renowned Colchester or Whitstable " Native." The fact that the drift or deep-water form of Ostrea glom- 

 erate, as it occurs in Australian waters, is most commouly found separated by a considerable interval of space 

 from its congener of the rocks or banks, is probably explained by the circumstance that the strong current 

 or scour which is essential for its healthy existence is wanting in the intermediate barren areas. A deep 

 well-scoured central channel in which the mollusc flourishes is commonly separated from the equally clean 

 tidally-exposed, and current-swept litoral margin by an intervening area of stiller water, within which 

 mud and sedimentary matters accumulate to an extent rendering it unsuited for oyster growth. 



In connection with the subject of " dredge" oysters, it is worthy of mention that the theory has 

 been advanced that profitable beds of the ordinary conimercial variety, Ostrea glomerata, probably exist 

 in deep water on the open coast-line of Queensland and New South Wales. The evidence adduced in 

 support of this theory is founded on the circumstance that oysters have been recently dredged under such 

 conditions off the Victorian coast-line in connection with the prospecting cruise of the Victorian Govern- 

 ment steamer " Lady Loch." The successful results there obtained were the outcome of a report I made 

 on the Victorian Oyster Fisheries, and in which, in consequence of the traces of the existence of 

 oysters observed by me along the Ninety-mile Beach and other portions of the coast, I foretold their 

 presence in extensive beds, and recommended to the Government that experimental dredging operations 

 should be undertaken with the view of their discovery. The species of oyster in this instance, however, 

 was the so-called mud oyster, Ostrea edulis, var. Anqasi, of which the largest natural beds are found in 

 the open sea. The Queensland and New South Wales commercial form, Ostrea glomerata, is an essen- 

 tially estuarine or brackish water type, and which, so far as my investigations and inquiries have extended, 

 is never met with in water that is permanently salt. There is consequently, I consider, little or no chance 

 of success attending any attempt that might be instituted to dredge for this oyster on the open sea-board. 

 With relation to the salinity of the water most favourable for the growth of the Queensland commercial oyster, 

 I have found, in association with a prolonged series of investigations, that a mixture of one portion of fresh 

 water to four of standard salt water represents the most normal conditions under which it flourishes. In 

 times of drought it frequently hajjpens that the oysters in many localities are immersed for considerable 

 periods in water that is entirely salt, and conversely during floods in purely fresh water. Should this latter 

 condition, however, obtain for over a week, disastrous results usually ensue, more especially with relation 

 to the immature stock. 



Experiments were also undertaken by me with the view of ascertaining the action of water of 

 varying density upon the newly born oyster embryos or spat. Of ova and milt commingled with one 

 another in purely salt water it was found that but a very small portion of the ova were fructified, and the 

 subsequent development of these few proceeded very slowly. Another series placed in water consisting 

 of an equal proportion of salt and fresh exhibited the most active vitality, all the ova being fertilised and 

 speeding quickly on their developmental career. In a third series experimented with, the proportions of 

 water used were one part of salt water to three of fresh. In this instance the ova were entirely deprived 

 of life, and soon commenced to disintegrate. This last experiment assists much towards demonstrating 

 the deleterious action exerted by floods on the embryonic brood, and where the proportion of fresh water, 

 as in the example tested, is greatly in excess of the salt. It is at the same time worthy of remark that 

 the access of flood water appears to give a pronounced stimulus to the oyster's reproductive faculties, an 

 abundant fall of spat commonly following after the advent of a flood, and thus compensating for its 

 ill-effects upon the previously developed brood. 



AETIFICIAL CULTIVATION. 



The artificial culture of oysters, as understood and practised in connection with the Queensland 

 Oyster Fisheries, and as applied to the single species, Ostrea glomerata, consists essentially of collecting the 

 immature brood, locally known as "cultivation," and separating and spreading it out on banks and 

 beds where the conditions are more favourable for its development to marketable dimensions. One 

 of the most important sources from which this ware or " cultivation" is derived, is represented by the 

 tidally-exposed reefs described on a preceding page, and from whence, with the least expenditure of 

 labour, vast quantities can be speedily collected. Not only have the oyster reefs and banks throughout 

 Moreton and Wide Bays been laid heavily under contribution for the supply of this "cultivation," but 

 supplies for the same purpose are now being imported from as far north as Eodd Harbour and Keppel Bay. 



Such is the enormous fecundity of the Queensland commercial oyster, and the extent of the areas 

 available for the adherence and development of the spat, that little or no occasion has hitherto arisen for 

 resort to the more elaborate methods of oyster cultivation practised in European waters, and which com- 

 prises as its most fundamental principle the provision of special apparatus for the catchment of the 

 embryo brood. SuiEcient, however, as the supply may be to meet the existing demand, it may be 

 predicted that, with the increased home consumption and greatly extended export trade that may be 

 reasonably anticipated within the nest decade, some more scientific method than that hitherto in force 

 will bo in request for saving some portion of the vast amount of oyster spat annually produced, which, 

 under present conditions, is literally lost at sea. By the lowest estimate arrived at by trustworthy 

 investigators it would appear that each mature female oyster produces at least from 2,000,000 to 

 3,000,000 embryos at the annual breeding season. Of the vast number thus produced it has been further 

 estimated by Mobius concerning the European species, Ostrea edulis, that less than one individual oyster 

 in each of these million embryos runs the gauntlet of the innumerable perils that beset its career, and 

 arrives at maturity. The greatest amount of mortality that decimates this embryo host is undoubtedly 

 associated with its failure, after the maturation of its shell, to fall upon ground or materials to which it 

 is able to secure an effective anchorage. Unless the surface on which it falls is clean and entirely free 

 from slime or sediment, adhesion is not accomplished, and the embryo drifts away or sinks 

 into the mud or sand to perish. The aim and end of the systematic methods of oyster 

 culture in operation in European, and most notably French, waters is to encompass the salvage 

 of the vast shoals of embryonic waifs that would naturally run to waste. The accomplishment 

 of this highly desirable result is effected mainly through the provision of apparatus styled 

 "collectors" that form attractive media for the adhesion of the spat. These collectors are 

 constructed of varying form and material. From the earlie.st days of oyster culture the old shells or 

 " cultch " of the oysters originally raised for the market have been systematically saved and placed 

 upon the beds with gratifying results ; such materials constituting, in fact, one of the most natural media 

 for the attachment of the embryo brood. Faggots of wood, best known by their French title of 



"fascines," 



