance, caught for the trade—vast numbers of them enter the mouths of the rivers and begin to make their way up-stream in their effort to reach the shallow head waters of each river, and of every one of its tributaries. It is at this time that they are caught by spearing, netting, and various contrivances; but laws prevent any general obstruction which would altogether stop the advance of the host, so that while tens of thousands are taken great numbers escape and pass on, as it is necessary they should do in order to lay eggs and so keep up the race.
This takes place far up at the heads of the streams in the foothills of the mountains; and having deposited the spawn, late in summer, the spent fish begin to drift down stream again. But all this time they have been eating nothing, they are worn with the long struggle against the rapids, often wounded by sharp rocks, and are good for nothing to catch or eat. In fact, so fagged out and weak are they that all of them die before any reach the mouth of the river. It is a strange fact that of all the vast host of salmon which each summer climb the rivers not a single one gets back to the sea.
A year later, however, the young hatched from the eggs which were left behind them at the heads of the streams swim down the rivers and enter the ocean. There they remain, probably not very far from land, for two or three years, feeding and growing until they are of full size and strength; and each season a class of them, having reached the right age and condition to spawn, force their way up to the spawning-grounds, to leave their eggs and then die, as did their parents before them.
Eels
The only other fresh-water fishes which we can notice are the eels, which look more like snakes than fishes, for they have long slender bodies, with a pair of tiny fins just behind the head, a long one running along the back and tail, like a crest, and another, equally long, under the body. And they are clothed with a smooth, slimy skin instead of with scales.
These curious creatures live in ponds and even in ditches as well as in rivers, and are very plentiful in all parts of the northern hemisphere. During the daytime, although they will sometimes bask at the surface in the warm sunshine, they generally lie buried in the mud at the bottom of the water, coming out soon after sunset to feed. And when the weather is damp, so that their gills are kept moist as they wriggle through the herbage, they will often leave the water and travel for some little distance overland.