PISCICULTURAL APPARATUS.
In order that gentlemen who have a bit of running water on their property may try the experiment of artificial hatching, I give a drawing of an apparatus invented by M. Coste suitable for hatching out a few thousand eggs—it could be set up in a garden or be placed in any convenient outhouse. I may state that I am able to hatch salmon eggs in the saucer of a flower-pot; it is placed on a shelf over a fixed wash-hand basin, and a small flow of water regulated by a stopcock falls into it. The vessel is filled with small stones and bits of broken china, and answers admirably. Out of a batch of about two hundred eggs brought from Stormontfield, only fifteen were found to have turned opaque in the first five weeks. Eggs hatched in this homely way are very serviceable, as one can examine them day by day and note how they progress, and in due time observe the development of the fish for a few days. The young animals can only be kept in the saucer about ten or twelve days, and should then be placed in a larger vessel or be thrown into a river.
As regards England, I should like to see one of the great rivers of that country turned into a gigantic salmon “manufactory.” Ponds might be readily constructed on one or two places of the Severn, or on some of the other suitable salmon streams of England or Wales, capable of turning out a million fish per annum, and at a comparatively trifling cost. The formation of the ponds would be the chief expense; a couple of men could watch and feed the fry with the greatest ease. The size adopted might be three times that of the ponds on the river Tay, and the original cost of these was less than £500. I would humbly submit that the ponds should be constructed after the manner of the plan I have elsewhere given. Except by the protecting of the spawn and the young fish from their numerous enemies, there is no way of meeting the present great demand for salmon, which, when in season, is in the aggregate of greater value than the best butchers’ meat. The salmon is an excellent fish to work with in a piscicultural sense, because it is large enough to bear a good deal of handling, and it is very accessible to the operations of mankind, because of the instinct which leads it to spawn in the fresh water instead of the sea. It is only such a fish as this monarch of the brook that would individually pay for artificial breeding, for, having a high money value as an animal, it is clear that salmon-culture would in time become as good a way of making money as cattle-feeding or sheep-rearing.
There are waste places in England—the Essex marshes, for instance, or the fens of Norfolk—where it would be profitable to cultivate eels or other fish after the manner of the inhabitants of Comacchio. I observed lately some details of a plan to rescue a quantity of land in Essex from the water; it would perhaps pay as well to convert the broad acres in question, from their being near the great London market, into a fish-farm. The English people are fond of eels, and would be able to consume any quantity that might be offered for sale, and the place being in such close proximity to the Thames, other fish might be cultivated as well. All the best portions of the hydraulic apparatus of Comacchio might be imitated, and to suit the locality, such other portions as might be required could be invented. The art of pisciculture is but in its infancy, and we may all live in the hope of seeing great water farms—but, to be profitable, they must be gigantic—for the cultivation of fish, in the same sense as we have extensive grazing or feeding farms for the breeding and rearing of cattle.
In Ireland, Mr. Thomas Ashworth, of the Galway fisheries, finds it as profitable and as easy to breed salmon as it is to rear sheep. His fisheries are a decided success; and, if we except the cost of some extensive engineering operations in forming fish-passes to admit of a communication with the sea, the cost of his experiments has been trifling and the returns exceptionally large. Mr. Ashworth put into his fisheries no less than a million and a half of salmon eggs in the course of two seasons—viz., 659,000 eggs in 1861, and 770,000 in 1862.[3] I am anxious to obtain a consecutive and detailed account of the operations carried out by the Messrs. Ashworth, but have not been able to get correct particulars. Mr. Ashworth has lately visited the oyster-farms of the Isle of Re, and has a high opinion of the efforts made for the multiplication of that favourite mollusc. He has very obligingly communicated to me a number of interesting statistics as to French oyster-culture, which I have incorporated into my account of the shell-fish fisheries.
Two recent achievements in the art of fish-culture, or at any rate in the art of acclimatisation, deserve to be chronicled in this division of the “Harvest of the Sea.” I allude to the successful introduction into Australia of the British salmon, and the equally successful bringing to this country of a foreign fish—the Silurus glanis.
Grave doubts at one time prevailed among persons interested in acclimatisation and pisciculture as to whether or not it were possible to introduce the British salmon into the waters of Australia; and an interesting controversy was about three years ago carried on in various journals as to the best way of taking out the fish to that country. Those very wise people who never do anything, but are largely endowed with the gift of prophecy, at once proclaimed that it could not be done; that it was impossible to take the salmon out to Australia, etc. etc. But happily for the cause of progress in natural science, and the success of this particular experiment, there were men who had resolved to carry it out and who would not be put down. Mr. Francis Francis, Mr. Frank Buckland, and Mr. J. A. Youl, took a leading part in the achievement; but before they fell upon their successful plan of taking out the ova in ice, hot discussions had ensued as to how the salmon could be introduced into the rivers of the Australian Continent. Many plans were suggested: some for carrying out the young fish in tanks, and others for taking out the fructified ova, so that the process of hatching might be carried on during the voyage. One ingenious person promulgated a plan of taking the parr in a fresh-water tank a month or two before it changed into a smolt, saying that after the change it would be easy to keep the smolts supplied with fresh salt water direct from the sea as the ship proceeded on her voyage.
The mode ultimately adopted was to pack up the ova in a bed of ice, experiments having first been made with a view to test the plan. For that purpose a large number of ova were deposited in an ice-house in order to ascertain how long the ripening of the egg could be deferred—a condition of the experiment of course being that the egg should remain quite healthy. The Wenham Lake Ice Company were so obliging as to allow boxes containing salmon and trout ova, packed in moss, to be placed in their ice vaults, and to afford every facility for the occasional examination of the eggs. Satisfactory results being obtained—in other words, it having been proved that the eggs of the salmon could with perfect safety be kept in ice for a period exceeding the average time of a voyage to Australia—it was therefore resolved that a quantity of eggs, properly packed in ice, should be sent out. The result of this experiment is now well known, most of the daily papers having chronicled the successful exportation of the ova, and announced that the fish had come to life and were thriving in their foreign home.
I do not wish to weary my readers, but must crave their indulgence while I give a few of the more interesting details connected with this important experiment.
The number of ova sent out to Australia was 100,000 salmon and 3000 trout. The vessel selected for the conveyance of the eggs was the Norfolk, which on one or two occasions had made very rapid voyages. The ova were procured from the Tweed, the Severn, the Ribble, and the Dovey rivers; thus England, Scotland, and Wales contributed to this precious freight. One hundred and sixty-four boxes, containing about 90,000 ova, were placed at the bottom of the ice-house, with a solid mass of ice nine feet thick on the top, so that every particle of this mass must melt before the ova would suffer. Sixteen boxes, containing above 13,000 ova, were placed in other parts of the ice-house, with ice below and above, as well as all round the boxes. The ova were taken between the 13th and 15th January, placed on board the ship on the 18th, and the Norfolk left the docks on the morning of the 21st, and Plymouth on the 28th January. Thirty tons of Wenham Lake ice were used in the experiment.