Production and yield of Penaeus semisulcatus (de Haan) cultured at different densities

Two trials were conducted with two sizes, grow‐out (80.0 mg b.w.) and fattening (5.0 g b.w.), of Penaeus semisulcatus to compare the production and yield of shrimp cultured at different stocking densities within an indoor running‐seawater system. In the first experiment, postlarvae were cultured at 50, 100, 150 and 200 m^?3 for 68 days, while in the second experiment, juveniles were cultured at 24, 50, 74 and 100 m^?3 for 126 days. The results of the two experiments showed significant decrease in weight of shrimp as the stocking density increased. During the grow‐out stage, no statistical differences were observed on survival rates among the shrimp stocked at different densities. Thus, as the primary factor to consider at this stage is the number of shrimp produced, it is recommended to use a density of 200 shrimp m^?3. During the fattening stage, the survival rate at the highest density was statistically lower than the other three densities. The mean yield was 437.02, 869.16, 1217.62 and 1446.78 g m^?3 for shrimp stocked at 24, 50, 74 and 100 m^?3 respectively. Although the average harvest size of juveniles at the lowest stocking density was statistically higher than those stocked at the highest stocking density, both sizes (18.12 and 16.67 g) will be classified as one size group in the market, i.e. medium. As the yield significantly increases as the stocking density is increased, it is therefore recommended that the stocking density for the fattening stage be 100 shrimp m^?3.     

杆状病毒性的皮下及造血组织坏死─对虾暴发性流行病的病原和病理学

１９９３年对虾暴发性流行病的患病对虾经光镜组织病理学研究和电镜观察，在对虾的皮下组织（包括前肠上皮、后肠上皮、真皮和鳃等）、结缔组织、造血组织、触角腺及血淋巴细胞等的细胞核均发现核肿大和深的嗜酸性着色。在电镜下，病变组织的细胞核内为一种杆状病毒充满，病毒大小为１２０ｎｍ×３６０ｎｍ，有囊膜，在细胞内不形成核型多角体或颗粒体类包涵体，属于杆状病毒属的无包涵体型杆状病毒亚群，即Ｃ型杆状病毒亚群。根据该对虾暴发性流行病的症状、病毒感染的靶组织和病毒的特征，该病毒被认为是一种新的对虾病毒，暂定名为皮下及造血组织坏死杆状病毒。     

Influence of Algal Exudates and Bacteria on Growth and Survival of White Shrimp Larvae Fed Entirely on Microencapsulated Diets

Intact microencapsulated protozoeal diets (MED), added to 5 m filtered hatchery water at the recommended concentration of 4 mg L^-1 gave no significant difference in bacterial numbers after 6 h, over a 48 h period compared to control groups in autoclaved hatchery water. Disruption of the MED resulted in a significant increase in bacterial numbers up to 12 h compared to controls with intact microcapsules. Protein leach rates were similar in sterile water and 5 m filtered water, indicating that leaching was independent of microbial activity. MED leached significantly less dietary solubles compared to a microparticulate diet (MPD). There was no evidence to suggest significant attachment of bacteria to diet particles for at least 48 h.In low-quality water after algal blooms, survival of white shrimp (Penaeus indicus) larvae was poor when reared in both sterile and 5 m filtered water. The addition of bacteria filtered from xenic algal cultures together with the algal exudates to such water gave significant improvements in survival to larvae fed MED in 5 m filtered water but not in autoclaved culture water. Live algal diets promote high larval survival and growth irrespective of the inclusion of bacteria.It is suggested that algal exudates act as selective bacteriocides and total replacement of algae with MED requires a balanced bacterial community which can be attained at times from natural sea water, or when the natural bacterial community balance is disturbed, corrected by the use of algal exudates.     

Larval metamorphosis and morphological characteristic analysis of triploid shrimp Fenneropenaeus chinensis (Osbeck, 1765)

Both MI and MII triploids were successfully produced by heat shock in Chinese shrimp Fenneropenaeus chinensis. The inducing conditions for MI and MII triploids were optimized. The highest inducing rate obtained for MI triploids reached more than 90%, and that for MII triploids reached nearly 100% at the nauplius stage as evaluated using flow cytometry. Comparisons of survival rates at larval stages between triploids and diploids or diploids experiencing treatment and diploids without treatment were performed. At larval stage from nauplii to postlarvae, heat shocks lowered survival at larval stages even if the ploidy was not changed. Ploidy did not affect shrimp larvae survival, and no significant difference was found in the survival of shrimp larvae between MI and MII triploids. Highly significant differences were observed in the morphology of triploids and diploids, and no apparent difference was found in the morphology of MI and MII triploids at the grow‐out stages. Discriminating formulae for triploid and diploid shrimp at grow‐out stage were developed and could be used to distinguish triploids from diploids based on morphological parameters. MI and MII triploids of shrimp have the potential to be used in aquaculture.     

南美白对虾肠道细菌菌群分析

对健康养殖南美白对虾胃、肝胰腺、肠道、肌肉中的需氧菌群进行研究。结果表明:胃、肝胰腺、肠道、肌肉中的异氧细菌总菌数分别为5.3×105~6.5×107cfu/g、6.6×105~5.2×106cfu/g、1.4×108~4.5×109cfu/g和1.0×104~1.1×105cfu/g。对从其肠道中分离出来的111株菌株进行属(科)的鉴定。这些菌株分属于13个属(科),发光杆菌属、弧菌属、气单胞菌属、肠杆菌科、黄单胞菌属、土壤杆菌属、芽孢杆菌属、棒状杆菌属、小球菌属、黄杆菌属、产碱杆菌属、假单胞菌属和色杆菌属,还有一株未鉴定的革兰阳性菌。其中优势菌为发光杆菌属、弧菌属,气单胞菌属、肠杆菌科、黄单胞菌属,次优势菌为土壤杆菌属、芽孢杆菌属、棒状杆菌属、小球菌属。     

辊轴式虾剥壳机开发设计与试验

针对国内虾剥壳设备缺乏,本文采用碾压揉搓挤压柔性剥虾的原理,基于碾压机构挺杆压缩弹簧实现柔性碾压,揉搓挤压剥壳机构五辊轴和三辊轴组合往复运动实现柔性剥壳,设计了辊轴式虾剥壳机,具有产能大、需要人工少的优点,并制作了虾剥壳试验样机进行剥壳试验。试验结果表明,该装备完全能够满足柔性剥虾壳的要求。     

2014年广东对虾产业发展形势与对策建议

分析了2013年国内外对虾产业市场供求现状,特别是广东省对虾产业发展现状、市场供需、价格等方面情况,对广东省2014年对虾业生产、市场需求、价格等进行总结;阐述了广东省对虾及相关产业科技进展和需求情况,并找出制约广东省对虾产业发展的主要因素,进一步得出了相关的建议与对策,以期为广东省对虾业的发展提供参考.     

东海区浙江海域海捕虾镉含量监测与健康风险评估

通过对东海区浙江海域4个品种共计40个海捕虾的镉含量监测,表明海捕虾镉含量均符合国家标准规定。样本中镉含量中位数为0.037 mg/kg,第95百分位的含量值为0.13 mg/kg。结合浙江沿海居民鱼虾类膳食消费特点,风险评估表明,浙江沿海城市居民和农村人口通过食用鱼虾类食物摄入的镉含量均低于美国食品药品监督管理局(FAO)和食品添加剂联合专家委员会(JECFA)制定的每月可耐受摄入量,浙江海域海捕虾镉风险较低。     

钼蓝分光光度法测定食品中磷的研究及改进

[目的]分析研究并改进食品中磷的测定方法.[方法]对钼蓝分光光度法测定食品中磷的测定方法进行改进,对消解液酸度的调节,显色剂进行了改进,并与国标方法钼蓝分光光度法测定食品中磷的测定方法进行对比分析.[结果]试验表明,该试验改进的方法不仅简化了操作过程,显色明显,而且标准曲线线性良好,得到了较好的准确度,测定结果与国标方法的测定结果比较无显著统计学差别.[结论]研究得出的改进的钼蓝分光光度法可用于食品中磷的测定.