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81.
中亚包括哈萨克斯坦、吉尔吉斯斯坦、塔吉克斯坦、土库曼斯坦、乌兹别克斯坦五国,是"丝绸之路经济带"的核心区域,内陆渔业资源禀赋雄厚,世界第一大湖里海以及第四大湖咸海均分布在域内。在前苏联时期中亚各国捕捞渔业和水产养殖发展态势良好,随着东欧巨变及前苏联政局陷入动荡直至解体,渔业生产急剧萎缩,至今虽有复苏但尚未能恢复到苏联时期的发展水平。本文主要基于我们前期研究基础以及FAO和世界银行等统计数据,提出对苏联解体后中亚各国渔业崩溃的原因解读,并探讨在"一带一路"框架下,中国和中亚各国可行的渔业合作方式以及重振中亚渔业的策略方法。  相似文献   
82.
种苗繁育是规范化种植的基础环节,为进一步规范辣木种苗繁育技术,于2013~2015年对辣木种苗繁育过程中的种子采收、种苗繁育、田间管理、采收运输及分级标准进行了总结,并制定了辣木种苗繁育技术操作规程(SOP),以期为辣木标准化的种苗生产提供依据。  相似文献   
83.
Surplus production modelling has a long history as a method for managing data‐limited fish stocks. Recent advancements have cast surplus production models as state‐space models that separate random variability of stock dynamics from error in observed indices of biomass. We present a stochastic surplus production model in continuous time (SPiCT), which in addition to stock dynamics also models the dynamics of the fisheries. This enables error in the catch process to be reflected in the uncertainty of estimated model parameters and management quantities. Benefits of the continuous‐time state‐space model formulation include the ability to provide estimates of exploitable biomass and fishing mortality at any point in time from data sampled at arbitrary and possibly irregular intervals. We show in a simulation that the ability to analyse subannual data can increase the effective sample size and improve estimation of reference points relative to discrete‐time analysis of aggregated annual data. Finally, subannual data from five North Sea stocks are analysed with particular focus on using residual analysis to diagnose model insufficiencies and identify necessary model extensions such as robust estimation and incorporation of seasonality. We argue that including all known sources of uncertainty, propagation of that uncertainty to reference points and checking of model assumptions using residuals are critical prerequisites to rigorous fish stock management based on surplus production models.  相似文献   
84.
This study aimed to investigate the possible causes for inconsistent performances of upland New Rice for Africa (NERICA) varieties in uplands and lowlands, while identifying important determinants in grain yield under deficient soil moisture. We compared the growth and yield of NERICA 1 and NERICA 5 to those of Yumenohatamochi, a Japanese upland variety, and Hinohikari, a Japanese lowland variety, subjected to different water management regimes (continually flooded, supplementary irrigation, and non-irrigation). Under conditions of deficient soil moisture, panicle number per square meter, spikelet number per panicle, and 1000-grain weight of NERICAs decreased, whereas the panicle number of the Japanese varieties experienced little change. In contrast, the grain filling ratio was unaffected by water management, irrespective of variety. The primary source of yield reduction under low soil water conditions was a decrease in spikelet number per panicle, and water stress intensity was the primary factor for the degree of this reduction. Variation in the abortion of secondary rachis-branches caused differences between NERICAs in their spikelet number response to soil moisture deficiency. The inconsistency in NERICA performance across uplands vs. lowlands can be partially attributed to variation in yield response to low soil water conditions. Moreover, water stress intensity and the presence of a water gradient along the vertical soil profile may combine to affect the fluctuation in NERICA performance under upland conditions.  相似文献   
85.
有色黏虫板对柑橘木虱的监测及防治研究进展   总被引:1,自引:0,他引:1  
柑橘黄龙病是柑橘生产中的重大病害,随着其在全球范围内的传播蔓延,该病已成为近年来柑橘生产和研究中普遍关注的热点。柑橘木虱(Diaphorina citri Kuwayama)是传播柑橘黄龙病菌(Candidatus Liberibacter asiaticus)的主要虫媒,对柑橘木虱种群的准确监测与有效防控是控制柑橘木虱传播黄龙病的关键所在。有色黏虫板是一种利用昆虫趋色性,对小型飞行昆虫进行监测与诱杀的重要物理防治手段。有色黏虫板同样适用于监测和诱捕柑橘木虱,但黏虫板的颜色、光源、气候条件、悬挂黏虫板的植物种类及其挥发性信息化合物成分等都会影响黏虫板对柑橘木虱的诱集效果。本文在综合国内外柑橘木虱防控技术的基础上,将近年来利用有色黏虫板,监测与防控柑橘木虱的最新进展进行综述,并对有色黏虫板的发展前景给予展望。  相似文献   
86.
Reconciling food security, economic development and biodiversity conservation is a key challenge, especially in the face of the demographic transition characterizing many countries in the world. Fisheries and marine ecosystems constitute a difficult application of this bio‐economic challenge. Many experts and scientists advocate an ecosystem approach to manage marine socio‐ecosystems for their sustainability and resilience. However, the ways by which to operationalize ecosystem‐based fisheries management (EBFM) remain poorly specified. We propose a specific methodological framework—viability modelling—to do so. We show how viability modelling can be applied using four contrasted case‐studies: two small‐scale fisheries in South America and Pacific and two larger‐scale fisheries in Europe and Australia. The four fisheries are analysed using the same modelling framework, structured around a set of common methods, indicators and scenarios. The calibrated models are dynamic, multispecies and multifleet and account for various sources of uncertainty. A multicriteria evaluation is used to assess the scenarios’ outcomes over a long time horizon with different constraints based on ecological, social and economic reference points. Results show to what extent the bio‐economic and ecosystem risks associated with the adoption of status quo strategies are relatively high and challenge the implementation of EBFM. In contrast, strategies called ecoviability or co‐viability strategies, that aim at satisfying the viability constraints, reduce significantly these ecological and economic risks and promote EBFM. The gains associated with those ecoviability strategies, however, decrease with the intensity of regulations imposed on these fisheries.  相似文献   
87.
以陕西省10市1区乡村旅游发展目的地为对象,以旅游地生命周期理论、适应性管理理论、可持续发展理论为指导,以陕西省各市、区及不同人文自然条件区域为空间分布单元展开实地调研,架构了各市及不同人文自然条件区域的适应性管理框架,以推动陕西省乡村旅游全面、健康、持续发展。  相似文献   
88.
  1. Tourist‐based activities, partly due to their rapid increase, have raised concerns regarding the impacts of anthropogenic activity on marine fauna. Documented effects on pinnipeds in proximity to humans include changes in behaviour, site use and potentially higher aggression levels towards people. Effects vary considerably between populations and sites, thus requiring separate assessment of human impacts on activity and energy budgets.
  2. Responses of the endangered Australian sea lion, Neophoca cinerea, to human visitation were recorded from November 2013 through April 2014. Exposure levels and response types to anthropogenic activities were assessed at two easily accessible locations with different management schemes, Seal (landing prohibited) and Carnac (landing permitted) islands, Western Australia. Exposure levels were measured as both stimulus type (i.e. ‘People’, ‘Paddlers’, ‘Small’, ‘Medium’, and ‘Large vessels’, ‘Tour vessels’, and ‘Jet skies’), and people (‘Direct’, ‘Attract’, ‘Interact’, ‘View’, ‘Incidental’, ‘Water’, ‘Low‐level’), and vessel activities (‘Interact’, ‘Approach/Follow’, ‘Anchor noise’, ‘Engine noise’, ‘Close to beach’, ‘Moderate/Fast travel’, ‘Slow travel’, ‘Transit’, ‘Drift/At anchor’, ‘Aircraft noise’).
  3. Exposure levels varied significantly between the islands in numbers, stimuli type, duration and minimum approach distances. The instantaneous behaviours of ‘Lift head’, ‘Interact’ and ‘Sit’ were the most frequent responses. ‘Aggressive’ and ‘Retreat’ responses, the highest disturbance levels measured, occurred on Carnac approximately once per day, but rarely on Seal Island. ‘Aggressive’ behaviour towards ‘People’ was observed only on Carnac Island and elicited only by ‘People’. ‘People’, ‘Tour vessels’, and scenic ‘Aircrafts’ on both islands as well as ‘Jet skis’ on Carnac Island had the highest probability of triggering responses. Owing to their relatively high visitation at Seal Island, ‘Paddle powered vessels’, followed by ‘Tour vessels’ elicited the highest number of responses, compared with ‘People’, ‘Small’, and ‘Medium vessels’ at Carnac Island. The majority of responses occurred when any stimulus type was at short‐range (≤10 m), and ‘People’ ‘Viewing’ N. cinerea elicited most. Vessels triggered more responses at larger ranges than ‘People’.
  4. To limit close‐range access to N. cinerea, one possibility is to close the beach at Carnac Island to human visitation and increase the minimum approach distance by vessels and ‘People’ by installing marker buoys at least 15 m from the shore.
© 2016 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons, Ltd.  相似文献   
89.
The objective of this study was to assess the effect of environmental variations on the abundance of Sardinella aurita and Sardinella maderensis in Senegalese waters in the upwelling system. Monthly data indicating the abundance of sardinella were first estimated from commercial statistics, using Generalized Linear Model from 1966 to 2011. Abundance indices (AIs) were then compared with environmental indices, at the local scale, a Coastal Upwelling Index (CUI) and a coastal Sea Surface Temperature (SST) index, and on a large scale, the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the Multivariate El Niño Southern Oscillation Index (MEI), using correlations and times series analyses. The results showed that the abundance of sardinella is determined by a strong seasonal pattern and inter‐annual fluctuations. The abundance of S. aurita peaked in spring and in autumn, whereas that of S. maderensis peaked in the warm season (July–September). The trend of the sardinella abundance was significantly correlated with the CUI, especially in autumn and spring. Interannual fluctuations of S. maderensis and S. aurita abundance are, respectively, driven by the precocity and the duration of the upwelling season that is attributed to distinct migration patterns. Both sardinella species also respond with a delay of around 4 years to the winter NAO index and the autumn CUI, and the AMO index, respectively, both related to migration patterns. The wide variations in sardinella biomass are caused by variations in environmental conditions, which should be considered in the implementation of an ecosystem‐based approach in sardinella stocks management.  相似文献   
90.
Since the 1970s, recreational fishing has become a mass hobby in Italy, reaching a large number of people, who, using modern equipment, increased their harvesting capacity, provoking serious conflicts with the professional fisheries. Recreational fishing is strictly regulated inside Italian Marine Protected Areas (MPAs) and is generally allocated to local residents, mainly to reduce the tensions caused by limitations of access to the resources. The aim of this study was to provide an analysis of recreational fishing activities within the Portofino MPA (Mediterranean Sea), to assess the possible impact on the local fish stocks and to plan potential management actions. Furthermore, some serious inconsistencies on the minimum lengths of fish caught as defined by law relative to the minimum size of first reproduction are discussed. Since 2014, all anglers exploiting the Portofino MPA have been obliged to fill out a logbook. The compilation of these was not completely satisfactory, when compared with a group of reliable anglers whose catches were accurately monitored, but allowed for estimated yields of about 24 kg/angler/yr. After 15 years of protection, the fish biomass has increased within the Portofino MPA, generating a positive spillover effect. At the same time, it has attracted many anglers whose gross harvesting was estimated at about 8 t/year, representing about the 8% of the total yield of the local small‐scale fishery.  相似文献   
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