Single seed oyster spat improves production

NEW ZEALAND
Saturday, September 29, 2001
http://www.fis.com/

From the summer of 2002 the Cawthron Institute will supply Pacific Oyster farmers with superior, hatchery reared, single seed spat.

This development has arisen partially from the restrictions on transferring spat from West Coast of the North Island to the East Coast where most of the farms are. This became a problem when the West Coast was affected by algal bloom. This crisis made oyster farmers aware that their supplies of spat were not assured and that to clean spat, so they could be brought from one coast to the other, was expensive.

The wild caught spat also lessened the changes of the farmers producing top quality oysters. Oysters farmed from wild spat develop on sticks and the densities of these are variable and this leads to uneven size, meat condition and shape.

In Australia many of these difficulties have been overcome by the use of single seed cultivation. For this the spat comes from a hatchery, it is uniform in size and from selected stock. It is easy to grade and lends itself to mechanisation because it is loose like fine sand. The oysters reach market maturity about the same time and have a uniform shape, colour and condition.

A year ago Pacific Marine Ltd started a trial with hatchery-grown spat.
Working in conjunction with the Cawthron, Pakihi Marine Farms introduced single-seed technology on a commercial scale. Another farmer Bob Nicolle of United Fisheries has been pioneering the Rotoshell system for single seed cultivation and is enthusiastic about it.

Because there is no commercial producer of high quality single-seed spat the Cawthron will fill this gap and supply the spat to growers. They promise cost effective spat production because of recent developments in technology and minimum capital investment. This will allow the industry to benefit from a government funded research and development grant in minimum time.

Cawthron's research on cryopreservation will also bear fruit and the frozen oyster sperm and embryos will bring further efficiencies in hatchery spat production.

By Jenny Haworth
FIS.com

(from Aquaculture Info List, e-mail: dave.conley@sympatico.ca)

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