Sustainable use of flatfish resources: Addressing the credibility crisis in mixed fisheries management

Many flatfish species are caught in mixed demersal trawl fisheries and managed by Total Allowable Catch (TAC). Despite decades of fisheries management, several major stocks are severely depleted. Using the Common Fisheries Policy (CFP) as an example, the failure of mixed-fisheries management is analysed by focussing on: the management system; the role of science; the role of managers and politicians; the response of fisheries to management. Failure of the CFP management could be ascribed to: incorrect management advice owing to bias in stock assessments; the tendency of politicians to set the TAC well above the recommended level; and non-compliance of the fisheries with the management regulations. We conclude that TAC management, although apparently successful in some single-species fisheries, inevitably leads to unsustainable exploitation of stocks caught in mixed demersal fisheries as it promotes discarding of over-quota catch and misreporting of catches, thereby corrupting the basis of the scientific advice and increasing the risk of stock collapse. This failure in mixed demersal fisheries has resulted in the loss of credibility of both scientists and managers, and has undermined the support of fishermen for management regulations. An approach is developed to convert the TAC system into a system that controls the total allowable effort (TAE). The approach takes account of the differences in catch efficiency between fleets as well as seasonal changes in the distribution of the target species and can also be applied in the recovery plans for rebuilding specific components of the demersal fish community, such as plaice, cod and hake.     

Ecosystem-based fisheries management: progress in the NE Atlantic

Fisheries management in the NE Atlantic has recently adopted a precautionary approach to setting catch limits. This has been accompanied by the development of more complex and multi-species modelling tools for predicting stock size and structure. The scientific community are now being asked to provide an ‘ecosystem-based approach’ to fisheries management. In this paper, we consider the science needs of this shift to a consideration of more complex systems to include both ecological and socio-economic components. At present, this involves use of the precautionary approach and multi-species management regimes, but will need to include multi-annual quota assessment, ‘stake-holder’ involvement and marine protected areas. How will these approaches sit together and how will science support them? As an example, we will consider what management of the North Sea demersal fishery may involve in 20 years time.     

Pullout Capacity of Horizontally Loaded Suction Anchor Installed in Silty Sand

Current floating structures require more reliable and higher anchoring capacities because of their increased size. A suction anchor is one of the most popular anchors for a floating system. In this study, the behavior of a suction anchor installed in cohesionless soil was investigated when the anchor was subjected to mainly a horizontal load. Three-dimensional finite element numerical analyses were carried out using ABAQUS, and three centrifuge tests were performed to calibrate the numerical analyses. A parametric study with different dimensions and loading points for the suction anchor was conducted. The horizontal capacity of the suction anchor was estimated, and the soil reaction distribution was analyzed when the load was applied at the optimal point. Based on the results, an analytical equation for calculating the horizontal capacity of a suction anchor was proposed that can be easily adopted for design.     

霍尔锚在粉细砂中抛锚深度模型试验

航船应急抛锚时锚板贯入土体可能会影响河床或海床中的结构物甚者造成破坏,因此在通航频繁的航道,结构物埋深的设计需要充分考虑应急抛锚时锚板的贯入深度。本文通过缩尺模型试验模拟了霍尔锚在中等密实度粉细砂中的抛锚贯入过程,研究了不同抛锚速度(1.15～4.4 m/s)及粉细砂相对密实度(0.45～0.65)对抛锚贯入深度的影响;基于太沙基极限承载力理论和能量守恒定律,推导出霍尔锚在粉细砂土中贯入深度的表达式,与模型试验结果对比显示理论计算结果偏于保守。基于试验结果提出修正系数,修正后的理论公式能够较好地快速预测霍尔锚在中等密实度粉细砂中的贯入深度。研究结果为粉细砂土河床或海床中的结构物埋深设计提供了一定的技术参考。     

Anchor deployment for deep water floating offshore equipments

In this work a planning methodology for deep water anchor deployment in offshore platforms and floating production systems aiming at operational resources optimization is explored, by minimizing a multi criteria objective function. As an additional advantage provided by the proposed methodology, planning automation is achieved. Planning automation overcomes the traditional way, using a trial error basis. With it, an engineer, using an anchoring software, decides how much work wire and anchoring line must be paid out from both the floating system and the tug boat. Additionally, he decides which horizontal force must be applied to the line, trying to settle the anchor on a previously defined target on the ocean floor.     

组合动力锚水动力特性数值模拟研究

作为海上浮式结构物的一种新型锚固基础,动力锚具有自安装、不受水深影响、适用范围广的特点。在动力锚的基础上研发的组合动力锚结合了动力锚自安装和板锚法向受荷的特点,具有安装快速、适用多种类型海床、承载效率高等性质。组合动力锚在水中自由下落时的水动力学特性（下落速度、方向稳定性等）会受到锚链、尾翼宽度和助推器质量等因素影响。若下落速度过小或方向稳定性过差,则会影响锚的安装成功率。采用计算流体动力学方法模拟流体对锚的冲击和锚在水中自由下落过程,以优化组合动力锚的尾翼尺寸;其次研究锚链作用力和助推器质量对组合动力锚下落速度和偏角的影响规律。计算结果表明：组合动力锚的拖曳阻力系数为0.45左右,尾翼宽度最优尺寸为翼板宽度的1.25倍。连接在锚眼处的锚链会减小组合动力锚的下落速度并加剧锚的偏转,需综合锚的下落速度和偏角来确定锚在水中下落高度。     

一种新型的海上锚固设施--火箭锚的作用机理及应用

介绍了一种新型的锚固设施——火箭锚,对其作用机理进行了探讨,同时还介绍了火箭锚的构造和布设方法,阐述了火箭锚在不同工程领域的应用前景．     

The many faces of ecosystem-based management: Making the process work today in real places

Despite the widely accepted need for ecosystem-based management of coastal and marine systems, many managers struggle with how to put these principles into practice. Commonly voiced concerns include complicated and expensive implementation, prohibitive data requirements, and lack of testing with long-term applications. We address some of these perceived barriers by providing guidance on strategies and approaches that can be used for the steps of one ecosystem-based management process, the integrated ecosystem assessment framework, including scoping, defining indicators, setting thresholds, risk analysis, management strategy evaluation, monitoring and evaluation. Importantly, we demonstrate how an ecosystem-based management approach can be utilized in a variety of contexts which vary widely in data quality and availability, governance structure, and time frame. We then illustrate the suggested steps in the process by exploring two case studies that represent realistic ends of the data/governance/time frame spectrum: Puget Sound, Washington, USA and Raja Ampat, Indonesia. By providing concrete suggestions for how to move forward with key steps in an integrated management process, we show that ecosystem-based management is feasible from a range of starting points and that for any given starting point there are numerous productive paths forward.     

DGPS走航测深验潮技术中的潮位信息提取方法

提出了一种提取观测海域潮位信息的新方法--DGPS走航测深验潮技术,即在走航ADCP重复测量断面潮周期流场观测的同时获取潮位信息,并实现水下地形的潮位改正.该方法通过重复测量点瞬时水深数据选取、潮位差数据计算、叠加拟合和迭代逼近等预处理与算法,可在潮差约1.6 m、地形起伏高达10～20 m的台湾浅滩沙波区,获取均方根误差小于0.1 m的潮位观测结果.     

Controlling the coast

This paper conceptualizes the coast as commons and treats the implications of collective governance driven by the characteristics of coastal commons. Institutional control is essential, and two key institutions – state and local resource management institution – are central to the control of the coast as every other institution, from international aid agencies to private sector and non-government organizations, must go through them to develop and manage the coast. In the practice of institutional control, spatial management critical to integrated coastal management and ecosystem-based management emerges as an innovative approach to the success of coastal management.     

Ocean robotics in support of fisheries research and management

South Africa’s small-pelagic fishery is a socio-economically important component of the country’s commercial fisheries sector, second in value only to the demersal trawl fishery. Management of this sector relies on infrequent hydro-acoustic surveys, which provide measures of anchovy Engraulis encrasicolus and sardine Sardinops sagax biomass used in the assessments of stock status and in the development of management plans for the sustainable utilisation of these resources. We demonstrate how technological capabilities in ocean robotics at the Council for Scientific and Industrial Research (CSIR) could augment the current resource-intensive hydro-acoustic ship-based survey programme and create opportunities for expanding its spatial and temporal resolution. We successfully implement and demonstrate an autonomous wave glider, fitted with a hydro-acoustic sensor and compare the data to a collocated ‘traditional’ ship-based acoustics survey. In the future these autonomous systems approaches could be seen as a means to lessen the cost burden of the ship-based survey, while at the same time with the added advantage of continuous collection over much wider spatial and temporal domains. This could enable a more reflexive stock management approach taking into account the seasonal characteristics of the fishery and its ecosystem. Gliders thus have potential to increase dramatically the quantity of information available to fisheries managers, thereby reducing uncertainty and contributing to improved management of valuable fish resources. They are likely to contribute to improved knowledge of the ecology of small pelagic fish species off the coast of South Africa in a changing climate and should potentially also permit the collection of biomass data for other marine resources currently not routinely monitored.     

新型伞状锚拉拔破坏机制与承载力数值分析

锚泊基础的承载性能直接影响着海洋浮式结构物的稳定性,因而研究新型有效的锚泊基础已成为海洋工程结构设计中的关键问题之一。文中提出了一种基于海洋软土液化特性的伞状锚,充分利用桩端土体增强抗拔承载能力。应用二维颗粒流分析程序,对该新型伞状锚的安装、抗拔承载能力进行了数值模拟,并与普通锚桩进行比较分析,验证其有效性。针对伞状锚与普通锚桩在拉拔过程中的土体破坏机制,从细观角度分析了其抗拔承载能力的提高机制。研究结果表明,对于相同抗拔锚泊设计竖向承载要求,伞状锚所需材料可大为减少,安装难度明显减低,是值得推广应用的新型锚泊基础形式。     

Incorporating uncertainty into the estimation of biological reference points for a spiny lobster (Panulirus penicillatus) fishery

The status of a fishery is often defined as the probability of fishing mortality rate exceeding a perilous level for long‐term sustainability. Lobster stock assessments are often subject to large uncertainty in input data and high levels of natural variability in lobster life history processes, which calls for incorporating uncertainty associated with both indicator and management reference points in an evaluation of biological risk of overfishing. Using a Monte Carlo simulation approach, we evaluated the impacts of uncertainty in modelling on the determination of the status of the Taitung spiny lobster (Panulirus penicillatus) fishery (Taiwan), which has not been quantitatively determined despite its commercial importance. The commonly used biological reference points derived from the per recruit model (F _0.1 the fishing mortality rate where the slope of the curve of yield‐per‐recruit model is 10% of the maximum slope and F _4Q%, the fishing mortality rate that reduces the expected egg production for a cohort of female lobsters to 40% of that produced in the absence of a fishery of the egg‐per‐recruit model) were influenced by uncertainties associated with lobster life history and fishery parameters. A large uncertainty in the current fishing mortality rate (F _cnr) and estimates of biological reference points (F _BRPs) increased the uncertainty in determining the risk of overexploitation throughout the confidence levels of the stochastic decision‐making framework. This simulation study suggests that the target reference point of F _40% is less sensitive to the input parameters’ uncertainty than F _0.1 We suggest a further evaluation of other F‐based references points and development of biomass‐based reference points before final selection and implementation for the management of the Taitung lobster fishery.     

Institutional stability and change in the Baltic Sea: 30 years of issues,crises and solutions

The shift from a classic sector-by-sector management system to an operational ecosystem approach is perceived as the way forward towards sustainable use of marine systems. The nine states bordering the Baltic Sea as well as the European Community signed the Baltic Sea Action Plan (BSAP) in 2007, intended to provide practical means for implementing the ecosystem approach in the region. However, whether this shift towards a new governance approach also constitutes a case of institutional change remains unclear. This study evaluates institutional change over 30 years in order to understand the process of emergence of the ecosystem approach for this international institution. This study adds to the otherwise largely theoretical debate on institutional change by testing two models of institutional change – gradualist versus punctuated equilibrium – against data from the Helsinki Commission. Relying on a novel methodology involving quantitative text analyses of 574 documents this study suggests that the signing of the BSAP did not cause change in the institution, nor was it the cause of an abrupt institutional change. Overall, findings support a gradualist model of institutional change where the BSAP is layered upon preexisting institutional structures. Results also indicate that institutional change has occurred in some parts of the institution, whereas other parts remain remarkably stable. It proves that in order to intentionally change an institution it is vital that the change processes cohere at all levels of the institution. The study also underlines the mismatch between ecosystems and institutions. Given the relatively slow dynamics identified here, it is unclear whether institutions are able to adapt to rapid and unpredictable ecosystem shifts.     

Spatial analysis of recreational boating as a first key step for marine spatial planning in Mallorca (Balearic Islands, Spain)

Recreational boating is an important, growing leisure activity on the island of Mallorca, Balearic Islands, Spain. This spatial analysis of anchoring of recreational boating along the coast of Mallorca is intended to generate new data to contribute to the achievement of a comprehensive marine and coastal spatial planning on the island in addition to providing important information related to the pressure of increasing demand for anchoring space that, if not properly managed, could jeopardize the coastal and marine environments. The study combines data from the natural (habitats, geology), physical (wave patterns), and social sciences (survey interviews), using Geographic Information Systems (GIS) as the main analytical tool. The final result is an estimate of the average amount of seabed available for anchoring during the highest levels of boating activity in Mallorca (i.e. summer high season) based on a number of different sustainability scenarios (i.e. average distance between boats, weather conditions). In addition to being applicable to any location wishing to manage recreational boating activity, the methodology presented in this study represents an integrated, multidisciplinary approach which could be applied to a number of management scenarios with a spatial dimension in marine environments.     

Assessment and management of South African marine resources during the period of the Benguela Ecology Programme: key lessons and future directions

Three important developments in resource assessment and management during the period of the Benguela Ecology Programme are discussed. The first is the recognition of the limited information content for assessment purposes of the available data for many of the Benguela's major pelagic and demersal resources. This has meant that management measures for these resources could attempt no more than to maintain the status quo, rather than to achieve "optimal" utilization. Secondly, a post mortem on the commercial extinction of the kingklip suggests a need to consider Bayesian methods as a means to incorporate additional information into stock assessments. Finally, changes to the management approaches for the hake and anchovy fisheries are argued to have been particular successes, notwithstanding the recent heavily reduced Total Allowable Catch (TAC) for the latter resource. "Management procedures" have been developed and simulation-tested for these two resources. The implications of this approach for the future basis, whereby TACs are set for South Africa's fisheries, are discussed.     

The science-policy interface in fisheries management: Insights about the influence of organizational structure and culture on information pathways

Understanding how information flows between scientific and decision-making communities is essential for the creation of effective strategies to link scientific advice to management decisions. Interviews of scientists and managers in two inter-related fisheries management organizations – the Department of Fisheries and Oceans (DFO) and the Northwest Atlantic Fisheries Organization (NAFO) – and direct observations at science and management meetings revealed important organizational characteristics that influence the production, communication, and use of scientific information in decision-making. Formal processes for communicating scientific advice to managers – DFO's Canadian Scientific Advisory Secretariat (CSAS) and NAFO's Fisheries Commission's Request for Advice – demonstrate the use of credible, relevant, and legitimate advice for operational decision-making for fisheries management. Such defined processes, in addition to governmental bureaucracy, departmentalization, and de-centralization, can limit communication as highlighted for Canada as a Contracting Party to NAFO. Administrative mechanisms can pose challenges to implementing ecosystem approaches to fisheries management (EAF) and to addressing the impacts of climate change. Emerging organizational structures and behaviours facilitate communication at the science-policy interface, within and between the organizations, thereby improving understanding of science and management needs and promoting trust relationships between scientists and managers. The involvement of multiple stakeholders in the information pathways addresses concerns about scientific uncertainty in assessment advice. A linear model of information flow typifies operational decision-making; however, collaborative models that incorporate different types of information, apart from fisheries science, are required to enable ecosystem-based management. The characteristics of the information pathways are particularly relevant as the organizations address their EAF mandates.     

Short-term response of the slow growing seagrass Posidonia oceanica to simulated anchor impact

Experimental evaluations about the impact of anchors of small vessels have previously shown that each anchoring can on average damage up to six shoots of Posidonia oceanica, removing small amount of biomass and, at the same time, interrupting continuity among shoots. The aim of the paper was to investigate the response of P. oceanica to different damage intensity at two levels of substrata compactness. Three treatments were considered: control (no damage); low damage (simulated anchor damage by three strokes of a hoe); and high damage (six strokes). Disturbance was higher where the substratum was highly penetrable and after one year significant variation was observed among treatments for both the number of leaves per shoot and shoot density. Conversely, the number of leaves per shoot by the end of the study was similar among all treatment combinations, suggesting that this was the only phenological feature that recovered, and probably the only result that through clonal integration could be achieved. These data strongly highlighted the role that anchoring might have on the slow growing seagrass P. oceanica meadow.     

Analytical study on comprehensive behaviors of drag anchors in the seabed

Attributed to good performance in the seabed, drag anchors are adopted as an effective anchoring solution in deepwater mooring systems. This type of anchors is drag installed, companying with comprehensive behaviors during movement of the anchor in the seabed, which make the anchor trajectory and therefore the final embedment position difficult to be predicted. On the basis of the mechanical model and analytical procedure, an analytical method is proposed for exploring comprehensive behaviors of drag anchors in both clay and sand. The anchor behaviors are classified as keying, pulling out and diving. The bearing capacity and the trajectory of the anchor can be predicted through the combination of the three behaviors. By comparing analytical predictions with experimental data and other predictions, the efficiency and veracity of the theoretical model are validated. A parametric study is also performed to investigate the effects of different parameters, and to further understand the comprehensive anchor behaviors in the seabed. The present work provides an efficient theoretical tool for analyzing comprehensive behaviors of drag anchors in either clayey or sandy seabed.     

An indicator-based adaptive management framework and its development for data-limited fisheries in Belize

Decisions regarding the selection and implementation of management strategies that constrain fishing pressure can be among the most difficult choices that fisheries managers and stakeholders must make. These types of decisions often need to be confronted in a data-limited context, where few if any management measures are currently in place or fisheries are managed independent of adequate scientific advice. This situation can sometimes create a high risk of overfishing and potential loss of economic and social benefits. To address this situation, simple model-free indicator-based frameworks have the potential to be effective decision-making platforms for fisheries where quantitative estimates of biomass and fishing mortality based reference points are lacking. In this paper, a multi-indicator framework is developed that enables decision-makers to proceed with management decisions in data-limited situations. Model-free indicators are calculated using trends in observed data, rather than stock assessment derived estimates of biomass and fishing mortality. The framework developed is adaptive so that adjustments to catch or effort are recursive and can respond to changing environments, socioeconomic conditions, and fishing practices. Using stakeholder-defined objectives as a foundation, indicators and reference points of fishery performance are chosen that can be evaluated easily by undertaking analyses of available data. Indicators from multiple data streams are used so that uncertainty in one indicator can be hedged through careful interpretation and corroboration of information from alternative indicators. During the adaptive management cycle, managers and stakeholders evaluate each indicator against the associated reference points to determine performance measures, interpret the results using scientific and local knowledge, and adjust fishery management tactics accordingly using pre-defined harvest control rules. The framework facilitates the interpretation of situations in which performance measures suggest divergent stock abundance or productivity levels. A case study is presented on this framework's development for conch and lobster fisheries of Belize.