Application of microparticle diets for Japanese flounder Paralichthys olivaceus larvae

ABSTRACT:   A feeding trial was conducted with two newly developed microparticle diets (MD-Q and MD-V), which differed in the mixing ratios of two types of casein hydrolysates (C700 and C800) as the protein source. The ratio of C700 and C800 were adjusted to 7:3 in MD-Q and 6:4 in MD-V, respectively. Japanese flounder larvae were fed from 7 days after hatching (d.a.h.) to 32 d.a.h. on live food (LF), MD solely, MD + 1/3 LF (either of the MD and one-third quantity of the live food) and 1/3 LF (one-third quantity of live food alone), respectively. They were then switched to Kyowa diet B from 33 d.a.h. until 40 d.a.h. The larvae fed on MD-Q exclusively had a higher survival rate (36.4%) than those fed on MD-V (24.2%) by 22 d.a.h. Unfed larvae could survive up to only 12 d.a.h. Larvae fed on MD-Q + 1/3 LF also had a significantly higher survival rate (34.2%) than those on MD-V + 1/3 LF (16.3%) and 1/3 LF solely (15.4%) at 32 d.a.h. These results suggest the potential of MD-Q as a part replacement for LF from the early developmental stage in the seed production of Japanese flounder.     

Development of microparticle diets for Japanese flounder Paralichthys olivaceus larvae

ABSTRACT:   Two newly designed microparticle diets (MD), with two kinds of peptide (C700 and C800) as a protein source were developed. Microparticle diet Q (MD-Q) contained C700 (molecular weight ∼30 000 Da) and C800 (molecular weight 1000–2000 Da); in contrast, microparticle diet T (MD-T) contained C700 only. Two separate trials, representing larvae from different hatches, were conducted. Japanese flounder Paralichthys olivaceus larvae were fed newly designed MD or a combination of them with live food (LF) between 3 and 10 days after hatching (d.a.h.) in experiment I, or between 11 and 20 d.a.h. in experiment II, and compared them to LF and a commercial diet (CD) feeding groups. The growth and survival rates in both experiments were the highest in the LF treatment. But in the microparticle treatment larvae fed MD-Q had a higher survival rate and better growth than those fed MD-T, either alone or in combination with LF. First-feeding larvae fed on MD-Q had a 20.5% survival rate and 1.12 mm gain by 10 d.a.h. Unfed larvae died within 6 d.a.h. These results indicate that using a mixture of different molecular weight peptides is good protein sources and also this type of microparticle diet can be applied to flounder from larval to juvenile stages.     

牙鲆盾纤毛虫病及防治技术研究

从牙鲆(Paralichthys oliuaceus)患病鱼体的溃烂组织中分离出一种盾纤毛虫,通过活体观察、碳酸银法和电镜观察,对其进行了形态学研究分析。鉴定该盾纤毛虫为贪食迈阿密虫(Miamiensis avidus Thompson & Moewus,1964)。这是国内关于贪食迈阿密纤毛虫感染养殖牙鲆的首次报道。同时本文在防治方法方面进行了初步研究,通过离体药敏实验表明:淡水、甲醛、双氧水对该纤毛虫有较好杀灭作用,而中草药的杀灭效果不理想。     

褐牙鲆♀×大西洋牙鲆♂杂交育种研究

为探讨褐牙鲆和大西洋牙鲆杂交育种的可行性，通过繁殖调控使褐牙鲆和大西洋牙鲆同步性成熟，采取正反交试验，获得了褐牙鲆（♀）×大西洋牙鲆（♂）杂交F1代——花关牙鲆（Paralichthysolivaceus早×Pdentatus6）。花关牙鲆受精卵卵径平均1．01mm；孵化适宜温度15—21℃，盐度25～35，孵化率平均71．3％，初孵仔鱼全长2．5～2．7mm；仔鱼在16—20℃下36d后伏底变态，变态个体全长平均11mm，育成率32．5％；反交受精率和孵化率极低，未获得杂交后代。简述了其发育时序和形态特征，探讨温度、盐度对花关牙鲆胚胎和仔鱼发育的影响，比较亲本与杂交鱼早期生长特征，初步分析反交不成功的原因。     

牙鲆消化道发育的组织学观察

牙鲆（Paralichthys olivaceus）肉质鲜美、营养价值高,是我国重要的海水养殖鱼类之一,同时,牙鲆二次变态显著,是研究硬骨鱼类变态发育很好的模式生物。在其变态过程前后,外型上最大的变化是其右眼的移位,内部器官如脑颅骨、骨骼肌等都发生结构和功能上的改变,而消化道的发育和分化,特别是其胃在变态前后有显著的变化。消化系统的发育关系到饵料的选择,与仔鱼成活率有直接关系,有较为重要的研究价值。[第一段]     

Optimal dietary taurine level for growth of juvenile Japanese flounder Paralichthys olivaceus

The requirement for taurine in juvenile Japanese flounder Paralichthys olivaceus was determined by feeding diets containing various levels of taurine and cystine. Test diets supplemented with 0.5, 1.0 and 1.5% of taurine or with 0.5, 1.0 and 1.5% of L -cystine were prepared. The basal diet contained 55% protein from white fish meal. These diets were fed to juvenile Japanese flounder with an initial mean bodyweight of 0.9 g (total length (TL) 48 mm) for 5 weeks. Approximately 1.4% taurine content in the diet was required for optimum growth of juvenile flounder. A positive linear relationship was noted between the content of taurine accumulated in the muscle, liver and brain and the level of taurine in the diet. However, there was no increased taurine content in tissues of fish fed the cystine-supplemented diet. In contrast, the fish fed control and cystine-supplemented diets showed higher contents of cystathionine in the tissues. The concentration of cystathionine in tissues rapidly decreased with an increase of taurine in the diet. It was also observed that for each of the dietary groups, a trace amount of taurine was excreted. These results suggest that the taurine content in the diet affects the sulfur amino acid metabolism of juvenile Japanese flounder, and indicate that juvenile flounder are unable to biosynthesize taurine from cystine.     

褐牙鲆♀×大西洋牙鲆♂杂交育种研究

为探讨褐牙鲆和大西洋牙鲆杂交育种的可行性,通过繁殖调控使褐牙鲆和大西洋牙鲆同步性成熟,采取正反交试验,获得了褐牙鲆(♀)×大西洋牙鲆(♂)杂交F1代——花美牙鲆(Paralichthys olivaceus♀×P.dentatus♂)。花美牙鲆受精卵卵径平均1.01mm;孵化适宜温度15～21℃,盐度25～35,孵化率平均71.3%,初孵仔鱼全长2.5～2.7mm;仔鱼在16～20℃下36d后伏底变态,变态个体全长平均11mm,育成率32.5%;反交受精率和孵化率极低,未获得杂交后代。简述了其发育时序和形态特征,探讨温度、盐度对花美牙鲆胚胎和仔鱼发育的影响,比较亲本与杂交鱼早期生长特征,初步分析反交不成功的原因。     

Effect of stocking density and feeding regime on larval growth,survival, and larval development of Japanese flounder,Paralichthys olivaceus,using live feeds

This research examined the effect of initial stocking density and feeding regime on larval growth and survival of Japanese flounder, Paralichthys olivaceus. Larval rearing trials were conducted in nine 50‐L tanks with different initial stocking densities combined with different feed rations (20 larvae/L with standard feed ration [LD], 80 larvae/L with standard feed ration [HD], and 80 larvae/L with four times the standard feed ration [HD+]). Larvae were stocked on 0 days posthatch (DPH) following hatching of the fertilized embryos. Larval total length (TL), survival rates, and final densities were observed on larval settlement (32 DPH) to evaluate larval rearing performance. At 32 DPH, there were no significant differences (p > .05) in TL or survival rates between the LD (46.5 ± 17.0%) and HD+ (40.3 ± 9.4%). The TL and survival rate of HD (23.1 ± 3.5%) were significantly lower than that of LD and HD+ (p < .05). However, the larval density of HD was significantly higher than that of LD (p < .05). HD+ achieved the best larvae production (32.27 ± 7.51 larvae/L), supported by sufficient food source, high water exchange, and proper water quality management (routine siphoning, surface skimming). The larval‐rearing protocols and larval development from hatching to metamorphosis is described in detail, with corresponding photographs taken during the experiment.     

Prevention of hypermelanosis by rearing Japanese flounder Paralichthys olivaceus in net-lined tanks

Fisheries Science - In artificially reared flatfish, especially the Japanese flounder Paralichthys olivaceus, pigmented skin (hypermelanosis) frequently appears on the fish’s blind side after...     

牙鲆亲本对子代贡献率的实验研究

利用18对高度多态性微卫星标记, 对13尾牙鲆(Paralichthys olivaceus)亲鱼的188尾后代进行亲子鉴定, 计算其非亲排除率、鉴定准确率以及亲本对子代的贡献率。使用4个微卫星标记进行亲子鉴定, 排除率≥0.999 9, 准确率为92.02%; 用6个标记的排除率≥0.999 999, 准确率为96.81%; 用8个标记的排除率≥0.999 999 999, 准确率为97.87%; 用10个标记的准确率为99.47%; 用12～18个标记的准确率为100%。亲子鉴定准确率随非亲排除率和微卫星标记数目的增多而升高。检验所有子代全部是实验亲本的后代, 即13个亲本对子代均有贡献, 但不同亲本的贡献率不同, 最高为47.34%, 最低为0.53%。实验表明, 基于多标记的非亲排除率检测方法可以用于牙鲆亲子鉴定, 其鉴定准确率可以达到100%; 不同亲本对子代贡献率不同, 差异很大, 产生差异的原因有待进一步研究。

     

舟山褐牙鲆（Paralichthys olivaceus）仔鱼摄食和生长的研究

试验研究了褐牙鲆Paralichthys olivaceus仔鱼的摄食和生长。结果表明,仔鱼初次开口摄食时间在6日龄（16～18℃）,初次摄食率为30％,8日龄饥饿仔鱼最大初次摄食率为65％,孵出后第9天达到不可逆点（PNR）,混合营养期为3d左右。初次摄食强度和初次摄食率开始时较低,在卵黄囊耗尽时达最高,然后下降。随着饥饿时间的延长,仔鱼出现“负增长”,孵化第11天存活率仅为10％,12日龄全部死亡。     

Progression of staining-type hypermelanosis on the blind side in normally metamorphosed juveniles and pigmentation progression in pseudoalbino juveniles of the Japanese flounder Paralichthys olivaceus using individual identification

Abnormal flounder coloration frequently occurs in flounder hatcheries and diminishes the commercial value of the fish. To understand hypermelanosis, the progression of staining-type hypermelanosis in normally metamorphosed juveniles and ocular-side pigmentation in pseudoalbino juveniles were examined in the Japanese flounder Paralichthys olivaceus. Sixty-five days post hatching, juveniles (total length, 6 cm) were individually identified by color-marker implantation, and the darkened area of the body surface was examined for 10 weeks by image analysis of digital photographs of the fish taken from above or below the transparent tank. Staining was observed to mainly begin at the upper and lower bases of the tail fin, expanded anteriorly along the peripheral part of the trunk, and ceased after 2 months. The individuals in which staining occurred earlier expressed severe staining and small body size by the end of the experiment. Further, pigmentation of the ocular side in pseudoalbino juveniles ceased after 2 months, but the order of pigmentation was different from that on the blind side. In this case, darkening began from the posterior, but expanded from the center to the periphery of the trunk. Even at the end of the experiment, ctenoid scales were exclusively found within the darkened area, together with cycloid scales.     

抗迟缓爱德华氏菌病牙鲆家系的筛选与分析

牙鲆(Paralichthys olivaceus)养殖病害日益严重,迟缓爱德华氏菌(Edwardsiella tarda)是牙鲆养殖中的主要致病菌,带来了极大的经济损失,为了培育出对该病抵抗能力强的牙鲆新品种,2014年4–6月间,利用我们长期以来建立和筛选出来的牙鲆抗病群体和家系的亲鱼,通过杂交,自交,雌核发育建立47个家系,9–10月间,对其中39个家系进行感染实验,先用少量鱼进行预实验摸索出半致死浓度,然后再进行正式感染实验,感染数量为每个家系80尾。各家系的存活率范围为1.19%~51.19%,最终平均存活率为20.29%,认为存活率高于30%的7个家系为抗病力强家系,存活率在20.29%~30%的9个家系为抗病力一般家系,平均存活率以下的23个家系为抗病力弱家系。1406#家系抗病力最强,它为1005#家系的自交后代,而其他抗病力强家系也大多是1005#、09104#、0915#的后代。而09104#为0768#的后代,并且0768#抗鳗弧菌病能力强。1005#为韩国群体自交后代,0915#为韩国群体和日本群体杂交后代。这些抗病力强的牙鲆可以作为新品系进行推广养殖,可望减少牙鲆腹水病发生。     

克隆牙鲆和普通牙鲆血液生理生化指标的比较

以中国水产科学研究院北戴河中心实验站养殖的双单倍体(DH)牙鲆(Paralichthys olivaceus)作为亲鱼, 采用冷休克方法抑制第二极体排出, 建立牙鲆克隆家系。以普通牙鲆的一个家系作为对照组, 在同样饲养条件下进行培育。实验组和对照组均为2⁺ 龄鱼, 克隆家系随机抽取5尾, 体质量(1 398±88) g; 普通群体随机抽取10尾, 体质量(1 749±125) g。分别采集血液进行血液生理和生化指标的比较分析。结果表明: 1) 克隆牙鲆的红细胞数量(RBC)、血红蛋白数量(HGB)、平均血红蛋白量(MCH)、红细胞压积(HCT)极显著低于普通牙鲆(P<0.01), 而在其他血液生理指标上二者没有显著性差异(P>0.05); 2) 克隆牙鲆在白球比(ALB/GLB)、谷草转氨酶/谷丙转氨酶(AST/ALT)比值、谷草转氨酶(AST) 3个指标上显著高于普通牙鲆(P<0.05), 其中AST差异达到极显著水平(P<0.01), 而碱性磷酸酶(ALP)、总胆固醇(CHO)、尿素氮(BUN) 3项指标, 克隆牙鲆极显著低于普通牙鲆(P<0.01)。克隆牙鲆血液生理指标的平均变异系数为5.50%, 普通牙鲆的则为9.21%, 其中克隆牙鲆红细胞平均体积(MCV)的变异系数仅为1.52%。克隆牙鲆血液生化指标的变异系数平均为10.56%, 普通牙鲆的则为27.23%, 达到克隆牙鲆的2.58倍。结果证实, 克隆牙鲆个体间的一致性较好, 作为指标生物, 效果优于普通牙鲆等海产鱼类。

     

野生与人工养殖褐牙鲆亲鱼微量元素组成的差异比较

分析了野生与人工养殖褐牙鲆亲鱼肝脏、背肌及卵中硒、铁、锰、铜、铬、镉和铅等微量元素的含量。结果表明,野生褐牙鲆亲鱼肝脏中硒、铁含量均显著高于养殖亲鱼(P<0.05),铜含量则显著低于养殖亲鱼(P<0.05),其他各元素间均未见显著差异(P>0.05);野生褐牙鲆亲鱼背肌中除硒和锰的含量显著高于养殖亲鱼外(P<0.05),其他各元素含量均基本保持恒定(P>0.05);野生褐牙鲆亲鱼卵中硒、铁和锰的含量均显著高于养殖亲鱼(P<0.05),其中硒的含量约为养殖亲鱼的1.7倍,铁的含量约为养殖亲鱼的2.0倍,而锰含量则为养殖亲鱼的2.8倍。养殖褐牙鲆亲鱼卵中镉含量与野生亲鱼相比高出78%(P<0.05)。两种亲鱼卵中铜、镉、铅3种重金属含量均未见显著差异(P>0.05)。