SALMON AND SEA-TROUT

In many ways nature is apparently very wasteful, and in nothing is this more marked than in the case of the salmon. Probably not more than one egg in a thousand produces a fish which reaches the smolt stage, and a still smaller proportion grows to the spawning stage. This great mortality which occurs among the eggs and young fish when left to nature may be very considerably reduced by artificial means, so that a very fair proportion of the eggs deposited by the female fish will not only be hatched out successfully, but the little fish will reach the smolt stage safely and have a good chance of reaching the sea. How successful artificial intervention may be has been proved over and over again in the United States and in Canada. In the case of more than one river in Canada, the artificial propagation and protection of salmon has resulted in what is apparently the actual manufacture of a salmon river, yielding an annual haul of fish far beyond anything known in Europe, from a river which before yielded no salmon, or hardly any.

These operations, carried out by the State, were of course far beyond anything which could be undertaken by the amateur, but I am sure that if several riparian owners on a salmon river carried on artificial hatching and rearing operations for several seasons, a marked increase in the number of fish in the river would ensue. The objection of most people to this course is that it is unfortunately only too apparent that they are benefiting chiefly, not the rod fisherman, but the netsman at the mouth of the river.

The different artificial means used to help nature in producing a good head of salmon in a river vary chiefly in the amount of the help given by each. It will suffice to say that the best is that which provides for the protection and feeding of the young fish till it is ready to take its first journey to the sea. The reason of this is obvious, as every day passed in safety is a day gained, both in strength and in power of self-preservation.

Though it is possible to purchase a certain number of salmon ova, this is not at all a satisfactory way of obtaining them. To begin with, it is impossible to get them in sufficient numbers to carry out operations on a large enough scale. Salmon ova are also expensive; and it is no use working with less than half a million in several stations if the river is of any size. It is advisable that the ova should be obtained from the fish. This may be done either by collecting the ova deposited by the fish in the spawning beds or from the gravid females. The latter course necessitates the ripe female and male fish being caught and artificially spawned. As in nature, at best but a comparatively small percentage of the ova are impregnated, and by artificial spawning over ninety per cent. of them may be successfully hatched out, there can be but little doubt as to which is the better way. It is difficult to make sure of catching the fish just at the time they are ripe, so it is advisable to impound them in a fenced-off portion of the river, where they may be got at easily.

In the ripe female the ova flow out very readily, and but little pressure is necessary. Hard pressure on the abdomen should never be applied, as it is sure to injure the fish. A ripe female having been obtained, from which the ova flow readily, the female is held over a perfectly clean tin or earthenware dish wet, but containing no water and the ova are caused to flow into it by gently but firmly pressing the hand on the abdomen, and stroking it down towards the vent. Milt from a ripe male fish is then allowed to run over the ova in the dish, and is made to run well between them by tilting the dish about from side to side. The ova will now adhere together, and some water should be added. This water should be poured off and fresh added till the superfluous milt is washed away, when the ova should be left in the water till they separate, which will be in about twenty minutes or half an hour.

The fertilized ova thus obtained may either be laid down in artificially protected hatching beds, or may be transferred to a hatchery. The latter proceeding, of course, requires a hatching house specially built and arranged, and as this is outside the scope of the present work, I would refer my readers to larger works upon the subject, such as An Angler’s Paradise, by J. J. Armistead. Of course, by using a hatchery a large number of the eggs will be saved, ninety per cent. of them should hatch out. This is, therefore, obviously the best way to proceed. A very much larger number of eggs will, however, be hatched out in properly-chosen artificial beds than would be the case if they were left to nature.

The necessary qualities of a good artificial bed are, a good supply of clean water which is not liable if there is a spate to deposit sediment on the eggs, protection from light, and protection from the many creatures which prey upon the ova. The hatching beds may be so arranged that the young fish may escape as soon as they like after hatching out, but it is best to watch and protect them for at any rate the first few weeks after they have begun to feed, and while continuing the feeding, to allow those of the fish that wish to escape.

The rearing of young salmon and sea-trout is practically the same as that of the common trout, except that they require more water. If kept in rearing ponds they grow more quickly than they do when left to find food for themselves. While young, the salmon is marked with transverse bars of a darker colour than the rest of the body. During the time it bears these marks it is known as a parr. In about fifteen months it loses these marks and becomes quite silvery, being now known as a smolt. Shortly after assuming the smolt dress, the young salmon takes its departure to the sea. In some cases the young salmon do not appear to go down to the sea till over two years after being hatched out, but they should always be set at liberty in March, April, or May in the year following that in which they were hatched out, according to how far they have developed the smolt or silver appearance.

If spring water is obtainable, particularly if the water, as is usually the case, is of an even temperature throughout the year, the troubles of the fish culturist are considerably lessened. Without a building for the hatching troughs it is almost impossible in many places to guard against frost unless such a spring is available. Sediment may be avoided by putting frames covered with flannel at the inlets to the hatching beds, these will, if kept clean, prevent any sediment from coming into the ponds, and will allow plenty of water to flow in. If hatching trays are not used, the bottom of the artificial bed should be covered with clean gravel.

The time which elapses from the impregnation of the eggs to their hatching out varies according to the temperature of the water, a fairly average time is about ninety days. The ova should be watched during this time, and the dead ones removed. For a short time after they are impregnated they are fairly hardy, but from then till shortly before they hatch out the very slightest concussion will kill or seriously injure them.

The management of sea-trout ova is similar to that of salmon, and the ova are obtained in the same way. As in the case of the salmon it is best to rear the little fish artificially, till they are ready to go down to the sea; they will thus escape dangers likely to cause the loss of about eighty per cent. of their number.

The same methods and the same precautions as advised in the chapters on rearing trout should be adopted in the case of salmon and sea-trout as far as is possible, and if this is done a very large percentage of the ova should be successfully reared to the smolt stage.