Growth and Survival of the Spat of Arkshell, Scapharca broughtonii in Intermediate Culture with Different Shape of Protective Net and Type of Preventive Net of Spat Loss

Growth and survival of the spat of arkshell, Scapharca broughtonii were investigated for the improvement of survival in intermediate culture with different shape of protective net and type of preventive net of spat loss. The growth performance of the spat of arkshell was observed for 60 days by using different forms of protective net, as the exposure form with an average shell length of mm(P mm, the cylinder form with mm and the last one is the rectangular form with mm. Their numerical value did not show any marked difference with each other. But in case of survival rate, the fish pot form showed highest survival rate which is 43.7% and the significantly lowest was showed by the exposure form, which is 5.4%(P mm, the next group was in a balsam pear net with mm, in a polyethylene net with mm and the control with mm which was not installed by preventive net of spat loss. The survival rate was 91.5% in a blackout curtain, 90.1% in a polyethylene net, 88.5% in a balsam pear net and 61.5% in a controlled group. It is seen that the highest growth and survival rate were observed in a fish pot form and cylinder form. These results were a little bit difference from those of the spat of arkshell cultured in the form of different preventive nets. There was no significant difference in survival rate in relation to the sorts of preventive net against carrying-away, but there was a difference in survival rate by more than 30% as against the non-installed controlled group. We expect that survival rate would be highly improved in intermediate culture carried out with fish pot form and cylinder form of protective net and preventive net of spat loss.