欧洲鳗水库网箱养殖试验

我站分别于1997年4月16日和5月12日调进欧鳗当年鳗种2500尾和隔年老鳗种2000尾用于水库网箱养殖试验，经过7～8个月的养殖，基本上达到了商品规格，商品率70％以上，现将试验情况介绍如下：一、材料与方法1．试验地点：试验地点选择在海拔600米，4～12月平均水温为24℃，正常水     

海水网箱养殖欧洲鳗技术

欧洲鳗苗种资源丰富，价格低廉，深受养殖者的青睐，但因它抗病能力较弱，对环境适应能力较差，水质要求较高，不耐高温等弱点，成为欧洲鳗养殖的制约因素，如何提高欧洲鳗养殖成活率和商品率及降低养殖成本是当前急待解决的课题。为此，我们于1996年4月在福清市柯屿海湾进行海水网箱养殖欧洲鳗，在生产实践中，初步探索并掌握了海水养殖欧洲鳗技术，现介绍如下：一、放养准备1．养殖水域选择水质良好，风浪小，水面较宽阔的海湾，要求最低潮位水深4米以上，流速0．3～0．8米／秒，最大不超过互米／秒，水温范围为8～30C，PH值7～8．5，海…     

封闭流水式网箱鳗鱼养殖新技术

封闭流水式网箱鳗鱼养殖新技术是参照陆基水泥精养鳗池的原理,采用不透水帆布类材料制成封闭流水式网箱,抽取15～20 m深处水温、水质稳定的水库中下层水进行流水养殖.该养殖模式是将装备技术、水质净化技术等技术进行整合、组装和集成,从而达到健康、快速和最大限度地提高单位水体产量和质量的目的,是一种既不产生内外环境污染、基本不消耗水资源,又不占地的鳗鲡健康养殖新模式.     

水库网箱养殖欧洲鳗的几个重要环节

由于欧洲鳗具有越冬和成本等方面的优势，特别是对欧洲鳗危害最大的指环虫、小瓜虫的发病率和死亡率大幅度下降，加上预防病害技术手段的提高，养殖者对病害及药物残留问题认识的提高，违禁药品的使用被有效抑制，经济效益不断提高，因此福建省内陆山区大部分鳗鱼养殖户仍然以养殖欧洲鳗为主，养殖方式也逐年向土池、水库网箱方向发展。     

海水网箱养殖欧洲鳗技术（二）

3欧洲鳗网箱养殖技术3．1选苗与放苗：购买鳗苗需慎重，以免买到鳗尾。每千克尾数2500－3500尾，宜选每千克3000－3500尾的白仔鳗，要求不仅颜色深，而且无外伤的健全苗为佳．投苗前，鳗苗预先做好消毒，消毒免疫是关系到网箱养殖成功与否的关键之一。一般采用20g／m2高锰酸钾进行浸洗鳗苗。结合定期消毒，严防交叉感染的发生．拔苗时先把装有苗的充氧袋放人挂在海水中的网箱让其调整温差，网箱入水深度50cm左右为宜。一般不采用留袋暂养，以免造成不必要损失。投放鳗苗密度要适宜，通常要求白仔鳗每平方米50o尾左右；黑仔苗每平方米250－40…     

海水网箱养殖欧洲鳗技术（一）

平潭县裕胜水产养殖场，于1995年7月7日-1996年4月15日，首次在该县竹屿港海水网箱投放每千克2500—3500尾规格的欧洲鳗苗1500尾，经精心喂养和科学管理，渡过了夏季的高温期，取得了阶段性的成果，并经有关部门组织现场验收，平均个体重达250．70g的商品鳗规格，成活率达85％以上，使该县首次海水网箱养殖欧洲鳗获得成功。取得全国既是“海水”，又是“网箱”养殖欧洲鳗成功两项突破。现将有关养殖欧洲鳗技术介绍如下：l海网养欧洲鳗的特点1．互原理由于网箱中的水体能不断得到更新，这就保证了网箱内优越的溶氧和水质，新鲜的条件，为高密…     

利用地热水养殖欧洲鳗操作技术

为了开发利用地下热水资源，发展特种水产养殖，湘潭县１９９８年承担了湖南省科委下达的星火计划项目“利用地热水养殖鳗鱼技术开发”。试验点碧泉潭温泉（流量０．３２／ｓ），位于锦石乡碧泉村，常年温度１９℃。鳗鱼由福建莆田养殖公司引进。养殖面积１０５６０，投放...     

网箱养殖鳗鱼技术

鳗鱼是具有较高养殖效益的水产品种之一。近年来，虽然鳗鱼市场价格波动，但选择鳗苗资源丰富、价格低廉的欧洲鳗等鳗鱼品种，进行开发性的海水网箱养殖，前景仍然看好，经济效益也非常可观。     

大黄鱼抗风浪网箱与传统网箱养殖生长对比试验

传统网箱养殖大黄鱼,由于养殖年份的延续、养殖规模的扩大和养殖密度的提高,导致了传统网箱养殖海区海水污染不断加重,养殖鱼类病害频发,生长速度减慢,最终导致经济效益不断下滑,严重影响了渔民的养殖积极性。而抗风浪网箱随着近几年的发展和摸索,已趋于成熟,同时也显示出了它的优势：一是大大提高海域利用率;     

水库网箱养鳗试验

鳗鲡Anguilla japonica是出口创汇、国内外市场都十分行销的鲜活商品,利用我国沿海宝贵的天然鳗苗资源,培育鳗种或饲养成鳗已引起产业部门的重视。目前国内外养鳗以流水或静水式水池养鳗为多见,存在着设备投资大,水质不易控制,生产成本高等缺陷。本试验在千岛湖(大型水库)中设置网箱1000余m~2,设计了整套放养技术措施,当年黑仔鳗养成的鳗种平均规格达到74.29克.每平方米产量为34.5公斤,其中16.7%的产量当年达到商品规格,较一般池塘养鳗显示出本轻利重的优越性。水库网箱养鳗的成功亦为水库开展其他高价值鱼类的饲养提供了一条有益的经验。     

Patterns of silver eel (Anguilla anguilla L.) sex ratio in a catchment

Abstract –  Changes in the numbers and size-class structure of European silver eels, Anguilla anguilla , in the River Frémur (France) were examined over a 9-year period after installation of downstream eel passes. The number of silver eels migrating downstream peaked in 1999, then decreased strongly and steadily after 2000, reaching relatively low levels. At the same time, a gradual shift in the silver eel sex ratio from a dominance of males (size from 270 to 442 mm, age from 3 to 6 years) to females (size from 366 to 1112 mm, age from 4 to 9 years) was recorded. Possible explanations for the escapement patterns observed are environmental sex determination and the installation of eel passes on the main hydraulic engineering structures in 1992 and 1996.     

Movement behaviour of large female yellow European eel (Anguilla anguilla L.) in a freshwater polder area

Due to a recruitment decline of more than 90% in 30 years, the European eel (Anguilla anguilla L.) has been classified by IUCN as critically endangered. Although the species has been studied intensively to obtain knowledge to improve management, studies about the resident yellow stage are relatively scarce. In this study, 52 large female yellow eels were tagged with acoustic transmitters in a Belgian polder system and tracked by a network of 23 automatic listening stations. We studied both circadian and seasonal movement patterns and the effect of environmental variables on these patterns. Large female yellow eels were most active at night in late summer and early autumn. A generalised linear mixed model showed that their movement is only slightly influenced by environmental variables. Moreover, as yellow eels show high site fidelity (i.e., the majority was detected only in the habitat type of their catch‐release location), they do not encounter many human‐induced connectivity problems in polder systems, which makes these systems highly suitable as eel growth habitat. These results can contribute to an effective eel management regarding habitat protection and restoration.     

Effect of insulin in the diet on the growth of European eels (Anguilla anguilla L.)

The effect of oral administration of insulin, in various concentrations, on the growth of European eels (Anguilla anguilla L.) was studied. In order to determine whether the insulin penetrated through the stomach or gills to the blood system, 5 ml insulin, suspended in an 0.6% solution of NaCl, was inserted via the mouth of eels, and the insulin content in the blood measured by radioimmunoassay immediately, and at one and two hours after administration. A control group was given 0.6% NaCl alone. Significantly increased levels of insulin in the blood plasma were found in eels which received high insulin concentrations compared to the control group. Eels administered 20 ppm and 40 ppm insulin in the diet grew significantly faster than a control group fed a diet without insulin, and a group fed 5 ppm insulin.     

Differences in head shape of the European eel, Anguilla anguilla (L.)

Differences in eel, Anguilla anguilla (L.), head shape were the result of greater increases in head width, rather than changes in head length. The ratio of head width:total length (HW:TL) increased significantly ( t -test, P < 0.05) from the glass-yellow eel stage. Cultured yellow eels were exclusively narrow headed (mean HW:TL = 0.027, range = 0.023–0.032), while wild yellow eels displayed an array of head shapes (mean HW:TL = 0.033, range = 0.023–0.046). Therefore, broad heads (HW:TL 0.033) occurred only among wild yellow eels sampled and may have resulted from diet. Cultured yellow eels consumed only small pellet material. Of wild yellow eels stomachs containing food, 78% of broad-headed eels consumed large and/or hard-bodied organisms (e.g. beetles, fish, molluscs and Notonecta sp.), while 83% of narrow-headed eels consumed exclusively small/soft-bodied prey (e.g. amphipods and chironomids).     

A critical consideration of the metamorphosis zone when identifying daily rings in otoliths of European eel, Anguilla anguilla (L.)

Otoliths of glass eels and larvae collected from the Rio Minho (Portugal/Spain) as well as from the Iberian continental slope from the Bay of Biscay were analyzed by scanning electron microscopy. Preliminary data are presented on the total radius of the otolith and the width of the zone exhibiting a diffuse structure which, in the literature, is suggested to be the zone of metamorphosis. It was found that the radius increased from the development stage I through stage II to the glass eel stage (Vb). The width of the diffuse zone also exhibited an increase. Calculations of the dimensions of the diffuse zone of specimens older than stage I revealed that the area of metamorphosis amounts to about 28–60% of the total diffuse zone. From these results it is evident that part of the diffuse zone must have formed during a larval phase of retarded growth, during which no formation of daily growth rings takes place. Only the outer portion of the diffuse zone can be accounted for by the metamorphosis. For these reasons, an exact age determination by counting daily rings seems impossible. A determination of the oceanic life of the eel recruits is difficult for other reasons too: all earlier and recent studies have indicated that Anguilla leptocephali and their metamorphosis stages do not occur on the continental shelf, which could add an additionally high amount of time needed until arrival at the coasts.     

A preliminary telemetry study of the migration of silver European eel (Anguilla anguilla L.) in the River Mosel, Germany

Abstract  – To study the behaviour of silver eels ( Anguilla anguilla L.) during their downstream migration, particularly near a hydroelectric power dam, we tagged nine eels with ultrasonic transmitters and tracked their paths in the River Mosel, Germany. The onset of migration coincided with the first flood event that followed the full moon but was independent of daytime, because migration and turbine passage occurred during both day and night. During migration eels swam actively downstream with a velocity of 0.3–1.2 m · s⁻¹. When migrating eels arrived at the dam, they either passed through the turbines immediately or stayed upstream of the powerhouse for up to 8 days, showing a characteristic circling behaviour. Circling eels repeatedly approached the trashrack, sprinted upstream, and finally passed through the turbines with the next high water discharge. These observations are discussed with regard to the design of appropriate downstream passage facilities.     

中草药对欧洲鳗病原菌的抑制作用研究

本文测试了中草药对五株欧洲鳗致病菌的单独、联合抑菌效果，并测试了中草药、化学治疗剂联合抑菌效果。黄连、地锦草、乌梅、黄芩对病原菌抑制效果显著，中草药联合无显著提高药效作用，其作用效果与抑菌效果最强药物的含量相关，中草药化学治疗剂联合对病原菌作用效果显著。     

Plasma lipoproteins in European eels (Anguilla anguilla): effects of estradiol

A dose-response effect was observed on the plasma concentration of vitellogenin (ALPP, alkali-labile protein P) over a 33 day time-course with repetitive estradiol-17 treatment of European eel (Anguilla anguilla). The plasma estradiol-17 concentration in the treated groups was not proportional to the doses injected. In the groups treated with a medium (0.5 mg kg BW^-1) or high dose (5 mg kg BW^-1) of estradiol there was a significant increase in the plasma total cholesterol concentration during the 33 day time course. The most marked dose-response effect of estradiol was that of plasma total lipids. The distribution of cholesterol between the different lipoprotein classes was dose-related: high density lipoproteins (HDL) predominated in the controls and in the low and medium dose groups, while low density lipoproteins (LDL) predominated over HDL in the group given the high estradiol dose. Plasma HDL concentration was markedly decreased in the high dose treated group; this finding is interesting since HDL plays an important role in the uptake of cholesterol from the extrahepatic tissue.