辽东湾河口区海洋垃圾赋存特征及管理对策

海洋垃圾已引起国际社会的广泛关注,是当前环境领域热点问题之一.为揭示我国渤海近岸海域海洋垃圾的赋存特征及其分布规律,于2018年丰水期（8月）在辽东湾河口区海域布设6个长度为5~10 km的调查断面,利用拖网同时采集海面漂浮垃圾与海底垃圾,初步调查辽东湾近岸海域海洋垃圾分布和组成特征,并对海洋垃圾来源进行了分析.结果表明:①辽东湾海面漂浮垃圾数量密度为67个/km2,质量密度为741 g/km2;海底垃圾数量密度为19个/km2,质量密度为2 544 g/km2.②在所收集的各类海洋垃圾中,塑料类垃圾数量占比约为50.9%,其中海底塑料类垃圾数量占比（62.1%）明显高于海面漂浮塑料垃圾数量占比（37.5%）.③由塑料垃圾形态特征和表面带有的标识判断,辽东湾近岸海域塑料垃圾主要是来源于生活塑料垃圾（84.9%）和渔业垃圾（15.1%）.在此基础上,建议加强源头管理以减少塑料垃圾进入海洋,主要包括完善当前海洋垃圾分类方法、加强渔业塑料垃圾回收、提升公民保护海洋环境意识和制定国家海洋塑料垃圾行动计划等.      

Knowledge and Use of Biodiversity in Brazilian Hot Spots

Hot spots in Brazil include a variety of ecosystems, such as mangroves, forests, and the Brazilian savannah, locally called cerrado. Some of the rural populations in these hot spots are the caiçaras in SE Atlantic Forest coast, and the caboclos in the Amazon. In this study, we are concerned especially with the knowledge of caiçaras and caboclos, associated with practices that might have implications for management. Data were gathered through interviews with adults at the various communities studied, and through systematic observations, including samples of fishing trips and the mapping of fishing spots used in the Atlantic Forest coast. The use of resources from the surrounding vegetation includes collection of plants, cultivated fruit gardens, the swidden system, and a careful and managed extraction of fibres. Among animal resources, food taboos seem to be useful practices that might contribute to the maintenance of local natural resources. Potential management practices should be locally developed, such as the informal division of fishing spots in Atlantic Forest sites, and the maintenance of the diversity of cassava varieties in both the Atlantic Forest and Amazonian areas.     

The Prestige oil spill and its economic impact on the Galician fishing sector

The sinking of the Prestige oil tanker on 18 November 2002 off the coast of Galicia, Spain, had important economic, environmental and social ramifications. The aim of this paper is to carry out an initial analysis of the costs related to a halt in fishing activities in Galicia between November 2002 and December 2003. This involves three different steps: an assessment of the cost of the preventative and palliative measures introduced by Spanish public administrations (compensation for affected fishermen and shellfish fisherman); an indirect evaluation of the implications of the disaster (via a study of data on production); and a direct appraisal of the economic impact of the event (reduction in income), using questionnaires completed by a representative sample of fishermen and shellfish fisherman. The results obtained from these three methods of estimating losses are compatible. By December 2003, losses to the Galician fishing sector stood at an estimated EUR 76 million.     

Exploring corruption in fisheries

This paper explores corruption in global fisheries. While reducing corruption is critical for the effective management of the fisheries sector and the fulfilment of the UN's sustainable development goals (SDGs, and SDGs14 and 16 in particular), to do so, it is necessary to first have a systematic and comprehensive understanding of what corruption is and how it is manifested in the sector. There is literature on illegal, unregulated and unreported (IUU) fishing, but not much on corruption. The paper proposes an analytical framework and applies it with six revelatory cases to improve the conceptual clarity of corruption in fisheries. Specific corruption problems found in licensing, negotiating access agreements, lax enforcement, extortion, political corruption, money laundering and tax manipulation, human trafficking, etc. can therefore be better identified through this analysis, which lays a base for systematic responses to tackling corruption in fisheries and accordingly furthering the sustainable development of the sector.     

Optimal Harvesting of the Norwegian Spring-Spawning Herring: Variable Versus Fixed Harvesting Strategies

In this paper we study optimal harvesting of the Norwegian spring-spawning herring stock. The biological model is described by a discrete time age-structured model. The optimal harvesting patterns are studied numerically and the results show that when using a linear cost function and constant price in the optimisation model, the optimal harvesting pattern is pulse fishing. However, optimal constant fishing effort gives only slightly lower profit. Moreover, when price is made responsive to harvest the optimal harvesting strategy is substantially smoothed. This revised version was published online in July 2006 with corrections to the Cover Date.     

The socioeconomic significance of nature-based recreation in Canada

In recognition of the many values that people ascribe to nature, federal, provincial, and territorial agencies worked inpartnership to complete the 'Survey on the Importance of Natureto Canadians' (SINC) in 1981, 1987, 1991, and 1996. Between 1981 and 1996, more than 80% of Canadians 15 years of age and older engaged in one or more nature-related activities. This paper describes the evolution of this cooperative monitoring program, defines a classification system as a context for the values examined by the SINC, highlights trends of some nature-related recreational activities measured by the survey, and comments onthe importance of this information to Canadians.     

Emission characteristics of offshore fishing ships in the Yellow Bo Sea, China

Maritime transport has been playing a decisive role in global trade. Its contribution to the air pollution of the sea and coastal areas has been widely recognized. The air pollutant emission inventories of several harbors in China have already been established. However,the emission factors of local ships have not been addressed comprehensively, and thus are lacking from the emission inventories. In this study, on-board emission tests of eight diesel-powered offshore fishing ships were conducted near the coastal region of the northern Yellow Bo Sea fishing ground of Dalian, China. Results show that large amounts of fine particles( 0.5 μm, 90%) were found in maneuvering mode, which were about five times higher than those during cruise mode. Emission rates as well as emission factors based on both distance and fuel were determined during the cruise and maneuvering modes(including departure and arrival). Average emission rates and distance-based emission factors of CO, HC and PM were much higher during the maneuvering mode as compared with the cruise mode. However, the average emission rate of Nitrous Oxide(NOx) was higher during the cruise mode as compared with the maneuvering modes. On the contrary, the average distance-based emission factors of NOxwere lower during the cruise mode relative to the maneuvering mode due to the low sailing speed of the latter.     

洱海浮游桡足类群落结构对季节性休渔的响应

为了解洱海浮游桡足类群落结构的季节动态特征,于2009年2~11月对洱海浮游桡足类进行逐月采样.结果显示:洱海浮游桡足类生物量的季节性分布呈"双峰型",峰值分别出现在休渔期中期和捕鱼期中期.在休渔期中期,桡足类以杂食性的剑水蚤Mesocyclops dissimilis为优势种;在捕鱼期中期,则以滤食性的哲水蚤舌状叶镖水蚤为优势种.季节性休渔不仅导致鱼类对桡足类的捕食压力出现季节性变化,而且通过影响枝角类的群落结构,改变枝角类对桡足类的竞争压力.在相对较低的捕食压力和较大的食物竞争压力影响下,桡足类以杂食性的剑水蚤为优势类群;在相对较大的捕食压力和较低的食物竞争压力下,以滤食性的哲水蚤为优势类群.     

Economics of harvesting age-structured fish populations

A generic age-structured model is developed to derive analytical results on optimal harvesting. Given two age classes, knife-edge selectivity, and no stock-dependent harvesting cost, the steady state is a unique saddle point. Adding harvesting cost does not alter the uniqueness, given that the utility is linear. Under specific conditions such as nonselective gear, optimal harvesting is proved to be a stationary cycle that represents pulse fishing. Optimal steady states are different if age-structured information is ignored and optimization is based on traditional biomass variables. This implies that the existence of optimal sustainable harvesting depends on age-structured information. Given a specific set of conditions such as low interest rate and knife-edge selectivity, optimal harvesting converges toward a unique saddle point independently of the number of age classes.