Effect of stock density of cultured Amazon Apple Snail Pomacea dolioides (Gastropoda: Ampullariidae) in Brazil

ABSTRACT This study evaluated the biomass gain, specific growth rate, absolute weight gain, and survival rate of the gastropod Pomacea dolioides cultivated in different stocking densities. To perform the experiment, samples were collected in March and June 2015. A total of 40 adult specimens were collected in the Jauary neighborhood (03°08′19.9"S, 58°27′32.5"W), municipality of Itacoatiara, AM, Brazil. They were kept in the laboratory for breeding to obtain the young P. dolioides, which were distributed into tanks containing 4 L of water and an aeration system, in three densities: 2.5 animals/L, 5 animals/L, and 10 animals/L, and were fed fish ration (34% gross protein). The specimens were measured for shell length and weight every fifteen days. The survival rate did not differ between treatments 2.5 and 5 animals/L (100%) and 10 animals/L (95.83%). The density with the best cultivation results was 2.5 animals/L, being most effective for the parameters of growth, weight gain, specific growth rate, and percentage weight gain, when compared with the other treatments after 225 days of the experiment. For future cultivation of this species, a density of 2.5 animals/L should be used to improve handling performance.

摘要 本研究评估了不同放养密度下养殖的腹足类软体动物Pomacea dolioides的生物量增益、比生长速率（specific growth rate）、绝对增重与存活率。为开展本实验，研究分别于2015年3月与6月采集样本。在巴西亚马逊州（AM）伊塔科蒂阿拉市雅乌阿里社区（03°08′19.9"S, 58°27′32.5"W）共采集到40只成体标本。将采集所得成体在实验室中繁育以获得幼体Pomacea dolioides，随后将幼体分配至装有4升水与充气系统的养殖桶中，设置3种放养密度：2.5只/升、5只/升与10只/升，投喂粗蛋白含量34%的鱼用配合饲料。每15天对实验标本的壳长与体重进行一次测量。各实验组存活率无统计学差异：2.5只/升与5只/升密度组存活率均为100%，10只/升密度组存活率为95.83%。实验开展225天后，与其余实验组相比，2.5只/升密度组的养殖效果最佳，在生长、增重、比生长速率与增重百分比等参数上均表现最优。若未来开展该物种的养殖，建议采用2.5只/升的放养密度以提升养殖作业效能。