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河蟹“颤抖病”始见于199。1年的池塘养殖，很少量的成蟹出现此病症。1995年以后病情迅速蔓延，导致河蟹养殖成活率逐年下降，许多塘口绝产绝收。“颤抖病”的病症：病蟹体瘦、壳软，活力差，腹部及附肢指节、掌节有红色水锈、不能正常蜕壳或蜕亮后不久便死；临死前活动呆滞，附肢僵硬并不停地痉挛（这是“颤抖病”这一俗称的由来），易并发黑鳃病和聚缩虫病。解剖病蟹可见肠道水肿、肌肉萎缩、肝脏糜烂等症状。有关单位初步研究表明：“颤抖病”的病原为病毒。发病时间及特征：7、8、9三个月是“颤抖病”的发病高峰期，高温季节该病表现为… 相似文献
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<正> 随着物质生活的日益提高,人们对特种水产品的偏爱和河蟹高利润的刺激,河蟹养殖在全国遍地开花,与此同时,人为过多的调控和干预,使河蟹疾病越来越多,危害程度日趋严重,尤其是令蟹农谈抖色变的“抖抖病”,更是来势迅猛,损失惊人。笔者在多年的技术推广中认为,只有树立蟹病“无病先防、有病早治、防治兼施、防重于治”的原则,重点做好“六消毒”工作,才能防患于未然,降低“抖抖病”造成的损失。 1 做好蟹种的消毒工作 生产实践证明,即使是体质健壮的蟹种,或多或少都带有各种病源菌。放养未经消毒处理的蟹种,容易把病源体带进池塘,一旦条件合适,便大量繁殖而引起疾病。因此,在放养前将蟹种浸洗消毒,是切断传播途径、控制或减 相似文献
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目前，由于水温的升高，不少蟹池因放养密度高，饵料投入不足，水体富营养化，病害日益突出，特别是蟹农对一些河蟹病害认识不清，尤其是河蟹“三毛”病很难识别，经常有混淆现象，一些蟹农难以对症下药，因而对河蟹的生长带来一定的影响。现将此病的识别及防治方法介绍如下：一、“絮毛”病也就是河蟹的水霉病，其病原主要是水霉科中的一些真菌如水霉菌、绵霉菌等。症状：发病蟹的蟹卵表面及病蟹的体表及附肢或伤口处出现灰白色棉絮状的病灶，导致卵停止分裂变态，病蟹伤口部位组织溃烂，食欲减退，身体瘦弱，行动呆滞，最后无法蜕壳而死亡… 相似文献
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在河蟹生长旺盛时期，常常出现规格在１００ｇ／只左右的“黄蟹”大批死亡的现象。据调查，造成死亡的原因主要是河蟹着毛病、颤抖病和蜕壳不遂症三病并发，其发病率高达２０％－４０％，尤以放养上年大规格幼蟹（即“扣蟹”）的发病率最高。１９９７年７月１６日，我县大纵湖乡北宋村宋某承包的蟹塘发生大批死蟹，笔者前去调查诊治。据了解，该池塘为滩面四周挖沟筑堆的“提水养鱼”水面，面积１３３ｈｍ~２，四周沟占总面积的１５％，深１．８ｍ，滩面水深０．８ｍ，此塘已养鱼３年，鱼虾蟹混养２年，沟中积存淤泥有０．５ｍ厚。年初在未… 相似文献
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中国水产科学研究院淡水渔业研究中心在中华绒螯蟹“颤抖病”研究上获得新突破。该中心承担的江苏省应用基础计划项目“中华绒螯蟹病害防治技术研究”,目前通过江苏省科委组织的成果鉴定。随着特种水产品养殖的迅猛发展,仅江苏省中华绒螯蟹养殖面积已超过２００万亩,产量５９万吨,但中华绒螯蟹的病害一直困扰着广大养蟹户。特别是死亡率高、危害大的暴发流行“颤抖病”。淡水渔业研究中心科技人员在苏州大学、上海水产大学和无锡轻工大学等有关单位协作下,经过三年努力,研究了危害成蟹养殖阶段的主要细菌性疾病———黑鳃和甲壳溃疡病的病原… 相似文献
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由杨先乐教授带领的河蟹“水瘪子”病研究团队从2016年3月份开始就驻扎在兴化养殖一线,在兴化市渔业技术指导站和安丰镇水产站的协助下,通过发放调查问卷、开展培训讲座、塘口跟踪以及开展一系列防控措施等方式对2015-2016年兴化市河蟹“水瘪子”病的发病情况进行了调查分析,现将调查情况汇总如下.
河蟹“水瘪子”病发生的明显特征是吃食量下降,症状主要表现为:病蟹甲壳颜色发黑,壳薄且脆;病蟹大多空肠、空胃,没有食线或者食线是断开的;病蟹鳃萎缩,附肢发软无力、肌肉萎缩,肝胰腺颜色变成土黄色、淡黄色至白色并呈浆糊化萎缩坏死;严重的病蟹甲壳凸起,腹腔积液. 相似文献
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江苏宜兴市新建镇有池塘养殖面积2000多亩,1998年发展河蟹池塘养殖486亩,上审商品蟹22600公斤,亩均产蟹46．5公斤,亩产值7400多元,亩效益3800多元。但有部分养殖户受到河蟹“抖抖病”的馒袭,经济效益不理想,个别养殖户出现了亏损。据统计,全镇“抖抖病”发病面积... 相似文献
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中国水产科学研究院淡水渔业研究中心助理研究员陈辉在中华绒螯蟹“颤抖病”研究上获得新突破。他们所承担的江苏省应用基础研究计划项目“中华绒螯蟹病害防治技术研究”，目前通过江苏省科委组织的成果鉴定。随着特种水产品养殖的迅速发展，仅江苏省中华绒螯蟹养殖面积已... 相似文献
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河蟹颤抖病是当前河蟹养殖中危害最大的疾病,严重地阻碍了河蟹养殖业的发展。据不完全统计,九九年该病的发生率达50％以上,死亡率达30％以上,甚至个别池塘达到死亡率在80％以上,给养殖户造成严重的经济损失,因此,养殖业者谈“抖”色变。河蟹颤抖病,又叫“宽爪病”或“抖抖病”等,其主要症状为：病蟹的援食减少,活力能力减弱或爬到池岸边或伏于水草之上,反应迟钝,步足连续颤抖,口吐泡沫,背部向下很难翻身。病蟹解剖后,蟹体的肉质糊化,甚至步足肌肉萎缩,中空。有些病蟹肝脏病变,肠道发炎,无食或少量食物,有些病蟹伴有腹水… 相似文献
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中华绒螯蟹血淋巴和肝胰腺的总蛋白含量与性早熟的关系 总被引：11，自引：3，他引：11
中华绒螯蟹扣蟹性腺发育与肝胰腺和血淋巴的蛋白质浓度相关.性早熟前后,雌雄扣蟹肝胰腺总蛋白浓度分别由(121.17±44.50)mg@g-1和(89.43±21.86)mg@g-1下降至(81.08±5.84)mg@g-1和(70.58±9.90)mg@g-1,雌性扣蟹的肝胰腺占体重的比值也由8.18%降至3.90%.血淋巴总蛋白浓度正常发育的雌性扣蟹为(99.55±12.06)mg@mL-1,明显高于性早熟雌性扣蟹的(72.26±17.87)mg@mL-1;而雄性扣蟹性早熟前后的血淋巴总蛋白浓度无显著差异.肝胰腺总蛋白浓度二秋龄雌蟹高于性早熟雌性扣蟹,但它们之间的血淋巴总蛋白浓度没有显著差异.二秋龄雄蟹的血淋巴和肝胰腺总蛋白浓度与性早熟雄性扣蟹相当,差异不显著. 相似文献
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John D. Castell J. C. Kean D. G. C. McCann Andrew D. Boghen Douglas E. Conklin Louis R. D'Abramo 《Journal of the World Aquaculture Society》1989,20(3):100-106
Obtaining reliable results from comparative crustacean nutrition studies requires a dietary reference protein which is available world-wide and is nutritionally optimal for growth and survival. Traditional protein sources include "vitamin free" casein, egg albumin, whole egg protein, soybean protein, and others. These have proven to be inadequate for juvenile lobster ( Homrus americanus ). Purified rock crab ( Cancer irroratus ) protein is proposed to be nutritionally superior to casein for inclusion in semi-purified lobster diets.
Eighteen week feeding trials with juvenile H. americanus were conducted to compare diets containing protein obtained from rock crabs ( Cancer irroratus ), and produced by several different purification processes with a control diet having casein as its primary protein source. Diets containing purified rock crab protein were found to be superior to the control diet. Among the differently derived purified rock crab protein products, the precooked, isopropanol-purified was the most effective dietary ingredient. 相似文献
Eighteen week feeding trials with juvenile H. americanus were conducted to compare diets containing protein obtained from rock crabs ( Cancer irroratus ), and produced by several different purification processes with a control diet having casein as its primary protein source. Diets containing purified rock crab protein were found to be superior to the control diet. Among the differently derived purified rock crab protein products, the precooked, isopropanol-purified was the most effective dietary ingredient. 相似文献
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为了探究不同龄期中国鲎幼鲎生长特性,实验测定了2～4龄幼鲎头胸部长(X1)、头胸部宽(X2)、腹部长(X3)、腹部宽(X4)、剑尾长(X5)、全长(X6)和体重(Y)等参数,运用相关分析和通径分析方法,探讨形态性状对体重的作用效果。结果显示,2～4龄幼鲎体重相关系数最高的形态性状均为头胸部宽(X2);通径分析发现,头胸部宽(X2)对2龄和3龄幼鲎体重直接影响最大,腹部宽(X4)对4龄幼鲎体重直接影响最大;各形态性状对体重决定程度分析与通径分析变化趋势一致。对2～4龄幼鲎头胸部宽和体重进行对数处理,获得异速生长方程回归系数(b)为2.746,表明此阶段幼鲎体重增长率大于头胸部宽增长率,处于正生长期。实验表明,不同龄期阶段中国鲎苗种筛选所依据的形态性状有所差异,中国鲎幼鲎阶段种质评价应考虑其异速生长规律,同时也为探究鲎的生长与性状、结构与生理之间的关系奠定基础。 相似文献
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Vibrio harveyi as a causative agent of mass mortalities of megalopa in the seed production of swimming crab Portunus trituberculatus 总被引：1，自引：0，他引：1
Xiao-Jun Zhang Xue-Song Bai Bin-Lun Yan Ke-Ran Bi Lei Qin 《Aquaculture International》2014,22(2):661-672
Outbreaks of mass mortalities among cultured megalopa of swimming crab (Portunus trituberculatus) occurred in a commercial hatchery during the spring of 2012 in Jiangsu province, P. R. China. Dominant bacteria were isolated and characterized by biochemical reactions, enzyme production, and sequencing analysis of the 16S rRNA, gyrB (DNA gyrase B subunit) genes, and two strains (DY1 and DY2) were selected as representative strains for virulence tests by immersion. The results showed that the characteristics of identified strains consist with Vibrio harveyi; the 16S rRNA and gyrB genes of the tested strains exhibited high similarity with V. harveyi; and the phylogenetic trees constructed using the neighbor-joining method based on 16S rRNA and gyrB genes. Two strains (DY1 and DY2) clustered with the V. harveyi and were supported by a higher bootstrap value, and two strains (DY1 and DY2) were found lethal to the healthy megalopa and juvenile crab. LD 50 of DY1 and DY2 to megalopa and juvenile crab were 2.4 × 106, 3.0 × 106, 1.9 × 106 and 2.5 × 106 CFU/ml, respectively. The results confirmed that the diseased megalopa were infected by V. harveyi. In addition, we analyzed the tested strains (DY1 and DY2) by PCR for the presence of virulence genes that were known in V. harveyi, and the results showed that five virulence genes (luxR, toxR, vhhA, vhhB and pap6) were detected by a specific PCR assay, further supporting the assignment of isolates to V. harveyi and its pathogenicity. To our knowledge, this is the first report of V. harveyi as pathogenic bacteria of megalopa of swimming crab. 相似文献
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河蟹仔蟹管道式饲养初步研究 总被引：1，自引：0，他引：1
采用封闭式的蜂窝状塑料管道作为蟹穴，对河蟹仔蟹进行两个月的饲养观察试验，每隔１５ｄ测定一次壳长、壳宽和体重，用数理统计方法分析了河蟹的个体生长特点，比较了蟹穴饲养和非蟹穴饲养以及不同形式的蟹穴饲养效果。结果表明，仔蟹的个体生长为跳跃式的非连续增长。蟹穴饲养对河蟹的壳长、壳宽和体重的生长无不利影响，而增重率明显优于散养，且Ｌ型蟹穴的生长效果比Ｉ型蟹穴要好 相似文献
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Effects of ammonia and nitrite on survival, growth and moulting in juvenile tiger crab, Orithyia sinica (Linnaeus) 总被引：3，自引：0，他引：3
Ja-Geun Koo Seong-Gil Kim Jung-Hoon Jee Jong-Man Kim Sungchul C Bai & Ju-Chan Kang 《Aquaculture Research》2005,36(1):79-85
The effects of ammonia and nitrite on survival, growth and moulting were investigated in juvenile tiger crab, Orithyia sinica (carapace length 3.91±0.15 mm, carapace width 3.84±0.23 mm, n=440), after 30 days exposure to ammonia‐N (0, 20, 50, 100 and 150 mg L?1) and nitrite‐N (0, 50, 100, 150, 200 and 250 mg L?1) using a continuous flow system. Survival rates of tiger crab exposed to ammonia and nitrite decreased linearly with the exposure time and concentration. The growth rate of tiger crab exposed to 50, 100 and 150 mg L?1 ammonia was significantly lower than that of control crabs. The growth rate of tiger crab exposed to nitrite decreased at 150, 200 and 250 mg L?1 nitrite. During the ammonia and nitrite exposure, the intermoult period of the juveniles of tiger crab O. sinica was shortened between the first and second moult, and the number of moulting of crabs exposed to a higher concentration were significantly higher than that of control crabs. 相似文献
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For the improvement of nursery culture of the mud crab Scylla paramamosain, a special nursery facility was purposely designed and built. This facility consists of nursery ponds (areas of 20, 50, and
120 m2, respectively) and a seed collecting pond connected to each nursery pond. There were 140 nursery facility units in operation
for large-scale juvenile crab production. A series of experiments were carried out using the facility to investigate the effects
of the age of megalopae, stocking density, and culture duration of both megalopae and first-stage crabs on the survival of
megalopae and early juveniles of S. paramamosain. The results showed that when megalopae were stocked at a density between 3,000 and 5,000 ind m−2 and reared to reach the first-stage crabs, a survival rate of up to 50% could be achieved. When the first-stage juvenile
crabs were stocked at a density between 2,000 and 3,000 ind m−2, their survival was more than 50% after 14 days of culture. 相似文献
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The functional response describes how consumption rate of individual predators changes as prey density changes, and can have important implications for the bottom culture of scallops. We examined (i) the functional response of rock crabs (Cancer irroratus) preying on juvenile sea scallops (Placopecten magellanicus); (ii) the effect of substrate type and scallop size on the functional response; and (iii) the underlying behavioural mechanisms of observed functional responses. Specifically, we quantified predation rate and behaviours, such as the proportion of time spent searching for prey, encounter rate between predators and prey and the outcomes of encounters, when individual rock crabs were offered a range of scallop density (2–50 or 11–111 scallops m−2) and two size classes of scallops (∼
∼25 and ∼
∼35 mm shell height) on two different substrate types (“glass-bottom” and “granule”). We found that crab predation rate on small juvenile scallops increased at a decelerating rate with prey density to a plateau at high prey density on both substrates, indicating a hyperbolic (type II) functional response. Crab predation rate on large juvenile scallops was independent of prey density (i.e., no functional response evident), suggesting that crabs were at their satiation level. Prey density did not influence any behaviour except encounter rate on small juvenile scallops, which increased as prey density increased. Substrate type influenced crab predation: maximum predation rate of crabs on small juvenile scallops and encounter rate with either size of juvenile scallops was lower on granule than on glass-bottom. Our results in the laboratory suggest that crabs could potentially be swamped if scallops are seeded at a high density in the field. However, many factors in the field may influence the functional response. For example, the presence of multiple prey types may lead to sigmoid functional responses, while the presence of many crab individuals may lead to aggregation of crabs in areas of high prey density. 相似文献
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Hongbo Jiang Kang Li Liqiao Chew Qun Wang Qigen Liu Lihe Liu 《Journal of the World Aquaculture Society》2005,36(4):515-520
Feeding experiments were conducted using amino acid test diets to determine the optimal dietary requirement for arginine and lysine of the Chinese mitten-handed crab Eriocheir sinensis juvenile. Crab megalopae with an average weight of 6.86 mg were randomly assigned to different tanks and reared on six experimental diets for 25 d. The six experimental diets were formulated for different combinations of arginine (0, 0.4, 0.8, 1.2, 1.6, and 2.0 g per 100-g diet) and lysine (0, 0.3, 0.6, 0.9, 1.2, and 1.5 g per 100-g diets), respectively. Survival and molting frequency were calculated at the termination of feeding trials. Optimal arginine and lysine requirements were determined by the diets at which the highest survival and molting frequency was reached. The highest survival and molting frequency were 41.75% and 2.4, respectively, and were reached when the crabs were fed with 2% arginine. After juveniles were fed with the diets with 2.55% lysine, survival was the highest (44.0%) and the molting frequency was 2.31. We suggest that the requirement of juvenile crabs for arginine is 2.0% in diet or 3.3% of dietary protein, and the requirement for lysine is 2.55%, in diet or 4.25% of dietary protein. This study provides critical information in formulating cost-effective aquaculture diets for the Chinese mitten-handed crab juvenile. 相似文献
20.
拟穴青蟹幼蟹耗氧率和窒息点的研究 总被引：3，自引：1，他引：2
在盐度20、温度28.0±0.2℃条件下,采用密封流水方法进行了拟穴青蟹幼蟹耗氧率和窒息点的研究。结果表明:拟穴青蟹Ⅴ期幼蟹的平均耗氧率高于Ⅵ期幼蟹,Ⅴ期幼蟹的窒息点也高于Ⅵ期幼蟹。其中,当蟹苗体质量为1.00±0.22 g时,耗氧率为0.437 2±0.083 mg/(g.h),耗氧量0.423 7±0.080 mg/(ind.h),窒息点为0.716 0±0.017 mg/L;当蟹苗体质量为1.81±0.30 g时,耗氧率为0.381 6±0.081 mg/(g.h),耗氧量0.671 7±0.140 mg/(ind.h),窒息点为0.698 7±0.011 mg/L。实验发现,拟穴青蟹幼蟹的耗氧率和耗氧量具有比较明显的昼夜变化规律,其峰值出现在20∶00及02∶00左右,谷值出现在08∶00及16∶00。研究结果可为拟穴青蟹养殖生产中制定合理的苗种放养密度和养殖工艺提供参考依据。 相似文献