神农架松干蚧生物学的研究     

吕昌仁  詹仲才 《林业科学》1989,25(6):577-582

华山松是我国亚热带西南部山地一种主要速生优良用材树种,集中分布在川、黔、滇以及秦巴山地。湖北省神农架和鄂西海拔800—2400m的地带,华山松林亦有较大面积的分布。湖北的华山松林除神农架近30万亩天然林外,其余大部分均系60年代引种营造的人工林,面积达100余万亩。长期以来,这些地方的华山松不断死亡,而近年来死亡现象日趋严重。据作者在神农架原始林区调查,华山松枯死株率达36％;而调查与之毗邻的巴东县绿葱坡人工纯林,枯死和濒死株率高达60％以上。如今不少地方不得不将未成材的华山松砍伐,而神农架原始林区的大量枯立木则任凭风吹雨打,病虫侵蚀而成为废物,经济损失巨大。自50年代起,国内不少学者和科技人员先后调查这一地区华山松的死因,但结果一直  相似文献   

水产养殖机器鱼设计与三维路径跟踪控制     

王懿偲  夏英凯  朱明  曾鑫  齐湘洪 《华中农业大学学报》2022,41(4):259-270

为方便监测水质与水下鱼群活动,本研究设计了一款面向全水域实时监测的水产养殖机器鱼,并搭建了机器鱼控制系统,开展了机器鱼三维路径跟踪控制研究。在Serret-Frenet坐标系下建立了机器鱼三维空间路径跟踪误差模型,并基于LOS制导律和李雅普诺夫理论设计了一种模糊滑模控制器,最后利用Matlab仿真对本研究提出的控制算法的有效性进行验证。仿真结果表明：所设计的控制器能使机器鱼在模型参数不确定性、外部干扰未知的情况下实现三维路径跟踪控制,其控制精度和鲁棒性明显优于常规PID与滑模控制器。  相似文献   

广东东莞松木山水库鱼类群落结构及其与环境因子的关系     

袁晨  裴瑞华  郑梓瑶  吴鹏举  黄娜  李一帆  胡忠军 《上海海洋大学学报》2022,31(4):940-949

为探讨广东东莞松木山水库鱼类群落结构特征及其与环境因子的关系,分析其结构特征在沉浮网间的差异性,在该水库设置3个采样点采用多网目刺网对鱼类进行了调查。结果显示,共采集到鱼类17种,隶属4目、6科,物种数以鲤形目为主（占58.82%）。相对重要性指数（IRI）显示,优势种为海南似鱎（IRI占比29.66%）、?（18.98%）、尼罗非鲫（18.46%）、鲢（14.85%）和莫桑比克非鲫（11.36%）,其中单位努力捕捞数量（NPUE）以海南似鱎（45.72%）占优、单位努力捕捞重量（BPUE）以尼罗非鲫（34.60%）为主。聚类分析表明,鱼类物种组成在季节间无显著差异,物种数、NPUE和BPUE亦无季节变化（P>0.05）。鱼类群落物种数、NPUE和BPUE沉浮网间无显著差异（P>0.05）,但鱼类数量组成沉浮网间存在显著差异（P<0.001）,与海南似鱎有关,其NPUE浮网显著高于沉网（P<0.05）,其他5种主要鱼类沉浮网间无显著差异（P>0.05）。透明度、pH和总磷是影响鱼类物种数量时空分布的关键环境因子。研究表明,松木山水库鱼类多样性低,可能与水面积较小、连通性低、外来种入侵及入库河道以人工排渠为主有关,为科学合理评估鱼类数量组成建议水库鱼类调查需要同时使用沉浮网。  相似文献   

鱼用基因工程疫苗的研究概况     

江水清  李婷  张一楠  黄晓红 《中国农业科技导报》2021,23(6):160-170

鱼病的化学药物防治会导致水质恶化、水产品药物残留超标或病原体耐药性增强等弊端。随着鱼类免疫学研究以及分子生物学技术的发展,鱼用基因工程疫苗的研究受到了广泛关注。系统地解析与梳理了鱼用基因工程疫苗发展的背景、意义及疫苗类型和国内外的研究与应用现状,明确现阶段我国鱼用基因工程疫苗发展面临的挑战并提出相应的发展建议,旨在为未来鱼用疫苗的开发和应用提供参考。  相似文献   

Modeling the egg and larval transport pathways of the Antarctic toothfish (Dissostichus mawsoni) in the East Antarctic region: New insights into successful transport connections     

Mao Mori  Kohei Mizobata  Taro Ichii  Philippe Ziegler  Takehiro Okuda 《Fisheries Oceanography》2022,31(1):19-39

The Antarctic toothfish (Dissostichus mawsoni) is an important fishery species widely distributed in the Southern Ocean, especially in areas covered by sea ice. Understanding fish distributions and life cycles, including the transport and survival of eggs and larvae, is essential for the assessment and sustainable management of the fishery. However, owing to difficulties with in situ winter observations, information on the early life stages of D. mawsoni is lacking. Here, we investigated the transport pathways of fish eggs and larvae through a particle tracking study, using satellite-derived ocean surface velocities in the East Antarctic region, which includes important D. mawsoni habitats and exploratory fisheries. Our results indicate that particles released from continental slopes are more likely to be successfully transported to suitable settlement grounds than those released from the BANZARE Bank (the southern region of the Kerguelen Plateau), which is situated further north and has been hypothesized to be a potential spawning ground for D. mawsoni. This study demonstrates successful source–settlement connections in relation to ocean recirculation and suggests important settlement regions for D. mawsoni larvae in the East Antarctic region.  相似文献   

The bioactivity of gonadotropin releasing hormones and its regulation in the gilthead seabream,Sparus aurata: in vivo andin vitro studies     

Y. Zohar  A. Goren  M. Tosky  G. Pagelson  D. Leibovitz  Y. Koch 《Fish physiology and biochemistry》1989,7(1-6):59-67

Thein vivo andin vitro potency of native and modified forms of gonadotropin releasing hormone (GnRH) to release gonadotropin (GtH) was studied inSparus aurata and correlated with their relative susceptibility to degradation by cytosolic-bound enzymes of the pituitary, kidney, and liver. Salmon (s) GnRH and luteinizing hormone-releasing hormone (LHRH) are equipotent whereas analogs of these peptides ((D-Arg⁶-Pro⁹NET)-sGnRH, (D-Ala⁶-Pro⁹NET)-LHRH, (D-Trp⁶)-LHRH) are superactive in inducingin vivo GtH release (at 10 μg/kg body weight). In anin vitro superfusion system of pituitary fragments all analogs are equipotent to the native peptides (at 10⁻¹⁰ to 2.5 × 10⁻⁷M). sGnRH and LHRH are rapidly degraded by cytosolic peptidases of the pituitary, liver, and kidney. The preferred site of cleavage is the Tyr⁵-Gly⁶ bond. Substitution of the position 6 glycine by D-amino acids renders the 5–6 bond resistant to degradation and shifts the main site of cleavage to the Pro⁹-Gly¹⁰NH₂ bond. Substitution at position 6 (as above) and at position 10 with Pro⁹NET results in analogs that are resistant to degradation. We propose that enzymatic cleavage terminates GnRH bioactivityin vivo and thus increased resistance to degradation is a major determinant of GnRH analog superactivity.  相似文献   

Use of geographical information systems as a tool for predicting fish yield in tropical reservoirs: case study on Sri Lankan reservoirs     

S. S. De Silva  U. S. Amarasinghe  & C. Nissanka  W. A. D. D. Wijesooriya  & M. J. J. Fernando 《Fisheries Management and Ecology》2001,8(1):47-60

Use of geographical information systems (GIS) in inland fisheries has hitherto been essentially restricted to site evaluation for aquaculture development and assessment of limnological changes in time and space in individual water bodies. The present GIS study was conducted on the land-use pattern of the catchments of nine reservoirs in Sri Lanka, for which detailed fishery data, viz. yield, fishing intensity, landing size of major constituent species, together with selected limnological data such as conductivity and chlorophyll- a , were available. Potential statistical relationships (linear, curvilinear, exponential and second-order polynomial) of fish yield ( FY , in kg ha⁻¹ yr⁻¹) to different land-use patterns, such as forest cover ( FC , in km²) and shrub-land ( SL , in km²), either singly, or in combination, and/or the ratio of each land type to reservoir area ( RA in km²) and reservoir capacity ( RC in km³), were explored. Highly significant relationships were evident between FY to the ratio of SL and/or FC + SL to RA and/or RC . Similarly, the above land-use types to RA and RC ratios were significantly related to limnological features of the reservoirs. The relationships of FY to various parameters obtained in this study were much better correlated than those relationships of FY to limnological and biological parameters used in yield prediction in tropical and temperate lacustrine waters previously.  相似文献   

Influence of site characteristics on fish community patterns in French reservoirs   总被引：2，自引：1，他引：2  

P. Irz  A. Laurent  S. Messad  O. Pronier  C. Argillier 《Ecology of Freshwater Fish》2002,11(2):123-136

  相似文献   

Structure and Management Issues of the Emerging Ornamental Fish Trade In Eritrea     

Tim M. Daw  Ginny C.C. Rogers  Paul Mapson  Jo E. Kynoch 《Aquarium Sciences and Conservation》2001,3(1-3):53-64

Following independence from Ethiopia in 1993, Eritrea resumed exploiting Red Sea and Arabian fish species for the ornamental trade in 1995 as a means to earn foreign exchange from sparsely exploited marine resources. This paper describes the findings of research conducted in 1997, in collaboration with the Eritrean Ministry of Fisheries. The capture, transport and export of aquarium fish were reviewed and potential impacts and the status of management were investigated through liaison with stakeholders and researchers. From 1995 to 1997 two companies exported approximately 60,000 fish per year, mainly to the USA, worth US$65,000 (export value). Seventy-five species (from 22 families) were exported. Damselfishes made up two-thirds of total exports but more valuable families (angelfishes and butterflyfishes) were more economically significant. To earn revenue for Eritrea, a 20% export tax was imposed, although this was calculated from declarations by the operators. The emerging nature of the trade allowed detailed monitoring by the Ministry of Fisheries. However, management efforts were constrained by a lack of capacity for enforcement and baseline research. Several potential effects of the trade exist but other, land-based impacts may be more pressing concerns for Eritrea's reefs. Research priorities for management are discussed as well as the implications of mariculture of Eritrean species by other nations.  相似文献   

海水经济鱼类遗传育种研究进展   总被引：1，自引：0，他引：1  

尹绍武  黄海  雷从改  陈国华  张本 《水产科学》2007,26(7):416-419

近二三十年来，海水养殖方式与设备的不断发展与完善，促进了海水养殖业的发展。但是，由于海水经济鱼类缺乏优良品种，大多数养殖种类为野生种或半野生种，许多养殖种群在累代繁殖后，出现品质退化、生长速度慢、发病率高等不良症状，严重地阻碍着海水经济鱼类养殖业的发展。因此，近年来，世界各国纷纷加强海水鱼类的遗传育种研究工作，  相似文献