# Oyster Farming

## How do they do it?

Brazil:Small Fishermen Trade in Nets for Oyster Farms By Fabiana Frayssinet[1]
Anyone out there from UWI who knows the whereabouts of a 1977 report on Culture of Local Oysters? Please get in touch


Mariculture Ref:fao.org

There is no commercial aquaculture in brackish or marine waters.

There is an area near Bowden on the southeast tip of Jamaica which has a natural population of oysters. Young seed oysters are extremely abundant and can be collected for growing elsewhere, if need be. There are five or six other sites where water conditions are suitable for growing oysters, but no information is available about the presence of spat there. A project was launched in 1977 on a pilot scale in order to study culture of local oysters in Bowden Bay, St. Thomas by the University of West Indies, Mona Campus, with the support of IDRC. In Bowden Bay spawning of the oysters and subsequent spat collection occurs during the rainy season. It has been determined that barnacle abundance is very high and then declines just prior to the time the young oysters set. To prevent collectors becoming fouled with barnacles, the setting of barnacles is monitored with glass slides. When the barnacles seem to have set, oyster cultch is laid.

Old automobile tyres cut into pieces of about 8 x 8 cm and aged in sea water for two weeks are used for oyster cultch. Ten pieces of cultch material are strung on a string of monofilament twine with about 1 cm spacing. The strings of cultch are then placed in the intertidal zone. Sufficient spat can be collected after approximately two weeks during the peak setting period. When sufficient spat have set on the cultch they are transferred to long growing lines with about 10 cm spacing. The growing lines are then suspended from rafts placed in the centre of the bay.

A single raft holds from three to four hundred strings. Each raft costs the equivalent of U.S.$45 and lasts for one year. The cost of materials for spat collection amounts to about U.S.$ 393 per raft. However, this material can be used repeatedly.

Market size is fairly small: 7–8 cm, and the oysters reach that size in six months. Selling price is U.S.$0.84 for 12 oysters. At this price it is calculated that a single raft would gross U.S.$ 1 120 every six months. One man could operate four rafts and have a half yearly income of U.S.\$ 4 500.

All work to date has been experimental except for one individual who operated his own raft. Because of theft he was not able to harvest enough oysters to show a profit. Efforts are now underway to entrust four individuals with four rafts each, on the understanding that all costs will be borne by the project and the participants will retain any profit.

Major problems encountered to date are poaching, disease, and fouling. It is felt that poaching can be controlled by closer supervision. An unknown disease occurs infrequently, always when salinity is in the range of 32 ppt. Fouling by colonial ascidians is a problem when salinity remains high for an extended period of time. This is controlled by sundrying the oysters for one or two days.

Jamaica has no laws concerning the use of water or sea bottom for aquaculture. Similarly, there are no regulations regarding sanitation or human health aspects for oysters or other shellfish. Refer:[2] end quote