Impact of minimum legal size increases on egg‐per‐recruit production,size structure,and ovigerous females in the American lobster (Homarus americanus) population off the Magdalen Islands (Quebec,Canada): A case study     

Louise Gendron 《新西兰海洋与淡水研究杂志》2013,47(3):661-674

In the mid 1990s, American lobster (Homarus americanus) from Canadian waters was considered overfished based on estimated levels of egg‐per‐recruit production (EPR). In 1997, the Department of Fisheries Oceans responded by adopting a goal of doubling the level of EPR from its 1996 level. In the Magdalen Islands (Quebec), results from a simulation model indicated that doubling EPR could be reached by increasing the minimum legal size (MLS) from 76 mm to 83 mm carapace length. This was done at a pace of 1 mm per year from 1997 to 2003. Following the increase of MLS, the size structure, mean size, and the abundance of ovigerous females improved significantly in the catches. However, levels of fishing effort are still very high. This could cause undesirable effects such as altering sex ratios and size structure of males, which could lead to sperm limitation, and reducing the contribution of multiple spawners to egg production, which could become an issue if egg quality is important. Consideration of these issues leads to the recommendation of a multidimensional approach to lobster conservation.  相似文献   

山东省区域经济发展状况GIS评价   总被引：1，自引：0，他引：1  

肖燕  孙壮 《测绘科学》2012,37(5):145-147

本文利用山东省2003年-2009年县市人均生产总值等经济数据,借助SuperMap的GIS空间分析功能进行山东省区域经济发展状况分析。方法上将单纯的统计数据与实际地理位置相关联。结果表明:山东省近7年间县域人均收入分布明显不均匀,呈现不利于经济长期持续发展的单峰分布状态;区域间的人均生产总值差距逐渐增加;人均生产总值与地理区位、资源分布和交通线路的分布有较大相关性。  相似文献   

Firewood consumption amongst poor inhabitants in a semiarid tropical forest: A case study from Piura,northern Peru     

《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(1):28-41

Semiarid forests are disappearing on a large scale and are considered to be the most endangered ecosystems in the lowland tropics. The deforestation rate in Peru is among the highest in Latin America and the Caribbean. Poor people are often more dependent on forest resources than those who are well off. However, little is known about poor people's use of forest resources or the effect of logging in semiarid forests. The article deals with household energy use and the source of firewood (bought or collected, either locally or over some distance) in two semiarid forests in Piura, northern Peru. The most used tree species and the vulnerability of the species are also examined in order to understand deforestation. Peru has introduced regulations on the use of forest resources and the article focuses on how these regulations are locally understood. The methodology includes questionnaires, recording local household practices, and in-depth interviews with local informants and both governmental and non-governmental organizations. The daily wood consumption rates per person were measured. The findings reveal that household economy is not the only factor affecting daily firewood consumption rate, but also climate, ecology, access to firewood, and traditions are contributing factors.  相似文献   

基于偏离-份额法的我国农民收入结构演进的省际比较   总被引：3，自引：0，他引：3  

万年庆  李红忠  史本林 《地理研究》2012,31(4):672-686

在对我国各省区农民收入结构对比分析的基础上,采用静态和动态偏离—份额法对我国1997～2009年各省区农民收入结构及演进态势进行探讨。随着农民收入的增长,农民收入结构发生了剧烈变化,家庭经营收入比重在降低,工资性收入逐步成为大多数省区的重要收入来源。静态偏离—份额分析显示东部省区农民收入结构优势高于西部省区,尤其是工资性收入的结构优势对收入增长贡献较大,而中西部省区的地区竞争优势高于东部省区,尤其是工资性收入增速较快;根据结构和竞争偏离分量的优劣势把各省区分为收入快速增长型、收入增长滞后型、结构优势推动型和竞争优势推动型4种类型。动态偏离-份额分析显示东部省区农民收入的增速在降低,竞争劣势更加突出,部分中西部省区竞争优势逐步增强,但结构优势并不明朗,对收入增长贡献不大。由此认为,加大力度提升农民收入结构层次,尤其是提高工资性收入水平对于协调农民收入增长区域差异具有重要意义。  相似文献   

COMMENT ON “WHO WILL FEED CHINA”     

陈百明 《中国地理科学(英文版)》1997,(1)

I.MR.BROWN'SMAINOPINIONMr.LesterBrown,'presidentoftheWorldWatchinstituteintheU.S.A,publishedalongicicletitledas"WhowillfeedChina"in1994(Brown,1995),whicharousedgreatresponSeSfromhomeandabroadandattractedmuchattentionfromallsides.Theadnideasofthearticleincludethefollowingthreepoints:(1)ItisestimatedthatthepopulationofChinawillincrare490whitionfrom1990tO2030,uptol,600whition;thecultivatedlandofChinaisaffectedbythemedeAnzationoftheeconomy,andisevendisap~ng;inaddition,thepotentiality…  相似文献   

中国重要矿产资源的需求预测   总被引：36，自引：22，他引：14  

王高尚  韩梅 《地球学报》2002,23(6):483-490

以往对矿产资源的中长期需求预测,大都基于纯数学模型或情景分析对已有数据的经验外推。由于缺乏对工业化过程矿产资源消费需求基本规律的把握,预测结果几乎无一例外地存在巨大偏差。笔者在深入分析工业化经济增长与矿产资源消费需求的相关关系、基本规律和模式的基础上,探讨了工业化过程中矿产资源消费从怎样的初始值通过什么样的方式到达多高的峰值,进而提取经济增长与矿产资源消费需求的模式参数,预测了中国未来30a能源、钢、铜、铝、锌的消费需求。  相似文献   

Convergence or divergence?: Status and prospects for US climate strategy     

Atle Christer Christiansen 《Climate Policy》2003,3(4):343-358

The objective of this paper is to assess recent developments and prospects for future changes in United States (US) climate strategy. In doing so, the paper explores some of the key factors that have shaped strategies and policies to date, distinguishing between factors related to institutional and governance structures, linkages between science and policy, energy technology and the role of interest groups. Against this background, the paper attempts to explore future development paths for US climate policy. More specifically, the paper assesses opportunities for policy changes compared to the preferences of the current administration, and the prospects for future linkages between US and international climate change strategies. In brief, the paper argues that substantial changes are unlikely to take place in the near to medium term, leaving open, however, the possibility of wide-ranging changes in domestic politics or major incidents that could facilitate a shift in the perceived need for near-term action.  相似文献   

近期我国省域经济增长的基本态势分析   总被引：11，自引：3，他引：11  

樊杰 《地理科学进展》1997,16(3):8-15

本文对1991年～1996年间，我国省域经济增长的区域差异性进行了分析。重点是：揭示国家宏观发展政策对省域经济发展格局的作用效果，总结省域经济发展水平变化及对国家经济总量增长贡献程度分异的规律，以及划分省域经济增长类型、并探讨主要类型形成的内在机制。  相似文献   

一个面向未来的历史性选择：—我国资源,环境问题与持续发展     

黄鼎成 《水文地质工程地质》1993,20(1):5-8

文章概述了我国正以历史上最为严峻的资源、环境状况,承载着历史上最多的人口群及其最大的活动能力。初步探讨了持续发展的必然选择。  相似文献   

多功能ASTATIC软件的改进与开发   总被引：1，自引：0，他引：1  

柳建新  王贵财  刘春明 《物探化探计算技术》2006,28(4):346-351

ASTATIC软件是美国Zonge公司生产的GDP系列大地电磁仪的配套数据处理软件,主要用于CSAMT数据的静态校正。但该软件功能有很大的局限性:①不能直接通过鼠标或键盘上的功能键进行编辑;②该程序只能显现编辑卡尼亚视电阻率数据,不能对电场振幅、磁场振幅、电场相位、磁场相位、相位差进行显现、编辑和输出;③在输出AVG数据文件的同时,不能根据需要输出便于直接成图的数据。这使得在生产矿山深边部资源勘探和工业发达、人文干扰大的地区工作时,有时为了剔除或编辑个别受干扰较大频点的数据时深感不便。为了更好地方便地球物理工作者处理数据和进行二次开发,这里对ASTATIC软件进行了改进,编写了功能更加完善的ASTATIC软件,并对软件的开发难点和功能作了详细的解释,同时给出了部分程序代码,以便地球物理工作者进行软件的二次开发。  相似文献