| FEMALE. | MALE. | ||
| Salmon-trout | with | White-fish. | |
| “ “ | “ | Brook-trout. | |
| Brook-trout | “ | Fresh-water Herring. | |
| “ “ | “ | California Salmon. | |
| “ “ | “ | “ Mountain-trout. | |
| Shad | “ | Striped Bass. | |
| “ | “ | Herring. | |
It is observable of all hybrids that they are shy and wild; more so usually than either of their parents, and that in appearance they favor their larger parent. The cross between the brook-trout and lake-trout has been repeated from year to year, till fish which are one-eighth salmon-trout and seven-eighths brook-trout have been produced which it is hoped will have the size and toughness of the mother, with the beauty and gameness of the father.
These experiments commenced with a cross of the brook-trout and California salmon, which had an interesting and instructive termination, and prepared the way by its failure for subsequent successes.
In September, 1879, the young of the brook-trout and California salmon were seen to be maturing their eggs. This was the first time in the history of fish culture that hybrids gave evidence of breeding. It is asserted that among animals, mules are occasionally known to produce young, but this is a most unusual exception to a general rule. No more was expected from the experiments in crossing varieties than the production of combinations which might be valuable in themselves, like the capons among fowls, or the mules among draught animals, but which must of necessity be purely ephemeral, and perishing with the lives of the individuals. But when these hybrid trout-salmon were opened and found to contain eggs quite large and well forward in maturity, it seemed possible that new species might be created and made permanent. The eggs were already larger than the mature eggs of the trout, although it was then early in the season, and seemed perfectly healthy. As time passed the parents were watched with care, and were soon seen to be going into the spawning-race. They apparently made all their preparations for spawning, began digging their nests, stayed about them, and proceeded in the regular way, except that they were never in pairs, but always single. This was not natural, and led to a careful examination of them individually. After examining some fifty out of the sixty, the conclusion was reached that they were all females, which eventually turned out to be the case. This was in the latter part of November, 1879. Some dozen male brook-trout were then placed among the hybrids, to see if they would induce the latter to spawn. Everything soon appeared favorable for this result, the trout paired with the trout-salmon, they entered the race-way together, and occupied themselves with parental duties, but no results were perceived. For some reason the spawn was not deposited. Then some of the fish were selected to be stripped by hand, and were found to be ripe, but the eggs were all crushed in passing from them. The vent of the ovaries or ovaduct was too small to allow the eggs, which had delicate shells, to pass. Attempts were then made to enlarge the vent, and some thousands of eggs were finally obtained in this way uninjured. To impregnate these the milt of the male trout was used. The parent fish were left in their pond and seemed to be uneasy. They were doubtless incommoded by the eggs which they could not pass, and moved about slowly with their heads towards the bottom, their tails upward, and their bodies at an angle to the surface. The eggs which it was hoped might be impregnated by hand, were retained until January 25, 1880, when it was found they were unimpregnated and dead, and they were thrown away.
Thus two extraordinary facts were ascertained, one that the eggs may be too large for extrusion in case the male parent is the larger variety of fish, and the other that the entire body of one hatching may be of a single sex as in this case when all were females, and in the case of the shad and herring in the Hudson River, which are all said to be males. It was on these two discoveries that subsequent improvements were founded. It is not yet positively determined that these cross-breeds will procreate their species in a natural way, nor even that they will be the improvement, which has been hoped, but that they can be bred artificially there is no further doubt.
An indirect result of fish-culture has been the introduction of foreign fish into home waters. The German carp has been brought to America, and has increased and multiplied vastly, and been found well adapted to certain waters, which are not valuable for finer fish. In dull, muddy, small ponds, they have not only lived, but they have grown to a remarkable size. We have also received some German trout, which hatched and grew well, and which promise finely for the future. Then we have sent our black-bass to Europe as well as our trout, the California trout and salmon. We have acclimated in California the Eastern shad, and imported from California the trout and salmon of that country. This interchange has been mutually advantageous and promises to be much more so in the future. The results of fish-culture have indeed far exceeded the most sanguine hopes of those who first took it up, and at present there seem to be no limits to its beneficial effects. The time will surely come when the streams, which have been so long utterly depopulated of their natural inhabitants will once more be restocked and yield as abundantly as ever. This has already happened with the Connecticut River, which from having been almost exhausted, has been so successfully restocked that it produced in one year more shad than had ever been caught from it since records had been kept. The Hudson River had been also rendered nearly worthless as a shad river when fish-culture was first applied to it, the nets were being taken up and the fisheries abandoned, the price of even small shad had risen so as to exclude them from all but the tables of the rich, whereas now the yield is nearly as numerous as ever, and much larger fish are taken. So while neglected Southern rivers are exhausted, the Northern ones are being replenished. The same will follow with the fresh waters. If the trout brooks have become too warm from the destruction of the forests, other varieties, such perhaps as the California trout will be substituted. There are millions of just such streams and ponds, which are now nearly valueless, but which could be made quite as valuable as the same amount of land. These will yet all be replenished till the streams and ponds will come to be regarded as the most valuable part of the farm or country place, and millions of property will be added to the wealth of the country.[18]
LARGE-MOUTHED BLACK BASS. (Grystes Salmoides)
FLIES.