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1.
Overcapacity is a major threat to the sustainability of tuna resources. Diverse actions are being carried out by tuna RFMOs to counteract this problem. This paper reviews and analyses both the historical development of fishing capacity management in tuna RFMOs and their state of the art practices. Despite the fact, that thus far, management measures have not yielded the expected results for capacity reduction, they provide a good basis for improved management of capacity at regional and global levels.  相似文献   

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3.
The eastern stock of Atlantic bluefin tuna (thunnus thynnus) was recently nominated for protection under the Convention on International Trade in Endangered Species of Flora and Fauna (CITES). That nomination failed, which leaves management of the heavily overfished stock in the hands of the International Commission for the Conservation of Atlantic Tunas (ICCAT). This paper reviews the history of ICCAT management of Atlantic bluefin tuna to show that (1) early elimination of competitive forces prevented agreement on management in keeping with scientific advice, resulting in the steep decline of the stock, (2) even just the threat of a CITES listing can provide temporary impetus for marked improvement in ICCAT management, and (3) long-term sustainable management by ICCAT will require continued economic and political pressure.  相似文献   

4.
The Western and Central Pacific Ocean (WCPO) tuna fishery is an important global food resource, and the economies of many Pacific Islands Countries (PICs) rely heavily on tuna industries. This paper proposes that governance by PICs is the key to improving the sustainability and profitability of tuna industries in the region. ‘Governance’ is usually used to refer to corruption, but here is interpreted more broadly to encompass the whole process by which decisions regarding public life are made and enacted, by government and also civil society. Argument is supported by empirical material from an interview study with stakeholders and a survey of reports.  相似文献   

5.
Some of the most important development goals for the countries and territories of the Western and Central Pacific Ocean (WCPO) involve the sustainable management of their fisheries in light of environmental, economic and social uncertainties. The responses of fish populations to variability in the marine environment have implications for decision making processes associated with resource management. There is still considerable uncertainty in estimating the responses of tuna populations to short-to-medium-term variability and longer-term change in the oceanic environment. A workshop was organised to examine how advances in oceanography, fisheries science and fisheries economics could be applied to the tuna fisheries of the WCPO and in doing so identify research priorities to improve understanding relevant to progressing management. Research priorities identified included: (i) improved parameterisation of end to end ecosystem model components, processes and feedbacks through expanded biological observations and incorporation of higher resolution climate models; (ii) development of seasonal and inter-annual forecasting tools enabling management responses to short-term variability in tuna distributions and abundances; (iii) improved understanding of the population dynamics of and the energy transfer efficiencies between food web components; (iv) assessment of the optimal value of access rights and overall fishery value under multiple scenarios of tuna distribution and abundance and influences on decision making by fisheries managers and fleets and (v) development of management strategy evaluation frameworks for utilisation in the implementing and testing of fishery management procedures and to help prioritise research directions and investment. Issues discussed and research priorities identified during the workshop have synergies with other internationally managed fisheries and therefore are applicable to many other fisheries.  相似文献   

6.
Non-indigenous species (NIS) can create significant risks when introduced to foreign ecosystems. One of the many vectors facilitating the global transport of NIS is ballast water, and as commercial shipping increases so does the threat of ballast water-mediated introductions. Despite Canadian regulations, consistent with international guidelines put forth by the International Maritime Organization in the early 1990s, ballast water remains a potential vector for the introduction of many NIS to Canadian marine ecosystems: there have been no new introductions in the Laurentian Great Lakes Region since 2006, yet marine ecosystems continue to see the introduction and establishment of NIS. This paper details and analyzes the development of Canadian ballast water management (BWM), in the context of marine ecosystems, and identifies issues therein. BWM in Canada has a number of management gaps that have persisted since large-scale BWM began in the late 1980s. These include BWM exemptions for vessels not exiting the North American continental shelf, and limitations of effectiveness of mid-ocean exchange as the predominant management method in marine ecosystems. In addition, ballast water regulations for the Canadian Arctic may require additional consideration as the Arctic will likely continue to see an increase in both warming and commercial shipping in the future, thereby increasing the potential risk of NIS. In order to adequately protect all Canadian marine ecosystems, it is recommended that the current BWM regime: fill gaps in management to help prevent further introduction and spread of NIS; focus equally on both marine and freshwater regions, and; look to other aggressive BWM strategies such as those being developed by the state of California.  相似文献   

7.
The Convention for ballast water management is approaching the threshold of enforcement. Many countries around the world formulate national laws and regulations to mitigate the hazards of non-indigenous aquatic species (NIAS) brought about by the discharge of ballast water from ships. Taiwan’s critical location as an important transportation hub in the Western Pacific Ocean makes it a hot spot for the invasion of NIAS. Therefore, devising strategies for the management of ballast water is urgently needed. This study explores the global trend in ballast water management, and discusses the possible strategies which Taiwan may adopt in response to the Ballast Water Convention, from the perspective of Taiwan’s stakeholders in relation to the ballast water issue. Some of the proper actions that Taiwan should take in the future regarding the management of ballast water include: delineating the area for ballast water exchange, establishing the ballast water declaration system for incoming vessels, assisting shipping companies in installing ballast water treatment systems, determining risk priority for incoming vessels, and inspecting ballast water-related parameters by means of port state control (PSC). In this way, the invasion of NIAS may then be prevented in compliance with the global standards.  相似文献   

8.
传统的渔业资源评估方法对数据有一定的要求,而现有的许多渔业缺乏相关数据,造成了渔业评估和管理上的障碍。特别是自然死亡率,由于观测和计算的困难,研究中一般通过经验公式等方法进行假话,而不同来源的数据和估算方法的结果存在较大差异,可能导致在渔业资源评估和管理中很大的不确定性。本研究以蓝点马鲛(Scomberomorus niphonius)为例,利用MSE比较了22种基于有限数据的渔业管理规程(MP),筛选出DCAC、SPMSY、curE75、minlenLopt1 4种对于M不确定性较为稳健的的管理方法,并针对不同年代的自然死亡率以及通过不同计算方法得出的自然死亡率对这4种MP进行了管理策略评价。结果表明:M自1980s至今的不同年代间有显著降低趋势,该变化对MP管理效果产生了较强影响。随着M降低,种群B>0.5BMSY的概率显著上升,而过度捕捞可能性在不同MP间有方向性的差异。M变化对对curE75、minlenLopt1的长期产量的影响较小,而对DCAC、SPMSY的AAVY<15%的可能性变化较大,即降低产量的波动。不同M估算方法的估计值相差不大,对MP管理影响不明显。综合结果来看,Cur75受自然死亡率不确定性影响较小,对于渔业资源的开发和保护两个方面有着最好的权衡,最适用于我国蓝点马鲛渔业的管理。  相似文献   

9.
Salt-water inflows into the Baltic Sea are important events for renewing the deep and bottom waters of the deep basins of the Baltic Sea. These events occur only at irregular intervals. The last strong event was in January 1993 followed by minor inflows in winter 1993/1994. As a result of these inflows, the deep water of the central Baltic basins was completely renewed.Based on extensive observations of polycyclic aromatic hydrocarbons (PAHs) in water, fluffy layer material and surface sediments between 1992 and 1998, the transformation of PAHs and the modification of their distribution in the Baltic deep water is discussed in connection with the spreading of the inflowing highly saline and oxygen-rich water along its pathway from the sills into the central basins. In the course of the inflows in 1993/1994, the PAH concentration in the deep water of the different basins increased significantly. The concentrations were elevated, at least by a factor of 2 and as much as seven to eight times (for the four-ring PAHs) compared to the previous and the following years. Two hypotheses for the causes were discussed: the inflowing salt water may have entrained more highly polluted surface water in the western Baltic Sea, or it may have entrained contaminated fluffy layer material or sediment particles along the route of transport.  相似文献   

10.
In the past 20 a, the gulf-scale circulation in the Beibu Gulf has been commonly accepted to be driven by a wind stress or density gradient. However, using three sensitive experiments based on a three-dimensional baroclinic model that was verified by observations, the formation mechanisms were revealed: the circula- tion in the northern Beibu Gulf was triggered by the monsoon wind throughout a year; whereas the southern gulf circulation was driven by the monsoon wind and South China Sea (SCS) circulation in winter and sum- mer, respectively. The force of heat flux and tidal harmonics had a strong effect on the circulation strength and range, as well as the local circulation structures, but these factors did not influence the major circulation structure in the Beibu Gulf. On the other hand, the Beibu Gulf Cold Water Mass (BGCWM) would disappear without the force of heat flux because the seasonal thermocline layer was generated by the input of heat so that the vertical mixing between the upper hot water and lower cold water was blocked. In addition, the wind-induced cyclonic gyre in the northern gulf was favorable to the existence of the BGCWM. However, the coverage area of the BGCWM was increased slightly without the force of the tidal harmonics. When the model was driven by the monthly averaged surface forcing, the circulation structure was changed to some extent, and the coverage area of the BGCWM almost extended outwards 100%, implying the circulation and water mass in the Beibu Gulf had strong responses to the temporal resolution of the surface forces.  相似文献   

11.
楔形体在波浪中自由入水的数值模拟   总被引:1,自引:0,他引:1  
物体入水时波浪的影响不可忽略,基于流体力学模型采用VOF法,并利用自定义函数,模拟了楔形体的自由入水过程;同时结合推波板原理及海绵层消波理论实现了数值水槽的造消波,完成了波浪中楔形体自由入水的模拟,计算了楔形体入水时所受的水作用力、自由液面变化及物面压强分布等,研究了不同波高、周期以及在波浪不同位置入水时对楔形体的影响。结果表明:本文建立的数值模型可很好地模拟楔形体入水造成的射流及空泡的形成发展过程,波浪对楔形体入水的影响主要由波浪内部流场变化及表面波形决定,在波浪不同位置处入水对楔形体受力及入水形态均有较大影响。  相似文献   

12.
Since 2009, there has been a shift in UK marine governance with the Marine and Coastal Access Act in which a core mechanism is marine planning, designed to replace a fragmented, ad hoc, and bureaucratic process of marine management with a strategic, integrated, and centralised system. This shift has been justified by the UK government as a more efficient procedure for delivering sustainable development (SD), which is the overarching objective of UK environmental policy. This article, which is based on data from key informant interviews and secondary sources, analyses the shift to understand its aspirations and the challenges facing it. The issues focused on include its holistic approach; its centralising tendencies; its streamlining processes; and its implicit commitment to renewable energy. In these four issues there are tensions between aspirations and challenges, and the conclusion is that the success of the new mode of marine governance depends on satisfactorily resolving these tensions.  相似文献   

13.
海底沉积物孔隙水地球化学特征能快速响应甲烷渗漏活动及其生物地球化学过程,从而记录甲烷渗漏活动特征。对采自南海南部北康盆地的3个重力沉积柱状沉积物孔隙水样品(BH-H75、BH-H13Y和BH-H61)进行了甲烷浓度、溶解无机碳(DIC)和碳同位素(δ13CDIC)、阴离子(SO42−、Cl−)以及主微量元素(Ca2+、Mg2+、Sr2+、Ba2+)等地球化学分析。(△DIC+△Ca2++△Mg2+)/△SO42−比率图解与δ13CDIC深度剖面特征揭示了有机质硫酸盐还原反应(OSR)和硫酸盐驱动-甲烷厌氧氧化反应(SD-AOM)在不同沉积柱中所占比例的不同,其中BH-H13Y沉积柱中OSR和SD-AOM共同存在;BH-H75沉积柱中OSR占主导;在BH-H61沉积柱中SD-AOM占主导,且其底部可能存在微生物产甲烷作用。硫酸盐浓度线性拟合关系指示BH-H13Y的硫酸盐-甲烷过渡带(SMTZ)的深度约为700 cmbsf。结合SO42−浓度、DIC浓度最大值和δ13CDIC最小值推测BH-H61的SMTZ深度约为480 cmbsf。BH-H61和BH-H13Y沉积柱中,较浅的SMTZ深度、上升的DIC浓度以及强烈负偏的δ13CDIC值指示研究区存在甲烷渗漏活动。此外,在BH-H61和BH-H13Y站位,硫酸盐浓度随深度降低的变化梯度在沉积柱下部较上部陡,指示向上迁移的甲烷通量在时间上逐渐增强。孔隙水中Ca2+、Mg2+、Sr2+浓度以及Mg/Ca、Sr/Ca比值变化特征指示研究区沉积物中可能有自生高镁方解石矿物生成;而BH-H61站位SMTZ界面以下,孔隙水中Ba2+浓度升高,指示了硫酸钡的溶解作用。  相似文献   

14.
No-take marine protected areas (MPAs), where all fishing is prohibited, have been shown to provide benefits that include greater productivity of fish stocks due to increased densities, average sizes, and reproductive output. A critical component of this success is the effective management of MPAs to ensure that only those activities deemed permissible, are allowed to occur. As of 2008, 161 MPAs had been designated on the Pacific coast of Canada by federal, provincial or municipal authorities. The objective of this study was to discover how many of these MPAs are intended to provide full protection to habitats and species from commercial fishing and whether management measures were put in place to actualize this conservation intent. The comprehensive spatial dataset was built illustrating commercial fisheries closures and this was overlaid with MPA locations in a GIS. The majority of MPAs were designated as IUCN Strict Nature Reserve (Type Ia), Wilderness Area (Type Ib), and National Park (Type II) marine reserves, which are intended to be free from exploitation. It was found that 160 of the 161 MPAs are open to some commercial harvesting within their bounds. One small municipal MPA and portions of three other MPAs are not open to commercial harvesting. The incongruence between management intent and fisheries permitted suggests a management failure between designation of MPAs and implementation of fisheries management regulations.  相似文献   

15.
莱州湾沿岸平原海水入侵灾害的发展进程   总被引:10,自引:0,他引:10  
莱州湾东、南沿岸平原的海(咸)水入侵是人为过量采取地下水和自然环境变化共同引发的灾害。根据多年观测数据绘制的地下水位负值区、淡水资源超采量和海(咸)水入侵面积等三标志划分灾害进程为初始阶段、发展阶段、恶化阶段和缓解阶段。给出了灾害发展模式。以此解释新区灾害,针对灾害发展的不同阶段,采取适时而有效的防灾减灾对策和措施。  相似文献   

16.
Fisheries management around the world has experimented with regulations to promote privatization, in order to reach such multifaceted goals as ending overfishing and reducing economic inefficiencies. This review surveys a wide range of empirical experiences in different contexts around the world to help provide a fuller picture of potential and sometimes disparate consequences from privatization in general and new ways of organizing around fishing that can follow in the wake of such measures. Looking at the many different participants in the fishing industry—from crew, small-boat owners, to households and communities—as well as the diverse sociocultural contexts in which fishing takes place, enables a better understanding of who and what is impacted, how they are impacted, why and with what further consequences, such that communities come to be seen less oppositional to economy, but rather constituted by multiple scalar processes and by economic relations comprising different motivations and behaviors.  相似文献   

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