Stock Handling Tips

Be prepared to change the way you handle selected lines of stock!

Here are some suggestions:

Q. What size mesh should I use for SOCo stock.

A. The mesh size should always be smaller than the mesh size the oysters were last graded on. For example, oysters purchased from a nursery retained on 4mm mesh should be placed on mesh no larger than 3mm. However,the mesh size should not be too small as this will could restrict flow to the oysters and potentially restrict growth. If you are using small mesh, especially 3mm or less, the oysters should be handled as often as possible (at least every four weeks) as small mesh will clog and water flow to the oysters will be severely restricted.

Q. What volume of oysters should I put in my growing container?

A. Generally the less the better. Some growing areas and systems will be able to get better results than others at higher stocking densities but all will do better with light stocking densities. If you find that only a small proportion of your oysters seem to be growing well this is an indication that you are stocking too heavily and/or not thinning and grading often enough. It is very easy to overstock as there could be tens of thousands per litre. Even if it looks like the oysters have plenty of room because of the small volume they may still be piled on top of each other which could result in variable growth. For example a ‘Stanway’ type of cylinder should ideally have around only ½ litre, with 1litre a maximum volume in a good growing area.

Q. How often should I handle my stock?

This depends on the size and time of year. Smaller oysters, 3-4 retained should be thinned and graded at least every four weeks during the warmer months. This can be done less often as the oyster get larger or growth rates slow. A good rule of thumb is to grade and thin when the volume of oysters in the container has doubled

Q. Where should I grow the small SOCo spat?

A. The small spat are fairly robust but should not be exposed to rough conditions, especially in floating containers. Generally a good flow is required to ensure plenty of water is going through the smaller mesh used for small oysters. Do not place the oyster in extremely ‘quiet’ areas with low flow rates as the oyster growth rates could be restricted.

 

SOCo Seed Counting Guidelines
Following the successful field days at Port Stephens and Batemans Bay, it became clear to the SOCo board that not everyone had seen/ received the guidelines SOCo had devised to assist with the counting of stock ex-nursery. Following is the link to download the PDF version of this document.

How to count nursery spat.