OYSTERS AND OYSTER FISHERIES OF QUEENSLAND. 257 



its Australian variety, 0. Angasi, as it occurs in the more southern colonies. In the former 

 instance it may be dredged in the open sea at a depth of as much as twenty fathoms, being then 

 represented by the large rough form commercially known as Channel oysters, or it may be gathered, 

 somewhat rarely in England, but more abundantly in the warmer waters of the Channel Islands or 

 on the neighbouring coast of France, adhering to the rocks, after the manner of Ostrca glomerafa. 

 It is this same species, moreover, in its coarser, natural, form, ordinarily taken with the dredge, 

 that is cultivated on so extensive a scale on the tidally-exposed foreshores of France, and that is 

 transformed, through a long and tedious course of manipulation, into the costly world-renowned 

 Colchester or Whitstable " Native." The fact that the drift or deep-water form of Ostrca glomemta, 

 as it occurs in Australian waters, is most commonly 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, littoral margin, by an interven- 

 ing 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 commercial variety, Ostrea glomerata, 

 probably exist in deep water on the open coast-line of Queensland and New South Wales. 

 The evidence 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 pro- 

 specting cruise of the steamer, Lady Loch. The successful results there obtained were the 

 outcome of a report to the Victorian Government made by the author on the Victorian oyster 

 fisheries, in which, in consequence of the traces of the existence of oysters observed by him 

 along the Ninety-mile Beach and other portions of the coast, he foretold their probable presence 

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

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

 however, was the so-called mud oyster, Ostrca editlis, var. Angasi, of which the largest natural 

 beds are found in the open sea. The Queensland and New South Wales commercial form, Ostrea 

 glomerata, is an essentially estuarine or brackish water type ; and, so far as the author's investi- 

 gations and enquiries have extended, it is never met with in water that is permanently salt. 

 There is consequently little or no chance of success attending any attempt that might be instituted 

 to dredge for this oyster on the open seaboard. With relation to the salinity of the water 

 most favourable for the growth of the Queensland commercial oyster, the author has demonstrated, 

 as the outcome of a prolonged series of investigations, that a mixture of one portion of fresh 

 water to four of standard salt water, is the most favourable mixture under which it will 

 flourish. It frequently happens that the oysters in many localities are, during times of drought, 



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