斑节对虾水质因子耐受性研究

在室内条件下进行了斑节对虾短期内对水温、盐度、pH、低氧的耐受性实验。结果表明:该虾类对这几个主要水质因子的耐受能力强。当水质因子呈渐变时,虾对水温、盐度、pH 的耐受极限分别 T:16～39℃,S:2～55‰,pH:6.71～9.04;而在急变情况下,虾对这些参数的耐受性减弱。该虾对低氧的耐受性随不同温、盐度而定,在适宜的温、盐度范围内(T:25～30℃,S:20～35‰),虾对低氧的耐受性最强,此时致死溶解氧的临界值为0.5～1.5ppm,在其它温、盐度,溶解氧为0.9～2.75ppm 时虾即发生侧倒,表明此时对低氧的耐受性下降。     

罗氏沼虾的养殖技术

八、其它养殖方式养殖罗氏沼虾除了采用一般池塘养殖方式外，还有工厂化养殖、网箱养殖、稻田养殖及河道养殖等方式。现分别予以简介：１．工厂化养虾工厂化养虾就是水温、水质、溶氧量等都在人为控制下不受自然干扰，应用全价颗粒饲料，投饲、管理达到高度机械化，单位水体内虾产量较高的一种养虾方式。（１）工厂化养虾的设施　　养虾池、贮水池、加温池和水质净化设施。（２）工厂化养虾的方法①放养　　一般采用３～４级放养方法，每级养殖１个月左右，第一级（淡化苗养至２～３ｃｍ），放养密度２０００～３０００尾／ｍ２，二级（３ｃ…     

罗氏沼虾养殖的几点误区

近期，作者走访了珠江三角洲的养虾区，发现在罗氏沼虾养殖过程中存在不少误区，现对较为普遍的问题总结如下。 1水质管理的误区 1.1投苗早期水质不肥 清塘后，水质还没有培肥，就急于投苗。由于池塘水体偏瘦，可供幼虾摄食的生物饵料缺乏，影响幼虾的生长和成活率。 1.2换水不科学 养殖的中后期，池水过肥，虾农常常一次性大量换水 (特别是换水方便的地方 )，引起池塘的水温波动太大，影响虾的摄食和生长。 1.3 盲目加深水位 罗氏沼虾养殖的最适水深为 1.5～ 1.8 m，水体过浅，则水温波动较大，溶氧量减小，易影响虾的的生长；水体过深…     

养殖南美白对虾池塘水质调控技术

水质调控是养虾中心环节,养虾就是养水。养水牵涉到方方面面,是一项综合性的系统工程。1良好水质理化因子指标1.1水色黄绿色或茶褐色。1.2透明度30～45 cm。1.3水温18～40℃,最适28～35℃。1.4盐度0～40,最适5～25,日变化不得超过5,在淡     

养殖南美白对虾池塘水质调控技术

水质调控是养虾中心环节，水既可养虾，又可灭虾。水质良好大大地提高成功率，水质恶化虾易发病，甚至全军覆灭。因此，要科学养虾必须首先掌握水质调控技术，创造良好生存环境，同时切断病害水平传播。笔根据多年养虾经验．撰供广大虾农参考。     

对虾养殖的水质管理

俗话说“养虾先养水”,水环境是对虾赖以生存的基础条件,管理好水质,是养虾成功的关键。即墨市对虾养殖经过了十几个春秋,有成功的经验,也有失败的教训。为了使养虾业能稳定、健康地发展,笔者及时总结对虾养殖户多年来的养虾生产实践,探讨形成了—套在对虾养殖中水质管理方面比较成熟的做法,供大家参考。     

点带石斑鱼幼苗驯食不同饵料的初步研究

通过对平均全长2．56cm的点带石斑鱼稚鱼及平均全长3．74cm幼鱼驯食不同饵料的试验。结果是：采用鱼糜、虾浆较配合饲料易驯食;幼鱼比稚鱼容易驯食。稚鱼驯食鱼糜、虾浆需2d时间,驯食配合饲料,需3-4d的时间;幼鱼驯食鱼糜、虾浆需时1d,驯食配合饲料需2～3d的时间。驯食鱼糜、虾浆水面容易产生油膜和水质较易恶化。驯食配合饲料组的水质明显优于驯食鱼糜和虾浆组的。生长速度则驯食鱼糜和虾浆组的快于驯食配合饲料组的。     

调节水质养殖罗氏沼虾试验

广东省高要市是“中国罗氏沼虾之乡”,自2006年开始,高要市养殖户发现罗氏沼虾在养殖过程中更容易发病,即使健康的罗氏沼虾的品质也明显不如从前。肇庆市、高要市两级水产主管部门对高要市养殖的罗氏沼虾进行抽样、检测,但未能从中检出病原;而抽样检测养殖水体的水质,却发现主要水质指标氨氮、亚硝酸盐都比正常偏高,有的甚至超出几倍。水质恶化问题已经直接影响到了产业的发展。作者是高要市水产技术推广工作的一线技术员,在工作中发现本地虾农不重视水质调节工作,很多虾农不知道用什么调水,有的认识到要调水又不知道如何用好调水药物。     

土塘养殖对虾早期发病率高的原因和对策

正多年来,徐闻地区土塘养殖早造虾成功率一直很低。早造虾发病一般在放苗15～30天,很多情况是刚开始投1号料,就发现有死虾出现在料罾和病虾在塘边漫游。经过检测,发现病虾多为空肠空胃、红肝、肌肉白浊,大多是弧菌感染引起。一、原因分析1.水质不稳定早造虾养殖的水温低、气候多变,且大多数养殖户放苗前没有肥水习惯,或肥水方法不当,导致水肥得快、清得也快,引起pH高,无法维持水质稳定。     

罗氏沼虾虾塘水质综合改良措施探讨

正"十二五"期间,江苏高邮市经济开发区罗氏沼虾养殖生产发展迅速,至2015年养殖面积已达14500亩。但每年7-9月,绝大部分虾塘会出现水质老化,发生"水华",严重制约了罗氏沼虾的生长,甚至造成泛池死虾事故,水质老化问题已成为制约罗氏沼虾高产高效的"瓶颈"。近几年来,结合渔业科技入户项目工程,在试验取得较好效果的基础上,指导示范户、带动辐射户,推广应用罗氏沼虾虾塘水质综合改良措施,大大减轻了"水华"等老化水质对罗     

The effects of artificial substrate and stocking density on Pacific white shrimp (Litopenaeus vannamei) performance and water quality dynamics in high tunnel-based biofloc systems

The use of artificial substrates in shrimp aquaculture may allow for production of shrimp at increased densities while providing a growth medium for microbes that assist with water quality processes and provide supplemental nutrition for shrimp. Greenhouse-based shrimp production systems can extend the shrimp production season in temperate climates while conserving water and energy. For this study, we evaluated the effects of providing extra substrate and shrimp density on water quality and shrimp production in greenhouse-based biofloc systems. Four 11-m³, wood framed, and rubber-lined tanks were constructed in each of four high tunnel greenhouses (for a total of 16 tanks). Four treatments were evaluated: high-density stocking with substrate (HDS), high-density stocking with no substrate (HDNS), low-density stocking with substrate (LDS), and low-density stocking with no substrate (LDNS). Each treatment was randomly assigned to one tank in each tunnel to block for location. No artificial heat was used, and shrimp were grown for 120 days. High-density systems were stocked at 200 shrimp/m³ while low-density tanks had 100 shrimp/m³. Adding substrate increased total in-tank surface area by 13.4%. The addition of substrate had no significant effect on any shrimp production or standard water quality parameters. Shrimp had significantly greater final weight, faster growth rate, and lower feed conversion rate in low-density treatments (P ≤ 0.02 for all). Total shrimp biomass production was significantly higher in high-density treatments (HD: 4.0 kg/m³; LD: 2.3 kg/m³; P < 0.05). There were no significant differences in survival between densities (HD: 91.3%; LD: 94.5%; P = 0.43). Peak and overall mean nitrite levels were significantly higher in high-density treatments compared to low-density treatments. Dissolved oxygen levels and pH over the course of the study were significantly lower in high-density treatments, likely due to increased respiration rates in the water column. This project shows the feasibility of shrimp production in temperate climates with no artificial heat using high tunnel greenhouses, few impacts of added substrate on shrimp production, and increased shrimp density can result in much larger harvests with few negative impacts on production metrics.     

对虾养殖对莱州湾氮、磷、COD的贡献

整理统计了莱州湾主要有机污染物入海通量，并于1998年7月，调查了莱州湾湾顶部对虾养殖区进、排水中氮、磷及COD的浓度，初步估算出了对虾病害发生后（1993年），对虾养殖过程中排入海中COD的增量增量平均约为1173.4t/a，为黄河年排放量的0.54%，小清河年排放量的0.29%；无机氮的增量平均为45.1t/a，为黄河年排放量的1.79%，小清河年排放量的1.10%。对虾病害发生后（1993年后）莱州湾沿岸对虾养殖的有机污染较黄河和小清河小的多。     

长江河口区中国对虾养殖用水水质状况调查

１９９３、１９９４年虾病流行期间对金山、奉贤、南汇等县有关对虾养殖场养殖用水的水质理化因子进行调查的结果，水质的主要理化指标呈现相对的稳定性和明显的季节周期性，怀以往正常年份的相比，无显著差异。     

噬菌蛭弧菌预防对虾弧菌感染的应用研究

采用16S rDNA特异引物对63F和842R对蛭弧菌标准菌株Bdellovi briobacteriovorus 109-J和实验菌株Bd-9913进行了PCR鉴定,使用Bd-9913菌株分别对3株虾类病原菌溶藻弧菌Vibrio alginolysticus LS01、HF09,副溶血弧菌V．parahaemolyticus V28以及1株大肠埃希氏菌Escherichia coli CH-42进行裂解。结果表明,10^5PFU／ml的Bd-9913对于10^9CFU／ml的宿主菌具有较好的裂解效果。采用3．0×10^5PFu／mlBd109-J和Bd-9913分别与饲料混合（v／w）后投喂3．0g左右的凡纳滨对虾幼虾,14d内未发现对虾异常,且在对虾肠道内检测不到Bd109-J及Bd-9913,证明二者对于凡纳滨对虾幼虾是安全的。对正常养殖了50d的室外集约化虾池水体分别泼洒终浓度0．3mg／L的二氯异氰脲酸、0．3mg／L季胺盐络合碘和3．0×10^5PFU／ml蛭弧菌,后者对于抑制水体弧菌活菌浓度的效果明显优于化学消毒剂。当每隔20d左右分别进行一次上述水体处理,通过比较体内弧菌感染的对虾个体数,发现从肝胰腺分离到弧菌的对虾数量二者无显著差异,但从血淋巴分离到弧菌的对虾数量,蛭弧菌处理组显著少于化学消毒剂处理组,显示了蛭弧菌在预防对虾弧菌感染方面的优越性。     

Influence of sediment characteristics on shrimp physiology: pH as principal effect

Penaeid shrimp reared in earthen ponds are exposed to sediment, which can, in some instances, induce a stress. In seawater, the osmoregulatory capacity (hyporegulation) is a useful tool to compare the physiological condition of shrimp exposed to various stressors. By keeping some shrimp in cages at different locations of a single pond heterogeneous in terms of sediment quality, it was possible, using osmotic pressure (OP), to identify some locations where the stress was maximum and some others where it was minimum. Simultaneously, sediment samples were taken and analysed in order to evaluate some physico-chemical parameters that could be related to the stress observed in the shrimps kept in the cages. This approach allowed to show a significant positive correlation between the pH of the sediment surface and the shrimp osmotic pressure. This result was confirmed in a study carried out in experimental 70-l tanks, where osmotic pressure decreased significantly as water pH decreased from 7.0 to 6.5. The methodology developed in this study may be useful to evaluate the stress caused by sediment in shrimp farms.     

Characterization of water quality in shrimp ponds of different sizes and with different management regimes using multivariate statistical analysis

Coastal shrimp aquaculture in Bangladesh is mostly practiced in an agricultural unit called a Gher, which is a special type of agricultural field with elevated surrounding embankments/borders situated by the side of a river that is used to grow rice in winter and shrimp in summer. Ghers of different sizes are managed in different ways. An on-farm project was carried out to study the effects of Gher size and their related management practices on water quality, shrimp production and the economic returns of shrimp farming in the Southwest coastal region of Bangladesh. We present here the results of this project with respect to water quality as explored through factor analysis, which was applied as a way to understand the nature and extent of the effects of different variables. For the majority of the variables and factors, one-half to two-thirds of their variability was explained by changes over time (months), and a further one-quarter to one-third was explained by Gher size and associated management practices. The alternating dry/monsoon season and water management practices determined long-term and large-scale (annual) water exchange in the Ghers that mainly affected processes related to live and dead particles suspended in the water column. Processes related to decomposition and nitrification were more dependent on short-term (days) water circulation in the Ghers, which is turn was reliant on the time span between the exchanges of water in the Ghers and river. Our results show that improved management leads to higher natural and shrimp productivity in the smaller Ghers and strongly support the argument put forward by the policy makers and scientific community in Bangladesh that the smaller the Gher, the better they can be managed and the better the possibility of increased shrimp survival and production.     

Zero-water exchange shrimp farming systems (extensive) in the periphery of Chilka lagoon, Orissa, India

The extensive zero-water exchange shrimp farming system in the periphery of Chilka lagoon (Orissa, India) was studied. The study aimed to describe this unique farming system with special reference to dynamics of macrozoobenthos, production characteristics and economics. The study conducted was based on a general survey as well as monitoring of five individual farms over a complete production cycle. The farming practice in this area is characterized by complete absence of water exchange during rearing. Ponds in this area are generally shallow (mean 72 cm). Most of the water and soil quality characteristics of these farms are within acceptable levels. Macrozoobenthos belonging to 12 taxa were collected, amphipods (81%) and polychaetes (13%) being most numerous. Overall macrobenthic density of farms studied varied from 968 to 11,470 individuals/m² with a gross mean of 5644 individuals/m². There was no general pattern to the variation in abundance of various taxa in different phases of the rearing cycle, suggesting a low predatory pressure by shrimp in the farms studied. Shrimp production was highly variable (91–250 kg/ha), but generally low with a mean of 145 kg/ha. The net income of these farms was estimated to be Rs. 63,250 per crop per ha. Compared with shrimp farming system with regular water exchange in the same area, Chilka farms generated high benefit-cost ratio indicating high profitability and sustainability.     

The effects of different solids and biological filters in intensive pacific white shrimp (Litopenaeus vannamei) production systems

Biofloc systems rely on suspended solids in the water to house microbes that can remove or cycle nitrogenous wastes; however, nitrogen cycling can be inconsistent. In contrast, external biofilters are used in many recirculating systems to provide a more consistent environment for microbes to process nitrogen. Regardless of the biofiltration approach, solids levels must be controlled to prevent issues in shrimp such as gill fouling, low dissolved oxygen levels, and other negative impacts. The purpose of this study was to examine the effects of settling chambers versus foam fractionators for solids filtration and to compare external biofilters to the biofloc approach as biofiltration strategies. Sixteen 1-m³ round, polyethylene tanks were randomly assigned to four treatments, each of which had four replicate tanks. Eight biofloc systems were established: four using settling chambers for solids control (BF-S) and four using foam fractionators (BF-F). The other eight tanks used external biofilters; four had settling chambers (EB-S) and the other four had foam fractionators (EB-F). All 16 systems were stocked with 250 shrimp at an average size of 4.3 g which were grown for 85 days. There were no significant differences in shrimp production between treatments; however, variability was high in biofloc systems. Nitrite levels were significantly lower in systems with fractionators compared to systems with settling chambers. The concentrations of dissolved Na, Mg, Ca, Sr and Ba in the water were significantly reduced in treatments with settling chambers. The results of this study show that filtration choices significantly impact short- and long-term water quality and reusability but may not have much effect on shrimp production in the short-term.     

Hydrology of inland brackishwater shrimp ponds in Chachoengsao, Thailand

This study focuses on a new trend in shrimp aquaculture, the development of brackishwater ponds for Penaeus monodon culture in inland freshwater areas of Thailand’s Central Plain. Water balances were calculated for ponds and reservoirs at an inland shrimp farm in Chachoengsao, Thailand, between May and July 1999. Regulated inflow and outflow were the largest water fluxes, averaging 0.94 and 0.70 cm/day. Other daily average water gains were rainfall (0.52 cm/day) and runoff (1.7 cm/day), and other water losses were evaporation (0.31 cm/day) and seepage (0.52 cm/day). Over an entire crop cycle, of average length 109 days, average water inputs were: initial pond filling (84 cm); regulated inflow (103 cm); rainfall (57 cm); and runoff (3 cm). Average outputs were: regulated outflow (76 cm); seepage (57 cm); evaporation (34 cm); and draining at harvest (87 cm). The main feature of note in the water balance is the large volume of regulated outflow. All regulated outflow and most (82%) of the pondwater drained at harvest went directly to the irrigation canal system. Such large volumes of discharge could have serious environmental implications because small inland waterways have low assimilative capacity and pond effluent is saline. Consumptive water use for 14 inland shrimp ponds and reservoirs averaged 0.83±0.14 cm/day. Consumptive water use was also measured for 11 nearby rice fields, the main land use in the regions where inland shrimp farming is proliferating. Rice paddy water use averaged 0.91±0.17 cm/day. There was no significant difference in the daily consumptive water use of shrimp ponds and rice fields, suggesting that conversion from rice farming to shrimp farming would have little net impact on water availability for irrigation.     

Optimizing multi-stage shrimp production systems

Multi-stage penaeid shrimp grow-out systems have considerable advantage over conventional single-stage grow-out systems. A multi-stage shrimp grow-out system has more than one production stage wherein the shrimp stocking density changes as the shrimp grow in size and are moved from one production stage to the next. The shrimp stocking density (shrimp/m²) is at its highest when the shrimp post larvae enter the first production stage and is reduced each time the shrimp are transferred to subsequent stages. The use of multi-stage instead of single-stage production systems has been considered by numerous authors. This paper presents a methodology by which to select the optimum number of stages for a production system and, using available data, demonstrates that optimum efficiency can be achieved, in most cases, by using a two-stage production system consisting of a prolonged nursery stage followed by a grow-out stage.