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1.
为探究离底拖网对游泳动物的群落结构以及捕捞量的影响,于2019年9月和2020年9月在福建海域兄弟岛渔场开展了36网次的底拖网专项试验,通过调整曳纲长度控制底拖网作业过程中的网位变动,分别保持底拖网作业在贴底或离底1 m的状态,以物种组成、渔获量对数均值、优势度、多度谱、多样性等参数,分析和比较了贴底拖和离底拖的游泳动物群落结构变化。结果显示:贴底拖和离底拖游泳动物的种类数分别为126种和79种,贴底拖游泳动物的总尾数和总体质量均为离底拖的3倍,贴底拖的渔获量对数均值比离底拖要高0.36,表明贴底拖网的渔获物以栖息于底层的游泳动物为主;贴底拖的游泳动物多样性、均匀度和丰富度分别为2.81、0.65和10.01,均高于离底拖(2.29、0.60和8.13),经济幼鱼的比例更高,说明贴底拖会对游泳动物的多样性以及幼鱼造成更大的损害;离底拖游泳动物的优势度指数为0.41,高于贴底拖的0.29,其多度谱曲线更陡,说明近底层游泳动物群落优势种分布更集中、数量分布不均匀。研究结果可以为底拖网渔业的科学管理提供依据。  相似文献   

2.
《水生生物资源》1998,11(2):75-85
The present work is based on a set of bottom trawl surveys performed in the Gulf of Lions between 1983 and 1992. A new method which couples the STATIS multitable approach with the logic of correspondence analysis (CoA) is proposed to study the stability of spatial organization of demersal assemblages in terms of species composition. This CoA version of STATIS has provided a clear representation of the stable part of the spatial structure of the assemblages. In addition, it gave an insight into the interannual variations of the distribution of each population around the reference structure. Our results showed that the demersal assemblages of the Gulf of Lions exhibited strong spatial structuring, mainly orientated along a bathymetrie gradient. This gradient is structured around three major regions: the coast, the continental shelf and the continental slope. Despite sampling variations that occurred during the course of the study, the analysis showed a high degree of reproducibility for this spatial pattern. With the exception of Mullus surmuletus, the species considered in this investigation exhibit limited variations in their spatial distribution. Finally, in the absence of log-books covering the activities of commercial fishing vessels, these findings constitute a base of reference for the analysis of the dynamics of fishing fleets exploiting the demersal resources of the Gulf of Lions.  相似文献   

3.
入世以来中国水产品贸易的格局特征及发展前景   总被引:2,自引:0,他引:2  
水产品是中国传统的出口优势产品。加入WTO以来,中国水产品贸易在进出口双向快速增长的局面下,保持了净出口态势。文章在总结中国水产品入世几年来进出口的发展趋势、产品结构以及国别特征的基础上,着重分析了其发展前景。结果表明,增强质量竞争力是优势水产品出口实现持续增长的关键,未来几年对国外捕捞类水产品进口将继续大规模增长,中国水产品进出口的产品结构特征短期内不会有显著变化。最后,基于提高出口水产品竞争力、优化中国水产品贸易格局的目的提出了一些对策建议。  相似文献   

4.
长江口外海域夏末温跃层与底层水低氧现象研究   总被引:4,自引:0,他引:4  
林军  闫庆  朱建荣  龚甫贤 《水产学报》2014,38(10):1747-1757
基于长江口外海域2009年夏末调查的温盐和溶解氧(DO)资料,采用垂向梯度法对夏末长江口外海域温度垂向结构类型进行划分,计算了温跃层深度、强度和温跃层处DO垂向梯度等参数。长江口外海域夏末水温垂向结构类型及其温跃层强度的分布表现为长江冲淡水、黄海沿岸流、台湾暖流表层暖水和台湾暖流深层冷水交汇、混合的态势。相关性分析表明,温跃层深度与温跃层处DO垂向梯度之间为负相关,温跃层深度与垂向最小DO浓度之间为正相关,温跃层强度与温跃层处DO垂向梯度之间为正相关。最接近DO供给源的上温跃层强度与温跃层处DO垂向梯度具有较强的相关性(r=0.69)。温跃层越浅、强度越大,对底层水低氧现象的影响越大。温跃层、特别是上温跃层引起的水体层化阻碍DO向底层输运,起到了物理隔氧的作用,与低氧现象具有紧密的联系,是低氧现象在长江口外海域从春末到秋季发生、发展、维持和消亡过程的重要环境控制因素。  相似文献   

5.
依据中国渔政指挥系统江苏省渔业船舶水上安全事故的统计资料,对2010—2019年事故的发生时间、事故起数、死亡人数、事故类型和事故等级等方面进行了统计分析。结果表明,江苏省渔业船舶水上安全事故以一般等级事故居多,事故发生时间呈现一定规律性,渔船自身安全隐患突出,从业人员岗位技能不足,渔船安全管理责任不到位。基于分析结果,提出压降一般等级事故,遏制较大等级以上事故,提高风险管控和事故防范能力的对策建议。  相似文献   

6.
The consequences of over-exploitation may seriously impair the integrity and functioning of ecosystems. When loss of species is accompanied by the loss of ecological processes, the effects are no longer just taxonomic and may affect the stability of the environments. Ornamental fishing is one of the main economic activities of the middle Negro River. Such activity is directed to a small number of species and has the Cardinal Tetra (Paracheirodon axelrodi) as the main target species. Given the potential effects this pressure and the lack of information on its consequences, the present study analysed, through simulations, the possible effects of depletion of ornamental fish populations on the functional structure of fish assemblages, represented by functional diversity (FD) and functional redundancy (FR) indexes. We sampled 13 streams exploited by the ornamental fishery, where we collected 4,286 specimens of 110 species, of which 22 were targeted as ornamental fishing. We found that the ornamental species corresponded, on average, to 27.8% of the species and 33.3% of the FD of the assemblages. In a scenario of complete exclusion of ornamental species, local communities would lose 24.6% of the FD and reduce up to 12% of the FR. With these results, it is possible to infer that the local extinction of exploited species would cause negative impacts on the multifunctionality and the resilience of the streams ecosystems. In this way, we emphasise the need for proper management of the ornamental fisheries aiming to the sustainability of the activity and to the conservation of ecosystem functionality.  相似文献   

7.
《水生生物资源》2002,15(4):197-210
Marine populations are distributed heterogeneously in space and time because of the diversity of habitats and the requirements of species life cycles. Human exploitation of these resources also varies as a function of space, time and the type of fishing activities performed. These three factors determine fishing strategy at different levels of integration. The purpose of this study was to describe and analyse, with respect to different time scales, the relations between the modalities of resource exploitation and the biological or demographic characteristics of the species involved. These investigations relate to the more general task of acquiring the basic knowledge needed for spatialised management of fishing effort. A fleet of trawlers from La Rochelle, operating in the Bay of Biscay, was studied over a 15-year period (1979–1993), which led to the development of a reference resource exploitation scheme for these vessels. The degree of stability of this scheme over time was determined from landing profiles of the 18 most important species fished (94% of landings). An annual cycle for the species composition of landings was determined by multiple factor analysis. Two factors account for more than 55% of the inertia of the data. The first, of biological origin, is closely related to the breeding activity of species and associated migrations between the coast and the open sea. The second is spatial in nature, corresponding to the distribution and availability of resources according to a bathymetric gradient. This organisational scheme persisted over the first 13 years, but showed signs of change toward the end of the study period. Analysis of multi-year trends indicated four periods marked by sustained levels of landings per unit of effort for some species (decreasing for sole and wedge sole, or increasing for Norway lobster, striped red mullet, rays and the smallspotted catshark). These changes are attributable to restrictions on resource access imposed on the fleet (regulations and/or competition among the fishing gears for occupation of space), variations in the abundance of traditionally fished populations (hake, anglerfish) and changes in the professional behaviour of fishermen.  相似文献   

8.
本文通过调研水产品在流通、加工、贮藏和零售四个产业链环节的损耗情况,对不同类型水产品损耗原因和差异进行分析,提出降低我国水产品产业链损耗的建议措施。单一水产品品种的损耗率数据通过调研直接获得,水产品(整体)及各品类产业链损耗率基于2008-2019年水产品品类及品种产量结构加权计算所得。结果显示:2008-2019年,我国水产品年均损耗量426.55万吨,年均损耗率8.09%。其中海水养殖、淡水养殖、海洋捕捞水产品的损耗率分别为12.37%、6.59%、5.82%。从产业环节看,水产品流通环节损耗量117.73万吨,损耗率2.23%;加工环节损耗量169.67万吨,损耗率3.22%;贮藏环节损耗量40.83万吨,损耗率0.77%;零售环节损耗量98.32万吨,损耗率1.86%。以鲜活方式流通与消费容易导致更高的损耗率,海水养殖产品损耗率较大、接近淡水养殖和海洋捕捞的总和,加工和流通是产业链的薄弱环节。为进一步降低损耗,应扩大加工产品消费,鼓励加工技术创新;升级冷链物流体系,降低产品物理损耗;促进组织化发展,提高标准化作业水平。  相似文献   

9.
真鲷幼鱼狂游症病毒病原学初步研究   总被引:1,自引:0,他引:1  
应用电子显微镜观察真鲷幼鱼内脏组织超薄切片。发现真鲷幼鱼脾脏存在大量病毒颗粒。病毒颗粒直径约120nm,呈六角形,有一层蛋白质外壳。核心主要为核心酸。病毒颗粒主要位于细胞核内。感染的细胞肿胀,比正常细胞增大5-6倍。在肠组织超薄切片中也发现少量形态相同的病毒颗粒。  相似文献   

10.
我国海水网箱养鱼发展现状是以个体联合体生产经营为主体的低技术水平的数量规模化,众多传统港湾已形成了大范围的严重超负荷养殖状态,其对环境巨大的污染力引发鱼病猖獗和频受赤潮侵袭,已面临严峻的养殖环境危机。本文综合分析了我国海水网箱养鱼的发展现状与负面效应及其现状危机,并初步进行了危机根源和可持续发展的讨论分析。  相似文献   

11.
编线工艺对渔用高强度聚乙烯编织线拉伸性能的影响   总被引:4,自引:1,他引:3  
2007年3月~2008年12月在东海水产研究所开展了编线工艺对渔用高强度聚乙烯(HSPE)编织线拉伸性能的影响研究。结果表明,在试验捻距范围(公称直径3.0 mm和3.9 mm编织线的试验捻距范围分别为11.1~29.2 mm、16.4~48.5 mm)内,若其它条件(包括线股结构、线芯用丝数量和线芯结构等)相同,则以不同捻距编织的相同公称直径渔用HSPE编织线的断裂强力及单线结强力均随捻距的增加而增加,而断裂伸长率及线密度则随捻距的增加而减小;多项式回归方程显示,断裂强力与捻距、单线结强力与捻距均显示较好的相关性(R2≥0.987 7)。在线芯用丝数量范围(公称直径3.0 mm和3.9 mm编织线的试验用线芯用丝数量范围分别为0~36、0~64)内,若其它条件(包括线股结构、捻距和线芯结构等)相同,则以不同线芯用丝数量编织的相同公称直径渔用HSPE编织线的断裂强力、单线结强力及线密度均随线芯用丝数量的增多而增加,而断裂伸长率则随线芯用丝数量的增加而减小;多项式回归方程显示,断裂强力与线芯用丝数量、单线结强力与线芯用丝数量均显示较好的相关性(R2≥0.969 5)。若其它条件(包括线股结构、捻距和线芯用丝数量等)相同,则将线芯结构由不加捻的平行丝束改为捻度为32 T/m的线股后,公称直径2.5 mm渔用HSPE编织线的断裂强力、单线结强力、断裂伸长率和线密度均有一定的增加。捻距、线芯用丝数量及线芯结构对渔用HSPE编织线拉伸性能的影响较大。  相似文献   

12.
以网片断裂强力、网片断裂伸长率和网片断裂强力保持率为指标,研究了不同K型网目对渔用乙纶网片拉伸力学性能的影响。结果表明:K型网目下网目内径之比在1.01~1.20时,网片断裂强力随着网目内径之比的增大而下降,两者呈密函数相关。同规格线的网片,K型网目下且两网目内径之比相同时,小规格网目尺寸的网片断裂强力损失小,断裂伸长率高,而大规格网目尺寸的网片断裂强力损失大.断裂伸长率低。  相似文献   

13.
In an experiment of 36 days duration 46 one-day-old chicks were divided into 5 groups and fed with different concentrations of vitamin D3. The animals of the group which lacked vitamin D3, showed the typical rachitic lesions. After a 15 days lack of vitamin D3 the chicks of another group were treated with standard food (2000 I.U. vitamin D3/kg food) with the consequence of an approximation of the analyzed parameters to those of the control group within 3 weeks. When fed with 60,000 I.U. of vitamin D3 after a 15 days lack of this vitamin, the animals showed an over-hasty healing process, ending up with signs of intoxication which were even more conspicuous when fed with 120,000 I.U. of vitamin D3. Besides an increasing calcification of osteoblasts and endothelial cell membranes as well as a degeneration of osteoblasts, a clear increase of eosinophilic granulocytes could be noticed. In all groups free erythrocytes within the ground substance were found. There was no evidence of necroses of osteocytes or of bone.  相似文献   

14.
During the combination of oral and intravenous application of saline solution for treatment of the COPD of horses the level of hydraemia basing on the total protein concentration in the serum, the urine production and the specific weight of urine was determined. Additionally the development of serum concentration and of renal excretion rates of potassium, calcium and magnesium were ascertained. The level of hydraemia resulting from the combined method is almost identical with the solely intravenous performed hyperinfusion therapy. Due to the excessive application of fluid an extremely high level of urine production is reached which causes a reduced specific weight as well as an increased renal excretion of potassium, calcium and magnesium. The result is a real loss of electrolytes which is - apart from hydraemia - the reason for the lower level of the corresponding serum concentrations. This seems to be important, especially for potassium and magnesium, because the organism is unable to compensate the loss of these electrolytes in the same way as the loss of calcium. In connection with the renal loss of electrolytes during the high level of urine production glucosuria is observed.  相似文献   

15.
中国对日水产品出口贸易之SWOT分析   总被引:5,自引:0,他引:5  
日本是中国水产品出口第一大市场,对日水产品出口的数量和金额呈逐年上升趋势。但对日水产品出口并不是一帆风顺,特别是在入世后出现过波动。通过SWOT分析,认为中国应该发挥渔业资源丰富和劳动力廉价的优势;遏制水产品科技含量低、生产经营主体竞争力弱、组织化和产业化程度低、监管制度落后的劣势;捕捉"中国制造"形成的良好声誉,政府政策和"暖春"带来的机遇;规避"肯定列表"、日本水产品贸易政策和其他对日水产品出口国的威胁,进而使对日水产品出口持续、健康、稳定地发展。  相似文献   

16.
文章在对中国农业现代化前期研究总体现状进行搜索并分类的基础上,对国内外农业现代化进程中农业流通现代化思想演变,生产要素流通现代化、农产品流通现代化、农业生产与流通现代化关系、现代农业流通现代化研究内容等相关研究文献进行述评。归纳出中国特色农业现代化进程中农业流通现代化研究的重点、特点和趋势。并根据中国农业现代化进程中的时代特征要求,对传统农业现代化研究视角进行讨论。  相似文献   

17.
朱凯  戴志远  沈清  郑振霄 《水产学报》2021,45(7):1213-1224
为了研究3种不同海洋脂质- 二十碳五烯酸(eicosapntemacnioc acid , EPA), 二十二碳五烯酸(docosapentaenoic acid , DPA)和二十二碳六烯酸( docosahexaenoic acid , DHA)对溃疡性结肠炎(UC)小鼠及其肠道菌群的影响,本实验采用葡聚硫酸钠(dextran sulfate sodium, DSS)诱导的C57BL/6小鼠为UC模型,以小鼠的体质量量减少量、疾病活动指数、结肠表观、结肠长度、结肠的重量与长度比、苏木精-伊红染色结肠组织切片的显微观察及组织学损伤评分为指标评价3种海洋脂质对UC的干预效果,采用16S rDNA高通量测序的方法研究了3种海洋脂质对小鼠肠道微生态的影响。结果表明,3种海洋脂质均可以有效抑制UC小鼠体质量的下降、疾病活动指数的升高、结肠长度的缩短及组织损伤评分的升高,其中DPA的在抑制体重下降、疾病活动指数升高以及组织损伤评分升高方面的干预效果显著优于其他两者。16S rDNA高通量测序的结果显示,3种海洋脂质可以有效抑制UC小鼠肠道内拟杆菌属、脱硫弧菌属、肠球菌属、埃希菌属/志贺氏菌属、乳球菌属、普雷沃菌属和毛螺菌属丰度的增加,阿克曼菌属、理研菌属、双歧杆菌属、布劳特氏菌属、丁酸杆菌属、真杆菌属和螺旋菌属丰度的降低,其中DPA对阿克曼菌属, 理研菌属, 丁酸杆菌属和埃希菌属/志贺氏菌属具有更加显著的调控作用。本研究表明,EPA、DPA和DHA这3种海洋脂质可以显著缓解UC小鼠的病症,并且可以显著改变UC小鼠肠道菌群的结构和组成,说明这3种海洋脂质对UC的管控作用或与其对肠道特定微生物的调控作用相关。本研究为海洋脂质,尤其是DPA的生物学效应提供了参考,并为膳食管控慢性疾病提供借鉴。  相似文献   

18.
用线粒体DNA的D-loop和Cytb基因序列分析方法研究了吉林延吉、敦化和辽宁法台3个区域的29尾拉氏鱼岁Phoxinus lagowskii Dybowsky的遗传多样性.经PCR扩增和测序,获得了783~785bp D-loop和818bpCyt b的同源序列.两者多态性遗传参数统计显示,29尾个体分别存在47(D-loop)和89(Cyt b)个变异位点,分别检测出15 (D-loop)和1l(Cyt b)个单倍型,总群体单倍型(Hd)分别为0.8966 (D-loop)和0.8990(Cyt b),核苷酸多样性指数(Px)分别为0.0246(D-loop)和0.0498 (Cyt b),平均核苷酸差异数(K)分别为19.2857(D-loop)和40.7365(Cytb).分子方差分析(AMOVA)结果表明,79.02%(D-loop)和81.69%(Cyt b)变异来自群体间,20.98%(D-loop)和18.31%(Cyt b)来自群体内.单倍型呈明显的地理差异,分成2个分支,一个以延吉群体为主,一个以法台群体为主.拉氏(鲮)的遗传多样性水平较高,群体间遗传分化明显.该结果可为拉氏(鲮)的种质资源保护提供参考.  相似文献   

19.
三种免疫添加剂对草鱼非特异性免疫功能的影响   总被引:1,自引:0,他引:1  
在饲料中添加不同剂量的Vc、酵母多糖和壳聚糖,连续投喂42d,并在试验的第14、28、35和42天取样检测,研究其对草鱼血清溶菌酶活性、血清超氧化物歧化酶活性(SOD)活性、血清碱性磷酸酶(AKP)活性、补体C3、含量丙二醛(MDA)含量和血液白细胞吞噬活性共6种指标的影响。结果显示:实验组与对照组相比,饲料中添加Vc可以提高血清溶菌酶活性、SOD活性、AKP活性、补体C3含量和血液白细胞吞噬活性高,并降低MDA含量。添加酵母多糖可以提高血清溶菌酶活性、AKP活性、补体C3含量和血液白细胞吞噬活性,并降低MDA含量,但不能提高SOD活性。添加壳聚糖可以提高血清溶菌酶活性、SOD活性、AKP活性、补体C3含量和血液白细胞吞噬活性,但不能降低MDA含量。饲料中添加Vc、酵母多糖和壳聚糖均对草鱼的非特异性免疫功能具有一定的促进作用。  相似文献   

20.
A literature review of surgical techniques used for resection of periocular tumors with conservation of the eyelid is accompanied by a report of the author's personal experience with blepharoplasty in cattle. Included are 13 cases of Fleckvieh cows with squamous cell carcinoma. Five animals were without tumor recurrence after an average time of 10.7 months, while seven animals with recurrence of the neoplasm had mean survival time of 10.6 months. Those five cows had been slaughtered for unrelated problems, the others because of recurrence of the ocular tumor. One patient was slaughtered five days after surgery because of complications of wound healing.  相似文献   

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