盐碱地池塘4种养殖模式的鱼产量及负荷力

在氯化物型盐碱地池塘中 ,采用围隔实验生态学方法对鲤、草鱼、罗非鱼和淡水白鲳等 4种鱼类混养模式的鱼产量、负荷力和搭配比例进行对比研究。结果表明 ,4种养殖模式中吃食性鱼类的日增重率和收获规格都随其本身放养密度的增大而减小 ,而鲢、鳙的日增重率和收获规格则随吃食性鱼类放养密度的增大而增大 ;吃食性鱼类的日增重率以淡水白鲳最快 ,草鱼生长最慢 ;吃食性鱼类的净产量为鲤模式 (CC) >罗非鱼模式 (TH) >淡水白鲳模式 (FP) >草鱼模式 (GC) ,混养的鲢在各种模式中的产量顺序为CC >GC >TH >FP ,鳙为CC >GC >FP >TH。CC、GC、TH、FP模式的总净产量分别为 4 .0 2～ 6 .5 5、3.0 5～ 5 .2 6、3.4 5～ 5 .86、2 .99～ 5 .34g/ (m2 ·d) ;FP、CC、TH、GC模式的负荷力分别为 0 .6 0 4、0 .4 92、0 .4 37和 0 .4 30kg/m2 。     

网箱养鱼的放养及投饵技术

一、网箱放养 １．放养品种：罗非鱼类有：单性罗非鱼、吴郭鱼、彩虹鲷等；鲤鱼类有：建鲤、丰鲤等；还有斑点又尾 等品种。 此外可以养殖的品种有：团头鲂、长吻 、南方大口鲶、鲈鱼、鳗鱼、淡水白鲳、草鱼、野鲮及花、白鲢等品种。 ２．放养密度：网箱的放养密度要根据养殖方式、即投饵和不投饵，并参考网箱的鱼产力来决定。可根据下列公式计算：放养密度＝ ３．品种搭配：利用天然饵料的网箱养鱼，常以鲢、鳙为主，搭配少量刮食性的鱼，以清洗网箱。采用投饵的网箱养鱼，养殖草鱼的网箱，因其刮食能力差，常搭配少量的团头鲂、野鲮、鲴。…     

淡水白鲳快速育成技术

2009年5月-11月湘潭岳塘区5家休闲渔场采用淡水白鲳80:20成鱼池塘高效养殖模式,即在池塘养殖时主养淡水白鲳(吃食性鱼)占80%,配养鱼类(滤食性鱼)占20%,投喂全价膨化颗粒饲料为主。淡水白鲳放养时间在5月6日至10日,此时水温稳定在20℃以上。鲢、鳙鱼投放时间为4     

淡水白鲳鱼的人工繁殖试验总结

淡水白鲳原名短盖巨脂鲤。是我国近几年来从国外引进的优良品种之一。食性杂(偏肉食性)、生长快、适应性强;最低临界温度为11°,比鲤鱼、罗非鱼还耐低氧,水中溶氧低10.5mg/1以下时,还能生存。淡水白鲳形状如鳊,肉质如鲤,属优质鱼类。既可以单养,也可混养,当年可长到0.521kg以上。为了解决我省养殖淡水白鲳苗种的需要,我们于1989年从广州引种,利用东宁电厂排出的温流水采取强化措施培育     

之三:奥尼罗非鱼与淡水白鲳池塘混养技术

奥尼罗非鱼是雄性奥利亚罗非鱼和雌性尼罗罗非鱼杂交仔一代, 具有适应性广、雄性率高、食性杂、饲料利用率高、抗病力强、群体生长快、产量高等优点,是一个优质高产的好品种,适合在各种水面进行养殖。淡水白鲳学名为短盖巨脂鲤,属脂鲤目、脂鲤科、巨脂鲤属,是热带和亚热带食用与观赏兼备的大型经济鱼类,具有体型大、生长快、食性广、病害少、耐低溶解氧、易起捕、好垂钓等优     

楚楼水库多方位发展网箱养鱼

1992年,河南荥阳县楚楼水库管理所,在网箱养鲤基础上还开展了网箱养罗非鱼、团头鲂、草鱼、革胡子鲶、淡水白鲳的试验。675m~2养鲤箱,产鱼12.5万kg:50 mZ罗非鱼箱,产鱼3000 kg.50 mZ革胡子她箱,产鱼1200 kg,25 mZ草鱼箱,产鱼3000     

罗非鱼养殖技术之三奥尼罗非鱼与淡水白鲳池塘混养技术

奥尼罗非鱼是雄性奥利亚罗非鱼和雌性尼罗罗非鱼杂交仔一代,具有适应性广、雄性率高、食性杂、饲料利用率高、抗病力强、群体生长快、产量高等优点,是一个优质高产的好品种,适合在各种水面进行养殖.淡水白鲳学名为短盖巨脂鲤,属脂鲤目、脂鲤科、巨脂鲤属,是热带和亚热带食用与观赏兼备的大型经济鱼类,具有体型大、生长快、食性广、病害少、耐低溶解氧、易起捕、好垂钓等优点,己成为池塘养殖的当家品种.     

大水域网箱养殖吃食性鱼类的管理重点

大水域网箱养鱼技术是近几年来发展迅速的一项水产养殖新技术,我国水域广阔,有发展网箱养鱼的良好条件和巨大潜力。网箱养鱼具有投资省、见效快、产量高、经济效益显著等特点,深受广大养鱼户的青睐。网箱养殖吃食性鱼类,是指网箱养殖除食浮游生物的鱼类(主要指鲢鳙鱼)以外的所有鱼类,主要包括鲤鱼、鲫鱼、草鱼、鲂鱼、罗非鱼、淡水白鲳、乌鳢、鳜鱼、鲶鱼等。大水域网箱养鱼已成为发     

池塘主养淡水白鲳成鱼试验

淡水白鲳(Colossoma brachypomum)原产于南美亚马逊河,是热带和亚热带食用与观赏兼备的大型经济鱼类之一。生长速度快,抗病能力强,食性广,耐低氧,肉味鲜美,是一种经济价值很高的养殖鱼类,深受广大消费者和养殖户的欢迎。但该品种自引进北方以来,仅作为一个搭配品种在精养鲤、罗非鱼池塘中套养,比例一般占主养鱼的10％左右。生产实践证明,精养池塘套养淡水白鲳,不能充分发挥该鱼的生产潜能,经济效益也不十分显著。淡水白鲳在南方主养较为普遍,在北方未     

固定式起鱼网

采用传统人工拉网的方法起捕成鱼,劳动强度大,又容易使鱼体受伤,根据鲤、鲫、草鱼、罗非鱼等吃食性鱼类集群摄食的生活习性,以色列水产养殖工作者设计了一种固定式起鱼网,取得良好效果。其结构和装配均较简单,在鱼塘池底淤泥较少,固定投饲位置地方,竖立     

关于陕西省农业生产技术效率的实证分析

文章采用DEA（数据包络）分析方法,从纵横两个方向对陕西省农业生产综合技术效率、纯技术效率和规模效率进行分析,对非DEA有效的地区进行松弛量分析和射影调整,指出其非有效的原因及程度,并给出其应调整规模的正确方向和大小。     

Economic efficiency of small-scale tilapia farms in Guangxi,China

ABSTRACT

The economic efficiency of small-scale tilapia farms in Guangxi, China were analyzed by using Data Envelopment Analysis (DEA). The mean technical (under CRS and VRS), allocative, and economic efficiencies of small-scale tilapia farms were 0.89, 0.97, 0.71 and 0.68, respectively. Efficiency analysis revealed that inefficient farms would have needed to increase production output levels by 32% to perform as well as the best practice farms. The decomposition of the economic efficiency showed that allocative inefficiency was the primary cause of economic inefficiency. There were positive relationships between economic efficiency and age, culture mode and period through Tobit regression, while experience, family members, and technology support had negative effects on economic efficiency. Lower input levels of feed quantity may help to increase the tilapia farming economic efficiency.     

RESOURCE ALLOCATION EFFICIENCY OF THE PRAWN-CARP FARMERS OF BANGLADESH

This paper evaluates resource allocation efficiency of prawn-carp polyculture systems by making use of the data of 105 farmers of Bangladesh. Data Envelopment Analysis (DEA) was employed to estimate the efficiency. Mean technical efficiency (TE), allocative efficiency (AE) and cost efficiency (CE) were 85%, 58%, and 49%, respectively. Fifty percent of prawn-carp farmers displayed full TE whereas only 9% were cost efficient. Actual input application largely deviated from the technical and cost-efficient levels. TEs and AEs showed a positive and negative correlation with pond size, respectively. Labor, fingerlings and feed were overused while organic and inorganic fertilizers were underused in general. Adjustments in actual input allocations were necessary to make use consistent with TE and CE levels. The study concludes that mere achievement of technical efficiency in prawn-carp production may be a short-run concern; the farmers have to be economically efficient in the long-run.     

中国对虾同化率和转换效率的初步研究

我国广泛开展对虾养殖已有近二十年的历史,由于发展和管理不当,产生了严重的环境污染和病害问题,使养虾产量大幅度下降［王清印１９９４］。虽然虾病的暴发性流行是对虾减产的直接原因,但环境条件的恶化也是一个主要因素。在中国对虾的池塘养殖中,其生长和代谢的能量...     

潜流湿地技术在高密度养殖尾水处理中的应用

构建"潜流湿地+生物净化"的湿地生态系统,并以纯生物净化系统作为对照区,研究其对池塘高密度养殖尾水中总氮(TN)、总磷(TP)、高锰酸盐指数(CODMn)、悬浮物总颗粒(SS)指标的去除效果,并对试验区与对照区内的产量与效益进行分析。结果表明:构建湿地生态系统后,区域内养殖面积有所减少,但产量与效益却有所提高。试验区的净化面积占整个养殖系统的7.9%,远远小于对照区的净化面积占比18.8%。对TN、TP、CODMn的去除率分别为80.8%～90.9%、78.95%～88.18%和23.20%～27.24%,对照区对相应指标的去除率分别为70.8%～88.7%、76.09%～87.14%和15.38%～25.08%,试验区的去除效率略高于对照区。至2011年,试验区与对照区的池塘生产各类水产品产量分别比2009年增长24.8%与19.2%、销售收入分别增长了26.4%与14.8%、利润分别增加了35.2%与18.64%。试验区产量与效益明显好于对照区。因此,潜流湿地方式净化水质节省了土地资源,提高了鱼池利用率及养殖效益,与纯生物净化相比具有明显的优越性。     

中国东海、黄海及南海捕捞能力的比较分析

以《中国渔业统计年鉴》中2009~2014年东海、黄海、南海的海洋捕捞渔船数、总功率、总吨位作为不变投入,专业劳动力作为可变投入,海洋捕捞产量为产出,使用数据包络分析法(data envelopment analysis,DEA)对捕捞能力利用度以及理想投入进行分析,总结2009~2014年各海域的规模效率和纯技术效率,计算无偏能力利用度,评价投入配置的合理性以及各生产投入因素对能力利用度的影响。结果表明:黄海海域捕捞纯技术效率较高,但能力利用度受资源衰退的影响明显,并有下降趋势,存在大比例的生产浪费,生产规模亟需优化;东海海域能力利用度和纯技术效率都呈稳定增长趋势,近年对生产投入的控制有一定成效,可变投入配置比例也较合理;南海海域能力利用度和技术效率趋势与东海海域相同,但减船转产实施的不明显,生产投入还有一定的缩减空间。     

Effect of various sources of dietary additive on growth,body composition and serum chemistry of juvenile olive flounder (Paralichthys olivaceus)

Asia traditional herbal feed additives have often been shown to have beneficial effects on disease resistance, growth, feed conversion and protein conversion. There have been few studies on the use of these feed additives in olive flounder diets. The present study was designed to determine if there are benefits associated with the inclusion of any of these traditional herbal feed additives in olive flounder diets. One thousand two hundred sixty juvenile fish averaging 6.5 g were randomly distributed into 36, 180‐L flow‐through tanks. No additive was included into the control (Con) diet. The aqueous type of additives: 2.5% bamboo (BB), 0.25% Prunus mume (PM), 2.5% Artemisia capillaris (AC), 2.5% cinnamon (CC), 2.5% Cirtus junos (CJ), 0.25% Cudrania tricuspidata (CT) and 2.5% Ficus carica (FC), and the powder type of additives: 1% Houttuynia cordata (HC), 1% safflower (SF) and 1% sea tangle (ST) were included into the experimental diets. Finally, 0.1% emulsifying oil (EO) was included into the experimental diet. Feed efficiency ratio (FER) of fish fed the BB, CT and SF diets was higher than that of fish fed the FC and HC diets. Protein efficiency ratio (PER) of fish fed the BB and SF diets was higher than that of fish fed the AC, FC and HC diets. None of serum criteria of fish was affected by any of dietary additives. Dietary additives did not affect weight gain and serum chemistry of olive flounder, but 2.5% bamboo extract and 1% safflower powder was effective to improve FER and PER.     

Efficiency of fisheries is increasing at the ecosystem level

Managing fisheries presents trade‐offs between objectives, for example yields, profits, minimizing ecosystem impact, that have to be weighed against one another. These trade‐offs are compounded by interacting species and fisheries at the ecosystem level. Weighing objectives becomes increasingly challenging when managers have to consider opposing objectives from different stakeholders. An alternative to weighing incomparable and conflicting objectives is to focus on win–wins until Pareto efficiency is achieved: a state from which it is impossible to improve with respect to any objective without regressing at least one other. We investigate the ecosystem‐level efficiency of fisheries in five large marine ecosystems (LMEs) with respect to yield and an aggregate measure of ecosystem impact using a novel calibration of size‐based ecosystem models. We estimate that fishing patterns in three LMEs (North Sea, Barents Sea and Benguela Current) are nearly efficient with respect to long‐term yield and ecosystem impact and that efficiency has improved over the last 30 years. In two LMEs (Baltic Sea and North East US Continental Shelf), fishing is inefficient and win–wins remain available. We additionally examine the efficiency of North Sea and Baltic Sea fisheries with respect to economic rent and ecosystem impact, finding both to be inefficient but steadily improving. Our results suggest the following: (i) a broad and encouraging trend towards ecosystem‐level efficiency of fisheries; (ii) that ecosystem‐scale win–wins, especially with respect to conservation and profits, may still be common; and (iii) single‐species assessment approaches may overestimate the availability of win–wins by failing to account for trade‐offs across interacting species.     

中国农业用水效率区域差异与空间交互机理研究

基于2005-2019年中国31省份面板数据，采用超效率SBM模型和全要素用水效率指标，测度中国农业用水效率。并利用向量自回归模型（VAR），探究中国省域间农业用水效率的交互作用和溢出效应。结果表明：中国农业用水效率总体偏低， 2019年为0.690，存在31%的提升空间。农业用水综合效率与纯技术效率、规模效率呈正相关，但省份之间相关程度存在差异。西藏自治区纯技术效率最高，为1.022，山西省规模效率最高，为0.995。研究期内，中国农业用水效率均值集聚特征不显著，浙江、西藏和海南等三省（区）处于孤岛状态。中国农业用水效率呈西高东低，北高南低总体分布态势。VAR脉冲分析显示中国农业用水效率存在正向空间交互作用，其中以东部地区对中西部影响最为显著。要提高中国农业用水效率，一方面要重视农业科技创新，提高农业用水纯技术效率；另一方面要加强区域协作，充分发挥高效率用水区域的溢出效应     

饲料中脂肪含量对七彩神仙鱼幼鱼生长和消化的影响

在水温29.0±1.0℃下,将140日龄、体质量8～10g的七彩神仙鱼(Symphysodon aequifasciata)幼鱼放入室内54cm×40cm×28era的水箱中,投喂以鱼粉和豆粕为蛋白源(粗蛋白45.0%)、以豆油为脂肪源配制的5种脂肪水平(10.21%、12.02%、17.17%、21.0%,和22.14%)的饲料.90d的饲养表明,七彩神仙幼鱼的成活率变化在96.67%～100.0%之间,各组间差异不显著(P>0.05).随饲料中脂肪含量的增加,鱼的特定生长率(SGR)、蛋白质效率(PER)和增重率均先增加而后降低;摄食含12.02%脂肪饲料的鱼SGR、PER和增重率极显著地高于摄食含10.22%和22.14%脂肪饲料的鱼(P<0.001),而当鱼摄食含17.17%和21.05%脂肪的饲料时,SGR、PER和增重率与摄食含12.02%脂肪饲料的鱼差异不显著(P>0.05).当饲料中脂肪含量为12.02%时,鱼对饲料中蛋白质的消化率最高;摄食含脂肪为10.22%、12.02%和17.17%的饲料时,对饲料蛋白的消化率差异不显著(P>0.05).实验表明,七彩神仙鱼幼鱼饲料中适宜脂肪含量在12.02%～17.17%之间.