大菱鲆南移网箱养殖试验

本文报道了大菱鲆鱼种南移网箱养殖试验结果,并探讨了其网箱养殖前景。在水温12~22℃,盐度26~28,pH值7.9~8.1条件下,平均体重168g的大菱鲆鱼种经3个多月养殖达到商品鱼规格(平均体重556g),大菱鲆鱼种运输成活率98.3%,养殖成活率95.5%。     

养殖大菱鲆使用甲醛残留状况研究

试验针对工厂化养殖大菱鲆大量使用甲醛的现状,研究使用甲醛后对大菱鲆食用安全性的影响。主要通过测定用药后不同时间大菱鲆体内的甲醛残留量,探索甲醛在大菱鲆可食部分中的残留状况。研究发现,用药初期甲醛在大菱鲆体内会有一定量残留,但随时间延长残留量不断下降,在一定时间后大菱鲆可食部分甲醛残留量可以达到未检出水平。试验结果提示,大菱鲆工厂化养殖规范化使用甲醛,在第8天可以达到未检出水平,不会影响产品可食部分。     

A sandwich ELISA to detect VHSV and IPNV in turbot

The recent demonstration that reared turbot (Scophthalmus maximus L) is a natural host for salmonid rhabdoviruses has made their rapid detection relevant to these fish species. A unique protocol to select and use non-competitive monoclonal antibodies (Mabs) for two high-sensitivity sandwich ELISAs has been developed to detect both infectious pancreatic necrosis virus (IPNV) and viral haemorrhagic septicaemia virus (VHSV) in turbot kidney extracts to assess the possibility of using them in field diagnosis. For maximum sensitivity, turbot kidney extracts can be two-fold diluted with high-ionic strength buffers and assayed for the presence of the major viral proteins (VMS rhabdovirus nucleoprotein N/Nx and/or IPN birnavirus protein VP3). The use of control plates coated with irrelevant mouse antibodies (IgG1 and IgG2a) in parallel ELISAs allows for a precise estimation of possible false positives. Turbot kidney extracts with low levels of virus might now be assayed directly without using cell culture, with high precision and in a short time during the acute phase of these viral diseases in reared turbot.     

Growth and gonadal development in diploid and triploid turbot (Scophthalmus maximus)

This study determined the effect of triploidy on the survival, growth and gonadal development of turbot from 6 to 48 months of age. From 6 to 24 months of age (first sexual maturity), survival was similar in both ploidies (P > 0.05). From 24 to 48 months of age, after the first sexual maturity, survival was 91.9% in diploids and 100% in triploids, which did not exhibit the post-spawning-associated mortality. Growth was similar for both ploidies during the first year of life. After that, triploids grew significantly (P < 0.05) more that diploids, with more marked differences after each spawning season. From 24 to 48 months, the average weight difference between both ploidies was 11.4 ± 1.9%, ranging from 4.3 to 23.0%. At 47 months of age, the biomass of triploids was 10.3% greater in total weight and 14.3% greater in eviscerated weight. Gonads of triploid males were similar to that of diploids, whereas in triploid females, they were significantly smaller and rudimentary. A histological analysis carried out at 47 months of age showed complete sterility of triploids in both sexes. Sex ratio was 1 male (M):0.6 female (F), for diploids, significantly (P < 0.05) different from 1:1, and 1 M:3.3 F for triploids, significantly (P < 0.05) different from 1:1 and from the diploids. Since females grow more than males, culture of triploids benefited from the high female ratio, which helped to reduce size dispersion. In addition, their sterility allowed better performance by avoiding the reduction in growth that takes place during the spawning periods. Together, these observations indicate that triploidy induction can be an interesting option for turbot aquaculture, especially for the production of large-size fish of more than 2 years of age.     

Microbially matured water: a technique for selection of a non-opportunistic bacterial flora in water that may improve performance of marine larvae

Before transfer to larval incubators, water was membrane filtered to remove >95% of the bacteria and then transiently maintained in a biofilter that promoted recolonization of the water by non-opportunistic bacteria. The process is termed microbial maturation of the water. Hypothetically the bacterial flora in the matured water should protect the marine larvae from colonization and proliferation by opportunistic bacteria. Testing of the hypothesis demonstrated 76% higher survival of yolk sac larvae of Atlantic halibut (Hippoglossus hippoglossus) in matured than in membrane filtered water. Proliferation of opportunistic bacteria was observed in the rearing water after hatching of turbot eggs (Scophthalmus maximus), but to a less extent in the microbially matured water. In the early phase of first feeding of turbot larvae, the matured water induced qualitative differences in the gut microflora. Significantly higher initial growth rate of the turbot larvae in the matured water affected 51% higher average weight of 13 days old larvae than in membrane filtered water. Algal addition to the matured water enhanced the larval growth further. The experiments conducted supported the proposed hypothesis that microbial maturation selects for non-opportunistic bacteria, which protects the marine larvae from proliferation of detrimental opportunistic bacteria.     

米曲霉AS 3.951发酵豆粕对大菱鲆摄食生长的影响

以初始平均体重2.07 ± 0.02g的大菱鲆（Scophthalmus maximus L.）为实验对象,进行为期70 d的摄食生长实验,研究不同添加水平的发酵和未发酵豆粕对大菱鲆摄食生长的影响。用米曲霉（Aspergillus oryzae）AS 3.951对豆粕进行固态发酵。经检测,与未发酵豆粕相比较,发酵豆粕中胰蛋白酶抑制因子、植酸、大豆皂甙、水苏糖和棉籽糖的含量分别下降了46.5％,26.6％、11.7％、30.1％和19.7％。实验共制作6种等氮等能的饲料,其中以全鱼粉饲料为对照饲料;未发酵豆粕蛋白分别替代25％、40％和55％的鱼粉蛋白;发酵豆粕蛋白分别替代40％和55％的鱼粉蛋白。结果表明,饲料中添加一定量的豆粕对大菱鲆的成活率没有显著的影响（P>0.05）。饲料中未发酵豆粕蛋白替代鱼粉蛋白的水平为25％时,对大菱鲆的摄食率、特定生长率、饲料效率和蛋白质效率均没有显著的影响,但替代水平为40％和55％时,以上指标显著降低（P<0.01）。饲料中发酵豆粕替代水平为40％时,未降低大菱鲆的摄食率、特定生长率、饲料效率和蛋白质效率,替代水平为55％时,显著降低大菱鲆的摄食率和特定生长率（P<0.01）。     

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。     

饲料中不同种类的碳水化合物对大菱鲆生长性能和代谢反应的影响

为探讨在低蛋白水平(40%)下,饲料中不同种类的碳水化合物(葡萄糖、蔗糖和糊精)对大菱鲆幼鱼[(8.12±0.04)g]生长、成活、饲料利用、体组成和血液生理生化指标等的影响,实验在对照组饲料中未添加可消化碳水化合物,含40%的蛋白质和18%的脂肪,然后在对照组饲料的基础上,调节脂肪水平为12%,分别添加15%的葡萄糖、蔗糖和糊精配制3组实验饲料。在流水式养殖系统中进行9周的大菱鲆生长实验。结果显示,各处理组大菱鲆成活率均高于95.24%,并且各组间无显著差异;对照组和糊精组大菱鲆的增重率(WGR)和特定生长率(SGR)均显著高于葡萄糖组和蔗糖组。各组间的日摄食率(DFI)没有显著差异。对照组和糊精组饲料效率(FE)显著高于蔗糖组,但葡萄糖组FE与其它各组无显著差异;各处理组间蛋白质和脂肪表观消化率(ADC)未受碳水化合物种类的显著影响,而可消化碳水化合物的ADC依次为:葡萄糖组>糊精组>蔗糖组(。葡萄糖组的能量ADC最高,蔗糖组的最低;除对照组肌肉脂肪含量显著高于其它各组外,碳水化合物的种类对大菱鲆肌肉常规组成及糖原含量无显著影响,但显著影响了肝脏的脂肪和糖原含量。大菱鲆肝脏脂肪含量依次为对照组>糊精组>蔗糖组>葡萄糖组,肝脏糖原含量依次为葡萄糖组>蔗糖组>糊精组>对照组;不同碳水化合物种类对大菱鲆幼鱼血浆葡萄糖含量没有显著影响,但显著影响血浆总氨基酸、胰岛素、总胆固醇(CHO)和甘油三酯(TAGs)的含量。结果表明,本实验条件下,大菱鲆对糊精的利用效率优于葡萄糖和蔗糖,并且不同种类的碳水化合物通过糖脂关联代谢等途径对大菱鲆幼鱼的体组成和血液生理生化指标造成一定的影响。