ROCK OYSTERS

New Zealand Herald, Volume LXXVI, Issue 23272, 15 February 1939, Page 15

ROCK OYSTERS

POOR BREEDING YEAR LOW TEMPERATURE OF SEA SUPPLIES FOR MARKET GOOD INCREASE EXPECTED Low and uneven temperatures of the sea appear to be adversely affecting the spawning of rock oysters, and unless there is a sustained period of warm weather it is considered that many on exposed rocks will not spawn at all. On the other hand there are such improved supplies of adult oysters, a condition attributed by the Fisheries Department chiefly to favourable breeding conditions in 1933 and 1934, that increased quantities will be marketed in the next selling season. Only 3037 sacks of oysters were put on the Auckland market in 1935, this total being the lowest recorded. Since ! then there have been relatively small | but progressive rises. In 1936 the total I marketed was 4033 sacks, in 1937 it was 4203 sacks, and in 1938 the quantity was 4870. In the coming season, the starting time of which has not yet been determined, it is expected that the 1934 total of 5267 will be exceeded, but there are always factors that may induce a change of plans by the department. In normal circumstances the indications for the next few years are for a progressive rise. Cultivation and Tending Work

The department has been carrying out a great deal of work in ridding rocks of grapeweed and in destroying pests that affect the oysters. In the past few years there has been a good deal of cultivation work done at Kaipara, but this year operations have been confined there to the cleaning of beds. i About twice "the usual activity in cleaning rocks of weed and destroying pests has been done in the Bay of Islands, and the tending of beds at Whangarei has been steady. In the Hauraki Gulf a gang has been operating since September in improving the beds, and it will continue until April. Kawau as Nursery Kawau is recognised as a natural nursery, and. this year 300 oysterencrusted concrete slabs have been removed from Kawau to Coromandel, where better conditions exist for the development of the oysters.. Three hundred new concrete slabs have been put down at Kawau to replace those taken away. The system of planting concrete slabs in good breeding grounds to attract the oyster spat, and their subsequent removal to places where the food supply is better for the development of the oysters, is considered as being well justified by results, and this year oysters are expected to be picked from 100 concrete slabs at Coromandel that came from Kawau.

It is also anticipated that oysters will be picked from a further 200 concrete slabs at Coromandel next year, and that increasing supplies ,will be available each year from this source.