1902 Encyclopedia > Oyster

Oyster




OYSTER. The use of this name in the vernacular is equivalent to that of Ostrea in zoological nomenclature; there are no genera so similar to Ostrea as to be confounded with it in ordinary language. Ostrea is a genus of Lamel-libranch Molluscs, belonging to the third order Monomya, the valves of its shell being closed by a single large adductor muscle. The degeneration produced by sedentary habits in all lameflibranchs has in the oyster reached its most advanced stage. The muscular projection of the ventral surface called the foot, whose various modifications characterize the different classes of Mollusca, is almost entirely aborted. The two valves of the shell are unequal in size, and of different shape; the left valve is larger, thicker, and more convex, and on it the animal rests in its natural state. This valve, in the young oyster, is attached to some object on the sea-bottom; in the adult it is some-times attached, sometimes free. The right valve is flat, and smaller and thinner than the left. In a corresponding manner the right side of the animal's body is somewhat less developed than the left, and to this extent there is a departure from the bilateral symmetry characteristic of lamellibranchs.

The organization of the oyster, as compared with that of a typical lamellibranch such as Anodon (see MOLLUSCA), is brought about by the reduction of the anterior part of the body accompanying the loss of the anterior adductor, and the enlargement of the posterior region. The pedal ganglia and auditory organs have disappeared with the foot, at all events have never been detected; the labial ganglia are very minute, while the parieto-splanchnic are well developed, and constitute the principal part of the nervous system.

According to Spengel the pair of ganglia near the mouth, variously called labial or cerebral, represent the cerebral pair and pleural pair of a gastropod combined, and the parieto-splanchnic pair correspond to the visceral ganglia, the commissure which connects them with the cerebro-pleural representing the visceral commissure. Each of the visceral ganglia is connected or combined with an olfactory ganglion underlying an area of special-ized epithelium, which constitutes the olfactory organ, the osphradium. This view (which, it may be pointed out, differs from that given under MOLLTJSCA) alone admits of a satisfactory comparison between the lamellibranch and the gastropod; if the parieto-splanchnic were merely an olfactory ganglion its connexion by a commissure with its fellow would be an abnormality, and the olfactory ganglion in the lamellibranch would innervate the gills, adductor muscle, mantle, and rectum, parts which in gastropods are innervated from the visceral ganglia. The heart and pericardial chamber in the oyster lie along the anterior face of the adductor muscle, almost perpendicular to the direction of the gills, with which in Anodon they are parallel. In Anodon and the majority of lamelli-branchs the ventricle surrounds the intestine; in the oyster the two are quite independent, the intestine pass-ing above the pericardium. The renal organs of the oyster were discovered by Hoek to agree in their mor-phological relations with those of other lamellibranchs.

The generative organs of the oyster consist of a system of branching cavities on each side of the body lying immediately beneath the surface. All the cavities of a side are ultimately in communication with an efferent duct opening on the surface of the body a little above the line of attachment of the gills. The genital opening on each side is situated in a depression of the surface into which the renal organ also opens. The genital products are derived from the cells which line the cavities of the genital organs. The researches of Hoek have shown that in the same oyster the genital organs at one time produce ova, at another spermatozoa, and that consequently the oyster does not fertilize itself. How many times the alternation of sex may take place in a season is not known. It must be borne in mind that in what follows the species of the European coasts, Ostrea edulis, is under consideration. The ova are fertilized in the genital duct, and before their escape have undergone the earliest stages of segmentation. After escaping from the genital aperture they find their way into the infra-branchial part of the mantle cavity of the parent, probably by passing through the supra-branchial chamber to the posterior extremity of the gills, and then being conducted by the inhalent current caused by the cilia of the gills into the infra-branchial chamber. In the latter they accumulate, being held together and fastened to the gills by a white viscid secretion. The mass of ova thus contained in the oyster is spoken of by oyster fishers as " white spat," and an oyster containing them is said to be " sick." While in this position the ova go through the series of changes figured in vol. xvi. p. 638 (fig. 6). At the end of a fortnight the white spat has become dark-coloured from the appearance of coloured patches in the developing embryos. The embryos having then reached the condition of " trochospheres " escape from the mantle cavity and swim about freely near the surface of the water among the multitude of other creatures, larval and adult, which swarm there. The larvae are extremely minute, about -jl^ inch long and of glassy transparency, except in one or two spots which are dark brown. From the trochosphere stage the free larvae pass into that of " veligers." How long they remain free is not known; Prof. Huxley kept them in a glass vessel in this condition for a week. Ultimately they sink to the bottom and fix themselves to shells, stones, or other objects, and rapidly take on the appearance of minute oysters, forming white disks ^ inch in diameter. The appearance of these minute oysters constitutes what the fishermen call a " fall of spat." The experiment by which Hoek conclusively proved the change of sex in the oyster was as follows. In an oyster containing white spat microscopic examination of the genital organs shows nothing but a few unexpelled ova. An oyster in this condition was kept in an aquarium by itself for a fortnight, and after that period its genital organs were found to contain multitudes of spermatozoa in all stages of development.

The breeding season of the European oyster lasts from May to September. The rate of growth of the young oyster is, roughly speaking, an inch of diameter in a year, but after it has attained a breadth of 3 inches its growth is much slower. Prof. Möbius is of opinion that oysters over twenty years of age are rare, and that most of the adult Schleswig oysters are seven to ten years old.

The development of the American oyster, 0. virginiana, and of the Portuguese oyster, 0. angulata, is very similar to that of 0. edulis, except that there is no period of incubation within the mantle cavity of the parent in the case of these two species. Hence it is that so-called artificial fertilization is possible ; that is to say, the fertilization may be allowed to take place in a tank or aqua-rium in which the conditions are under control. But if it is possible to procure a supply of spat from the American oyster by keeping the swarms of larvae in confinement, it ought to be possible in the case of the European oyster. All that would be
necessary would be to take a number of mature oysters containing white spat and lay them down in tanks till the larvae escape. This would be merely carrying oyster culture a step further back, and instead of collecting the newly fixed oysters, to obtain the free larva; in numbers and so insure a fall of spat independently of the uncertainty of natural conditions.

Natural beds of oyster occur on stony and shelly bottoms at depths varying from 3 to 20 fathoms. In nature the bods are liable to variations, and, although Prof. Huxley is somewhat sceptical on this point, it seems that they are easily brought into an unproduc-tive condition by over-dredging. Oysters do not flourish in water containing less than 3 per cent, salt; and hence they are absent from the Baltic. The chief enemies of oysters are the dog-whelk, Purpura I'apillus, and the whelk-tingle, Murex erinaceus,which bore through the shells. Starfishes swallow oysters whole. Cliona, the boring sponge, destroys the shells and so injures the oyster; the boring annelid Lencodore also excavates the shell.

The wandering life of the larvae makes it uncertain whether any of the progeny of a given oyster-bed will settle within its area and so keep up its numbers. It is known from the history of the Liimfjord beds that the larvae may settle 5 miles from their place of birth.
The genus Ostrea has a world-wide distribution, in tropical and temperate seas; seventy species have been distinguished. Its nearest allies are Anomia among living forms, GrypAma among fossils. For the so-called Pearl-Oyster see PEARL. (J. T. C).

Oyster Industry.

The oyster industry of the world is seated chiefly in the United States and France. Great Britain has still a few natural beds remaining, and a number of well-con-ducted establishments for oyster culture. Canada, Holland, Italy, Germany, Belgium, Spain, Portugal, Denmark, Norway, and Russia have also oyster industries, which are comparatively insignificant, and in the case of the two countries last named, hardly worthy of consideration in a statistical statement. Recent and accurate statistics are lacking except in two or three instances. A brief review by countries in the order of their importance is here pre-sented.

United States. —This is by far the most extensive of the fishery industries of the country, yielding products three times as valuable as those of the cod fishery and six times those of the whale fishery. In 1880 it employed 52,805 persons, and yielded 22,195,370 bushels, worth to the fishermen $9,034,861. On 13,047,922 bushels there is a rise of value in passing from producers to market, which amounts to $4,368,991, and results either from replanting or from packing in tin cans. The value of the capital invested in the industry is returned as $10,583,295. There are employed 4155 vessels, valued at $3,528,700, and 11,930 boats. The actual fishermen number 38,249, the shoresmen 14,556. Fully 80 per cent, of the total yield is obtained from the waters of Chesapeake Bay.

France.—The oyster industry of France employed in 1881 29,431 men, women, and children in the parks, bods, and preserves. The number of such establishments upon the public domain was 32,364, with an area of 19,891 acres, and 970 establishments upon private property, with an area of 926 acres. From these 374,985,770 oysters were dredged during the season of 1880-81, from September 1 to June 15, worth 2,061,753 francs, while the total number of oysters disposed of during this period amounted to 680,372,750, worth 17,951,114 francs. This total includes the oysters dredged in the sea as well as those gathered from the arti-ficial breeding-grounds or parks.

Great Britain.—A brief discussion of the British oyster fisheries may be found under FISHERIES, vol. ix. p. 265. A recent estimate gives the total value of the oysters obtained from British seas at ¡£2,000,000, worth 2d. each, or, perhaps, 240,000,000 in all. An extensive import trade is carried on with the United States, which has grown up within the past decade, as is shown by the following statement of import values:—1874, $41,419; 1875, $38,733 ; 1876, $99,012 ; 1877, $121,301 ; 1878, $254,815 ; 1879, $306,941 ; 1880, $366,403 ; 1881, $414,584 ; 1882, $372,111 ; 1883, $371,497.

Holland.—Since 1870 tfie beds in the province of Zealand have been greatly enriched by careful methods of culture and protection; and in 1881 the product amounted to 21,800,000 oysters, worth about 1,350,000 guilders. About half the product of the Dutch oyster fishery is sent to England, and large quantities of the young oysters are laid down to fatten in the English oyster-beds.

Germany.—Germany has a small oyster industry on the west coast of Schleswig-Holstein. According to Lindeman, the largest annual product of these beds has rarely exceeded 4,000,000 oysters. From 1859 to 1879 they were rented to a company in Flensburg for an annual payment of 80,000 marks. In 1879 the lease was trans-ferred to a Hamburg firm, who paid for that year 163,000 marks.

Italy.—Oyster culture in Italy, according to Bouchon-Brandely, is carried on in only one locality, Taranto, though small quan-tities of natives are obtained from the Gulfs of Genoa and Naples, from the coasts of the Adriatic, and from the ponds of Corsica. The sea of Taranto is leased by the city to a company that pays an annual rent of 38,000 francs. The product of this body of water is estimated variously at from 6,000,000 to 10,000,000 oysters yearly. The entire annual product of Italy does not probably ex-ceed 20,000,000 oysters, valued at about £40,000.

Belgium.—Oyster culture is carried on upon a small scale at Ostend. There being no native beds, the seed oysters are brought from England, a practice which, according to Lindeman, originated as early as 1765. The product probably does not exceed 10,000 bushels a year, and is consumed chiefly in Germany and Holland, though there is a small exportation.

Spain.—According to a recent report by Don Francisco Sola, there are forty-three establishments in Spain for the cultivation of oysters and other shell-fisheries. The amount of oysters annually produced is estimated at 167,673 kilogrammes (368,880 lb), valued at 50,296 pesetas (about £2000). These are exported to Algiers, France, Portugal, and South America.





Portugal. —There appear to be no statistics for Portugal. Considerable quantities of seed oysters are planted at present in the Bay of Arcachon and elsewhere in France, and in England the Anglo-Portuguese oyster is apparently growing in favour.

Denmark.—The very insignificant oyster fishery of Denmark has its seat chiefly in the Liimfjord and at Frederikshaven. All the oyster-beds, being Government property, are carefully protected by law. Statistics for late years are not accessible. In 1847 the product of the Frederikshaven beds was about 200,000 oysters; but the yield of late years has been much smaller. The Liimfjord beds were dis-covered about 1851. From 1876 to 1881 the Danish oyster fisheries were leased to a firm in Hamburg, which paid 240,000 kroner (£13,000) as yearly rental.

Russia.—Grimm states that a species of oyster, Ostrea adriatica, is found in considerable numbers along the coast of the Crimea, and is the object of a considerable trade. Oysters brought from Theodosia cost in St Petersburg about 3s. sterling the score.

Norway.—The average value of the yield for the five years ending 1881 was 7600 kroner (£420). The quantity produced in 1881 was 267 hectolitres (735 bushels), valued at 7000 kroner (£390). The industry is seated for the most part in the districts of southern Trondhjem and Jarlsberg, the product of the latter province being nearly half that of all Norway.

Germany 4,000,000
Belgium 2,500,000

Subjoined is a rough estimate of the total number of oysters obtained annually from the sea (North America, 5,572,000,000; Europe, 2,331,200,000):—

Spain.. Portugal.. Denmark. Russia .... Norway..
1,000,000 800,000 200,000 250,000 250,000
United States ....5,550,000,000
Canada 22,000,000
France 680,400,000
Great Britain 1,600,000,000
Holland 21,800,000
Italy 20,000,000

The oyster industry is rapidly passing from the hands of the fisherman into those of the oyster culturist. The oyster being sedentary, except for a few days in the earliest stages of its existence, is easily exterminated in any given locality; since, although it may not be possible for the fishermen to rake up from the bottom every individual, wholesale methods of capture soon result in covering up or otherwise destroying the oyster banks or reefs, as the communities of oysters are technically termed. The main difference between the oyster industry of America and that of Europe lies in the fact that in Europe the native beds have long since been practically destroyed, perhaps not more than 6 or 7 per cent, of the oysters of Europe passing from the native beds directly into the hands of the consumer. It is probable that 60 to 75 per cent, are reared from the spat in artificial parks, the remainder having been laid down for a time to increase in size and flavour in shoal waters along the coasts. In the United States, on the other hand, from 30 to 40 per cent, are carried from the native beds directly to market. The oyster fishery is everywhere, except in localities where the natural beds are nearly exhausted, carried on in the most reckless manner, and in all directions oyster grounds are becoming deteriorated, and in some cases have been entirely destroyed. It remains to be seen whether the Government of the States will regulate the oyster fishery before it is too late, or will permit the destruction of these most important reservoirs of food. At present the oyster is one of the cheapest articles of diet in the United States; and, though it can hardly be expected that the price of American oysters will always remain so low, still, taking into consideration the great wealth of the natural beds alpng the entire Atlantic coast, it seems certain that a moderate amount of protection will keep the price of seed oysters far below European rates, and that the immense stretches of submerged land especially suited for oyster planting may be utilized and made to produce an abundant harvest at much less cost than that which accompanies the complicated system of culture in vogue in France and Holland.

The most elaborate system of oyster culture is that practised at Arcachon and elsewhere in France, and, to a limited extent since 1865, on the island of Hayling, near Portsmouth, in England. The young oysters, having been collected in the breeding season upon tiles or hurdles, are laid down in artificial ponds, or in troughs, where the water is supplied to them at the discretion of their pro-prietors. The oysters are thus kept under control like garden plants from the time they are laid down to that of delivery to commercial control. The numerous modifica-tions of this system are discussed in various recent reports.

The simplest form of oyster culture is the preservation of the natural oyster-beds. Upon this, in fact, depends the whole future of the industry, since it is not probable that any system of artificial breeding can be devised which will render it possible to keep up a supply without at least occasional recourse to seed oysters produced under natural conditions. It is the opinion of almost all who have studied the subject that any natural bed may in time be destroyed by overfishing (perhaps not by removing all the oysters, but by breaking up the colonies, and delivering over the territory which they once occupied to other kinds of animals), by burying the breeding oysters, by covering lip the projections suitable for the reception of spat, and by breaking down, through the action of heavy dredges, the ridges which are especially fitted to be seats of the colonies.1 The immense oyster-beds in Pocomoke Sound, Maryland, have practically been destroyed by over-dredg-ing, and many of the other beds of the United States are seriously damaged. The same is doubtless true of all the beds of Europe. It has also been demonstrated that under proper restriction great quantities of mature oysters, and seed oysters as well, may be taken from any region of natural oyster-beds without injurious effects. Parallel cases in agriculture and forestry will occur to every one. Möbius, in his most admirable essay Die Auster und Die Austernwirilischaft, has pointed out the proper means of preserving natural beds, declaring that, if the average profit from a bed of oysters is to remain permanently the same, a sufficient number of mother oysters must be left in it, so as not to diminish the capacity of maturing. He further shows that the productive capacity of a bed can only be maintained in one of two ways :—(1) by diminish-ing the causes which destroy the young oysters, in which case the number of breeding oysters may safely be decreased; this, however, is practicable only under such favourable conditions as occur at Arcachon, where the beds may be kept under the constant control of the oyster-culturist; (2) by regulating the fishing on the natural beds in such a manner as to make them produce perma-nently the highest possible average quantity of oysters. Since the annual increase of half-grown oysters is estimated by him to be four hundred and twenty-one to every thousand full-grown oysters, he claims that not more than 42 per cent, of these latter ought to be taken from a bed during a year.

The Schleswig-Holstein oyster-beds are the property of the state, and are leased to a company whose interest it is to preserve their productiveness. The French beds are also kept under Government control. Not so the beds of Great Britain and America, which are as a general rule open to all comers,2 except when some close-time regulation is in force. Prof. Huxley has illustrated the futility of " close-time " in his remark that the prohibition of taking oysters from an oyster-bed during four months of the year is not the slightest security against its being stripped clean during the other eight months. " Suppose," he continues, " that in a country infested by wolves, you have a flock of sheep, keeping the wolves off during the lambing season will not afford much protection if you withdraw shepherd and dogs during the rest of the year." The old close-time laws were abolished in England in 1866, and returned to in 1876, but no results can be traced to the action of parliament in either case. Prof. Huxley's conclusions as regards the future of the oyster industry in Great Britain are doubtless just as applicable to other countries,'—that the only hope for the oyster consumer lies in the encouragement of oyster-culture, and in the development of some means of breeding oysters under such conditions that the spat shall be safely deposited. Oyster culture can evidently be carried on only by private enterprise, and the problem for legislation to solve is how to give such rights of property upon those shores which are favourable to oyster culture as may encourage com-petent persons to invest their money in that undertaking. Such property right should undoubtedly be extended to natural beds, or else an area of natural spawning territory should be kept under constant control and surveillance by Government, for the purpose of maintaining an adequate supply of seed oysters.

The existing legislation in the United States is thus admirably summarized by Lieutenant Francis "Winslow :3—

"The fishery is regulated by the laws of the various States, the Federal Government exercising no control, and consequently the conditions under which the pursuit is followed are many and various. At the present time the laws relating to the oyster fishery may be said to be based upon one of two general principles. The first, the basis for the regulations of most of the States, con-siders the oyster-beds to be inalienable common property. Laws based upon this principle are generally of a protective nature, and are in reality regulations of the State, made by it in its capacity of guardian of the common property. The second principle assumes the right of the State to dispose of the area at the bottom of its rivers, harbours, and estuaries, and, having disposed of it, to consider the lessee or owner as alone responsible for the success or failure of his enterprises, and the State in no way called upon to afford him other assistance than protection in iegitimate lights. In general terms, under the first principle the beds are held in common; under the second, in severalty. But one State permits the pre-emption of an unlimited tract of bottom, and the holding of it in fee—the State of Connecticut. Rhode Island leases her ground for a term of years, at $10 per acre ; but the person holding an area has no legal power of disposing of it beyond the limits of the lease. Massachusetts, New York, New Jersey, Maryland, and Virginia all permit pre-emption of small tracts by individuals for indefinite periods, and on the coast of Long Island the various towns along the shore lease tracts of considerable extent to private cultivators.

" Various restrictions are also placed upon the time and manner of conducting the fisheries. Some of the States, noticeably Virginia, prohibit entirely the use of the dredge or scrape; others, noticeably New Jersey, prohibit such use in some localities, and permit it in others. All the States, with one exception, prohibit the use of steam vessels or machinery, or fishing by other than their own inhabit-ants. Connecticut again forms the exception, and quite a large fleet of steam dredging vessels are employed on her beds.

"The laws of the various States have several common features. All general fishing is suspended during the summer months. No night fishing Is permitted. No steamers are allowed to be used. No proprietary rights to particular areas are given beyond the right to 'plant' a limited number of oysters on bottoms adjoin-ing land owned by the planter, and peace officers and local authorities are charged with execution of laws relating to the fishery. In a few States or localities licences are required to be obtained for each fishing vessel; and in one State, Maryland, a regularpolice force and fleet of vesselsare maintained to support the law. These regulations are easily evaded, except those relating to the steamers and pre-emption of ground. Naturally, no one will put down oysters without being able to protect them ; and steamers are too readily detected to make their illegal employment possible. In Connecticut and Rhode Island, the beds being virtually private property, there is no restriction of the fishery, except that it shall not be conducted at night."

The method of gathering oysters is simple, and much the same in all parts of the world, the implements in use being nippers or tongs with long handles, rakes, which are simply many-pronged nippers, and dredges. The subjoined account of the American method is abridged from that of Lieutenant Winslow:—

The character of the vessel or boat used depends in a measure upon the means of the fisherman and the constancy of his employment, and is also influenced by the character of the oyster ground, its location, and the laws governing the fish-ing. The last-named condition also decides the implement to be used; when permitted, it is the dredge—either the enormous one employed by the steamers, the smaller toothed rake-dredge, or smooth-scrape. When dredging is prohibited, the tongs, or nippers, with two handles, sometimes 30 feet long, are used. The dredges are usually worked by an apparatus termed a "winder," many forms of which are employed, the best and most recent form being so designed that if, while reeling in, the dredge should "hang," that is, become immovably fixed by some obstruction on the bottom, the drum is at once automatically thrown out of gearing, and the dredge-rope allowed to run out. Small craft use a more simple and less expensive description of winch, and frequently haul in by hand, while the steam dredgers have powerful machinery adapted for this special purpose. The number of men employed varies with the size of the craft; two, three, and four men are sufficient on board the smaller dredgers, while the larger cany ten and twelve.





While a great many oysters are transported in the shell to markets distant from the seaboard, the largest part of the inland consumption is of "opened" or "shucked" oysters, and nearly every oyster dealer along the coast employs a larger or smaller number of persons to open the oysters and pack and ship the meats. Some of these establishments are small, having as few as half a dozen people engaged; others are large buildings or sheds, and employ hundreds of " shuckers." After having been removed from their shells and thoroughly washed, the oysters thus dealt with are transferred either to small cans, holding a quart of oysters, or to barrels, kegs, or tubs; when packed in tubs, kegs, or barrels, they go in bulk, witli a large piece of ice; when packed in the tin cans, the cans are arranged in two rows inside of a long box, a vacant space being left in the centre, between the rows, in which is placed a large block of ice. The cans are carefully soldered up before packing, and together with the ice are laid in saw-dust. Oysters packed in this way can, in cool weather, be kept a week or more, and sent across the continent, or to the remote western towns.

The steaming process is that by which the " cove" oysters are prepared. The term "cove" is applied to oysters put up in cans, hermetically sealed, and intended to be preserved an indefinite time. The trade in coves is confined principally to the Chesapeake region, and the process of preparing them is as follows. The oysters, usually the smaller sizes, are taken from the vessels and placed in cars of iron frame-work, 6 or S feet long. These cars run on a light iron track, which is laid from the wharf through the "steam-chest" or "steam-box" to the shucking shed. As soon as a car is filled with oysters (in the shell) it is run into the steam-chest, a rectangular oak box, 15 to 20 feet long, lined with sheet iron and fitted with appliances for turning in steam ; the doors, which woik vertically and shut closely, are then let down, the steam admitted, and the oysters left for ten or fifteen minutes. The chest Is then opened and the cars run into the shucking shed, their places in the chest being immediately oecupied by other cars. In the shed the cars are surrounded by the shuckers, each provided with a knife and a can arranged so as to hook to the upper bar of the iron frame-work of the car. The ste.uning having caused the oyster shells to open more or less widely, there is no difficulty in getting out the meats, and the cars are very rapidly emptied. The oysters are then washed in iced water and transferred to the " fillers'" table. The cans, having been filled, are removed to another parr, of the room and packed in a cylindrical, iron crate or basket, and lowered into a large cylindrical kettle, called the "process kettle" or "tub," where they are again steamed. After this they are placed, crate and all, in the " cooling tub;" and when sufficiently cool to be handled, the cans are taken to the soldering table, and there " capped"—that is, are hermetically closed. From the "cappers" they are transported to another department, labelled, and packed in boxes for shipment. The whole steaming pro-cess will not occupy an hour from the time the oysters leave the vessel until they are ready for shipment.

The extension of the area of the natural beds is the second step in oyster culture. As is well known to zoolo-gists, and as has been very lucidly set forth by Prof. Möbius in the essay already referred to, the location of oyster banks is sharply defined by absolute physical con-ditions. Within certain definite limits of depth, tempera-ture, and salinity, the only requirement is a suitable place for attachment. Oysters cannot thrive where the ground is composed of moving sand or where mud is deposited; consequently, since the size and number of these places are very limited, only a very small percentage of the young oysters can find a resting-place, and the remainder perish. Möbius estimates that for every oyster brought to market from the Holstein banks, 1,045,000 are destroyed or die. By putting down suitable " cultch " or " stools " immense quantities of the wandering fry may be induced to settle, and are thus saved. As a rule the natural beds occupy most of the suitable space in their own vicinity. Unoccu-pied territory may, however, be prepared for the reception of new beds, by spreading sand, gravel, and shells over muddy bottoms, or, indeed, beds may be kept up in loca-tions for permanent natural beds, by putting down mature oysters and cultch just before the time of breeding, thus giving the young a chance to fix themselves before the currents and enemies have had time to accomplish much in the way of destruction.

The collection of oyster spat upon artificial stools has been practised from time immemorial. As early as the 7th century, and probably before, the Romans practised a kind of oyster culture in Lake Avernus, which still sur-vives to the present day in Lake Fusaro. Piles of rocks are made on the muddy bottoms of these salt-water lakes, and around these are arranged circles of stakes, to which are often attached bundles of twigs. Breeding oysters are piled upon the rookeries, and their young become attached to the stakes and twigs provided for their reception, where they are allowed to remain until ready for use, when they are plucked off and sent to the market. A similar though ruder device is used in the Poquonnock river in Connecti-cut. Birch trees are thrown into the water near a natural bed of oysters, and the trunks and twigs become covered with spat j the trees are then dragged out upon the shore by oxen, and the young fry are broken off and laid down in the shallows to increase in size. In 1858 the method of the Italian lakes were repeated at St Brieuc under the direction of Prof. P. Coste, and from these experiments the art of artificial breeding as practised in France has been developed. There is, however, a marked distinc-tion between oyster culture and oyster breeding, as will be shown below. The natural beds of France in the Bay of Arcachon, near Auray in Brittany, near Cancale and Gran-ville in Normandy, and elsewhere, are, however, carefully cultivated, as it is necessary that they -should be, for the support of the breeding establishments.

More or less handling or "working" of the oysters is necessary both for natural and transplanted beds. The most elaborate is that which has been styled the " English system," which is carried on chiefly near the mouth of the Thames, by the Whitstable and Colchester corporations of fishermen and others. This consists in laying down beds in water a fathom or more in depth at low water and constantly dredging over the grounds, even during the close time, except during the period when the spat is actually settling. By this means the oysters are frequently taken out of the water and put back again, and it is claimed that in this way their enemies are baffled and the ground put in better condition to receive the spat. As a matter of fact, however, the oysters have not for many years multiplied under this treatment, and the system is practically one of oyster-parking rather than one of oyster-culture, One of tho advantages of the frequent handling is that the fishermen, in putting the oysters back, can assort them by sizes, and arrange them conveniently for the final gathering for market purposes.

American oyster culture, as practised in the ',' East River" (the western end of Long Island Sound), in eastern Connecticut, and to some extent in Long Island and New Jersey, is eminently success-ful aud profitable, and there seems to bo no reason to doubt its permanence, conducted as it is in close proximity to the natural beds, and with due regard for preservation. In the Long Island Sound alone, in 1879, the labours of 1714 men produced 997,000 bushels, or perhaps 250,000,000 of native oysters, valued at $847,925, while all France produced in the following season 375,000, worth about $412,000. There was also a side product of 450,000 bushels (122,000,000) of transplanted oysters, worth $350,000, handled by the same men in the American beds, while France employed an additional force of 28,000 people to produce 305,000,000 artificially bred oysters, worth $3,179,000. The Long Island Sound system consists simply in distributing over the grounds, just before the spawning season, quantities of old oyster shells to which the young oysters become attached, and left undisturbed for from three to five years, when, having reached maturity, they are dredged for use. Spawning oysters are frequently put down in the spring, two months before the ground is shelled ; this is done even when the natural beds are near, but is not so essential as when a rather remote piece of bottom is to be colonized.

An excellent summary of the methods of planting in different parts of the United States may be found inWinslow's paper already quoted.
The laying down or temporary deposit of dredged oysters in estuaries on floats or in tanks, to fatten, increase in size, or improve in flavour, is a concomitant of oyster culture, and may be used in connexion with any of the systems above referred to. It is in no sense oyster culture, since it has no relation to the maintenance of the supply. A system of this kind has been practised since the 16th century at Marennes and La Tremblade on the west coast of France, where oysters from natural beds are placed in shallow basins communicating with the sea during the spring tides, and where they obtain food which gives them a green colour and a peculiar flavour much esteemed by Parisian epicures. Similar methods of parking are practised at Cancale and Granville.

In England, brood oysters are laid down in fattening beds on the coast of Essex and in the Thames estuary, where they acquire deli-cacy of flavour, and to some extent, especially in the Thames, the green colour already referred to. Belgium has also, near Ostend, fattening beds supplied with foreign spat, chiefly from England.

In the United States an extensive business is carried on in laying down seed oysters from the Chesapeake Bay in the estuaries of southern New England and the Middle States.

Oyster-culturists practise in many places what is called " plump-ing," or puffing up oysters for market by exposing them for a short time to the effects of water fresher than that in which they grew. By this process the animal does not acquire any additional matter except the water, which is taken up in great amount, but it loses a part of its saltness, and, in flavour, becomes more like an oyster from brackish waters.

There are large oyster reservoirs at Husum in Schleswig-Holstein, and at Ostend, which serve the double purpose of fattening the oysters and of keeping a uniform supply for tho markets at times unsuited to the prosecution of the fishery.

The artificial impregnation of oyster eggs has been successfully accomplished by many experimenters, and in 1883 Mr John A. Eyder of the United States Fish Commission succeeded in confining the swimming embryos in collectors until they had formed their shells and become fixed. The utility of this experiment seems to consist in the greater facility which it gives to oyster-culturists in securing a sure supply of spat, independent of the vicissitudes which currents and changes of weather entail upon those who rely upon its deposit under natural conditions. The spat thus secured can be reared either by the American, English, or French systems. 11 is not probable that the common European species, Ostrea edulis, can be so readily handled by this method as the Portuguese species, Ostrea angulata, or the American, Ostrea virginica, though this can only be determined by trial. For the details of Mr Ryder's experiment, see the Bulletin of the United States Fish Commis- sion, vol. ii. pp. 281 -y 4. (G. B. G.)


Footnotes

107
The statistical summary prepared for the Fisheries Division of the Tenth Census by Mr Ernest Ingersoll shows the details, by States, of the oyster industry of the whole country.
Bouchon-Brandely stated in 1877 that the industry of oyster culture in France supported a maritime population of 200,000. It is difficult to reconcile this statement with the official statistics.
That of Mr James Ct. Bertram in Brit. Quart. Rev. for January 1883.
Derived from the records of the United States Treasury.

108

Hubrecht, " Oyster Culture and Oyster Fisheries of the Netherlands " (conference paper, International Fisheries Exhibition) ; Hoek, " Ueber Austernzucht in den Niederlanden " (circular 2, Deutsche Fischerei-Verein, 1879 ; translated in Report of the United States Fish Commis-sion, part viii. pp. 1029-35).
Möbius, Die Auster und die Austernwirthsclwft (1877, pp. 126 ; translated in Report of the United States Fish Commission, part viii. pp. 683-751).
Rapport au Ministre de l'Instruction sur la pisciculture en Prance et VOstréiculture dans la Méditerranée (Paris, 1878) ; the portion relating to oyster culture in the Mediterranean is translated in the Report of the United States Fish Commission, part viii. pp. 907-28.
See Renaud, Notice sur ÏHuttre Portugaise et Française cultivée dans la Baie d'A reaction ; translated in the Report of the United States Fish Commission, part viii. pp. 931-41.

6 See especially the following English parliamentary papers :—Report of the Commissioners appointed to inquire into the Present State of the Oyster Fisheries of France, England, and Ireland, 1870 ; Report of the Select Committee appointed to inquire what are the Reasons for the Present Scarcity of Oysters, &c, 1876 ; Report on the Principal Oyster Fisheries of France, with a short description of the System of Oyster Culture pursued at some of the most important places, &c., 1878.


109
3 Catalogue of the Economic Mollusca exhibited by the United States National Museum at the International Fisheries Exhibition, London, 1883.

110
See Report of the United States Fish Commission, part viii. pp.
2 The Oyster Industry, by Ernest Ingersoll (Washington, 1881)
739-41, 753-59, 885-903, 931-41.
Möbius, Pie Auster und Die AustemuArthsehaft; and Ee Bon, Ostrilculture en 1875.

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1 Even Prof. Huxley, the most ardent of all opponents of fishery legislation, while denying that oyster-beds have been permanently annihilated by dredging, practically admits that a bed may be reduced to such a condition that the oyster will only be able to recover its former state by a long struggle with its enemies and competition,—in fact that it must re-establish itself much in the same way as they have acquired possession of new grounds in Jutland, a process which, according to his own statement, occupied thirty years (Lecture at the Royal Institution, May 11, 1883, printed with additions in the English Illustrated Magazine, i. pp. 47-55, 112-21).
2 Connecticut has within a few years greatly benefited its oyster industry by giving to oyster-culturists a fee simple title to the lands ander control by them.



The above article was written by two authors:

-- Introduction, Biology, etc.
J. T. Cunningham, B.A., Fellow of University College, Oxford

-- Oyster Industry
G. Browne Goode, U.S. National Museum, Washington.



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