44 



NATURE 



[November 12, 1891 



to constitute the most productive and economic collectors. In 

 Tasmania, as in all the other Australasian colonies, tiles being 

 much too expensive for such a purpose, a cheap and efficient 

 substitute for them was effectually improvised out of the thin 

 roughly-cleft boards known as "split palings," which can be 

 produced in timber-producing districts at a cost of from Sj. to 

 los. per 1000. These paling collectors are coated on their 

 under surface with cement, a brick or stone is fastened under- 

 neath at each end to give them stability, and a wire loop secured 

 through the centre of their upper surface forms a convenient 

 handle by which they can be manipulated on shore or raised 

 with a boat-hook from beneath the water. 



The results have been most satisfactory. Last year oysters 

 had become so plentiful at Spring Bay that the Hobart market 

 was glutted, and the sale price was reduced 50 per cent. Thus 

 an important industry has been revived, and there can be little 

 doubt that by the due maintenance of the breeding-reserves the 

 oyster-fisheries of Tasmania will be restored to more than their 

 former prosperity. In accordance with Mr. Saville-Kent's re- 

 commendations, all holders of private oyster-beds in Tasmania 

 are bound by the terms of their leases to retain a certain amount 

 of breeding-stock— not less than 10,000 mature oysters to the 

 acre— permanently on their oyster-beds. This regulation con- 

 tributes materially towards the distribution of spat throughout 

 the surrounding water, and to there-establishment of the oyster- 

 fisheries upon a durable basis. 



Referring next to Victoria, Mr. Saville-Kent says that the 

 specific form of oyster indigenous to the Victorian coastline is a 

 so-called mud oyster, identical with that produced in Tasmanian 

 waters, and to all outward appearance indistinguishable from 

 the British native, Ostrea cdiiHs. In former years vast quanti- 

 ties of this oyster were obtained from Western Tort Bay, Port 

 Albert, and Corner Inlet, Over-dredging, however, has re- 

 duced these prolific natural beds to the very verge of extinction, 

 so that Victoria has for many years been dependent upon New 

 South Wales, Queensland, South Australia, and New Zealand, 

 for her oyster supplies. Some time ago Mr. Saville-Kent was 

 invited by the Government of Victoria to make a tour of and 

 report upon the fisheries of the colony, giving special attention 

 to the practicability of reviving the oyster-fisheries. As a result 

 of that tour of inspection, he strongly recommended the adoption, 

 at Western Port and Port Albert more particularly, of the 

 methods which had proved so effective in Tasmania. One such 

 reserve with a very small stock of oysters was formed at Port 

 Albert. Unfortunately, however, the Government omitted to 

 make provision for periodical skilled supervision, and the reserve 

 dwindled away. As Mr. Saville-Kent says, unless such reserves 

 can be maintained in efficient working order, and the operations 

 periodically required thereon be supervised by a practical ostre- 

 culturist, the money expended on their establishment is simply 

 wasted. 



At various parts of the Victorian coast-line, Mr. Saville-Kent 

 ob'ierved considerable numbers of oyster-shells, evidently derived 

 from deep water, that had recently been cast upon the shore by 

 storms. He consequently predicted that more or less extensive 

 beds would be found off the coast ; and off-shore beds have in 

 fact been since discovered. Mr. Saville-Kent points out that a 

 most favourable opportunity is thus afforded for the restocking 

 of the in-shore fisheries. 



In New South Wales a separate species of'oyster has to be 

 taken into consideration. The commercial species of this colony 

 is the rock oyster, Ostrea glomerata. At the same time a mud 

 oyster, identical with or most closely allied to the Victorian and 

 Tasmanian type, Ostrea ednlis, occurs in some numbers upon 

 the coast, but in consequence of the hitherto profuse abundance 

 of the rock variety it has not been considered worthy of com- 

 mercial attention. In form and general aspect the New South 

 Wales rock oyster somewhat resembles the Portuguese oyster, 

 Ostrea angulata, and also the American Ostrea virgineana. 

 With these two species it further corresponds in its breeding 

 habits, which are essentially distinct from those of the English, 

 Victorian, and Tasmanian mud oyster, Ostrea edu'tis. In the 

 cas-e of the Australian rock oyster there is no nursing of the 

 )oung brood, which is turned out to shift for itself, not only in 

 a shell-less but even in an unfertilized condition. Like the spawn 

 of many fishes, these ova are fertilized in the water. They can 

 be readily fertilized artificially, and Mr. Saville-Kent has found 

 that four days after fertilization the shells, which make their ap- 

 pearance on the second day, become so dense that the embryo 

 oysters can no longer support themselves in the water, but sink 



NO. I I 50, VOL. 45] 



to the bottom, where they assume their permanently fixed con- 

 dition. Such is the fecundity of this oyster that the rocks and 

 every available hiding-place in the bays, estuaries, and inlets of 

 the districts it affects become literally plastered with the embryo 

 brood ; and until quite recently, artificial culture in the scientific 

 sense has in New South Wales been usually regarded as an un- 

 profitable and unnecessary superfluity. Lately, however, the 

 oyster- fisheries of the colony have been seriously damaged by 

 a disease which either destroys the oyster or makes it unfit for 

 food. Mr. Saville-Kent attributes this disease to the pollution 

 of rivers. If he is right in this view, in support of which he 

 has much to say, the oyster-growers of New South Wales will, 

 as he says, have to make the most of the water area left to them 

 where the water is pure. They may also have to turn their at- 

 tention to the cultivation of the New South Wales variety of the 

 mud oyster. 



In Queensland, as in New South Wales, the only oyster used in 

 commerce is the rock variety, which may be said to attain its 

 maximum development in both quantity and quality in the 

 Moreton and Wide Bay districts. In these areas the species is 

 so abundant that large consignments, above those required for 

 home consumption, are exported to New South Wales and 

 Victoria. The disease which has so seriously depleted the 

 fisheries of New South Wales has not yet affected the 

 Queensland beds. Mr. Saville-Kent thinks that this immunity 

 is probably due to the circumstance that the Queensland oyster- 

 fisheries are chiefly located in bays and channels in close 

 proximity to the open sea, from whence, even after heavy floods 

 from the tributary rivers, they are speedily revived by an inflow 

 of sea-water. He urges the Queensland authorities to preserve 

 these tributary streams as far as possible from pollution by 

 chemical or other noxious works, which if allowed to increase to 

 any considerable extent cannot fail to exert a very deleterious 

 effect upon both the oyster and all other fisheries of the bays 

 into which the rivers flow. Artificial oyster-culture, with the 

 exception of one or two small experiments, has been so far 

 carried out in Queensland waters on the simple lines only of 

 transporting the young brood or ware, locally known as 

 "cultivation," from one locality and laying it down on ground 

 where it will develop more speedily to maturity. Mr. Saville- 

 Kent believes, however, that it would be profitable to use split 

 palings as spat collectors. One advantage possessed by this 

 form of collector is the shelter from the sun's heat afforded 

 to the young brood when left high and dry by the receding 

 tide. Millions of the Australian rock oyster are destroyed 

 annually through exposure to the overpowering heat of the sub- 

 tropical sun in the early days of their attachment to exposed 

 rocks near high-water mark. The overhanging ledges of larger 

 rocks and the shady sides of stone jetties or embankments are 

 invariably found to attract and support the greatest amount of 

 oyster brood, and this shelter, which is naturally sought, plainly 

 indicates the lines that may be most profitably followed in 

 operations connected with the artificial cultivation of the species. 

 We may note that since Mr. Saville-Kent's lecture was pub- 

 lished a report by him- on "Oysters and Oyster- fisheries of 

 Queensland " has been issued by the Queensland Government. 

 In this report, which is carefully illustrated, full details are given 

 as to the conditions which must he specially taken into account 

 by all persons connected with Queensland oyster-fisheries. 

 Referring to the "split paling" collectors, Mr. Saville- 

 Kent emphatically repeats what he says in their favour in his 

 lecture. After considerable experience he expresses his con- 

 viction that they are the most convenient and economic form for 

 use in Australian waters, and that they may be characterized as 

 an essentially Australian product. About half-tide mark repre- 

 sents the z )ne within which— at all times of the year, but 

 especially in the months of February and August — they gather 

 the most abundant harvest of spat. On their first attachment to 

 the cemented collectors, the young oysters adhere to the cement 

 by the entire surface of the attached shell. After attaining to 

 about half an inch in diameter, the free edges of the shells 

 begin to grow outwards, and this direction of their growth is 

 continued until at an age of about six months they project an 

 inch and a half or two inches from the collector. At this stage 

 the young oysters may be easily detached with or without the 

 cement, and be laid on the banks as ordinary "cultivation." 

 The collectors may then be re-cemented and re-laid for the 

 catchment of a second crop. 



Of the oyster-fisheries of South and West Australia Mr. Saville- 

 Kent is not able, in his lecture, to give precise details. He says, 



