西非海洋渔业资源非法捕捞现状和对策     

符跃鑫  张振克  任则沛  陈影影  蒋大亮 《世界地理研究》2014,(4):14-22

海洋渔业(尤其是小型海洋渔业)为世界各地的沿海居民提供了重要的食物来源、就业、经济收入。西非临近海域是世界上海洋渔业资源最丰富的地区之一,在西非沿海地区数百万居民以捕鱼为生,然而,西非众多捕鱼区却是最贫穷的地区。在全球化不断推进的今天,非法捕捞已严重威胁到海洋生态系统安全。西非临近海域的非法捕捞问题尤为严峻。在整合相关文献资料的基础上,分析了非法捕捞的主要影响,并对西非地区的非法捕捞现状和问题进行了讨论,认为部分欧盟国家是非洲西部海洋渔业资源主要非法捕捞者,西方学者认为中国是西非地区主要的非法捕捞者是不符合事实的。非法捕捞的根本原因是持续的鱼类需求和捕捞活动缺乏控制。基于以上分析,提出了西非非法捕捞的应对措施,以期有助于解决西非非法捕捞问题。  相似文献   

US catch share markets: a review of data availability and impediments to transparent markets     

《Marine Policy》2015

A growing number of US fisheries are managed with catch share programs, which allocate exclusive shares of the total allowable catch from a fish stock to individuals, cooperatives, communities, or other entities. All of these catch share programs allow transferability of catch privileges in some form. Information on these transfers, particularly prices, could be valuable to fishery managers and to fishery participants to support management and business decisions and to increase efficiency of the catch share market itself. This article documents the availability and quality of data on transfers of catch privileges in fourteen US catch share programs. These catch share programs include several individual fishing quota (IFQ) programs and a number of programs that allocate catch privileges to self-organized cooperatives. Price information on catch share transfers is found to be limited or unavailable in most US catch share programs. Recommendations are made on how to improve the design of catch share programs and associated data collection systems to facilitate effective catch share markets, collection of catch share market data, and better use of information from catch share markets.  相似文献   

射电望远镜控制系统中的数据传输序列化分析     

李军  王娜  刘志勇  宋祎宁  杨垒  王吉利 《天文研究与技术》2022,(1)

控制系统能衔接、集成和管理射电望远镜的软硬件系统。控制系统的序列化工具可以将射电望远镜的不同设备、操作系统、编程语言和网络之间传输的信息进行编码和解码,增强系统之间数据的传输效率。分析和比较了3款二进制序列化工具Msgpack,Protobuf和Flatbuffers的编码原理及特性,并通过一个实例测试了它们的序列化数据大小、序列化时间和中央处理器利用率。结果表明,Msgpack的综合性能优于Protobuf和Flatbuffers,适用于周期长、需求易变的射电望远镜系统之间传输信息的编码和解码。  相似文献   

Joint exploration of regional importance of possibilistic and probabilistic uncertainty in stability analysis     

《Computers and Geotechnics》2014

Stability analysis generally relies on the estimate of failure probability P. When information is scarce, incomplete, imprecise or vague, this estimate is imprecise. To represent epistemic uncertainty, possibility distributions have shown to be a more flexible tool than probability distributions. The joint propagation of possibilistic and probabilistic information can rely on more advanced techniques such as the classical random sampling of the cumulative probability distribution F and of the intervals from the possibility distributions π. The imprecise probability P is then associated with a random interval, which can be summarized by a pair of indicators bounding it. In the present paper, we propose a graphical tool to explore the sensitivity on these indicators. This is conducted by means of the contribution to sample probability of failure plot based on the ordering of the randomly generated levels of confidence associated with the quantiles of F and to the α-cuts of π. This presents several advantages: (1) the contribution of both types of uncertainty, aleatoric and epistemic, can be compared in a unique setting; (2) the analysis is conducted in a post-processing step, i.e. at no extra computational cost; (3) it allows highlighting the regions of the quantiles and of the nested intervals which contribute the most to the bounds of P. The method is applied on two case studies (a mine pillar and a steep slope stability analysis) to investigate the necessity for extra data acquisition on parameters whose imprecision can hardly be modelled by probabilities due to the scarcity of the available information (respectively the extraction ratio and the cliff geometry).  相似文献   

13000 m科学超深井钻探技术          下载免费PDF全文

张金昌  刘秀美 《探矿工程》2014,41(9):1-6

对国内外科学钻探实践进行了简要回顾,对超万米科学钻探工程面临的技术难题进行了分类描述。在此基础上,考虑沉积岩和结晶岩2种地层条件,提出了13000 m科学超深井的钻探技术方案。  相似文献   

一种新型绳索钻具打捞器     

明文威  苑春雷  雷明善 《吉林地质》2014,(4)

绳索钻具打捞器在地质勘探取心过程中有着相当重要的作用,不论是取心还是深孔投放钻具都要用到打捞器,这就要求打捞器在投放过程中有极高的可靠性,保证脱卡器能够顺利脱卡。同时打捞器在被提出钻外后要求有很高的安全性,保证不会空中脱钩伤人。本文所述的一种新型绳索打捞器具有较高的可靠性和安全性,并且兼具重锤的功能,无需打钻过程中投放重锤,可以大大提高钻探效率。  相似文献   

The influence of neoliberalization on the success and failure of fishing cooperatives in contemporary small-scale fishing communities: A case study from Yucatán,Mexico     

《Marine Policy》2017

This paper examines the effects of neoliberalization on the opportunities and constraints that fishing cooperatives face in Yucatán, Mexico. Cooperatives have the potential to enhance small-scale fishing livelihoods and participate in sustainable resource governance. However, promoting cooperatives’ success entails developing a realistic understanding of the political and economic contexts in which they operate. Drawing on interview and census data, the analysis employs the theory of club goods to examine how the neoliberalization of Mexican fisheries policies in the 1980s and 1990s has affected cooperatives’ ability to provide members with collective benefits, and thus the success and failure of fishing cooperatives in the region. In general, neoliberalization has reduced support to fishing cooperatives and generated greater challenges for their success in Yucatán. The results of this study are likely relevant to many other small-scale fisheries in the South that have undergone similar processes of neoliberalization.  相似文献   

Accountability,transformative learning,and alternate futures for New England groundfish catch shares     

《Marine Policy》2017

Environmental change heightens the need for governance structures that enable transformative social learning across socio-ecological scales. Questions arise concerning the ability of audit-based accountability to deliver such adaptive outcomes, particularly if implementation is hampered by communicative divides between insider and outsider groups. In the New England region of the United States, groundfish policy and its catch share system present an illustrative case. Despite severe depletion of cod and other species, governance insiders prevent consideration of regulatory alternatives. An insider-outsider activist strategy based in the state of Maine aims to regain fishery access, intensify grassroots community organizing to support owner-operators attentive to conservation ethics, broaden participation within conventional science and management venues, and improve prospects for community-based area management through strategic policy networks. Adaptive, polycentric accountability therefore seems more feasible, but requires further development.  相似文献   

Stronger together: Strategies to protect local sovereignty,ecosystems, and place-based communities from the global fossil fuel trade     

《Marine Policy》2017

In the Pacific Northwest, residents are mobilizing to prevent the coastal export of fossil fuels and protect unique ecosystems and place-based communities. This paper examines the diverse groups, largely from the Bellingham area, and how they succeeded in blocking construction of what was to be the largest coal-shipping port in North America, the Gateway Pacific Terminal (GPT). Tribes, environmental organizations, faith-based groups, and other citizen groups used a multitude of approaches to prevent development, both independently and in concert. This paper reviews the various ways in which the groups collaborated and supported one another to resist the neoliberalization of the coast and support local sovereignty, unique ecosystems, and place-based communities. Groups like Power Past Coal, Protect Whatcom, and Coal-Free Bellingham fought for important and protective changes and evidenced communitywide political support, but the sovereign rights of the Lummi Nation were the legal bar to constructing the coal terminal.  相似文献   

中日两国渔船的性能和发展情况的比较研究     

邱天霞  焦志刚 《海洋湖沼通报》1999,(2):24-31

本文是在对两国渔业发展情况调查研究的基础上,对比了两国渔船在性能方面的差异,分析了日本渔船的发展趋势,提出了中国渔船近期发展的方向。日本渔船改为节能型后,两国渔船的船型相近,其稳定与适航性指标亦相差不大。日本渔船的装备优于中国的渔船,平均单船功率为46．5kW／艘,中国的平均单船功率为23．03kw／艘。日本渔船的助渔设备、机电设备、制冷设备均较先进,主机推进系统多采用可变螺距螺旋浆或多级减速,中国渔船的推进方式多为定距浆,现在正推广多级减速装置。日本渔船业的发展趋势为：控制规模,提高性能,确保安全,改善适居性。我国渔船的发展方向是：减少渔船的数量,适度发展外海和远洋作业渔船,改善渔船装备,改造小型渔船,大力发展FRP渔船。  相似文献