234 



NA TURE 



\_7au. 6, 1887 



foreshore inclosed has proved to be well adapted for the con- 

 struction of these ponds, as immediately beneath a thin super- 

 ficial covering of sand it is composed of pebbles and tenacious 

 clay so firmly amalgamated as to almost resemble concrete ; any 

 excavations made in this bed are consequently thoroughly 

 water-tight. In the preparation of this site for the required 

 purpose, it was found desirable to divert the course of that portion 

 of the Sandy Bay Rivulet which formerly at low tide flowed over 

 the area now occupied by the ponds. This has been accomplished 

 by further excavating the main channel of the stream straight 

 out to sea, and away from the area inclosed, and by interposing 

 between the two a barrier or groin of rocks and tree-trunks, 

 which has had the desired effect of accumulating along its 

 course a natural sand-bank which effectually shuts off the water 

 of the creek. One of the ponds constructed in the inclosure, 

 measuring sixty feet long by thirty wide, is situated imme- 

 diately beneath the hatchery, and serves as a reservoir for the 

 constant supply of the tanks. This pond, being fenced round 

 with wire netting, is further utilised for the storage and culture 

 of a variety of edible fish in addition to oysters. With each ebb 

 and flow of the tide the water in this pond is more or less com- 

 pletely renewed, and the fish under these conditions are found to 

 thrive remarkably. A list of the edible species of fish th.at have 

 been cultivated in the pond and tanks since the establishment 

 of the fishery at Battery Point — that is, between the months of 

 February and July 1886 — is herewith annexed. 



1. Native Salmon (Arripis salar). 



2. Sea Carp (C/floJac/yliis allf-orti), 



3. Black and Silver Perjh {C/iilodactylus macroplenis), 



4. Magpie Perch (Chilodactylus gibbosus). 



5. Real Trumpeter {Latris hecateia). 



6. Silver Bastard Trumpeter (Latris forsteri). 



7. Rock Gurnet {Scbaslcs fcrcoitics). 



8. Flathead {Plat) cephalus basscnsis). 



9. Tasmanian Whiting [Sillago ciliata). 



10. Snotgall Trevally (Ncptonemus brama). 



11. Sea Mullet (.4 gonostoma forsteri). 



12. Kock Cod [Pseiidophycis barbatus). 



13. Tasmanian Ling (Genyptcrus blacoiies). 



14. Flounder {Rhombsolea monopus). 



In both the ponds and tanks of the Fisheries Establishment 

 the chief attention is at present being given to the culture of 

 oysters. There is already upon the premises a stock of some 

 eight or ten thousand oysters of different varieties, and in all 

 stages of growth, which stock it is proposed to yet further 

 increase in anticipation of the approaching spatting-season. The 

 varieties include the irregular-shaped Rock Oyster [Ostrea 

 angulata) from New South Wales ; the smooth variety of 

 0. cdiilis froin New Zealand, and many modifications of the 

 indigenous type of the same species. The majority of these 

 oysters have now been acclimatised in the tanks and ponds for 

 the last three or four months, in which space of time it is 

 gratifying to have to record that all of them have thriven and 

 considerably increased the size of their shells. This is par- 

 ticularly noticeable of the New South Wales species, which 

 it is anticipated from this experience it will be found possible to 

 establish and propagate in these waters. The experiment now 

 in course of trial, as to whether they will be able to withstand 

 the severity of the Tasmanian winter months, will be an import- 

 ant factor in this question. The series under cultivation includes, 

 in addition to the stock of adult oysters for breeding purposes, 

 samples of brood raised last summer at Little Oyster Cove and 

 other Government reserves. Among the useful functions accom- 

 plished by the Oyster-Culture Department of the Fisheries 

 Establishment at Battery Point may be mentioned the rcilc it 

 fulfils of an accessible model for the advantage of those who, in 

 increasing numbers, are taking up oyster-culture as a private 

 enterprise, and who can there obtain information and instructions 

 as to the best methods upon which to conduct their operation'^. 

 It is also of much value as a central station, at which practical 

 experiments can be made with the view of solving the many 

 vexed problems that present themselves to the pioneers of this 

 industry, and of discovering newer and more profitable methods 

 of cultivating and breeding this mollusk. Already among 

 eminent .\merican and European oyster-culturists it is main- 

 tained that the secret of obtaining a far larger percentage of the 

 brood produced by the parent oyster than has hitherto been 

 accomplished is to be solved through the medium of tidal ponds 

 and tanks, wherein the oysters will be supplied with all the 

 equirements necessary for their healthy growth and develop- 



ment, and wherein at the same time suitable provision is made 

 for the retention of the produced sp.it. Tentative experiments 

 having this object in view are now in course of progress under 

 scientific direction in all of the more important oyster-growing 

 communities, and it is hopefully anticipated that some material 

 assistance towards the solution of this important question maybe 

 forthcoming from this newly-established practical br.anch of the 

 Fisheries Department of this colony. 



Among the more important points to which my attention 

 h.as been recently directed and advice solicited is the widely 

 recogni=ed desirability of discovering some method for cultivating 

 oysters in localities in all respects suitable for their growth, with 

 the exception that the labour involved in keeping them constantly 

 clear from sedimentary deposits, or from sinking beneath a 

 too yielding bottom, is too costly for their profitable culture. 

 Experiments made with the view of surmounting this diffi- 

 culty have resulted in the invention of a species of frame 

 or cr.adle composed of wood and strong g.\lvanised wire netting, 

 measuring 6 feet long and 3 feet wide, upon which the 

 oysters are placed, and raised to a height of from 9 to 10 inches 

 off the ground. This description of frame so completely answers 

 the purpose for which it was devised that they are being supplied 

 to all of the Government reserves, and are recommended for the 

 use of private growers. Each frame of the dimensions above 

 quoted, which are found to be most portable, conveniently 

 c.irries as many as 500 adult oysters, so that for a well-stocked 

 bed of, say, 10,000 oysters, a score of them will be sufficient. 

 Having the stock placed on frames of this description, a vast 

 amount of labour usually bestowed in keeping the beds clean 

 and the oysters free from sediment can be dispensed with. In 

 place of the tedious process of dredging the bed through and 

 raising the oysters a few at a time, to be cleaned and re-deposited 

 on the cleared ground, each frame, with its contents, can be 

 raised to the surface, a few shakes suffice to get rid of the sedi- 

 ment that may h.ive accumulated upon them, and they may 

 again be lowered to their pUce. This object may indeed be 

 accomplished in many instances without raising the frames to the 

 surface, it being sufficient merely to tilt the frame to and fro a 

 few times, as it lies on the bottom, with the aid of a boat-hook, 

 such agitations effectually getting rid of all the sedimentary 

 matter. Wire handles for raising the frames to the surface of the 

 water, with the aid of a biat-hook, should be .attached.' Further 

 advantages are attached to this frame-systetn of oyster-culture, 

 since not only can the frames and their contents be raised to 

 the surface at all times to be cleaned and manipulated, but it 

 affords facilities, hitherto unprovided, of keeping an accurate 

 estimate of the amount of stock placed upon the beds, and of 

 watching, from time to time, the progress it is making in 

 development. The form of spat collector that can be most 

 advantageously utilised in conjunction with these oyster-frames 

 is the one figured and described in my last Report under the title 

 of the "single pale" collector, consisting, as its name implies, 

 of a single split paling 4 feet long by 8 or 9 inches wide, 

 having its under surface coated with cement and a brick attached 

 at either end to retain it in the desired position. The experience 

 gained by the pa^t season has demonstrated this to be the most 

 economic and productive form of collector, no alteration in its 

 construction being suggested, with the exception that, by placing 

 a single wii-e loop or handle in the centre instead of one at each 

 end, as hitherto, their portability, both in and out of the water, is 

 greatly increased. The adaptability of these paling collectors for 

 use in conjunction with the newly-invented frames is very obvious, 

 and their size is such as to allow of their being placed over the 

 oysters in either a single or in two or more transverse rows. It is 

 anticipated that the oysters placed upon the frames will of them- 

 selves constitute very efficient spat-collectors, their under surfaces, 

 exposed through the meshes of the wire netting, being kept free 

 from slime and sediment, and raised to a height above the 

 ground favourable for the adherence of the spat. Empty shells 

 or cultch similarly placed on frames in the vicinity of the breeding 

 stock are also likely to prove favourable fulcra for the brood to 

 adhere to. A remaining direction in which the oyster culture 

 department of the Fisheries Establishment at Battery Point is 

 found to be of great assistance in the operations now in course 

 of progress relates to its value as a central depot for the reception 

 and temporary storing of the stock brought from a distance for 

 distribution among other reserves. 



^ The frames arc raised to the surface of the water by blocks and cord 

 attached to a tripod ; where the boat is sutificiently large to carry a mast, 

 the same apparatus m.iy be more conveniently worked from a small derrick 

 alifixed to the mast. 



