CULTURE OF OYSTERS

Evening Post, Volume CX, Issue 133, 3 December 1930, Page 17

CULTURE OF OYSTERS

USE'" OP, STAKES' AND S

■'■ ■ Very1- .promisiiig experiments, in .'the cultivation .. of 'Aiiekland... .rQck. oysters upon wooden stakes -and wirC'iietting trays are being 'conductec! by tffQcers of tliQ Marine- Department a.t: a nmiiber of points on the east and west coasts, under the supervision of the chief -inspector of /fisheries, Mr. E. H. Hfefferd (states tho "New Zealand Herald"). ■For a : nurnber of years^the.-department has been restoring depleted oyster beda and- establishing new ones by the process of building, rock 'walls below water' mark iv carefully-choSeii posir tions, ■' and 'placing oh or near theni pieces of oyster-covered rock taken from other beds. By'such an arrangement tho "spat" or minute baby oysters, which float freely in the water during the spawning season, are" encouraged to attach, themselves to the, rocks.. For the purposes of. the scheme it is necessary, to place the walls and the pieces of oyster-covered rock -with vqry. careful regard to tide:eurrents'and the general suitability of the -neighbourhood for oyster- culture,' so- that the "spat" shall bo carried from the parent oysters to rocks intended for its ■reception. In some, cases it has been sufficient to lay rocks in.'gno'd. positions close to. existing beds. The policy,. generally, has been most-successful,, especially when oysters from distant 'bods . have been used to introduce a new strain. An effort is now being mado to grow oysters in waters -whore,.-for various reasons, it is impracticable to lay down rocks. The Auckland oyster requires something substantial upon which to grow. It has no objection to a muddy locality, so long as there is a mangrove trunk, old pile, or similar object to provide it with a home. In tho tidal rivers of New South ■ Wales oysters aro grown most successfully upon wooden stakes driven, into the mud of the foreshore, and in trays of. wirenetting fastened upon posts at a suitable level, so that high tide may cover them. Last year the -■ Marino Department, which had previously given all its attention to establishing rock beda and fighting the "borer" pest, decided' to give Australian methods a trial in sheltered waters. It planted in all nearly a. thousand 6ft stakes of green mannkaj which resists, the teredo, at Coromandel, Mahurangi, and the Bay of Islands, in Bon Accord and the.North Harbours, Kawau Island, and in the Kaipara Harbour. It also fitted up trays containing pieces of rock at. the same places. ■ The work was completed about October, 1929, and so far has given very good results, of the stakes at Kawau are each carrying about 100 young oysters, which should.be mature and fit for picking about two years hence. The same is true of most other localities, and tray culture also appears to bo satisfactory. How the harvesting .will be' carried out is not certain at present, but it is believed that tho mature oysters can bo removed without injury to the younger ones. If this is not possible, it is likely that the small oysters can bo transferred to trays'to complete their -growth. • The officials are.careful to point put that the whole procedure is definitely in the experimental stage. Tho question of tho durability of tho stakes and trays, and of cost generally, has to be considered, apart from the condition of the mature oysters, beforo it ertn bo said that such methods of culture will be a commercial-success. If hopes are realised, the plan will greatly ex lend II|O urea available for raising oysters in northern waters, and will help the Marino Dopnrtmeitfc-t'o supply l-ha demands oC a growing population i'or ii'i'iivuuritc sea food. '