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 theactual 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 certainnumber 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. Aripe 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 asAn Angler's Paradise, by J. J. Armistead. Of course, by using a hatchery a large number of the eggs will be saved, ninetyper 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 thesemarks it is known as a parr.[3]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.
[3]All the trouts go through this stage, which is distinguished by "finger marks" upon the sides.
[3]All the trouts go through this stage, which is distinguished by "finger marks" upon the sides.
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 traysare 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.
Compared to what is known about the early part of the life history of theSalmonidæ, our knowledge of coarse fish is small. Fortunately, however, such lengthy and complicated proceedings as are necessary to obtain a good stock of trout are not necessary to obtain a good stock of coarse fish. If even a few rudd, perch, dace, pike, or carp are put into water where they have a good supply of food to begin with, and which is suitable otherwise for their well-being, the amateur's chief trouble after a few years, if the water is not heavily fished, will be to keep down the stock of coarse fish in proportion to the supply of food.
I have seen many cases where rudd, perch, dace and carp have increased to an enormous extent from a few fish introduced into the water. Some four years ago we put a few small ruddinto a mill-pond at home, thinking that the fry they produced would serve admirably as food to the trout which also inhabited the pond. In about twenty months the pond was full of small rudd, and last year we netted out many hundred, as the water was terribly over-stocked with them. The same thing has happened in almost every case which has come to my knowledge; that is, of course, where the waters have been stocked with food, and suitable to the fish introduced.
The way in which dace will increase when put into a suitable water is, if possible, even more remarkable than what happens in the case of the rudd. I will quote one instance, which proves this very conclusively. A few years ago there were no dace in the Sussex Ouse. Pike fishermen, however, used to bring live dace to use as baits. Some of these escaped, or were set free by the fishermen at the end of their day's fishing, and now the Sussex Ouse contains more dace for its size than any other river I have ever seen.
While rudd thrive best in a pond or lake into which a stream flows, dace require a river or stream to do well. They will, however, thriveand increase rapidly in a river where trout are not a success. A muddy bottom with occasional quickly running shallows, seem to constitute the best kind of water for dace. The largest, and by far the best conditioned dace I have seen, have come from the tidal parts of rivers, where the water is brackish at high water. Dace from such a water have also the advantage of being very good eating, as they have, as a rule, not got the unpleasant muddy taste usual in this fish.
Perch and pike will thrive both in rivers and in ponds or lakes which have a supply of water from a stream or from springs. They both increase in numbers very rapidly, and when protected, are more likely to require thinning down every few years, than artificial assistance from the amateur.
The king-carp is the best fish for the amateur who wishes to obtain good bottom fishing from an absolutely stagnant pond. This fish is much bolder and a more free feeder than the common carp. It increases so rapidly in numbers, and is a hard fighting and lively fish.
Most of the coarse fish deposit a much larger number of eggs than do any of theSalmonidæ—thatis to say, in proportion to their size. In stocking a water which contains no fish, the amateur may wish to hurry on the process of nature in the case of coarse fish; and, fortunately, this is fairly easily managed. In the case of perch, rudd, pike, and carp, but little change of water is required to hatch out the eggs. The eggs of these fish take but a short time to hatch; and if they are protected, and this protection is also given to the little fish for a few weeks, it will generally be found that an amply sufficient result is obtained. The eggs should be spread out carefully on wicker-work or the lids of baskets and kept in the light. A trickle of water which is sufficient to change the body of water in the pond in which the ova are put will, as a rule, be enough. The amateur must be careful that the pond in which he hatches the eggs does not contain any of the many enemies I have described in former chapters. If it is at all possible to protect the eggs and the little fish, it is best to hatch out the eggs in the pond which it is intended to stock, for it is exceedingly difficult to keep the newly-hatched fish in a rearing-pond on account of their very smallsize. It will be necessary to use muslin or flannel screens instead of perforated zinc. Care must be taken that there is not too great a flow of water, as this will cause the little fish to be drowned at the outlet screen.
Sir,—In your last issue I have read with pleasure the eminently practical notes on fish culture by Mr. Charles Walker. He is perfectly right in all he says with reference to the useful and preventive results of the use of "common garden" earth, or vegetable mould in checking any fungoid development,Saprolegniaor other. It must, however, be admitted that the said addition is not an element of beauty in a box; therefore it should be avoided, or only used when necessity dictates. However, the fry, when thoroughly restored to health, may be transferred by muslin net to another box free from earth should it be necessary to count out certain numbers for the satisfaction of customers' orders. Again, the earth employed may, and in some waters does, give rise to other ill effects on the health of the "fry" or young fishes. Affection of the eye is not unheard of as the result of over-use of earth. Perhaps the best way to obviate any trouble of this nature would be to pound and dry the earth, and keep it in a canister or other closed vessel till required for use. Spores of fungi are nearly, if not quite, omnipresent; and their effects are so insidiousthat too many precautions cannot well be taken to avert the introduction of "trouble" in the hatchery. Indeed, were it not for the risks arising from attacks of fungi, pisciculture, as now understood and carried on, would be an unalloyed pleasure and unbounded success. We can practically hatch 995 out of 1,000 eggs, or thereabouts. It is the risks of rearing that stand in our road, and these, as time goes on, and experience increases, must diminish. There would appear, then, to be a good time coming for fish culture, and those who earnestly follow it.
Practice is the only safe guide, as circumstances, geological, physical, and meteorological so vary the conditions of works that no definite rule of procedure will avail. Earnest work and close observation, combined with ready resource, are the only safe guides to success. Troubles of some sort are sure to supervene; the man who succeeds is he who can anticipate, and so remedy them. To be always on the watch and notice the first indication is a very safe maxim, more easy to inculcate than to put in practice.
There can be no question but that the practical removal of difficulties in the path of fish culture is work of the highest value, well worthy the attention and acknowledgment of those in authority at Whitehall and elsewhere at home, as has been the case abroad.
C. C. C.
Sir,—Your correspondent "C. C. C." inLand and Waterof last week disagrees with the constant and free use of earth, which I had advocated in my article on fish culture which appeared the preceding week. Naturally one must admit that earth at the bottom of a pond is not so great an element of beauty as is clean gravel, but the advantages are so many, that beauty must give way to usefulness. Besides this, "C. C. C." must know that it is almost impossible to keep the gravel clean enough to look pretty, when the water is inhabited by a large number of little fish which are being constantly fed. I cannot at all agree with his advice that "earth should be avoided, or only used when necessity dictates." I believe that one of the first principles of success in fish culture is always to prevent any disease or mishap, rather than to wait for, and then try to remedy it. Trout in their natural surroundings get a dose of earth every time that there is a spate. It is very evident that the earth contains some ingredients which are not only beneficial but almost a necessity to the fish.
I have never heard of earth as an actual cure for "fungus" and should hardly think that it is active enough. There is, however, no doubt that it is one of the best preventatives to "fungus," for if it is properly and freely used it stops all chance of any decomposing material being exposed to the action of the water, andlaying the fish open to the chance of a great many evils.
If suitable earth is used once a week, and even oftener on occasions, it can do no harm, and will keep the fish safe from a great many risks besides doing them very material good. I do not of course mean that the usual weekly dose should be a large one, as this would fill up the pond before the end of the season, but that a small dose should be given generally, and a large dose occasionally. I am quite sure, too, that clean earth with some nice weeds growing in it, looks better than gravel which is dirty. Gravel shows the dirt so much, that it is almost impossible to keep it looking nice where there are many fish, and it also gives the water free access to any decomposing matter.
I have never come across a case of disease caused by the use of earth, and should like to hear the details of "C. C. C.'s" experiences with regard to this matter.
Charles Walker.
Advantages of rainbow trout,72-5Air bubble in yolk sac,40Alders round rearing ponds,32at water side, importance of,19Alevins,39-41diseases of,40-1Alpine char,78American brook trout,15rearing of,75-6spawning of,76Aquatic creatures, serving as food for fish,10-2,62-6Aquatic plants suitable for deep water,13suitable for margins,13Aquatic vegetation, importance of,7development of,9Arrangement of rearing boxes,34Artificial spawning of salmon,83-4Asellus aquaticus,65
Advantages of rainbow trout,72-5
Air bubble in yolk sac,40
Alders round rearing ponds,32at water side, importance of,19
Alevins,39-41diseases of,40-1
Alpine char,78
American brook trout,15rearing of,75-6spawning of,76
Aquatic creatures, serving as food for fish,10-2,62-6
Aquatic plants suitable for deep water,13suitable for margins,13
Aquatic vegetation, importance of,7development of,9
Arrangement of rearing boxes,34
Artificial spawning of salmon,83-4
Asellus aquaticus,65
Black spotted trout of the Rocky Mountains,76-8Blue swelling,41Breeding char, difficulties in,78-80Breeding. (SeeRearing.)Brown trout, suitable water for,14Bullrushes,13Byssus,37-8
Black spotted trout of the Rocky Mountains,76-8
Blue swelling,41
Breeding char, difficulties in,78-80
Breeding. (SeeRearing.)
Brown trout, suitable water for,14
Bullrushes,13
Byssus,37-8
Caddis-worms,61-3in hatching trays,38-9Carp, suitable water for,18Char,16,78-80Alpine,78difficulties in breeding,78-80hatching out of,78-9introduction of, to the south,80kinds of,78rearing,79-80suitable water for,16Windermere,78Charring wood, importance of,33, 50Chub, suitable water for,18Coarse fish,88-92ova of,90-1Colorado River trout,77Columbia River trout,77Conchifera,12Corixæ,10,49,63Covers for rearing ponds,31Creatures, aquatic, serving as food for fish,10-2,61-6Crowfoot, water,13Cure for fungus,50Cut-throat trout,76-8Cyclops quadricornis,12,48,65-6Cypridæ,65-6
Caddis-worms,61-3in hatching trays,38-9
Carp, suitable water for,18
Char,16,78-80Alpine,78difficulties in breeding,78-80hatching out of,78-9introduction of, to the south,80kinds of,78rearing,79-80suitable water for,16Windermere,78
Charring wood, importance of,33, 50
Chub, suitable water for,18
Coarse fish,88-92ova of,90-1
Colorado River trout,77
Columbia River trout,77
Conchifera,12
Corixæ,10,49,63
Covers for rearing ponds,31
Creatures, aquatic, serving as food for fish,10-2,61-6
Crowfoot, water,13
Cure for fungus,50
Cut-throat trout,76-8
Cyclops quadricornis,12,48,65-6
Cypridæ,65-6
Dace,18,89-90suitable water for,18Daphnia pulex,12,48,65Dead alevins, removal of,41Dead ova, removal of,37Difference between beetles andCorixæ,11Diseases of alevins,40-1ova,37-9Dytiscus marginalis,11,49,58-60,63Earth in rearing boxes,46,93-6doses of, in rearing pond,54,93-6Effects of soft food on trout,24Ephemeridæ,12,64-5larvæ of,64-5catching larvæ of,64
Dace,18,89-90suitable water for,18
Daphnia pulex,12,48,65
Dead alevins, removal of,41
Dead ova, removal of,37
Difference between beetles andCorixæ,11
Diseases of alevins,40-1ova,37-9
Dytiscus marginalis,11,49,58-60,63
Earth in rearing boxes,46,93-6doses of, in rearing pond,54,93-6
Effects of soft food on trout,24
Ephemeridæ,12,64-5larvæ of,64-5catching larvæ of,64
Feeding of the fry,42-9Feeding yearlings,67Food, importance of, in waters,5,7Fresh-water shrimp,10,49,65snails,10-2Friends and enemies of the fish,58-66Fry, feeding of,42-9separating large from small,45turning out of rearing box,51-2Fungus,38-9cure for,50
Feeding of the fry,42-9
Feeding yearlings,67
Food, importance of, in waters,5,7
Fresh-water shrimp,10,49,65snails,10-2
Friends and enemies of the fish,58-66
Fry, feeding of,42-9separating large from small,45turning out of rearing box,51-2
Fungus,38-9cure for,50
Gammarus pulex,10,49,65Gold-fish, suitable water for,18Grannom, introduction of,12Grass round rearing ponds,32Grayling, possible harm done by, to trout,16suitable water for,17Great water moss,13
Gammarus pulex,10,49,65
Gold-fish, suitable water for,18
Grannom, introduction of,12
Grass round rearing ponds,32
Grayling, possible harm done by, to trout,16suitable water for,17
Great water moss,13
Hatchery, suitable spot for,21-6Hatching out char,78-9ova of coarse fish,91-2Hatching trays, arrangement of,34caddis-worms in,38-9construction of,32placing ova in,34-6removal of,42-3shrimps in,36Herons,60-1Hydrophilus piceus,59-60
Hatchery, suitable spot for,21-6
Hatching out char,78-9ova of coarse fish,91-2
Hatching trays, arrangement of,34caddis-worms in,38-9construction of,32placing ova in,34-6removal of,42-3shrimps in,36
Herons,60-1
Hydrophilus piceus,59-60
Important points in rearing young trout,56-7Inlet to rearing ponds,29-30
Important points in rearing young trout,56-7
Inlet to rearing ponds,29-30
King carp, suitable water for,18Kingfisher,49,53,60
King carp, suitable water for,18
Kingfisher,49,53,60
Lake Tahoe trout,77Lakewort,13Leaf screen to rearing ponds,29Lobelia, water,13
Lake Tahoe trout,77
Lakewort,13
Leaf screen to rearing ponds,29
Lobelia, water,13
May fly, introduction of,12Moss, great water,13Mussels,12
May fly, introduction of,12
Moss, great water,13
Mussels,12
Nautonecta glauca,10,64Natural food, importance of,24natural food for fry,48-9Netting for rearing ponds,31
Nautonecta glauca,10,64
Natural food, importance of,24natural food for fry,48-9
Netting for rearing ponds,31
Ova beds, artificial salmon,85Ova, care of,36-9dead, removal of,37hatching of,39of coarse fish,90-1of sea-trout,87placing in hatching trays,34-6
Ova beds, artificial salmon,85
Ova, care of,36-9dead, removal of,37hatching of,39of coarse fish,90-1of sea-trout,87placing in hatching trays,34-6
Perch,19,90-1suitable water for,19Pike,18-9,90-1Planting weeds in ponds,7in streams,8Ponds for yearlings,70-1
Perch,19,90-1suitable water for,19
Pike,18-9,90-1
Planting weeds in ponds,7in streams,8
Ponds for yearlings,70-1
Rainbow trout,14-5,72,75advantage of,72-5freedom from fungus,73-4rearing of,72-5suitable water for,14spawning time of,21Rearing, important points in,56-7Rearing box, arrangement of,34construction of,31cover for,38,49Rearing char, difficulties in,79-80fry of salmon,85-7fry of sea-trout,85-7rainbow trout,72-5Rearing ponds, alders round, 32; grass round,32construction of,22,27-9covers for,31gravel in,23importance of allowing water to run through for some weeks,21inlet to,29-30netting for,31pipes to,22,27removal of yearlings from,70separating fish in,54-6size of,23-4use of earth in,54,56,93-6vegetation round,33,55willows round,32,55Restocking, best time for,24Rio Grande trout,77Rudd,17,88-9,91suitable water for,17
Rainbow trout,14-5,72,75advantage of,72-5freedom from fungus,73-4rearing of,72-5suitable water for,14spawning time of,21
Rearing, important points in,56-7
Rearing box, arrangement of,34construction of,31cover for,38,49
Rearing char, difficulties in,79-80fry of salmon,85-7fry of sea-trout,85-7rainbow trout,72-5
Rearing ponds, alders round, 32; grass round,32construction of,22,27-9covers for,31gravel in,23importance of allowing water to run through for some weeks,21inlet to,29-30netting for,31pipes to,22,27removal of yearlings from,70separating fish in,54-6size of,23-4use of earth in,54,56,93-6vegetation round,33,55willows round,32,55
Restocking, best time for,24
Rio Grande trout,77
Rudd,17,88-9,91suitable water for,17
Salmo irideus,14-5,72-5fario,15mykiss,76-8Salmon and sea-trout,81-7Salmon, artificial spawning of,83-4artificial ova beds,85mortality among ova and young fish,81rearing fry,85-7scale upon which rearing should be carried out,83success in artificial intervention in stock of,81-2Salt, as cure for fungus,50dose of, for yearlings,69-70Salvelinus fontinalis, 15.(SeeAmerican brook trout.)Saprolegnia,38-9.(SeeFungus.)Sea-trout, ova of,87rearing fry of,85-7Sea-water as cure for fungus,50Separating yearlings,68Shrimp, fresh-water,10,49,65Shrimps in hatching trays,36Snails, fresh-water,10-12Soft food, effects of, on trout,24Spawning time of American brook trout,76Stocking waters with food,7Stonewort, water-,13Suitable fish and suitable water,14
Salmo irideus,14-5,72-5fario,15mykiss,76-8
Salmon and sea-trout,81-7
Salmon, artificial spawning of,83-4artificial ova beds,85mortality among ova and young fish,81rearing fry,85-7scale upon which rearing should be carried out,83success in artificial intervention in stock of,81-2
Salt, as cure for fungus,50dose of, for yearlings,69-70
Salvelinus fontinalis, 15.(SeeAmerican brook trout.)
Saprolegnia,38-9.(SeeFungus.)
Sea-trout, ova of,87rearing fry of,85-7
Sea-water as cure for fungus,50
Separating yearlings,68
Shrimp, fresh-water,10,49,65
Shrimps in hatching trays,36
Snails, fresh-water,10-12
Soft food, effects of, on trout,24
Spawning time of American brook trout,76
Stocking waters with food,7
Stonewort, water-,13
Suitable fish and suitable water,14