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21.
Migrants from Mexico to the U.S. tend to be healthier than non-migrants in their origin – part of a pattern termed the “healthy migrant effect”. With climate change altering livelihoods across the globe, we ask how the migration-health connection may be altered by environmental strain. On the one hand, positive health selectivity may be intensified if migration becomes more challenging – and therefore increasingly likely to be undertaken by only the healthiest. On the other hand, positive health selectivity may decline if the “push” associated with environmental strain acts upon individuals regardless of health. We use Mexican Migration Project data to model Mexico-US migration by male household heads with consideration of migrant health as well as recent rainfall conditions in communities of origin. Results reveal intriguing interactions such that when moderately dry regions experience rainfall shortage, health selectivity is lower – meaning that less healthy household heads also engage in international migration. We posit that social networks may underlie this association. We further argue that since environmental context may alter the relationship between migration and health, future research on the “healthy migrant effect” should consider environmental conditions. As to implications, if climate change yields pressure on less healthy individuals to migrate, the need for migrant-sensitive health systems and services may be intensified in destination regions. 相似文献
22.
This text follows the public regulatory and the private certificatory paths undergone in the last decade by the widely criticized salmon industry in Chile, with the purpose of exploring the political process that underlies this path. The discussion focuses on the several instances in which both industrial actors and oppositional groups have stabilized those conflicts by sitting down at formally established dialogue tables, which, as we will see, have conducted public and private processes of regulation. In particular, we follow two paths: one promoted and overseen by the public sector and the other a process of self-organization and self-control of the industry at the national and global levels, which initially led to processes of self-certification and third-party certification. We argue that it cannot be reduced to an industrial learning due to the economic cost of disease outbreaks but rather that it is the outcome of a contested political process with interplay between global and local actors. This argument challenges the learning narratives espoused by the industry, contributing to a political ecology of certification processes. It analyzes the outcome of this process showing its contested political and social legitimacy, and the interplay between labor and environment within this regulatory path. 相似文献
23.
Chou CL 《Marine pollution bulletin》2007,54(6):720-725
The study was undertaken to investigate the uptake of mercury in salmon throughout the entire farming period at the net cage. Mercury concentrations in muscle, liver, kidney, and gill and responses to the various dietary mercury concentrations were determined. The accumulation of mercury is in the order of kidney>gill=liver>muscle. The highest mercury peak concentrations were observed for both kidney and gill at the parr-smolt period, while liver and muscle mercury peaked one month later after caging at the grow-out site. High dietary sodium and calcium fed to the salmon contributed to the elevation of mercury in kidney and gill during the smolting process. The mercury burden over the grow-out period increased sharply with a linear relationship of mercury uptake. The tissue mercury burden per gram of growth was calculated using the slope of mercury burden and the slope of growth over the period of each stage. The results showed dietary mercury loadings on marketable salmon were within tolerance limits of FDA and US EPA. Rapid growth of salmon and low dietary mercury progressively reduces the uptake of mercury in salmon. The time series of mercury monitoring showed that mercury concentrations in salmon were greater at the parr stage in freshwater than at the grow-out stage in salt water. 相似文献
24.
Through the case of the salmon aquaculture sector in Chile, the risks involved in the development of a non-traditional export sector are reviewed, in order to point to failings (lessons not learned) and opportunities (lessons learned, new plans), and the changing scales of stakeholder interactions. In particular the paper highlights the ways in which sustainability considerations have gained ground in terms of evaluating sectoral development and what is expected from this development. These considerations have emerged as a result of the increasing globalisation of the sector, through investment, exports and international ‘attention’ from an increasingly diverse set of stakeholders. These sustainability considerations have generated a range of conflicts linked to these diverse actors. The actors are local, national and global, operating through alliances to bring pressure on others. The conflicts relate to environmental quality, foreign direct investment (FDI), local socio-economic development, regional development, national economic strategies, and new globalised issues relating to the production and consumption of foodstuffs. The contemporary panorama in the sector is significantly different from the early origins in the 1980s under the dictatorship – the period of ‘the socio-ecological silence’ – also different from the 1990s period of economic expansion – ‘the economic imperative’. Over the past twenty-five years, the Chilean aquaculture sector has evolved from experimental production to a major global industry. Regulatory frameworks and civil society awareness and mobilisation have struggled to ‘catch up’ with the dynamism of the sector, however the gap has reduced and the future of the sector within the contemporary context of ‘glocal’ sustainability is now under the microscope: the ‘sustainable globalisation perspective’. The collapse of the sector during the period 2008–2010 as a consequence of the ISA virus is a key moment with production severely diminished. The way out of the crisis, via new legislation and inspection regimes, will create a new structure of aquaculture governance. Nevertheless, the crisis marks a turning point in the industry, revealing the weaknesses built into the former productive system. 相似文献
25.
The pollution effects of cage aquaculture represent an external cost to society, and the challenge for environmental economists has been to estimate the magnitude of these costs and to suggest ways in which they can be mitigated or ‘internalised’. One possible mitigation strategy involves the development of integrated production systems based on polyculture, and this paper examines the financial viability of such a system that integrates the farming of salmon and mussels. The results demonstrate the commercial potential of an integrated salmon–mussel production system under present market conditions, but highlight the critical role played by future price trends. 相似文献
26.
采用禁食试验方法进行了太平洋鲑生长鱼经8—32d饥饿后对其鱼体脂肪与脂肪酸变化的影响研究。结果表明,饥饿期间脂肪是太平洋鲑主要的能量来源,饥饿初期太平洋鲑主要消耗肝脏脂肪作为能量维持生命活动,能耗较低;饥饿中后期主要以消耗肠系膜脂肪和肌肉脂肪作为能量维持生命活动,能耗逐步增加(P<0.05)。饥饿后,鱼体肝脏、背肌和肠系膜脂肪中大多数饱和脂肪酸(SFA)和单不饱和脂肪酸(MUFA)比例显著性下降(P<0.05),大多数多不饱和脂肪酸(PUFA)(P<0.05)比例显著性上升,表明太平洋鲑饥饿期间主要消耗SFA和MUFA供能,而PUFA多予以保留,较少消耗供能;二十二碳六烯酸(DHA)和二十碳五烯酸(EPA)比例和DHA/EPA比值均升高显著性上升(P<0.05),表明太平洋鲑在饥饿条件对脂肪中的DHA和EPA,特别是DHA有较强选择性保留能力。鱼体对肝脏、背肌和肠系膜脂肪利用差异性的主要原因是其组织器官中脂肪酸比例不同。鱼体主要利用体内不同组织脂肪中的SFA和MUFA供能,从而节约了机体蛋白质与脂肪中的PUFA以维持重要的生命活动。 相似文献