排序方式： 共有44条查询结果，搜索用时 0 毫秒
21.
Nguyen Thanh Phuong Tran Ngoc Hai Tran Thi Thanh Hien Tran Van Bui Do Thi Thanh Huong Vu Nam Son Yoshinori Morooka Yutaka Fukuda Marcy N. Wilder 《Fisheries Science》2006,72(1):1-12
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. 相似文献
22.
对虾养殖计算机管理系统 总被引：2，自引：0，他引：2
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。 相似文献
23.
The discontinuous variation in male mating behaviour is termed alternative mating tactics. A distinction is commonly made between alternative mating tactics that are fixed for life or flexible with simultaneous or sequential switches between tactics over the sexually mature life. Freshwater species of the genus Macrobrachium demonstrate flexible tactics with sequential (i.e. developmental) switch between tactics. Sexually mature populations of the commercially important giant freshwater prawn M. rosenbergii consist of three morphologically and behaviourally distinct male morphotypes: small males, orange claw and blue claw males, representing (respectively) successive stages in the developmental pathway of sexually mature males. The dominant blue claw males secure mating by guarding receptive soft‐shelled females with their long chelipeds while the subordinate SM use an alternative tactic of sneak mating to fertilize females. Current knowledge of the mating behaviour and reproductive success of these male morphotypes, including male competition over females, female mate choice and the involvement of pheromones, is reviewed. So far, the occurrence of distinct sexually mature male morphotypes has been described in 24 species within the genus Macrobrachium. The prevalence of distinct male morphotypes and alternative mating tactics among Macrobrachium species is discussed in view of the phylogeny of the genus, based on molecular markers. The environmental and genetic determination of the male morphotypes is discussed, as well as the evolution of the developmental alternative mating tactics in the genus Macrobrachium. Possible implications for prawns’ aquaculture and future research are suggested. 相似文献
24.
25.
杂交青虾“太湖1号”苗种在池塘养殖中的适宜放养密度 总被引：1，自引：0，他引：1
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。 相似文献
26.
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... 相似文献
27.
Penaeus merguiensis densovirus (PmergDNV) is currently present on several Queensland prawn farms culturing Penaeus merguiensis. Densoviruses have been linked to mortality and stunting that has caused significant financial loss to prawn farms in Asia. A histopathological study for PmergDNV was initially undertaken to compare broodstock to grow out factors from 60 broodstock animals from each of 22 ponds. There was a significant negative correlation (r = -0.61) between the number of animals with PmergDNV lesions and healthy animals. Furthermore, a higher number of septic hepatopancreatic tubules was correlated (r = 0.48) to high PmergDNV loads. Hence, a polymerase chain reaction analysis of 10-day-old post-larvae (PL) was conducted to determine whether PmergDNV infection was resulting in production losses. An attributable risk analysis of PL from 190 ponds over a 2-year period revealed that 28-29% of ponds with below average survival will have at least average survival following the removal of or decreased levels of PmergDNV. P. merguiensis culture facilities in Queensland should have at least a 14.5% increase in production, equating to an increase of $2.25 million within the first year alone, following the removal or reduction of PmergDNV in their ponds. Hence, focussing efforts on prevention, better management practices and maintaining healthy stock should be of top priority. 相似文献
28.
用对虾的致病病毒人工感染克氏原螯虾 总被引：20，自引：1，他引：20
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 相似文献
29.
Steven L. Slattery David J. Williams Caterina Torrisi 《Journal Of Aquatic Food Product Technology》2013,22(3):284-293
Industry acceptance of alternative sulphite treatments for preventing blackspot in prawns is limited. This study demonstrated that dipping prawns (Penaeus monodon and Fenneropenaeus merguiensis) in a less concentrated solution for longer times provides better control of blackspot formation than the recommended 2 minute dip in 50 mg/L 4-hexylresorcinol. Protection improved as modified dipping times and solution concentrations increased. Blackspot protection provided by most of the modified dip methods was more effective than a 1 minute dip in 1% sodium metabisulphite. The recommended 2 minute dip method should be limited to 125 kg when used on consecutive 25-kg batches of prawns. Yields increased by less than 10% even after 72-hour exposure in the modified dip. The new dipping method meets most international residue standards when applying the modified treatments evaluated. 相似文献
30.
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. 相似文献