An agent-based model for simulating trading of multi-species fisheries quota

Individual transferable quotas (ITQs) are increasingly seen as a way to make fisheries more profitable and halt over-capitalisation. ITQs allocate to users of a resource a share of a total allowable catch (TAC) which they are free to use, lease, or sell. We outline an approach to modelling the effect of an ITQ system in a multi-species, multi-sector fishery and apply it to the Coral Reef Fin Fish Fishery (CRFFF) in Queensland, Australia. An ITQ model, based on the assumption that operators seek to maximize profits, simulates the use of tradeable quota units by operators in the fishery, taking account of the initial quota allocation to operators, seasonal fish prices and individual operator variable costs, their fishing efficiency and experience, and constraints on vessel movements. Rationalization of the fishery is predicted to occur under an ITQ system for the CRFFF, which will lead to reductions in effort, increases in profits, and changes over time in quota prices. The ecological consequences of transferable quota in the multi-species fishery are seen in the catch and discard levels of the less profitable species, even though a TAC was set. This had flow-on effects on biomass. For example, simulations showed that the TAC for the primary target species, coral trout, was used more fully than that for a less valuable target species, red throat emperor, and that this was achieved through increased discarding of red throat emperor. Catches of both coral trout and red throat emperor that were derived from the model were higher than those recently observed in the fishery. The effort predicted by the model, however, closely approximated the actual effort observed in the fishery following implementation of ITQ management.     

CLIMATE IMPACTS ON URBAN WATER RESOURCES IN THE SOUTHWES THE IMPORTANCE OF CONTEXT1

ABSTRACT: Stresses on water resources in the Southwest take many forms and emanate from many different sources, among which are complex institutional arrangements, significant areal and temporal climatic variability, and high urban growth rates. Further challenges to managing supply and demand in this water‐scarce region are posed by environmental, social, and legal differences within and between the individual urban areas. Analysis of the sensitivity of the urban water sector in the Southwest to climatic variability requires careful consideration of these factors. Such analysis, in turn, provides an essential foundation for effective evaluation of the region's sensitivity to longer term climate change.     

A Global Baseline for Spawning Aggregations of Reef Fishes

Abstract: Species that periodically and predictably congregate on land or in the sea can be extremely vulnerable to overexploitation. Many coral reef fishes form spawning aggregations that are increasingly the target of fishing. Although serious declines are well known for a few species, the extent of this behavior among fishes and the impacts of aggregation fishing are not appreciated widely. To profile aggregating species globally, establish a baseline for future work, and strengthen the case for protection, we (as members of the Society for the Conservation of Reef Fish Aggregations) developed a global database on the occurrence, history, and management of spawning aggregations. We complemented the database with information from interviews with over 300 fishers in Asia and the western Pacific. Sixty‐seven species, mainly commercial, in 9 families aggregate to spawn in the 29 countries or territories considered in the database. Ninety percent of aggregation records were from reef pass channels, promontories, and outer reef‐slope drop‐offs. Multispecies aggregation sites were common, and spawning seasons of most species typically lasted <3 months. The best‐documented species in the database, the Nassau grouper (Epinephelus striatus), has undergone substantial declines in aggregations throughout its range and is now considered threatened. Our findings have important conservation and management implications for aggregating species given that exploitation pressures on them are increasing, there is little effective management, and 79% of those aggregations sufficiently well documented were reported to be in decline. Nonetheless, a few success stories demonstrate the benefits of aggregation management. A major shift in perspective on spawning aggregations of reef fish, from being seen as opportunities for exploitation to acknowledging them as important life‐history phenomena in need of management, is urgently needed.     

连云港近海海域水质状况调查与评价

近海海域水环境对沿海城市的可持续发展具有重要意义.根据1997～2005年连云港近海海域水质监测资料,对海域的水质状况进行了分析和评价.结果表明,pH、DO和COD年际变幅不大且符合GB3097-1997第一类海水水质标准;1998-2002年油类含量超出国家二类水质标准,虽然近几年污染减弱,但总体来看,油类已成为该海域的主要污染物;无机氮和活性磷酸盐虽然没有超出二类标准,但逐年有上升趋势;NO3-N和NO2-N的全年最高值多在8、9、10月,与该季节河品泄洪将大量营养物质带入大海有关,有可能引发赤潮,应引起相关部门注意.     

温州近海海域海水及滩涂沉积物中PFOS和PFOA污染特征分析

为了解温州近海海域全氟辛烷磺酸(PFOS)和全氟辛酸(PFOA)的污染状况和特征,采用固相萃取/高效液相串联质谱检测法分析了采自乐清湾、瓯江口、西湾、飞云江口及洞头半屏岛的近海海水和滩涂沉积物中PFOS和PFOA污染水平。结果显示,温州近海海水普遍存在PFOS和PFOA污染,其中,PFOS的浓度范围为<1.0～31.36 ng/L,中位浓度为2.29 ng/L;PFOA的浓度范围为<1.0～23.66 ng/L,中位浓度为5.29 ng/L。滩涂沉积物样品中PFOS和PFOA的浓度范围(干重)分别为(<1.0～11.91)×10-9(中位浓度为3.60×10-9)和(1.84～34.01)×10-9(中位浓度为6.83×10-9)。温州近海海水中PFOS和PFOA的污染水平明显高于香港沿岸、中国南海海水、韩国沿岸海水和近海珠江三角洲,与大连湾的海水相当,海岸滩涂沉积物中的PFOS和PFOA浓度远高于珠江和黄浦江沉积物中的浓度。     

Response of balanced network models to large-scale perturbation: Implications for evaluating the role of small pelagics in the Gulf of Maine

Exploring the response of an ecosystem, and subsequent tradeoffs among its biological community, to human perturbations remains a key challenge for the implementation of an ecosystem approaches to fisheries (EAF). To address this and related issues, we developed two network (or energy budget) models, Ecopath and Econetwrk, for the Gulf of Maine ecosystem. These models included 31 network “nodes” or biomass state variables across a broad range of trophic levels, with the present emphasis to particularly elucidate the role of small pelagics. After initial network balancing, various perturbation scenarios were evaluated to explore how potential changes to different fish, fisheries and lower trophic levels can affect model outputs. Categorically across all scenarios and interpretations thereof, there was minimal change at the second trophic levels and most of the “rebalancing” after a perturbation occurred via alteration of the diet matrix. Yet the model results from perturbations to a balanced energy budget fall into one of three categories. First, some model results were intuitive and in obvious agreement with established ecological and fishing theory. Second, some model results were counter-intuitive upon initial observation, seemingly contradictory to known ecological and fishing theory; but upon further examination the results were explainable given the constraints of an equilibrium energy budget. Finally, some results were counter-intuitive and difficult to reconcile with theory or further examination of equilibrium constraints. A detailed accounting of biomass flows for example scenarios explores some of the non-intuitive results more rigorously. Collectively these results imply a need to carefully track biomass flows and results of any given perturbation and to critically evaluate the conditions under which a new equilibrium is obtained for these types of models, which has implications for dynamic simulations based off of them. Given these caveats, the role of small pelagics as a prominent component of this ecosystem remains a robust conclusion. We discuss how one might use this approach in the context of further developing an EAF, recognizing that a more holistic, integrated perspective will be required as we continue to evaluate tradeoffs among marine biological communities.     

黄海近岸底栖贝类体内典型有机污染物分布

根据第二次全国海洋污染基线凋查数据,确定黄海近岸底栖贝类体内典型有机污染物的含量、分布及其潜在的生态风险.结果表明,在35%以上的站点,物种体内石油烃含量超过国家海洋生物质量第一类标准(15 000 ng/g),大连湾附近海域贝类体内含量甚至高出第二类标准(50 000 ng/g).在威海、大连湾和胶州湾出现多环芳烃和酞酸酯少数相对高值站点(300 ng/g左右),而其它大多数站点贝类体内多环芳烃和酞酸酯的含量都较低.中、高环组分占优指示近岸海区的多环芳烃主要来源于热解过程;二丁基酞酸酯和2-乙基己基酞酸酯是酞酸酯的主要组分.在所有站点,底栖贝类体内PCBs的含量普遍很低(<10 ng/g).贝类体内DDTs含量超过第一类标准(10 ng/g)的站点大部分集中在南黄海沿岸,海州湾内一站点已超出第二类标准(100 ng/g),而组分以代谢产物DDD和DDE为主.在所有站点的贝类体内都有p,p'-DDT检出,尤其在北黄海的大连湾和蓬莱附近海区(比例高于50%),指示周边地区存在潜在的DDT输入源.据此,大连湾、威海、胶州湾沿岸贝类体内石油烃和多环芳烃含量较高,胶州湾、海州湾附近海域贝类体内DDTs含量较高,这些属于较高生态风险区,而大连湾、蓬莱近岸可能的DDT新输入对底栖环境构成一定威胁.     

关于环境监测站在事业单位改革浪潮中转型发展的思考

根据事业单位分类改革政策,环境监测站属于公益性二类事业单位.通过分析监测站目前运行过程中存在的问题和面临的形势,提出了包括增强服务意识、提升综合素质、推进内部机制改革、参与市场竞争与合作等一系列实现转型发展的对策.     

INSTITUTIONS AND TECHNOLOGY: KEYS TO BETTER WATER MANAGEMENT1

Seven considerations which bear upon the achievement of better water management are discussed. First, separation of judgments of fact from judgements of value is helpful in deciding upon what actions to take. Second, separation of social values from matters of individual or group interest is crucial to institutional design. Third, achieving economically efficient water management may create a surplus of benefits which can be divided among the parties in order to resolve conflicts. Fourth, surpluses also can be used inappropriately, whether to reward undesirable behavior or to penalize unjustly. Fifth, avoidance of external costs is best achieved through restructuring of rewards and penalties. Sixth, technological solutions are too easily selected in place of less costly institutional change. Seventh, water management technology is too often selected in place of more cost-effective, water-related technology. Selected examples of each of these considerations are offered. However, better water management is not easy to define. The social process criterion adopted in this paper is discussed briefly.     

论我国鱼类多样性与渔业的可持续发展

本文简要介绍了我国鱼类多样性现状和我国渔业发展中鱼类多样性的保护利用及其效益,并对鱼类多样性保护与利用策略进行了探讨.