Wikibooks: School Science/Oyster cultivation in seawater ponds

• Format: Book
• Language: English
• Subjects: Crassostrea gigas
• Online Access: https://en.wikibooks.org/wiki/School_Science/Oyster_cultivation_in_seawater_ponds

Crassostrea gigas the Japanese oyster is ideally suited for cultivation in sea water ponds or in the water from seawater ponds. Major advantages of this oyster are igas does well in water with high concentrations of phytoplankton the normal situation in marine ponds which are growing fish or prawns and which therefore have high nutrient loadings. pat (the juveniles) of gigas are readily available from hatcheries all over the world and are also not too difficult to reproduce in a modest mariculture hatchery. igas has a ready market and is a fast grower. In phytoplankton rich water it becomes very fat (lots of glycogen stored) and as a result is very tasty. igas can survive a wide range of temperatures from near freezing up to 30 degrees although it grows fastest and fattest at around 20 degrees. = Experimental Cultivation of gigas = A simple way to test if the oysters will thrive is to construct some simple baskets of stiff plastic mesh (netlon for instance). Put in a few tens of small young gigas and suspend the baskets from the monks (water outlet structures) of the pond. Use mesh of at least 10mm opening so that it doesn t plug up too quickly with marine fouling organisms. A simple way of doing this is to cut two disks of say 30cm diameter one for the top and one for the bottom and a strip of say 10cm wide for the side. Sew up with plastic cord and leave a place where the baskets can be opened to add and remove oysters as necessary. Attach three cords equally spaced around the upper rim tie them together and attach a cord long enough to suspend baskets in the pond. Gigas grown this way in Elat reached a total weight of 75 grams in 9 months and had very high quality indices. Crassostrea produce large amounts of faeces and pseudofaeces when they are in plankton rich water so every few days they will need to be agitated to remove this material. Otherwise they will smother. Further along in this module we describe a way of growing the oysters so that they are pretty well immune from this build up of sediment. = ...