香港牡蛎人工苗种池塘生态中期培育效果

Effects of Ecological Intermediate Cultivation of Oyster Crassostrea hongkongensis Juveniles in Onshore Ponds

同一批初始壳高(3.90±0.96)mm的香港牡蛎(Crassostrea hongkongensis)分成四份,每份10串,分别放在四个不同的养殖地点,采用浮筏养殖进行中培。每周测量一次稚贝的生长、养殖海水的温度、盐度和饵料密度,分析不同中期培育模式下香港牡蛎稚贝的中间培育效果及其影响因素。结果显示:四个中培地点的水温相近且均呈下降趋势,无显著差异(P>0.05);四个地点盐度由高到低依次为青菜头、亚公山、沙井港和海边池塘,青菜头和亚公山盐度显著高于沙井港和海边池塘(P<0.05),实验期间四个地点盐度均呈上升趋势。池塘饵料密度较高且含量稳定,沙井港饵料密度也较高但波动较大,青菜头和亚公山饵料密度较低。池塘生态中培的牡蛎稚贝生长速度最快,平均壳高增长(16.34±2.56)mm,存活率为93.60%;其次为沙井港、亚公山,青菜头稚贝生长最慢,平均壳高增长(6.23±1.44)mm,存活率为80.68%。池塘生态中培的牡蛎稚贝的生长率显著高于海上间的稚贝(P<0.05),效果最好,盐度和饵料密度显著影响中间培育效果。本研究结果可为香港牡蛎养殖提供理论指导及新的思路。

The same batch of artificial seedlings(juveniles)of oyster Crassostrea hongkongensis with an initial shell height(3.90±0.96)mm were cultured in the ponds in floating rafts at a rate of 10 stings per pond by ecological culture method, and then the growth rate and survival rate of the oyster juveniles and the environmental factors including water temperature, salinity and bait density were weekly measured compared with the traditional marine intermediate culture mode to evaluate the intermediate culture effect and possible factors influencing the growth rate and survival rate of the oyster juveniles in different intermediate culture modes. The results showed that there was similar water temperature in the four intermediate culture sites during the experiment, showing a downward trend, without significant difference(P > 0.05). The descending order of salinity in the four sites were expressed as Qingcaitou,Yagong Mountain, Shajing Port and Onshore pond, significantly higher in Qingcaitou and Yagong Mountain than that in Shajing Port and Onshore pond(P < 0.05), showing an upward trend during the experiment. There was high and stable bait density in the Onshore pond, and high and greatly fluctuated bait density in Shajing Port, with low bait density in Qingcaitou and Yagong Mountain. The oyster juveniles cultured in the onshore pond had the best growth, and average shell height of(16.34 ± 2.56)mm and a survival rate of93.60%, followed by Shajing Port and Yagong Mountain. While the oyster juveniles cultured in the onshore pond had the poorest growth at Qingcaitou, and an average shell height of(6.23 ± 1.44)mm and a survival rate of 80.68%. There was significantly higher growth rate in the onshore pond than that in the other three sampling sites(P < 0.05), with the best ecological intermediate cultivation effect in onshore pond and the salinity and bait density had a significant influence on the intermediate cultivation effect. The findings can provide theoretical guidance and new ideas for intermediate cultivation of C. hongkongensis juveniles.