共查询到19条相似文献，搜索用时 422 毫秒
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利用组织病理、微生物、血液电解质、寄生虫检查方法对欧鳗"狂奔病"进行分析，发现无论是淡水养殖还是海水网箱养殖，病鳗的组织病理变化基本一致，鳃、肠破坏较为明显，肝、脾、肾、心均有不同程度的充血.从微生物学的分析来看，病毒的检出率并不高，形态也不一致，细菌和寄生虫的感染多样化.病鳗的血液电解质检查结果较为一致，主要以氯离子降低为主，下降幅度在30％～50％之间.由此认为本病不象是病毒、细菌和寄生虫所致. 相似文献
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僵鳗促长饲料养殖日本僵鳗及欧鳗的效果 总被引：1，自引：1，他引：0
将僵鳗促长饲料分别按１％￣２％比例添加于常规鳗鱼配合饲料中进行了养殖日本僵鳗及欧鳗试验。结果表明,饲料效率日本僵鳗添加组比对照组提高了３１％￣４０％;欧鳗添加组比对照组高出６８．９％￣２５０％。成活率日本僵鳗添加组高于或等于对照组;欧鳗添加组比对照组高出５２％￣６２％。养殖每公斤鳗的饲料成本,日本僵鳗添加组比对照组下降了１３％￣２０％,而欧鳗添加组比对照组下降了３６％￣５４％。证实了用僵鳗促长饲料 相似文献
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研制欧鳗配合饲料是养鳗业之急需。经１９９４年饲喂试验结果饲料系数为１．０１，净增重６６．４％，初获成效。通过两年多在省内外５０多个鳗场推广使用，效果明显。 相似文献
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"海马"牌配合饲料喂养大黄鱼的试验 总被引：2，自引：0，他引：2
本文笔者于2000年5月17日至7月5日在霞浦海区网箱养殖大黄鱼中，进行"海马"牌配合饲料(按不同比例搭配小杂鱼)喂养大黄鱼试验.结果表明在相同的管理和养殖条件下，10％幼鱼粉搭配90％小杂鱼、50％幼鱼粉搭配50％小杂鱼、膨化饲料搭配小杂鱼在提高大黄鱼的生长速度、存活率和降低养殖成本方面均优于单一使用小杂鱼. 相似文献
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本文论述引进欧鳗苗养殖的情况，总结养殖失败的原因及成功者的经验，然后用生态方法对欧鳗黑仔进行养殖。经过２个月养殖，死亡率仅０．１％，平均月增长２倍，饲料效率７５．６９％。 相似文献
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１９９５年分别在邵武欣隆绿色养殖有限公司养殖池和诏安桥东溪雅鳗场对规格１１０ｐ／ｋｇ、７２ｐ／ｋｇ、７２／ｐｋ的欧鳗用我公司开发的欧鳗专用饲料－“海马”牌黑仔７＾＃饲养７１ｄ与６７ｄ的试验。结果表明，投饵率为１．２％－１．８％；成活率为９９％；饵料效率在８２．１％－８４．５％之间。 相似文献
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本文报道了国产α-淀粉与鱼粉亲和力的试验，以及使用国产a-淀粉与进口α-淀粉的饲料在欧鳗养殖中的对比试验.结果表明国产a-淀粉基本能满足鳗饲料生产对粘弹性的要求；而且，使用国产α-淀粉与进口a-淀粉的饲料，在饲料效率方面没有明显的差别. 相似文献
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本文初步概述饲养欧洲鳗鲡（Anguillaanguilla）的食性特征，对蛋白质的表现消化率和日粮蛋白质的需求量、驯饵、饲料形态、给饲率以及实用的欧鳗配合饲料。建议采用膨化颗粒饲料，制订欧级饲料实验方法和条件的规范。 相似文献
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《Marine Policy》2017
In 2007 CITES included the Critically Endangered European eel on its Appendix II, thereby regulation international trade. In 2010 the EU member states adopted a ‘zero-quota’ policy thereby banning all commercial international trade. Given the continued high demand for eel in East Asia shifts have occurred to source European eel from non-EU eel range countries. Using official export figures from two independent databases, I here quantify to what extend Morocco, Tunisia and Algeria are fulfilling this demand. The ban had little effect on the annual export volumes in live eel from Morocco (mean of 41.3 metric ton / year), Algeria (15.5 t) or Tunisia (56.2 t) or chilled/frozen eel from Algeria (11.7 t) and Tunisia (20.0 t) but this trade from Morocco increased significantly (from 27.4 to 237.2 t). Prior to the ban the trade in eel from North Africa was almost exclusively to European countries (live 93–98%) and very little to East Asia, whereas after the ban East Asia became the main importer (live 91–93%). The monetary value of the trade totalled US$126 million and did not increase over time, but the importance of the live eel trade increase from 76% prior to the ban to 93% after. It is unclear on what basis Morocco and Tunisia were able to decide what level of trade was not detrimental to the survival of European eel in the wild, and I argue for better monitoring to ensure that international trade is not an impediment to the conservation of European eel. 相似文献
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European eel (Anguilla anguilla) recruitment is declining dramatically since the 1980s. Causes for this decline are explained by a combination of environmental changes basically affecting oceanic larval stages and a variety of anthropogenic impacts during the continental phase. Today, evidence is growing that poor silver eel quality has a major impact on reproductive success, implying that habitat quality plays a key role in stock decline. Since eels are frequently moving through a variety of different habitats during their life cycle, a better understanding of the implications of individual diadromous behaviour and habitat choice on spawner quality are crucial for management considerations for a stock recovery. The present study tested whether individual migratory behaviour and habitat choice of European eels affect spawner quality. Therefore, the migratory behaviour of 287 European eels from marine, brackish and freshwater stations in the North Sea, the Baltic Sea and from Northern German inland waters was examined by otolith strontium/calcium analysis. All individuals were classified either as freshwater residents, coastal residents, downstream shifters, upstream shifters or interhabitat shifters. As indicators for eel quality, muscle fat content, infection with the introduced swimbladder nematode Anguillicoloides crassus and body length at onset of spawning migration were assessed. Results indicate that individuals that exclusively inhabited freshwaters had significantly lower muscle fat contents and were more seriously infected with A. crassus than eels that never entered freshwaters. Since high fat contents are considered as prerequisites for a successful transoceanic spawning migration and high A. crassus loads have a negative impact on condition, this study outlines the importance of brackish waters as eel habitats in temperate latitudes. Furthermore, it questions the net benefit of stocking programs for the European eel population, since they include the translocation of eels from coastal waters into freshwaters. 相似文献
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Spyridoula Zompola George Katselis Constantin Koutsikopoulos Yannis Cladas 《Estuarine, Coastal and Shelf Science》2008
Glass eel migration of the European eel Anguilla anguilla (L., 1758) in the eastern Mediterranean is poorly known despite the increasing state of anxiety for the future of the stock. In the present study, glass eel migration was investigated from October 1999 to April 2000, using experimental fishery with fyke nets, in two coastal systems along the western Greece (Ionian Sea): at the Sagiada marsh in the delta area of Kalamas River and at the mouth of Alfios River. The main period of the glass eel entrance was from December to March and the migration pattern was similar to those observed along the Atlantic coast of southwestern Europe. The variance of daily glass eel catches between the two studied sites was significantly different. The univariate and bivariate time series spectral analysis showed that glass eel short-term freshwater migration: (1) consisted of waves with periods from 5 to 40 days and (2) was correlated with environmental factors such as water temperature, atmospheric pressure, rainfall and moonlight. The observed differences between the two sites reveal the importance of the inland ecosystem characteristics. 相似文献
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采用水体中设置生物膜净水栅对比实验的方法,在12口土池开展生物膜原位修复技术对土池淡水养殖日本鳗鲡的节水减排、养殖效益及机理的研究。结果表明,在172d的养殖期间,处理组比对照组节水减排78%(P<0.01);处理组的氨氮、NO2-N、CODMn、溶解性正磷酸盐和浊度分别低于对照组31.7%、49.7%、29.6%、24.2%和26.2%(P<0.01);藻类密度的变化幅度及蓝藻相对密度分别低于对照组58.8%、52.6%(P<0.01);净产量、起捕尾重和生长速度分别高出对照组38%、22.7%和27.1%(P<0.01);饲料系数低于对照组14.2%(P<0.01);处理组每公顷池塘增加养殖利润约77.25万元。池塘生物膜原位修复低碳养殖技术具有成本低、节水减排、增产增收、操作简便与易推广等优点,具有广阔的应用前景。 相似文献
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采用水体中设置弹性填料对比实验的方法,在12口聚乙烯水槽实施淡水精养殖日本鳗鲡,进行对鳗鲡精养殖水体生物膜原位修复节水增效效果、机理及应用前景的研究。结果表明,在207天的养殖期间,生物膜原位修复技术应用处理组的平均日换水率仅1.2%,比对照组显著节水减排74%(P0.01);处理组的主要水质因子pH、DO、TAN、NO2-N、NO3-N、COD等浓度均符合相关的渔业水质标准;处理组的起捕尾重、产量、生长速度分别比对照组高106%(P0.2)、108%(P0.2)和220%(P0.15),饲料系数低于对照组38.4%(P0.1)。此外,处理组弹性填料设置的适宜密度为填料占水体体积的10%。因此,精养殖水体生物膜原位修复技术,具有节水、减排与节能效果显著,投资与运行成本低,环保、低碳、安全,操作简便、易推广等优点。该革新性的生态工程低碳养殖技术对推动我国水产养殖发展方式从高耗费资源型向资源节约与环境友好型转变将产生重大影响。 相似文献
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鳗鲡(Anguilla)作为我国优质水产养殖种类,精准掌握其数量对高效养殖有重要意义。为实现对循环水养殖鳗鲡的准确计数,提出了一种基于深度学习的改进Faster RCNN模型。针对检测目标即鳗鲡头部尺寸小的问题,选择在特征提取网络ResNet50中加入FPN结构来作为模型的骨干网络,以提取并融合多尺度的特征;针对原模型锚框都是基于人工经验设置的,并不适用于鳗鲡数据集的问题,使用k-means聚类算法对训练集中标注的鳗鲡头部检测框进行聚类分析,获得了适合鳗鲡数据集的15种不同尺度的锚框;针对图像中存在鳗鲡头部重叠的问题,选择使用Soft-NMS算法替代原NMS算法对RPN部分生成的候选框进行筛选,以减少模型对鳗鲡重叠部分的漏检情况。试验结果表明:改进后的Faster RCNN模型对鳗鲡头部的检测精度(mAP0.5)高达96.5%,较原Faster RCNN模型(Backbone为ResNet50)显著提升了14%,与SSD300和YOLOV3模型相比分别显著提升了24.9%和15%;在鳗鲡计数上,利用改进后的Faster RCNN模型检测结果进行计数,计数准确率达到90%以上,提升了模型对鳗鲡的检测识别能力。 相似文献
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《Marine Policy》2015
Following the decision in 2007 by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) to include European eel Anguilla anguilla on its Appendix II, and the 2010 ban of all eel exports by EU member states, a shift has occurred to tropical Asian eel species to meet the demand from East Asia. Here the focus is on the role Indonesia played in fulfilling this demand using official export figures, reports in the Indonesian media and government documents. Despite Indonesia first putting in place restrictions on the export of eel in 1974 the export has increased exponentially over the last 25 years. Prior to the EU ban it exported ~1.4 million kg/year. With the infrastructure in place, and close trade links to East Asia, and helped by government encouragement, Indonesia was in an excellent position to step in where the EU posed restrictions. Exports increased to 3.2 million kg/year (2007–2009), to 4.0 million kg/year (2010–2012), and to 6.1 million kg (2013). The interest in eel trade in Indonesia increased in parallel with the exports. From 2010 onwards the searches for the Indonesian equivalent of eel (“ikan sidat”) became frequent enough for it to be picked up by Google Trends. Indonesia is home to five species of eel, and while it is unclear in what quantities each is traded, Indonesian media reports suggest that the majority comprises A. bicolar and A. marmorata. More stringent management schemes, possibly including CITES-listing, and better monitoring are needed to ensure that international trade is not an impediment to the conservation of tropical eels. 相似文献