OYSTER PROPAGATION.

New Zealand Herald, Volume LVIII, Issue 17708, 17 February 1921, Page 8

OYSTER PROPAGATION.

ARTIFICIAL BEDS IN NORTH.

PROGRESS OF THE WORE.

METHOD OF CULTIVATION.

The laying out of artificial beds for the propagation of oysters at the Bay. of Islands is progressing tinder the direction of the chief inspector of fisheries, Mr. L. F. Ayson. The necessity for artificial cultivation ha 3 arisen partly because the constantly increasing demand far exceeds the capacity of present natural beds, and partly on account of the ruthless depletion of many of the best oyster-bearing localities prior to Government protection being introduced.

Last year a small experimental section was laid down, and the success attained by the use of artificial rock formation in collecting oyster spat has encouraged the department to continue its operations, and at present a staff of seven men, under the supervision pf Inspector Flinn, v of Russell, is engaged at this work, -which will be carried on until March. Operations are confined to the more sheltered parts of the harbour, and already an area of varying depth, five miles in extent, is ready to receive spat. It is anticipated that the present annual yield of 140 sacks in Wharengare Bay will be increased to 700 in five years' tune, when the new growth will have reached maturity.

Early|Stages of Shellfish. To convey an idea of the method by which this prospective return is to be brought about it must be explained that the best oysters are found at the lower extremity of tidal level. In less experienced days theEe ,were naturally sought after first, with the result that the higher situated, and consequently less vigorous, were left to continue the species. The action of wind and tide resulted in the young oyster spat being forced higher up the rocks, deteriorating in the process through an extended absence from water into a very weedy resemblance to the original sturdy parent stock. Though the oyster is seen at its best on the warm aspect of a tidal waterway, in the very early stage of its growth, it avoids prolonged exposure to the sun. The plan adopted for its artificial cultivation is to build up walls of rock, from hi-h-tide mark to low-water level, angled so as to give one well-shaded side. The lower open space between these parallel walls is filled rock carrying live shell, and thus a new low-water growth is attracted. Scope of the .Work. To a great extent the present work consists of joining up detached circum-' scribed areas into one extensive bed. The largest area of wholly artificial formation is located on a tidal exposed bank in the lower reaches of the Keri Keri Biver. At low spring tide this island comprises about 30 acres, and it is hoped that next session a grant will be put on the Estimates to enable the department to deal with the whole of this area, in addition to other coast-line work. By reason of its climate, situation and possession of a large foreshore area, practically all the magnificent tidal estuaries of North Auckland can be converted into profitable oyster-rearing beds. Scientific Oyster culture has been carried on for many years in different parts of the world. In Australia the work has been particularly successful, New South Wales alone lifting close on 20,000,000 oysters annually from artificially cultivated ground. & The Need for Protection of Beds. The natural oyster beds of Whangaroa afford not only an apt illustration of the unportance and value of the new work, out also evidence of the necessity of closer protection of the oyster fields generally. Fifteen years ago 800 bags were picked each season in this locality. Owing to lack of supervision a few years ago, these beds were so depleted by casual visitors that to collect, even one bag was a matter of some difficulty. The Marine Department therefore appointed a local inspector, and commenced re-stocking every old oyster ground with spat from the Bay of Islands. Now extensive fields of young oysters cover every point of any consequence, and the department officials feel assured that within a couple of years picking activities can be recommenced upon a larger scale than ever.