首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 109 毫秒
1.
我国幅员辽阔,淡水渔业资源丰富,大体估算,可供养殖的鱼虾不下二、三十种。近年来,随着农村经济体制改革的深入发展,各种生产责任制的建立,调动了广大渔农的生产积极性。充分利用各类水面,大力发展水产养殖生产,已为越来越多的地方所接受和重视。但是,随着生产规模的扩大、产量的提高,  相似文献   

2.
《重庆水产》2005,(2):9-10
江津市温泉热带鱼养殖专业合作社成立于2002年,合作社位于德感办事处,共有养鱼户250户,其中养殖大户6户,有各类鱼池1500亩,年生产各类优质鱼种1.8亿尾,生产各种商品鱼120万kg,是西南地区最大的热带鱼养殖基地。  相似文献   

3.
《海鲜世界》1992,(1):1-5
一九九二年是实施“八五”规划的第二年。按照“八五”规划着重“质”的改造和提高的基本指导思想及市农办《关于1992年郊区农村经济发展计划的安排意见》,京郊农村经济工作,要依靠科技进步,全面提高经济运行的整体素质,在各类生产中突出先进技术、先进工艺的应用、推广;在管理上突出科学化、规范化,使生产要素合理配置;在经营上,突出高效益、高效率,  相似文献   

4.
为改善鲟科鱼类工厂化生产的生物学技术,确定商品鲟科鱼类的生产前途,有必要查明在生产条件下各类鲟科杂种适宜刺激的界限。本工作研究了各类杂种幼鱼对急剧的温度落层、盐度和水中氧含量的强刺激的抵抗能力。  相似文献   

5.
辽宁是重要渔业省份之一,海岸线较长,渔船渔港众多,全省沿海25个县(市、区)拥有渔民20余万人,各类渔船3万多艘。长期以来,因海上生产条件差,环境极其恶劣,渔船比较分散,管理难度越来越大,渔业安全生产形势十分严峻,各类渔船海损事故频繁发生,给渔民造成极大损失,  相似文献   

6.
农村经济体制改革以来,我省的农业和农村经济得到了高速发展。特别是进入九十年代以后,以粮食为主要标志的各类农副产品产量迅速提高,成为全国重要的商品粮及农业生产大省。但随着经济体制改革的深入,社会主义市场经济体制的初步确立和完善,农业和农村经济中业已存在的千家万户分散的生产经营方式同建立在社会化大生产基础上的国内外大市场连接脱节、农业生产比较效益低同农民收入与城市居民收入拉大、农业结构单一同缺乏区域分工和规模化专业生产等深层次矛盾逐渐显露出来,并已  相似文献   

7.
林仕梅 《内陆水产》2002,27(11):43-45
我国加入WTO将对重庆渔业发展产生极为深刻的影响,如何利用加入WTO带来的机遇并化解挑战,充分发挥自身优势,调整渔业生产结构,提高生产效率和产品质量,融入世界渔业经济市场,在国际竞争中占据更加主动的地位,这是需要深入研究的问题。1重庆市水产品生产现状1.1渔业资源状况重庆市地势沿河流、山脉起伏,形成南北高、中间低,从南北向长江河谷倾斜,起伏较大。地貌状况以山地、丘陵为主,成层性明显。气候属亚热带湿润季风气候,冬暧夏热,雨量充沛,光、热资源较好,适于进行多种水产动物的养殖生产。全市有各类可养殖水面4…  相似文献   

8.
江浙沿海桁拖网作业性能的初步研究   总被引:2,自引:0,他引:2  
本文报道了江浙沿海桁拖网作业性能试验的初步结果。作者将现用的桁拖网分为三个类型、五种结构模式,经过网具模型静水池试验和海上实测,对各类桁拖网的作业性能进行了比较研究。试验的结果表明,在现用的各类桁拖网中,以大网目双囊虾、蟹两用拖网的性能最佳,在相同拖曳阻力条件下,其网口高度最大,而且生产上能兼捕虾蟹。但其网口部位的网目似乎存在偏大的缺点,有漏虾现象。在其他各类中,小网目多囊桁拖网的性能一般优于双囊桁拖网。作者认为,桁拖网捕虾的渔获效率主要取决于网具的水平扩张即桁杆长度。现用桁拖网的桁杆长度已达到渔捞操作所允许的最大长度,但实际作业拖网所用功率一般都在渔船额定功率的10%以下,存在着能耗极不经济的状况,对此,极有研究改进之必要。  相似文献   

9.
薛晖 《水产养殖》2009,30(6):41-42
近年来,随着罗氏沼虾、青虾养殖面积的持续扩大,集约化程度不断提高,各类病害频发,现将生产中几种常见的罗氏沼虾、青虾病害的病因及防治方法介绍如下。  相似文献   

10.
苟金明 《内陆水产》2002,27(6):38-39
宁夏作为西北省区之一,水产养殖业相对发达,已发展成为西北地区重要的水产品生产基地和集散中心。随着经济的发展,宁夏区水产业步入了一个新时期。认清宁夏水产业的现状和存在的主要问题,寻求对策,对于充分发挥水产业在农业中的比较效益优势,保持水产业健康发展具有重要的现实意义。1宁夏水产养殖业生产现状宁夏区位于黄河上中游,国土面积6.6×106公顷,占西北地区国土面积(304.25×106公顷)的2.0%。养殖水域面积1.15×106公顷,为西北地区养殖面积(13.54×106公顷)的8.5%。在各类养殖水…  相似文献   

11.
Yongshun Xiao   《Fisheries Research》2004,70(2-3):311-318
Fishing effort is a function of many (continuous) variables which fishers can manipulate. However, when catch and fishing effort data are analysed using a generalized linear model, individual types of fishing effort usually enter as a composite quantity. But not all quantities can be combined into a composite quantity. Use of such data this way generally leads to a loss of information and incurs a model bias. In this paper, I analyse catch and effort data for the blue swimmer crab off South Australia by a direct use of individual types of fishing effort to extract a relative index of biomass, and use the concept of homogeneous functions to present some of the results. I also give formulae for choosing a combination of different types of fishing effort to effect a specified level of catch in both absolute and relative terms. Assuming that catch follows an independent gamma, normal, negative binomial, or Poisson distribution, fitting of a generalized linear model with a log-link function to the commercial catch and effort data suggests that: (1) the exploitable biomass remained relatively constant from 1 July 1983 to 30 June 1996; (2) the relative instantaneous rate of fishing mortality of a particular sex and age (if gear selectivity was constant over time) slightly increased over time; (3) a 1% increase in the number of days fished gave about 0.85% increase in catch whereas a 1% increase in the number of people on a boat led to only about a 0.45% increase in catch. This implies that use of a composite measure of fishing effort such as boat days and man days when analysing catch and effort data is inappropriate for this fishery. Although a generalized linear model may be a reasonable first-order approximation, catch and effort data are best interpreted through a process model.  相似文献   

12.
采用RT-PCR和cDNA末端快速扩增技术(rapid amplification of cDNA ends,RACE),首次克隆了西伯利亚鲟(Acipenser baerii)的CXCR7a和CXCR7b基因的全长cDNA。CXCR7a的cDNA全长为2 325 bp(登录号为:JQ034508),包括207 bp的5'端非翻译区(UTR)、可编码362个氨基酸的1 086 bp的开放阅读框(ORF)及包括poly(A)尾巴在内的大小为1 032 bp的3'端非翻译区(UTR);CXCR7b的cDNA全长为2 423 bp(登录号为:JQ034509),包括209 bp的5'端非翻译区(UTR)、可编码370个氨基酸的1 110 bp的开放阅读框(ORF)及包括poly(A)尾巴在内的大小为1 104 bp的3'端非翻译区(UTR),并对它们编码的蛋白质序列的分子特征进行了分析。氨基酸序列相似性(similarity)分析表明,CXCR7a与人(Homo sapiens)、小鼠(Mus musculus)、非洲爪蟾(Xenopus laevis)、斑马鱼(Danio rerio)的CXCR7相似性分别为82.6%、81.4%、80.9%、81.0%;CXCR7b与人、小鼠、非洲爪蟾、斑马鱼的CXCR7相似性分别为82.9%、82.3%、80.8%、82.5%;西伯利亚鲟CXCR7a与其CXCR7b的相似性最高为96.5%。系统进化树分析显示,西伯利亚鲟与斑马鱼聚为一簇,两栖类聚为一簇,其它高等脊椎动物再进行聚类。对CXCR7a和CXCR7b在各发育时期胚胎及仔鱼的表达状况分别进行定性分析表明,CXCR7a在除卵裂期、囊胚期的胚胎外,其在原肠胚中期至出膜1 d的仔鱼的各时期中均具有表达,CXCR7b在卵裂期至出膜1 d的仔鱼的各时期中均具有表达。另外,从基因组DNA水平上表明CXCR7a和CXCR7b来自不同的基因拷贝。这些结果为进一步研究CXCR7在西伯利亚鲟侧线系统发育中的作用提供了新的基础资料。  相似文献   

13.
刘宁  黄欣  刘寒  王卫民 《水产学报》2021,45(2):161-169
Hox基因家族在调控动物早期胚胎发育、组织和器官生长起重要作用,因此这类基因家族被广泛应用到物种进化和发育调控的研究中。为了探究Hox基因在团头鲂中分布,进化及表达调控作用,同时为了探究Hox基因与团头鲂肌间刺发育的关系,研究基于团头鲂全基因组数据,结合生物信息学分析方法对其Hox基因家族进行鉴定、染色体分布、系统进化和表达模式分析。结果显示,在团头鲂基因组中共鉴定出49个Hox基因,根据系统进化分析分为5个亚类;其中49个Hox基因不均匀的分布在5条染色体上,并分为7个基因连锁群(HoxAa、HoxAb、HoxBa、HoxBb、HoxCa、HoxCb和HoxDa);表达模式分析结果表明,团头鲂Hox基因家族成员具有不同的表达模式;团头鲂和斑马鱼所有Hox基因在肌肉中的表达水平存在显著差异。此外,团头鲂不同发育阶段及不同组织转录组结果显示,HoxA基因群集中,HoxA2a、HoxA3a在幼鱼阶段高表达,其他基因在肌肉、肌间刺及结缔组织中表达量低甚至不表达;HoxB基因群集中,HoxB9a、HoxB3a、HoxB8a、HoxB1b、HoxB5a、HoxB5b在幼鱼阶段高表达;HoxB7a、HoxB10a、HoxB9a在成鱼肌肉、结缔组织及肌间刺中高表达;HoxC基因群集中,HoxC3a、HoxC4a在幼鱼阶段高表达,HoxC3a、HoxC8a在成鱼的3个组织都有表达;HoxD基因群集中,HoxD9a、HoxD10a和HoxD11a在胚胎S2期表达量较高。研究表明,Hox基因在团头鲂早期胚胎时期和肌间刺的形成中有表达,提示团头鲂肌间刺的形成可能受Hox基因家族调控。  相似文献   

14.
海参皂苷的研究现状   总被引:5,自引:0,他引:5  
海洋中蕴涵着丰富的天然资源,海参作为一种食品和药材,具有很高的保健功能和药用价值。海参皂苷是海参体内的一种次生代谢产物,具有广泛的生理药理活性,因此潜藏了极大的应用价值。本文就近年来国内外关于海参皂苷性质的研究状况做一些简要的概述,为进一步研究海参皂苷提供较为详尽的参考资料。  相似文献   

15.
16.
French Polynesia is renowned for the production of Tahitian black pearl. These gems are obtained by grafting a nucleus into the gonad of a receiving oyster together with a graft, i.e. a small section of mantle tissue of a donor oyster. This procedure initiates the formation of a pearl sack around the nucleus, and subsequently, the deposition of concentric layers of nacre. The nucleus plays a key‐role in pearl formation and its characteristics influence markedly the quality of the final product. As it is manufactured from mollusc shells, it contains a small percentage of organics. In the present paper, we used a set of biochemical techniques to characterize and compare the organic matrices from two types of nuclei that are currently used in French Polynesia: that from the freshwater mussel Amblema sp., and that from the pearl oyster Pinctada sp. To this end, we extracted the matrices from nuclei and performed FT‐IR, monodimensional electrophoresis, and enzyme‐linked immuno‐sorbent assay (ELISA). Our data show that the matrix associated with Amblema nuclei has a very different biochemical signature from that of Pinctada nuclei, a fact that may explain the improved tolerance of grafted oysters to nuclei of Pinctada origin. In the absence of complex physical methods of investigation, simple immunological techniques and FT‐IR performed on the extracted organic matrix are extremely reliable and effective for discriminating nuclei from these two sources. We assert that such techniques can be used as a diagnostic test to track unambiguously the biological origin of nuclei to avoid fraud.  相似文献   

17.
Viral haemorrhagic septicaemia (VHS) is a notifiable fish disease, whose causative agent is a rhabdovirus isolated from a wide range of fish species, not only in fresh but also in marine and brackish waters. Phylogenetic studies have identified four major genotypes, with a strong geographical relationship. In this study, we have designed and validated a new procedure – named binary multiplex RT‐qPCR (bmRT‐qPCR) – for simultaneous detection and typing of all four genotypes of VHSV by real‐time RT‐PCR based on dual‐labelled probes and composed by two multiplex systems designed for European and American/Asiatic isolates, respectively, using a combination of three different fluorophores. The specificity of the procedure was assessed by including a panel of 81 VHSV isolates covering all known genotypes and subtypes of the virus, and tissue material from experimentally infected rainbow trout, resulting in a correct detection and typing of all strains. The analytical sensitivity was evaluated in a comparative assay with titration in cell culture, observing that both methods provided similar limits of detection. The proposed method can be a powerful tool for epidemiological analysis of VHSV by genotyping unknown samples within a few hours.  相似文献   

18.
A stochastic simulation model was developed to examine the impact of risky economic variables on the profitability of a small-scale shrimp farm. Sources of risk included input and output prices, random-kill events, and hurricane damages. Success was measured using the probability distribution of the net present value (NPV). A baseline model that assumed capital costs of $493,993, a stocking density of 100 shrimp per m2, a harvest survival of 80%, and a discount rate of 8% failed to generate a positive NPV. Subsequently adding a $0.66 price premium also failed to establish a positive NPV. Further reducing initial capital costs by 50% resulted in a 2% probability of a positive NPV. Incrementally reducing the discount rate generated increasingly positive NPV probabilities ranging from a 9% probability of success (7% discount rate) to a 94% probability of success (3% discount rate). Additional analyses suggested that probabilities of financial success were also sensitive to random-kill and hurricane events.  相似文献   

19.
Prior to marketing, ornamental tropical fish are currently sorted, graded and counted manually; a process that is labor intensive, stressful to fish and inaccurate. Manipulation of fish movements at our will is a key element in the development of a device for automatically sorting, grading and counting fish by a computer vision system, and the present study is one step towards the development of such a fish-friendly sorting device. The positive phototactic and rheotactic innate responses of guppies (Poecilia reticulata) were exploited to induce them to swim through transparent pipes or narrow channels, to render them ready for inspection by a computer vision system. Water flow direction and velocity, water level, and illumination were effective in inducing fish to move from one container into the other via a narrow transparent pipe. It was attempted to separate guppies moving in groups into individually spaced fish, by introducing an obstacle into a narrow channel or narrowing the transparent pipe.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号