甲胺磷、90-消毒剂对欧洲鳗仔鳗的急性毒性作用

采用静水实验法进行甲胺磷乳剂,９０－消毒剂对欧洲鳗仔鳗急性毒性试验研究。结果表明：在试验浓度３２－５６ｍｇ／Ｌ范围内,欧洲鳗仔鳗中毒死亡发生在３０－４４ｈ,对甲胺磷乳剂急性中毒死亡的时间集中且持续短促;甲胺磷乳剂对欧洲鳗仔鳗的半致死浓度为３５．９ｍｇ／Ｌ,安全浓度为３．６ｍｇ／Ｌ。     

鳗苗饲养技术

目前,由于鳗苗不能人繁,价格昂贵,鳗苗饲养显得很重要,直接影响着养鳗成本和经营的效益。我场从1979年开始试养鳗鱼,并获得成功,现今形成了一套鳗鱼养殖技术,尤其是饲育的鳗苗历年来成活率都在95％以上,开食一个月的增重倍率为8至10倍,为出售黑仔鳗和成鳗养殖打好了基础,现将鳗苗饲养技术简介如下:     

提高黑仔鳗养殖成活率的几点做法

江苏东台市从1986年开始温室养鳗以来,由于重视鳗种养殖的技术普及工作,及时总结推广高产经验,养殖成活率不断提高,1992年全市生产黑仔鳗种2600多万尾,成活率高达98％,关于提高黑仔鳗养殖成活率的技术措施,归纳起来是把住了6关。     

水库网箱养殖黑仔鳗试验

1988年在新安江水库设网箱6只,26.44平方米,投放规格0.973克/尾黑仔鳗11203尾,经163天饲养,收获313.21公斤,规格34.118克/尾,成活率81.94％,出成率8.7％,净产量11.43公斤/平方米,饵料系数2.15。1989年设箱12只,60平方米,投尾重2.018克黑仔鳗47456尾,收获1203.9公斤,成活率86％,出成率8％,规格28.47克/尾,净单产59.14公斤/平方米。饵料系数2.65。本文总结了试验方法与结果。     

澳洲鳗适宜养殖温度的研究

通过测定不同水温下的采食率，间接确定澳洲鳗（Anguilla austrulis)的适宜养殖温度，并观察高温下的死亡状况和极限生存温度，发现澳洲鳗的适宜养殖温度接近于24℃，略高于欧洲鳗，略低于日本鳗，在18℃和35℃水温下，澳洲鳗仍有较强的采食率，致死上限温度为37℃，鱼苗比隔年老鳗有更好的耐热能力。     

欧鳗投饲技术

一、投饲与鳗鱼规格的关系欧鳗规格大小是决定投饲率的前提之一。众所周知，规格越小投饵率越高，但究竟要达到多高的投饵率才能保证其健康生长，又保持较高的生长速度和饲料效率。一般认为，在水温适宜、鳗体健康、饲料品质保证、放养密度适宜时，应保持的投饲率为：白仔阶段投喂红虫时期，可不控制投饲率，尽量让白仔吃饱。在转为白仔后期和黑仔期时投饲率可参照表１：表１白仔后期与黑仔期投饲率在３０尾／公斤以内，许多教科书或文章提倡应低于２．５％，在１０尾／公斤以内应低于２％，在５尾／公斤以内应低于１．５％。但从本人几年的…     

欧鳗的健康养殖及防病技术（连载）

三、欧洲鳗病害防治技术疾病防治始终贯穿欧鳗养殖的全过程，养殖的最终效益也取决于欧鳗的成活率及商品上市合格率，因此，开展欧鳗疾病防治是欧鳗养殖成功必不可少的重要措施。一、细菌性疾病（一）肝肾病１．病原：迟钝爱德华氏菌２．症状：主要损害欧鳗肝脏和肾脏，可见肝脏有脓肿，出现点状出血，或斑点状溃疡灶，严重时呈蜂窝状糜烂，腹腔膜溃烂，肾脏瘀血，溃烂，挤压腹部会从肛门流出红色的粘稠液，皮肤和鳍条有不同程度的充血。３．流行情况：此病从白仔到成鳗都可发生，黑仔到养成阶段发病率高。发病期长，一年四季均可发生，尤以…     

欧鳗苗种培育技术

近几年 ,欧洲鳗的养殖迅速崛起。如何克服欧鳗地理上的差异 ,提高成活率 ,将白仔鳗顺利培育成大规格的黑仔鳗种 ,是整个欧鳗养殖的关键。笔者在多年的养殖实践过程中 ,总结出以下四点技术关键。1　把好苗种关投放优质的鳗苗 ,是整个苗种培育的基础。目前 ,我国欧鳗养殖的苗种主要产于法国、英国、西班牙等 ,其中法国产的鳗苗最佳 ,较能适应我国的环境 ,且鳗苗个体整齐 ,一般在 2 80 0～ 380 0尾 ｋｇ。优质的鳗苗应通体透明 ,体表无任何白点、白斑或白浊物 ,肠道未见进食 ,个体大小均匀 ,游动敏捷 ,逆水有力 ,对光敏感 ;入池后 ,能迅速集群…     

论证僵鳗促长饲料的养殖效果

本文以欧洲鳗为养殖对象，分别从鳗苗培育至成鳗养成品不同生长阶段，以及土池、水泥精养池两种养殖模式论证“僵鳗促长饲料”的养殖效果。结果表明，僵鳗促长饲料具有减少僵鳗数量、提高饲料效率和鳗苗成活率、降低饲料成本等作用，在生产上的应用效果明显，是目前国内解决僵鳗生长问题较为有效的中药预混饲料。     

网箱养殖“老头鳗”试验

体重２０ｇ的“老头鳗”经２个月的饲养,体重可达５０ｇ,再分疏饲养９个月,平均体重可达６８０ｇ以上,商品率８０％以上。添加“复合添加剂”组净产为３４９ｋｇ／ｍ２,比对照组高１２２％;成活率为８９７％,比对照组高９３％;商品率达９１９％,比对照组高１１％。     

欧洲鳗鲡精养高产技术研究

与日本鳗鲡相比，欧洲鳗鲡食欲不旺盛，易患细菌性疾病和寄生虫病。但只要掌握欧洲鳗鲡的生活特性，采取相应的技术措施，其商品鳗养殖可以获得较高的成活率和出成率。     

Variability in growth rates of freshwater eels (Anguilla spp.) in New Zealand

Abstract— Both species of New Zealand freshwater eels (the shortfinned eel Anguilla australis and the longfinned eel A. dieffenbachii ) are widespread and abundant, supporting important commercial and recreational fisheries. This article reviews growth studies from 35 widely distributed sites throughout New Zealand and discusses factors that influence growth rates. Length at given age is characterized by high intra- and inter-population variability; growth rates for eels >30 cm are typically slow (2–3 cm per year) and linear, with females generally growing faster than males. Water temperature affects the length of the growing season, although growth rates are not correlated with latitude. Other factors suggested as affecting growth rates are eel density, quantity and quality of food, and interactions between both eel species. Al though growth of some New Zealand eel populations is the slowest recorded for any species of Anguilla , growth in culture can be rapid, similar to that of other temperate eel species.     

Sex differentiation and sex determination in eels: consequences for management

The aim of this review is to present an overview of the sex differentiation and sex determination processes in eels in relation to the urgent need to provide scientific knowledge to better protect and manage the Anguilla genus. Indeed, the global decline of the three main temperate eel stocks, Anguilla anguilla, Anguillidae (Fisheries Management and Ecology, 2003, 10, 365); Anguilla japonica, Anguillidae (Casselman, Eel Biology, Springer Japan, 2003, 293) and Anguilla rostrata, Anguillidae (Tatsukawa, Eel Biology, Springer, Japan, 2003, 255), raises concerns about the necessity to better understand all stages of the life cycle of eels (Righton and Walker, Journal of Fish Biology, 2013, 83, 754). Little is known about the mechanisms involved in the production of males and females in this species with environmental sex determination. Previous reviews identifying the density of individuals as the major factor influencing sex determination were undertaken (Krueger and Oliveira, Environmental Biology of Fishes, 1999, 55, 381; Reviews in Fish Biology and Fisheries, 2005, 15, 37). Here, we review the current advances on the subject, focusing on the roles of early growth rate and interindividual relationships, which are mechanisms underpinned by density, as well as the sex differentiation process, and we question how this knowledge might influence global conservation measures.     

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.     

The Growth Performance and Nutrient Quality of Asian Swamp Eel Monopterus albus in Central Java Indonesia in a Freshwater Aquaculture System with Different Feeds

The Asian swamp eel (Monopterus albus) is a high protein content fish with delicious taste that can survive for 6–8 months. The growth performance and nutrient quality of Asian swamp eels in a freshwater aquaculture system in Central Java, Indonesia was studied using a completely randomized design. Golden snails, snails, silkworms, and earthworms were the feeding treatments at 5% of total body weight. The test animals weighed 5.68 ± 0.35 g after a 60-day culture, and the density was 36 eels/m². Providing different types of feed had significant effects (P < 0.05) on relative growth rate (RGR), feed intake, and survival rate (SR) but did not significantly affect the protein efficiency ratio (P > 0.05). The best final weight, RGR, and SR results were 11.80 g, 2.64%, and 80.95% during a 60-day culture with silkworms used as feed. The nutrient quality in a similar treatment found with the best proximate composition was 76.90% protein, 3.24% fat, 25.19% palmitic acid, 15.41% oleic acid, 15.9% glutamic acid, 8.2% isoleucine, and 8.9% lysine.     

Effects of silvering state on induced maturation and spawning in wild female Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis>

ABSTRACT:   The effects of silvering state of wild female Japanese eels Anguilla japonica on the success of induced maturation and the following spawning were examined. Thirty-eight females, collected in Mikawa Bay, were divided into four stages based on their silvering state: yellow (Y1), late-yellow (Y2), silver (S1) and late silver eels (S2). Despite injections of salmon pituitary extract (SPE) through the standard technique, Y1 and Y2 eels did not respond to the treatment with undeveloped gonad (gonad-somatic index [GSI]: 0.3–0.9), and all these females died by 5 weeks, probably due to an abnormal physiological condition. Most S1 (81%) and S2 eels (100%) matured completely (GSI: 17.8–51.4), and finally spawned successfully (69% for S1, 89% for S2). S2 eels fully matured with oocytes of over 750 μm in diameter by significantly smaller number of injections of SPE (5–6 times) than the case of S1 eels (6–8 times). The amount of eggs released by S2 eels (0.65 ± 0.11 g/fish per body weight [BW]) was significantly larger than those by S1 eels (0.54 ± 0.09 g/fish per BW). There was no difference in fertilization and hatching rates between eggs released by S1 eels and those of S2 eels. These results indicate that the success of induced maturation and spawning in wild female Japanese eels depends on their silvering state, and matured eggs can be obtained efficiently through the use of S2 eels rather than other stages.     

鳗鲡仔,幼鱼年龄生长的研究

辽东半岛黄海北部沿岸河口4—6月溯河的白仔鳗,全长53.5—64.5毫米,平均58.83毫米,体长频率高峰位于57.1—59.0 毫米体长组,其体长体重呈直线相关。白仔鳗与幼鳗群体的体长、体重则是指数相关,其方程为W=1.136×10~(-7) L~(3.3871)。12尾白仔鳗耳石平均日轮数为146.3,据此对其产卵期进行了推测,观察证实,在不同生态条件下生活过的幼鳗耳石的环纹有过渡带存在。     

The history of commercial fisheries for European eel commenced only a century ago

The stock of the European eel is in decline throughout its distribution area—for decades, if not for centuries. Its population dynamics are not well understood. The extremely scattered occurrence, as well as the general lack of quantified information before 1950, prevents a straightforward analysis. This article discusses the history of eel fisheries across Europe, reviewing the literature published before 1940. A follow‐up study is advocated, to unearth primary information in archives across Europe. In the late 1800s, development programmes were initiated in central Europe, complementing the widespread subsistence fisheries with “modern” commercial exploitation of new areas, new markets and new products. In the early 1900s, increasing fisheries and trade were reported throughout northern Europe, and new developments started in the south. This lasted until about 1950—when the current multidecadal decline set in. The eel fisheries have never experienced a period of stable, sustainable exploitation. The decline in the stock is probably not a simple case of overfishing, but a continent‐wide serial depletion of local resources—eventually depleting the whole stock—in times of growing non‐fisheries impacts. Consequences for the European eel protection programme and for the derivation of restoration targets are discussed.     

Stanniocalcin kinetics in freshwater and seawater european eel (Anguilla anguilla)

The kinetics and hypocalcemic potency of stanniocalcin (STC) were examined in freshwater and seawater eels. The secretion rate and the metabolic clearance rate of STC were calculated from the STC disappearance curve after intra-arterial injection of trout STC. Basal plasma STC concentrations in freshwater and seawater eels did not differ but the STC secretion rate and metabolic clearance rate in seawater eel were 70–75% higher than in FW eel. The increased STC distribution space in seawater eels suggests that the STC receptor density was increased. STC had a higher hypocalcemic potency in seawater than in freshwater eels. These observations support the hypothesis that seawater fish require more hormonal control over transcellular influx of calcium than freshwater fish.To whom correspondence should be addressed.