Current status of freshwater prawn culture in Vietnam and the development and transfer of seed production technology

ABSTRACT:   In Vietnam, the giant freshwater prawn Macrobrachium rosenbergii is becoming an increasingly important targeted species, as its culture, especially in rice fields, is considered to have the potential to raise income among impoverished farmers. The production of M. rosenbergii based on aquaculture reached over 10 000 tons per year in 2002, having increased from about 2500 tons since the 1990s. Until recently, lack of a stable supply of seed had been an important obstacle to the further expansion and development of M. rosenbergii culture, but cumulative research on larval rearing, especially in the 1990s, has led to the development of new seed production technology based on the 'modified stagnant green water system'. Following its dissemination by the efforts of provincial authorities, hatchery operators, and farmers, the freshwater prawn seed production industry developed rapidly in the Mekong Delta with over 90 hatcheries producing 76.5 million postlarvae in 2003. This is considered to have affected the expansion of rice–prawn farming in the Mekong Delta, leading to increased aquacultural production in the region. This paper reviews the current status of freshwater prawn culture in Vietnam and background history, and presents a socioeconomic evaluation of seed production technology implementation.     

对虾养殖计算机管理系统

采用现代化方法管理对虾养殖势在必行。对虾养殖计算机管理信息系统是根据对虾育苗规范和养成技术规范，按照软件开发规范设计完成，操作简单，安全可靠，具有数据录入，数据分析，统计查询，自动打印报表，数据维护等功能，可大大提高对虾养殖工作效率和管理质量，为有效遏制对虾疾病的暴发流行及时提供信息。     

虾蟹类遗传育种学研究

虾蟹类在分类学上属十足目（Ｄｅｃａｐｏｄａ）甲壳动物,在水产养殖业中占有极为重要的地位。六十年代以来,随着众多经济虾蟹类（如对虾、罗氏沼虾、中华绒螯蟹）人工培育苗种的成功,其养殖业发展迅猛,特别是近年来特种水产养殖业的兴起,使虾蟹类的身价倍增。据不完...     

用对虾的致病病毒人工感染克氏原螯虾

用从对虾闰料提取的无包埋体对虾病毒（ＮＯＳＶ）人工接种淡水的克氏原螯虾,螯虾发病死亡。再用死亡螯虾组织接种健康螯虾传代,传至第９代,接种的螯虾每代都发病死亡。用显微镜发病螯虾的组织切片,发现其胃,前肠上皮,鳃,结缔组织等的细胞核明显肿在和嗜伊红着染。经超薄切片观察,在发病螯虾的胃肠部,鳃组织的细胞核内有大量的杆状样病毒粒子,病毒大小为１１０－１４０ｎｍ×３４０－４３０ｎｍ,有囊膜,在细胞核内不形成     

杂交青虾“太湖1号”苗种在池塘养殖中的适宜放养密度

以饲料系数、养殖产量、成虾规格、体长与体质量特定生长率作为判据,水质状况作为参考,以杂交青虾"太湖1号"为实验对象,在放养密度为60、105、150、195、240尾/m35个梯度下进行为期100 d的养殖试验,研究杂交青虾"太湖1号"苗种在池塘养殖中的适宜放养密度。结果显示,150尾/m3组的饲料系数显著低于195尾/m3和240尾/m3组(P<0.05),而养殖产量及成虾规格显著高于其它各组(P<0.05)。在高于150尾/m3的高密度组中,虽然产量也显著高于低密度组(P<0.05),但成虾规格较小。养殖期间各养殖水体的水质均能满足养殖虾的生长需求;高温季节除了高密度组的亚硝态氮盐指标稍有升高以外,水体pH、DO、NH4+-N等指标基本保持一致。将放养密度分别与饲料系数、增重率、体长与体质量特定生长率等指标之间进行二次回归曲线方程拟合,计算出杂交青虾"太湖1号"的适宜放养密度为117～150尾/m3。     

Effect of Customized Probiotics on the Physiological and Immunological Responses of Juvenile Western King Prawns (Penaeus latisulcatus Kishinouye, 1896) Challenged with Vibrio harveyi

Juvenile western king prawn P. latisulcatus were fed 10⁵ colony-forming units (CFU)/mL of two probiotics Pseudomonas synxantha and P. aeruginosa for 28 days. P. latisulcatus were then challenged with V. harveyi at 0 (control), 10³, 10⁵, and 10⁷ CFU/mL. During the seven days of challenge, disease resistance of the probiotic-fed prawns was compared with that of prawns not fed probiotics. The immunological responses of the prawns did not improve during the challenge period in terms of total haemocyte count, hyalinocyte, semi-ganulocyte, granulocyte, clotting time, bacteraemia, and intestinal bacterial load. Overall, when prawns were challenged with V. harveyi, the LT₅₀ values got shorter as V. harveyi concentration increased. LT₅₀ values of prawns fed probiotics were significantly longer (P < 0.05) than those not fed probiotics. At a V. harveyi concentration of 10³ CFU/mL, the 100% survival of the prawns fed probiotics was three times more likely than those of the prawns not fed probiotics.     

Effect of various medium compositions on survival and hatching rates of embryos of the giant freshwater prawn Macrobrachium rosenbergii cultured in vitro

SUMMARY: The effectiveness of in vitro embryo culture of the giant freshwater prawn Macrobrachium rosenbergii depended on the age of the embryos at the onset of culture and on the concentrations of various compositions in the medium. Embryos that started being cultured on day 0.5 after oviposition were more sensitive to variations in the medium compositions than those that started being cultured on day 10.5 after oviposition. An optimal NaCl level was essential for embryonic development, survival, hatching and survival of the newly hatched larvae. Variations of NaCl or KCl levels dramatically altered embryonic development, and variation of the MgCl₂ + MgSO₄ level significantly lowered survival of the embryos that started being cultured at the early stage of development. In contrast, no significant change in embryonic development was observed upon variation of the CaCl₂ level. Hatching of the embryos required the presence of NaCl and CaCl₂ but not KCl or MgCl₂ + MgSO₄. The ionic requirements of the newly hatched larvae differed from that of the developing embryos. Variations of NaCl, KCl or CaCl₂ but not MgCl₂ + MgSO₄ levels significantly influenced the survival of the newly hatched larvae.     

3种对虾的图像测量技术与人工测量方法的比较分析

对虾形态参数测量传统上使用游标卡尺,但误差较大。为提高对虾形态测量的智能化水平,实验录用图像测量技术测量凡纳滨对虾、日本囊对虾和刀额新对虾3个品种的体长、头胸甲长和头胸甲宽,所得结果与游标卡尺测量值比较。实验共测量对虾421尾,获得数据15 156个。基于Bland-Altman作图法和组内相关系数(intraclass correlation coefficient,ICC)开展2种测量方法的一致性评价和重复性评价。结果发现,(1)图像测量技术与游标卡尺测量结果的差值95%以上落在LoA范围内,且LOA CI在专业意义上可接受,说明二者一致性好;(2)图像测量技术对每尾对虾同一角度的识别结果一致;识别3个角度的ICC分别为0.996、 0.973、 0.957,与1名测量者用游标卡尺3次测量的ICC(ICC=0.997、0.980、0.965)无显著差异,但高于3名测量者(ICC=0.991、0.952、0.947),说明图像测量技术同一角度的重复性最佳;(3)图像测量技术识别同一角度的结果最接近假定真值,变异程度最小,相对误差分别为1.52%、2.37%、3.74%。研究表明,图像测量技术与游标卡尺一致性好,且重复性优于后者,具有非接触、测量快、适用广泛等特点,可代替游标卡尺应用于对虾形态参数测量之中。