养殖密度对循环水系统中大菱鲆(Scophthalmus maximus)生长的影响

将初始体重为(580.9±44.65)g的大菱鲆成鱼按照低密度A组14.30 kg/m2、中密度B组20.49 kg/m2、高密度C组31.32 kg/m2的标准分为3个不同养殖密度组,并放养于循环水养殖系统中120 d,同时对大菱鲆成活率、体重差异、饵料系数、溶菌酶水平及养殖水体中总氨氮(TAN)、亚硝酸氮(NO2--N)、COD浓度的变化进行测定。研究表明,实验结束时A、B、C三组大菱鲆养殖密度分别达到30.09、41.30、60.07 kg/m2,各实验组成活率都在95%以上。大菱鲆养殖密度对增重率的影响主要体现在研究前期,并且随着养殖密度的增加,各实验组体重差异度出现显著变化(P0.01)。大菱鲆A、B、C组的饵料系数分别为0.73、0.75、0.82,与养殖密度呈正相关。研究开始第5天,高密度组大菱鲆溶菌酶水平升高,20 d后血液溶菌酶水平逐渐降低,40 d之后显著低于低密度组。研究期间系统运行稳定,循环水养殖大菱鲆的不同密度对系统各项水质指标总氨氮(TAN)、亚硝酸氮(NO2--N)、COD浓度的变化有显著影响(P0.05)。研究结果显示,随着养殖密度的升高,各项水质指标显著升高,但高密度组各项水质指标均未超过渔业水质标准所规定的浓度。     

不同水循环率对大菱鲆生长和水质的影响研究

研究了封闭循环水养殖系统中不同水循环率对大菱鲆(Scophthalmus maximus)生长和水质变化的影响。试验设置4个水循环率梯度12,24,36,48次/d,大菱鲆初始平均体重为200.36 g。经43 d养殖,12次/d组大菱鲆最终平均体重为277.98 g/尾,而48次/d组达到了296.24 g/尾;12次/d组水体氨氮(TAN)和亚硝酸盐氮(NO2--N)浓度分别为0.41~1.50 mg/L和0.12~0.38 mg/L,而48次/d组分别为0.33~0.56 mg/L和0.05~0.09 mg/L。试验结果显示,提高水循环率可降低系统中氨氮和亚硝酸盐氮的积累速度,优化养殖水质,减小水中有害物质对大菱鲆的胁迫作用,从而加快大菱鲆的生长速度,但对化学需氧量(COD)的去除没有显著影响。     

封闭循环水系统中养殖密度对大菱鲆生长和免疫的影响

研究了大菱鲆幼鱼在封闭循环水系统中养殖密度对其摄食、生长、饲料利用率及免疫机能的影响。实验设计了4组不同处理,初始养殖密度分别为0.66 kg/m2、1.26 kg/m2、2.56 kg/m2、4.00 kg/m2,每个密度组设3个重复,为期100 d,实验结束时养殖密度分别为4.67 kg/m2、7.25 kg/m2、14.16 kg/m2、17.77 kg/m2。结果表明:大菱鲆生长速度与养殖密度呈负相关,各实验组的持定生长率(SGR)值分别为2.67、2.33、2.29、1.98;随着养殖密度的增加,各实验组大菱鲆的体重差异度出现显著变化(P<0.01);大菱鲆的饵料系数与养殖密度呈正相关,实验组1的饵料系数为0.70;实验组4的饵料系数为0.76;养殖密度对大菱鲆的免疫指标碱性磷酸酶(AKP)、酸性磷酸酶(ACP)及肝脏的脏器系数的影响不大。本实验结果可为鱼类循环水工厂化养殖管理提供参考。     

拥挤胁迫对已接种疫苗的大菱鲆部分免疫和应激指标的影响

通过对3个养殖初始密度(低、中、高密度组分别为5、10、20 kg/m~2)的大菱鲆(Scophthalmus maximus)接种减毒迟缓爱德华氏菌疫苗,观察其血液、脾脏、头肾、鳃和皮肤中部分免疫和应激指标的变化规律,研究经接种疫苗操作后大菱鲆应对拥挤胁迫的应激响应。结果显示,低密度养殖的白细胞介素(1L-1β)、补体(C3)、免疫球蛋白M(IgM)、溶菌酶(LZM)和肿瘤坏死因子(TNF-α)等免疫指标显著高于中、高密度组(P0.05),高密度组血液中皮质醇的含量高于中、低密度组(P0.05);通过基因表达分析发现,高密度组的热休克蛋白(HSP70)表达量显著高于中、低密度组;低密度组的免疫球蛋白M(IGM)表达量高于中、高密度组。研究表明,为提高大菱鲆的免疫效果、减少应激反应,可以采用低密度(5 kg/m~2)养殖。     

叶轮气浮装置设计及其在海水循环水养殖系统中的净化效果

为使气浮分离技术在工厂化循环水养殖水处理中的应用更加优化与规范化,改善气浮分离法的集成应用效果,通过优化设计适于循环水养殖水处理需求的各零部件,组装成叶轮气浮装置,集成应用于石斑鱼海水(盐度15)循环水养殖系统中。水质检测结果显示,进气量10 m3/h、水力停留时间(HRT)25 min是本实验叶轮气浮装置的最佳运行工况;最佳工况下,本叶轮气浮装置对总悬浮颗粒物(TSS)、总氮(TN)、化学需氧量(COD)、总氨氮(TAN)和亚硝酸盐氮(NO2--N)的平均去除率分别为42.13%、35%、32.69%、10.27%和7.64%,最高去除率分别为46.76%、40%、38.31%、14.04%和13.87%。研究表明,叶轮气浮装置能通过泡沫分离去除有机物,同时降低水体中的COD和TN水平,而对溶解性的TAN和NO2--N去除效果较差。     

不同放养量与水交换率对大菱鲆幼鱼的养殖效果及水质条件的影响

经过 6 0d的试验养殖 ,在每日 2、 4、6个循环水量的条件下 ,研究放养量从 0 .74～ 1.99kg/m2 大菱鲆 (Scophthalmusmaximus)幼鱼的平均体重增长、养殖成活率、饵料系数和养殖水中的溶解氧、氨氮含量等养殖生态状况。结果表明 ,日水循环量为 2个全量时 ,放养量为 1.5 4kg/m2 的实验组的平均体重增重与放养量低的实验组 (0 .75kg/m2 、1.0 1kg/m2 、1.31kg/m2 )平均体重增重无显著差异 (P >0 .0 5 ) ,而与高于此实验组 (1.74kg/m2 、1.99kg/m2 )的增重比较则差异显著 (P <0 0 5 ) ;水循环量的增加可以改善水质条件 ,加快幼鱼的生长速度 ,但对幼鱼的饵料系数影响不大。     

工厂化养殖条件下大鲵适宜养殖密度的研究

在工厂化养殖条件下,研究了养殖密度对2~5龄大鲵(Andrias davidianus)摄食与生长的影响。结果表明:2龄大鲵适宜养殖密度为27尾/m2,该组特定生长率显著高于9尾/m2组、18尾/m2组(P<0.05),且饵料系数最低;当养殖密度为17尾/m2时,3龄大鲵的增重率、特定生长率最大,饵料系数最低且与低密度5尾/m2组差异显著(P<0.05),确定3龄大鲵的适宜养殖密度为17尾/m2;4龄大鲵特定生长率的最大值出现在养殖密度为10尾/m2,显著高于16尾/m2组(P<0.05),且饵料系数最低,4龄大鲵的适宜养殖密度为10尾/m2;5龄大鲵的适宜养殖密度为5尾/m2,特定生长率与高密度组9尾/m2差异显著(P<0.05),饵料系数最低。大鲵适宜养殖密度与体重存在显著的负相关性,关系式为y=-0.016 4x+25.34(r2=0.839 9)。     

循环水养殖半滑舌鳎成鱼摄食活动对主要水质因子的影响

在封闭循环水养殖条件下,半滑舌鳎(Cynoglossus semilaevis Günther)的平均养殖密度(15.07±0.22)kg/m3,观测半滑舌鳎的呼吸频率,检测养殖水体中溶氧、氨氮、亚硝酸氮等24 h内摄食和代谢的变化规律。结果表明:(1)半滑舌鳎摄食前、后的呼吸频率平均值分别为27.3次/min和34.7次/min,摄食后的呼吸频率显著高于摄食前;(2)投喂前、后2.5 h内,水中溶氧一直处于下降趋势,在摄食2.5 h后,水中溶氧处于稳定的上升趋势;(3)投喂后,氨氮、亚硝酸氮浓度显著增高,2.5 h后达到峰值,随后缓慢降低,在下次投喂前0.5 h达到最低值。说明半滑舌鳎摄食活动对循环水养殖水质的影响呈现规律性,也说明循环水养殖模式可以满足半滑舌鳎对水质的基本要求。     

臭氧前后置工艺变化对循环水半滑舌鳎养殖系统水环境的影响

为了进一步优化封闭式循环水处理的系统工艺和运行参数,通过循环水养殖半滑舌鳎(Cynoglossus semilaevis)的试验手段,将循环水处理系统工艺中的臭氧投加位置进行前置与后置的比较分析,探讨臭氧工艺变化对半滑舌鳎循环水养殖系统水环境的影响.结果显示,养鱼池进水口化学需氧量(COD)浓度都随着氧化还原电位(ORP)的增加而降低,臭氧后置比前置COD浓度下降更快,在ORP达到356 mV时,COD浓度降低29.38％;养鱼池进水口的氨氮、亚硝酸氮浓度后置低于前置;随着臭氧添加浓度的增加,系统对COD、氨氮、亚硝酸氮的去除率都显著增加(P＜0.05),且当达到356 mV时,后置时系统对COD、氨氮、亚硝酸氮的去除率达到最大分别为34.89％、50.63％、20.64％.结果表明臭氧最佳的投加位置在循环水处理工艺的后端,臭氧投加量控制在ORP指标350 mV时,对氨氮、亚硝酸氮的去除效果更具优势,并可清新水质,节省纯氧用量.     

循环水养殖大菱鲆试验

通过循环水养殖大菱鲆,养殖250 d后大菱鲆平均体重550 g,平均日增重2.3 g,饵料系数1.1。循环水养殖大菱鲆,既能减少环境污染,又能节水、节煤、节电,1000 m2养殖面积能降低生产成本近10万元。     

养殖密度对温室湿地循环水系统中鲫生长、生理及免疫指标的影响

研究了基于两级人工湿地的温室循环水系统中,养殖密度对鲫（Carassius cuvieri）生长、脏器系数、血清生理免疫指标及对嗜水气单胞菌（Aeromonas hydrophila）抵抗力的影响。试验设2 kg·m^-3、4 kg·m^-3、8 kg·m^-3和16kg·m^-3共4种密度组,每组2个平行,养殖68 d。结果显示：1）各养殖密度下鲫生长及脏器系数不存在显著差异;2）与2 kg·m^-3组鲫相比,16 kg·m^-3组鲫血清丙二醛（MDA）质量摩尔浓度显著升高,溶菌酶（LSZ）、酸性磷酸酶（ACP）和碱性磷酸酶（AKP）活性显著降低,超氧化物歧化酶（SOD）活性和总蛋白质量浓度虽有不同程度升高,但差异不显著;3）高密度组鲫对嗜水气单胞菌的抵抗力较低密度组弱。以上结果表明,如果以生长为考量指标,温室湿地循环水系统中鲫养殖密度可达16 kg·m^-3,但如此高的密度会对鲫免疫力造成负面影响。     

全封闭循环水养殖系统中养殖密度对钝吻黄盖鲽生长的影响

为了评估全封闭循环水养殖系统中养殖密度对钝吻黄盖鲽生长的影响及水质变化情况,将体质量为(250.00±50.83)g的钝吻黄盖鲽分成8个试验组(放养密度分别为18、22、26、30、34、38、42、46 kg/m³),进行了3个月的饲养试验,检测不同养殖密度下鱼的成活率、体质量增长率及饲料系数,同时对试验期间氨氮、亚硝酸盐和溶解氧等各项水质指标的动态变化进行监测。试验结果显示,各试验组鱼的成活率均达到96%以上,但随着养殖密度的增加,钝吻黄盖鲽的成活率总体呈现降低的趋势;低密度组(18 kg/m³)的体质量增长率最高,为36.1%,高密度组(46 kg/m³)的体质量增长率最低,为24.8%,且体质量增长率随着养殖密度的增加而逐渐降低;随着养殖密度的增加,饲料系数呈逐渐升高的趋势;养殖期间各项水质指标均保持在适宜钝吻黄盖鲽生长的范围内。结果表明,在本试验的循环水养殖系统中,综合考量养殖生长指标及单位面积产量,钝吻黄盖鲽规模化生产的最适养殖密度为42～46 kg/m³。     

循环水养殖系统生物滤器负荷挂膜技术

循环水养殖系统启动运行前往往需要经过一段时间的生物膜预培养,使生物膜达到成熟稳定,从而保证系统的水质净化功能。本研究通过养殖试验,研究了生物滤器负荷挂膜的技术方法,以期实现生物膜的快速成熟和系统的快速启动。为此,构建了6组循环水系统组成的养殖车间,建成后立即投入试验生产。试验为期120 d,养殖种类为红鳍东方鲀,初始放养平均体重(632.5±2.26)g。期间,红鳍东方鲀平均增重29.91%,养殖成活率98.7%,养殖密度由(19.34±1.89)kg/m3增加到(32.17±3.40)kg/m3,投饵率由0.2%增加到0.5%–0.7%,每日换水量由50%逐渐减至10%。结果表明,在生物膜的生长期,通过对投饵量及新水补充量的有效调节,可以把养殖水体中的氨氮和亚硝氮浓度控制在安全范围以内,以保证养殖鱼类的生长。生物膜在50天左右达到完全成熟,此后便可依靠生物膜的净化作用将氨氮浓度控制在0.5?1.2 mg/L、亚硝氮浓度控制在0.2?0.5 mg/L、pH值控制在6.5–7.5、COD值低于4 mg/L、细菌总数控制在800–2100 cell/ml的安全范围内。利用生物滤器负荷挂膜技术,在合理调控水质指标的条件下,循环水养殖系统建成后可以立即投入生产,实现生物滤器挂膜与养殖生产的同步进行。     

Production Characteristics, Water Quality, and Costs of Producing Channel Catfish Ictalurus punctatus at Different Stocking Densities in Single-batch Production

Channel catfish Ictalurus punctatus farming is the largest component of aquaculture in the USA. Culture technologies have evolved over time, and little recent work has been conducted on the effects of stocking density on production characteristics and water quality. Twelve 0.1‐ha ponds were stocked with 13‐ to 15‐cm fingerlings (16 g) at either 8600, 17,300, 26,000, or 34,600 fish/ha in single‐batch culture with three replicates per treatment. Fish were fed daily to apparent satiation with a 32% floating commercial catfish feed. Nitrite‐N, nitrate‐N, total ammonia nitrogen (TAN), total nitrogen, total phosphorus, chemical oxygen demand (COD), Secchi disk visibility, chlorophyll a, chloride, total alkalinity, total hardness, pH, temperature, and dissolved oxygen (DO) were monitored. Ponds were harvested after a 201‐d culture period (March 26, 2003 to October 13, 2003). Net yield increased significantly (P < 0.05) as stocking density increased, reaching an average of 9026 kg/ha at the highest density. Growth and marketable yield (>0.57 kg) decreased with increasing stocking density. Survival was not significantly different among densities. Mean and maximum daily feeding rates increased with density, but feed conversion ratios did not differ significantly among treatments (overall average of 1.42), despite the fact that at the higher stocking densities, the feeding rates sometimes exceeded 112 kg/ha per d (100 lb/ac per d). Morning DO concentrations fell below 3 mg/L only once in a 34,600 fish/ha pond. Concentrations of chlorophyll a, COD, nitrite‐N, and TAN increased nominally with increasing feed quantities but did not reach levels considered problematic even at the highest stocking densities. Breakeven prices were lowest for the highest stocking density even after accounting for the additional time and growth required for submarketable fish to reach market size. While total costs were higher for the higher density treatments, the relatively higher yields more than compensated for higher costs.     

Effect of Stocking Density on Growth,Physiological Responses,and Body Composition of Juvenile Blunt Snout Bream,Megalobrama amblycephala

The impact of stocking density on growth performance, physiological indicators, and body composition of juvenile blunt snout bream in recirculating aquaculture system was investigated in this study. Juvenile blunt snout bream were raised at stocking densities of 75, 150, 225, 300, and 450 fish/m³ for 12 wk with three replicate tanks at each density. All treatment tanks were supplied with water from the same recirculating system to ensure uniformity of water quality across groups. This study has shown that higher stocking densities had a negative effect on individual growth performance. Final body mass, specific growth rate (SGR), and weight gain decreased significantly as stocking density increased. Individual body mass as well as body length were more uniform in fish stocked at densities of 75 and 150 fish/m³ than in other groups. Stocking densities of 225 and 300 fish/m³ resulted in significant increases in serum total protein, triglyceride, lactate, and cholesterol levels, whereas blood glucose concentrations decreased significantly. In addition, decreased body lipid content and increased body moisture content were observed at stocking densities of 300 and 450 fish/m³. Overall, a density of 150 fish/m³ resulted in higher SGR and more uniform size among juvenile blunt snout bream.     

添加光合细菌对糙海参幼苗培育阶段的影响研究

以受精后24h孵化出的糙海参（Holothuria scabra）耳状幼体为研究对象,探讨养殖水体不同量光合细菌对糙海参苗期生长、成活、消化道消化酶活性和养殖水体水质变化的影响。试验设4个处理,光合细菌（浓度为1×10^11cfu·mL^-1）添加量分别是0m L（组1,对照组）、50m L（组2）、100m L（组3）和150m L（组4）,每个处理设3个重复,每个重复放养4×10^4尾幼体于室内水泥池（5m×3 m×1.5m）中,试验周期为41 d。结果表明,添加光合细菌组的糙海参出苗体质量和成活率均显著高于对照组（P〈0.05）,而组3和组4的体质量和成活率又明显优于组2（P〈0.05）,组3和组4之间的差异不显著（P〉0.05）。添加光合细菌还能不同程度地影响糙海参苗体消化道蛋白酶、淀粉酶和纤维素酶的活性,试验组3种酶的活性均显著高于对照组（P〈0.05）,而组3和组4的蛋白酶活性和纤维素酶活性显著高于组2（P〈0.05）,淀粉酶活性在3个试验组之间无显著差异（P〉0.05）。在试验第10天后,各试验组氨氮（NH3-N）和亚硝酸盐含量显著低于对照组（P〈0.05）,在试验第20天后,各试验组化学需氧量（COD）的值显著低于对照组（P〈0.05）,而总磷（TP）的差异不大（P〉0.05）。表明光合细菌可以促进糙海参幼体的生长,提高消化酶活性和成活率,并改良育苗水体水质。     

Moderate stocking density does not influence the behavioural and physiological responses of rainbow trout (Oncorhynchus mykiss) in organic aquaculture

Welfare in farmed fish got particular attention during the last decades from both governmental and public sides. In aquaculture context, welfare concerns are mainly related to handling procedures, water quality and stoking densities. In Europe, authorities had to clarify the threshold limits of stocking densities to maintain fish good welfare, including for organics aquaculture through the EC regulation 710/2009. However, effects of stocking density on fish welfare are complex and sometimes contradictory. Moreover, there is a lack of knowledge about the impact of density on fish welfare in organic aquaculture. Thus, the aim of the study is to asses welfare state of rainbow trout (Oncorhynchus mykiss) at two initial stocking densities (low density, LD: 12 kg/m³ and high density, HD: 17 kg/m³) fed using organic feed by combining the monitoring of growth performances, behaviour (swimming activity) and physiological indicators (i.e. cortisol, glucose, lactate, hematocrit, red blood cellule count and lysozyme). At the end of experiment, the stocking density reached 21 kg/m³ and 30 kg/m³ for the LD and HD respectively. Overall, growth performances, swimming activity and level of physiological indicators of stress and welfare were similar between HD and LD over the experiment duration. To conclude, we observed no alteration of fish welfare between the two stocking densities monitored. This study suggests that a final stocking density of 30 kg/m³ can be considered for organic aquaculture of rainbow trout respecting welfare.     

Effects of Dietary Nutrient Density on Water Quality and Growth of Red Drum Sciaenops ocellatus in Closed Systems

A 10-wk growth trial was conducted to determine the effects of dietary nutrient density (protein and energy) on the growth of red drum Sciaenops ocellatus and on water quality in closed recirculating systems. Four test diets, with increasing nutrient density, were formulated to contain 32%, 36%, 40%, and 44% protein and 3.4, 3.5, 3.6 and 3.8 kcal/kg energy, respectively. In addition to growth, total ammonia-nitrogen (TAN), nitrite-nitrogen, nitratenitrogen, biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), total suspended solids, net solids accumulated and total phosphorus were measured periodically throughout the study. Significant differences in weight gain and total biomass corresponded to increasing dietary nutrient density. Feed efficiency ratios and protein conversion efficiencies increased with increasing nutrient density of the diet indicating the production of fewer waste products per unit gain. Accumulated waste (net solids accumulated expressed as g/kg of fish) decreased with increasing dietary nutrient density. Additionally, there was a significant decrease in COD and suspended phosphorus with increasing dietary nutrient density. TAN, nitrate-N and BOD₅ showed no significant trends presumably due to the ability of the biological filter to process these nutrients. Based on the observed results, manipulation of dietary nutrient density can reduce metabolic wastes and at the same time improve fish growth in an aquaculture system.     

An experimental study on nitrification biofilm performances using a series reactor system

Total ammonia nitrogen (TAN) concentration is often a key limiting water quality parameter in intensive aquaculture systems. Removing ammonia through biological filtration is thus the first objective in recirculating aquaculture system design. In this study, the performance characteristics of a steady-state nitrification biofilm were explored using a series of reactors. Four nitrification kinetics parameters were estimated using the data collected from the experimental system, including minimum TAN concentration, half saturation constant, maximum TAN removal rate and maximum specific bacterial growth rate. Experimental data showed that a minimum TAN concentration was needed to support a steady-state nitrification biofilm. For the temperature of 27.2°C, the mean minimum TAN concentration was 0.07 mg/l. For a single substrate-limiting factor, the relationship between TAN removal rate (R) and TAN concentration (S) was represented by an empirical equation [R=1859(S−0.07)/(S+1.93)]. The characteristics of nitrite oxidation were also demonstrated by the experiment system. The results of this study will help to better understand the characteristics of nitrification biofilters applied in recirculating aquaculture systems.     

三角帆蚌对综合养殖水体水质及鱼蚌生长的影响

在草鱼(Ctenopharyngodon idellus)养殖池中进行鱼蚌综合养殖试验,以探究三角帆蚌(Hyriopsis cumingii)吊养密度和深度对水质、鱼和蚌生长的影响。试验共分4个处理组,三角帆蚌放养模式分别为对照组0只/m^3(C)、水下40 cm处单层吊养9只/m^ 3(D-6)、水下40 cm处单层吊养18只/m^3(D-12)、水下40 cm和80 cm处双层吊养18只/m^ 3(S-12)。结果显示:试验期间,各组透明度和溶氧均随时间的延长呈现下降趋势。吊养组(D-6、D-12、S-12)TN、NH+4-N和COD的平均含量均低于C组。各组TP平均含量无显著差异。吊养三角帆蚌后草鱼的成活率和增重率显著提高,其中D-12组鱼和蚌的存活率和增重率最高。同等三角帆蚌密度下,单层吊养(D-12)的水质化学指标、鱼和蚌的存活率和增重率均优于双层吊养(S-12)。从改善水质、鱼蚌生长情况等指标考虑,在草鱼养殖池中,三角帆蚌最佳吊养密度和深度分别为18只/m^3和40 cm。