Mr. Frank Buckland has been fortunate enough to actually see this taking place. The oyster appears to await its opportunity, it stealthily opens its shell, and a lot of spat looking like a dense cloud is ejected. After a minute or two another cloud appears, and this is continually repeated till the performance is concluded. Myriads of young oysters thus liberated from parental control now enter upon the free swimming or locomotive stage of their existence. That is to say they remain near the surface of the sea, although incessantly moving in every direction.
After a variable time, however, they suddenly descend and attach themselves to any suitable substance, on which they at once become distinctly visible in the form of white dots. In their restless stage they are scarcely discernible by the naked eye, but they settle down so rapidly and in such numbers that they appear to fall down through the water. This is known to oyster fishermen as a "fall of spat," and we shall see that this fall of spat is an important occurrence, but that it varies greatly in different seasons.
THE FAILURE IN THE NEW SOUTH WALES AND VICTORIAN OYSTER SUPPLIES.
In both New South Wales and Victoria the condition of affairs in connection with the oyster fisheries and the oyster yield is extremely discouraging. So much so, that unless something is done—and done quickly—we may have to rely mainly on outside resources for our supply. Even at the present time this is the case to a greater extent than most people have any idea of. In support of this statement, as far as New South Wales is concerned, it is only necessary to turn to the last Fisheries Report for the year ending 1890. There it is pointed out that in that year, notwithstanding the enormous length of our oyster-bearing foreshores, we are brought face to face with the fact that we are indebted to other colonies—New Zealand and Queensland— for TWO-THIRDS of our supply. Again, Mr. Lindsay Thompson, the chief inspector of New South Wales fisheries, in his recent official work, THE FISHERIES OF NEW SOUTH WALES, makes the following statements:—In the year 1871 no less than 93,000 bushels of oysters were obtained from the New South Wales beds, which, indeed, helped to supply the Victorian as well as our own needs; in the year 1883 there was a fall to 46,377 bushels; while in 1891 our fisheries yielded only 14,181 bushels. This is a very significant shrinkage, and shows a remarkable falling off in the winnings. It is still maintained by some, however, that there has been a succession of bad spatting years, and that the supply may yet reach to something of its old proportions.
It will be instructive, then, in this connection to refer briefly to the efforts which legislation has made to remedy matters in New South Wales. Under the old Oyster Beds Act of 1868 the areas given to lessees were somewhat large, and consequently what with the prolific natural supply, and a relatively small population, they appeared to be doing too well. It was urged, therefore, that the holdings should be more restricted in size, and that in this way a large number of small occupiers would be afforded a means of living, while at the same time these smaller areas would receive more attention. By the Fisheries Act of 1881 a new era dawned upon the oyster fisheries of this colony, and a system of licensing small holdings was initiated. Under this Act licensed dredging was permitted, but with such disastrous results that within two years a Fisheries Act Amendment Act had to be passed. What happened, in short, was that the beds were actually skinned, so that the total disappearance of the oyster was looming in the distance. But even the passing of this latter Act was powerless to check the evil, and by the Oyster Fisheries Act of 1884 (the present Act) there was a reversal to the old system of long leases and larger holdings. Even at the present time matters are far from perfect, and in the opinion of the Commissioners of Fisheries some radical change is necessary if oyster production is to have a place at all. Now, it is true that the present Act has checked the wholesale extermination of oysters on the part of licensed dredgers. But, unfortunately, in its passage through Parliament, some unhappy amendments totally altered the intention of the Bill. For instance, one clause makes it penal to remove oysters from a reserve or leased area without authority; but omits the protection of oysters on adjoining foreshores which may not be under lease at all; and it has accordingly happened that unprincipled persons have proceeded to rob the adjacent unleased beds of every single oyster they contained.
But while faulty and inoperative legislation may be responsible in part for the failure in our oysteries, it is certain that other causes must be at work to bring about such a disastrous result. And in the different annual reports on the fisheries of the colony this is attributed to various reasons. Thus at some places, between the Richmond and Port Macquarie, it has been set down to the presence of quantities of decomposing sea-weed on the oyster beds; in the Manning to deposits of mud and sand; and elsewhere again to the ravages of a small worm. Besides these causes, too, it has been ascribed to the long continued absence of floods, with a consequent increased salinity of the water—the latter being considered inimical to oyster life. In the opinion of scientific writers, water containing 3 per cent. of salt is most suitable for oyster development, water above that salinity being too strong, and that below it too weak. It has also been well pointed out by Mr. henry Woodward, in his admirable pamphlet on Oyster Culture in New South Wales, that most of our deep water beds are situated in the rivers, a little way from the sea. Under favourable circumstances there is just that commingling of the fresh water from the river and the salt water from the sea which produces the oyster to perfection. In times of drought, however, the salt water drives out the oysters from the deeper beds by reason of its greater density. On the other hand, the fresh water, being the lighter, floats at the top and enables the oysters to live in the shallower parts, by maintaining the required 3 per cent. of salinity. It is evident from this, that the lessees have acted in direct opposition to this natural law, for they have stripped the oysters from the shallow water, where they would have done well, and laid them down on the deep beds, where the increased percentage of salt water has proved too much for them.
Dr. James C. Cox, of Sydney, the President of the Fisheries Commission, and our best known authority on conchology, has contributed a very valuable paper upon "The Australian Oyster, its Cultivation and Destruction," to the recent official work, THE FISHERIES OF NEW SOUTH WALES, already referred to. A brief summary of his views will, therefore, be full of interest. First of all, then, he separates oysters into three classes, namely, drift oysters, mud oysters, and rock oysters. Now, this classification must be clearly borne in mind, as it will the better enable the reader to understand what follows. He attributes the want of success in our oysteries to several causes, which have not been sufficiently heeded. One of these is that the oyster culturists have expected that the seed oysters which they obtained from between high and low water mark (rock oysters) would produce drift oysters if placed on beds on which drift oysters once throve in abundance. Dr. Cox maintains, however, that these two kinds of oysters, the rock oysters and the drift oysters, are quite different, and, as it will be seen, believes that they require different food. It can be well understood from this, then, that rock oysters will fail to grow on drift-oyster beds.
As to the mud oyster, he thinks very highly of it, and regrets that it has been so ignored by our oyster culturists. He is quite sure that if our mud oyster were cultivated and educated as it is now in Europe, it would be brought to the same perfection as the European and American oyster. It has been said of our mud oyster that it will not keep, and will not carry; but the same was said of its European representative until its cultivators came to discover that by a gradual process of raising it could be educated to keep quite long enough for all commercial purposes.
To come to the real point on which Dr. Cox considers that all oyster culture has failed in Australian waters. It is an established fact that the drift oyster and also the mud oyster require a diatomatic food for their existence. These two varieties of oysters no doubt consume other forms of food, but living diatoms constitute by far the greatest part. On the contrary, the rock oyster does not appear to need the diatomatic nutriment to sny extent, and is fed chiefly by larval forms of marine life. Thus, knowing that the drift and mud oysters require different food from the rock oyster, it is easy to see why our oyster culturists have failed in establishing new beds of oysters in various places. For the whole purport of Dr. Cox's paper may be summarised into expressing his belief that sufficient attention has not been devoted to the replenishment of our natural beds, WITH THEIR OWN KIND.
In former days, when our drift and mud oysters were in their prime, there were many pools of naturally preserved fresh water—in fact, often very extensive lakes—on the banks of many of the estuaries and inlets running up into our rivers and creeks. Now, these reservoirs appear to have been constantly supplied by subaqueous springs of fresh water, and in consequence the supply of diatomatic food was abundant. It was abundant, because, as it is well known, diatomatic life depends for its existence, to a great extent, on the presence of fresh water. These collections of fresh water no longer exist, so that the diatomatic food supply is not forthcoming to maintain the drift and the mud oyster. But there are other additional causes for the disappearance of these latter. The surrounding ground has been cleared for agricultural purposes, and the earth, broken up by ploughing, has been washed into these estuaries, and has suffocated, as it were, the oysters in their natural position. Again, the water which flows over the oysters is continually being disturbed by the different steamers passing up and down. The stirred-up mud they create gets into the gills, and destroys the oysters.