Ecological criteria used for evaluation of suitability of the culture site are followings :
Good culture bed should sited in a shallow bay sheltered from strong wind and wave action. The regular strong wave action can either wash the cockle up on the beach or into the mangrove, or cause the bottom mud to be shifted such that it buries the cockle.
The best culture bed is a mud flat with clay or silty clay substrate bordering mangrove forests. The upper layer between 6 to 10 inches depth of the substratum should be a grey color-without fragmented shells containing particles size less than 0.053mm about 80–90 per cent. The water content of the substrate should about 47–50 per cent. Organic detritus should present between 6–11 per cent after ignition at 475 degree celsius for 7 hr.
For convenience in culture operation and to avoid the long exposure during the extreme low water spring tides (ELWS), the area with a water depth of about 1–2 m mean tide level (MTL) is considered as a good potential area.
The best culture bed should have a moderate slope seaward between 5–15 degree. It the gradient of slope is too small, the culture area will expose too long between the tides, and where is too great, the cockle do not grow well, and working conditions will be difficult.
The site should not be in the vicinity of strong current. A current speed between 0.02–0.1 m/sec is justify for cockle culture operation, and strong enough to transport natural food for the cockle.
Feeding activity of the cockle, A. granosa function efficiently at salinities above 23 ppt. It decreases substantially at salinities less than 20 ppt. Young cockle has better tolerance limit and able to continue its normal life at a lower salinity, at least down to 18 ppt. For potential culture site, the salinity should be within the range of 25–30 ppt which allow to be subjected to long and short-term fluctuations.
