Ecological performance indicators in the North Sea: development and application

Different signals of distress from the North Sea ecosystems started a discussion on the protection of the ecosystem at the third North Sea Ministers Conference in 1990. This was followed by a number of workshops on ecological indicators under the auspices of the North Sea Task Force and the Oslo and Paris Commissions (OSPAR). In 1997 the member countries around the North Sea agreed to develop and apply an ecosystem's approach in the management programs for both the North Sea fisheries and the marine environment. Following this agreement the identification of the ecological qualities objectives for the North Sea ecosystem started. Further work in this direction has lead to the setting up of various national projects geared towards creating a better understanding of the North Sea ecosystem.In the Netherlands, two departments (Water management and Nature and fisheries management) from the Ministry of Transport, Public works and Water Management (V&W) and the Ministry of Agriculture, Nature and Fisheries Management (LNV) agreed to integrate their policies for the management of the Netherlands section of the North Sea. The results from these projects (started in 1996) should enable the policy makers and managers to formulate policies that could lead to the creation of a balance between the effects of human activities and the preservation of the natural qualities of the North Sea ecosystem.One of the projects is strictly designed to develop ecological indicators for the Dutch part of the North Sea. These indicators are based on various monitoring data and related in one way or another with human activities. In this way it is possible to evaluate the effects of human impacts on the ecosystem. Long-term changes in the ecological performance of the ecosystem can be elucidated by the use of the ecological indicators. Thereby making it possible for the policy makers and the managers of the NCP to evaluate the effects of their policies and management recommendations on the quality of the ecosystem.This paper describes the process and the steps taken by the authorities in the countries around the North Sea to develop a set of ecological indicators for the management of the North Sea ecosystem. Focus will be made on the efforts made in the Netherlands to develop indicators that did provide the basis for the development of Water and Nature conservation policies and new management strategies for maintaining the sustainable use of the Dutch section of the North Sea.     

Review of indicators in fisheries management – a development perspective

A review of indicators for an ecosystem approach to fisheries management is presented, focusing on multispecies fisheries and limited resources for assessments and implementation, as often is the case in developing countries. Emphasizing the need to link indicators to management objectives, indicators from the literature are grouped into four categories, relating to the immediate fisheries resource base (single-species and multispecies indicators) and the wider ecosystem (habitat structure and ecosystem functioning). The usefulness of these indicators is assessed along three dimensions of acceptability among stakeholders, observability, and relation to fisheries management using a traffic light approach. The top ranking indicators are highlighted as a generally good start for any particular fishery management case. It is, however, argued that, even with similar management objectives, indicators need to be specific to both ecosystems and the institutional set-up if they are to be effective for management, and that indicators may consequently differ considerably between individual management applications.     

Evaluating impacts of pulse fishing on the effectiveness of seasonal closure

Seasonal fishing closures are often used in fisheries management to conserve overfished stocks.As one of the unintended consequences,fishermen often contend for maximizing catches immediately after reopening fisheries.The resultant large catch landings in a short time period(i.e.,pulse fishing)may undermine the benefit of closure.We implemented an end-to-end model OSMOSE-JZB(Object-oriented Simulator of Marine ec OSystem Exploitation OSMOSE)modelling ecosystem in the Jiaozhou Bay located in China to evaluate the impact of pulse fishing on the effectiveness of seasonal closure at levels of fish community,population,and individual.Our study demonstrated that the three-month closure was successful in conserving fish stocks.There were small variations on ecological indicators(i.e.,total biomass of the community,mean trophic level of the community,mean trophic level of the catch,and Shannon-Wiener biodiversity index)when pulse fishing occurred.Pulse fishing seemed not to result in a great shift in community structure.Compared to other species,the biomass of two large predatory fishes were more susceptible to pulse fishing.Pulse fishing could change the pressure of predators to fish stocks via food webs,especially for young individuals.Our simulations indicate that we can improve the effectiveness of seasonal closure by managing pulse fishing.Although the results derived in this study may be specific to the target ecosystem,the general approach is applicable to other ecosystems when evaluating fishing impacts.     

A spatio-temporal ecosystem model to simulate fishing management plans: A case of study in the Gulf of Gabes (Tunisia)

The Gulf of Gabes located in southern Tunisia is one of the most productive ecosystems in the Mediterranean Sea. Despite its ecological importance, it is subject to high fishing pressure affecting the different components of the ecosystem. Given the multispecies, multigear nature of the fishery, there is a need to manage trade-offs between environmental and economic objectives. In this study, an Ecospace model was developed based on the previously constructed Ecopath model of the Gulf of Gabes and calibrated for the period 1995–2008 to investigate the response of the ecosystem to a set of alternative spatial management scenarios. These scenarios were derived from the current fishery regulation owing the important interest expressed by local fishery managers to assess new management measures. The results showed for each management scenario how bottom trawling and coastal fishing impact the different trophic groups and the complexity of interaction between these two fishing activities. Furthermore, spatially explicit simulations were performed to identify regions where the management measures are effective. Results suggested that for some trophic groups, these regions are well-defined which would be interesting to propose more accurate spatial measures. Finally, several indicators were calculated to evaluate the proposed management plans and provide managers with a straightforward set of decision rules to describe the potential trade-offs and fulfill both fisheries and conservation management objectives in the context of an ecosystem approach. The decision rules were based on observed trends to reduce uncertainty relative to the model complexity and provide consistent advice to decision-makers.     

Development of an integrated fisheries co-management framework for new and emerging commercial fisheries in the Canadian Beaufort Sea

The Canadian Beaufort Sea is one of the last places on Earth that has not experienced large-scale commercial fisheries. The aboriginal people of the western Canadian Arctic, the Inuvialuit, have become increasingly concerned about the potential effects of large-scale commercial operations on key subsistence species of fish and marine mammals and the marine ecosystem upon which they depend. A 1984 comprehensive land settlement agreement (treaty) between Canada and the Inuvialuit established a co-management regime for limited aspects of fish and marine mammal resource management, and gave the Inuvialuit rights to subsistence fisheries and existing commercial fisheries but no preference for new commercial fisheries. The Fisheries Joint Management Committee (the fisheries co-management body), the Canada Department of Fisheries and Oceans, the Inuvialuit Regional Corporation and the Inuvialuit Game Council have developed an integrated fisheries management framework agreement for the review and assessment of any proposed commercial fisheries within the Canadian Beaufort Sea. The agreement provides clarity and transparency for decision making and strengthens the protection of fish stocks. The development of the framework depended upon a history of cooperation between the parties and a bridging initiative by the Fisheries Joint Management Committee and an NGO that brought together the Inuvialuit and the government.     

Current and future use of indicators for ecosystem based fisheries management

Implementing ecosystem based fisheries management (EBFM) will require a suite of ecological indices to track the state of an ecosystem, in addition to monitoring species-abundance for both economically important species, as well as species that are not targeted for harvest. However, EBFM implementation requires an examination of current methods and applications of ecological indices that are being used. This paper identifies four key uses for ecosystem indices in the context of EBFM and discusses the implications of each: (1) motivation for socio-political action, (2) information for individual users to modify their behavior, (3) implementation of decision rules for management evaluation, and (4) discovery of ecosystem functions to advance scientific knowledge. In a fisheries management context, ecological indicators will be linked to decision rules based on the definitions of both “ecosystem overfishing” and the current single-species definitions of overfishing. Two components of common ecological indicators are species weightings (i.e. catch or abundance data by species) and the species-specific ecological attributes (e.g. mortality rates, body size, trophic level). We discuss statistical issues that arise from estimating the parameters in ecological index calculations from both fishery-dependent and independent data and the potential biases introduced by using catch-per-unit-effort (CPUE) data, catch data, and abundance estimates. Given the range of biases that arise, often the best estimates of species weightings (abundances) are those derived from fish stock assessments. This implies that progress in EBFM may be best served by increasing the number of species for which single-species assessments are done and to expand the list of species to include species which may not be economically important. The policy framework exists to carry out EBFM; however, future works needs to focus on empirical management strategy simulations, as well as theoretical works to identify management criteria based on those indicators.     

The MSY concept in a multi-objective fisheries environment – Lessons from the North Sea

One of the most important goals in current fisheries management is to maintain or restore stocks above levels that can produce the maximum sustainable yield (MSY). However, it may not be feasible to achieve MSY simultaneously for multiple species because of trade-offs that result from interactions between species, mixed fisheries and the multiple objectives of stakeholders. The premise in this study is that MSY is a concept that needs adaptation, not wholesale replacement. The approach chosen to identify trade-offs and stakeholder preferences involved a process of consulting and discussing options with stakeholders as well as scenario modelling with bio-economic and multi-species models. It is difficult to intuitively anticipate the consequences of complex trade-offs and it is also complicated to address them from a political point of view. However, scenario modelling showed that the current approach of treating each stock separately and ignoring trade-offs may result in unacceptable ecosystem, economic or social effects in North Sea fisheries. Setting F_MSY as a management target without any flexibility for compromises may lead to disappointment for some of the stakeholders. To treat F_MSY no longer as a point estimate but rather as a “Pretty Good Yield” within sustainable ranges was seen as a promising way forward to avoid unacceptable outcomes when trying to fish all stocks simultaneously at F_MSY. This study gives insights on how inclusive governance can help to reach consensus in difficult political processes, and how science can be used to make informed decisions inside a multi-dimensional trade-off space.     

Performance of a northwestern Mediterranean bottom trawl fleet: How the integration of landings and VMS data can contribute to the implementation of ecosystem-based fisheries management

The European Union has established a framework to achieve or maintain good environmental status in the marine environment by 2020. The Marine Strategy Framework Directive requires the application of the ecosystem approach to the management of human activities, covering all sectors having an impact on the marine environment. However, fisheries in the Mediterranean are far from a systematic implementation of an ecosystem-based fisheries management (EBFM). Aiming to address this issue, this study explores the potential of the relationship between daily yield by vessel (landings and income by species) and vessel position (known via vessel monitoring system) as a tool for fleet management. This approach is possible due to the current dynamics of Mediterranean fleets, with vessels returning daily to the harbour where landings are registered as weight and income by vessel. Moreover, vessels of >15 m total length have been compulsory monitored by VMS since 2005. A bottom trawl fleet that operates in the northwestern Mediterranean was chosen to develop this approach. Different groups of trawlers were identified, which could be linked to the strategies displayed by the fishermen that were mainly driven by the target species dynamics. Accurate knowledge of the fishing targets driving the fleet dynamics and of the fishing strategies at the vessel level (i.e. fishing ground habitat where the fishing pressure is exerted and corresponding landings) are shown to be a feasible tool for fleet management.     

Constraints and solutions for managing Pacific Island sea cucumber fisheries with an ecosystem approach

The ecosystem approach to fisheries (EAF) is a holistic paradigm that considers stocks of exploitable species, marine ecosystems and stakeholders. Management agencies must strike a balance between their capacity constraints and the requisites of management measures. Most small-scale sea cucumber fisheries of Pacific Islands have been plundered while others are being opened to commercial exploitation. Data from fishery managers and a regional workshop were used to assess the current problems, institutional constraints and solutions to the management of sea cucumber fisheries in 13 Pacific Island countries (PICs). Technical capacity was often strong for some management actions such as developing marine reserves but weak for others, such as enforcement. Using multi-disciplinary indicators, half of the fisheries were diagnosed by their managers as being overfished or depleted, despite evidence of optimistic bias. Fishery governance varied greatly among the PICs, and co-management frameworks were not typical of any cultural region. Management objectives were prioritised differently among managers but most highly ranked was to protect ecological resilience. The fishery managers proposed different sets of regulatory measures and various management actions, such as surveys to collect socio-economic and fishery-dependent data, support for local governance and strong enforcement – all widely under-practised. Pacific sea cucumber fisheries exemplify how the transition to an EAF by management institutions must involve reorganisation of their technical and human-resource capacities among management tasks. Levies on exports need to be internalised to fund improved management. Management agencies should consider a shift in resources from developing marine reserves, conducting underwater surveys and aquaculture-based restocking to strengthening enforcement capacity, stakeholder involvement and communication with fishers. In concert with these actions, short fishing seasons, shortlists of allowable species and tighter enforcement at export points may serve to turn the tide on boom-and-bust exploitation and safeguard biodiversity.     

Estimating global discards and their potential reduction for the Galician fishing fleet (NW Spain)

This study presents the first comprehensive estimation of discard amounts in the Galician fishing fleet, in order to provide an integral view of this increasing environmental problem at a regional scale. Subsequently, a series of improvement actions relating to discard minimization are suggested with the goal of enhancing the performance of the Galician fishing fleet through discard minimization. Discard estimates were constructed individually for the different Galician fisheries by aggregating primary data obtained from a total of 89 fishing vessels and secondary data for those fleets that were not directly sampled. Results showed that roughly 60,250 t of marine organisms were discarded by the Galician fleet in 2008, representing 16.9% of the total capture. Moreover, an important percentage of these discards were linked mainly to trawling vessels and to a lesser extent, to certain long lining fisheries. Therefore, improved management measures in target stocks should take into account the fact that alternative fishing gears other than trawl nets may reduce the amount of discards for certain species. This estimation may improve the assessment of stocks and help to quantify the damage that discards may have on wild ecosystems.     

From krill to convenience stores: Forecasting the economic and ecological effects of fisheries management on the US West Coast

There is a need to better understand the linkages between marine ecosystems and the human communities and economies that depend on these systems. Here those linkages are drawn for the California Current on the US West Coast, by combining a fishery ecosystem model (Atlantis) with an economic model (IO-PAC) that traces how changes in seafood landings impact the broader economy. The potential effects of broad fisheries management options are explored, including status quo management, switching effort from trawl to other gears, and spatial management scenarios. Relative to Status Quo, the other scenarios here involved short-term ex-vessel revenue losses, primarily to the bottom trawl fleet. Other fleets, particularly the fixed gear fleet that uses pots and demersal longlines, gained revenue in some scenarios, though spatial closures of Rockfish Conservation Areas reduced revenue to fixed gear fleets. Processor and wholesaler revenue tracked trends in the bottom trawl fleet, which accounted for 58% of total landings by value. Income impacts (employee compensation and earnings of business owners) on the broader economy mirrored the revenue trends. The long-term forecast (15 years) from the Atlantis ecosystem model predicted substantial stock rebuilding and increases in fleet catch. The 15 year projection of Status Quo suggested an additional ∼$27 million in revenue for the fisheries sectors, and an additional $23 million in income and 385 jobs in the broader economy, roughly a 25% increase. Linking the ecological and economic models here has allowed evaluation of fishery management policies using multiple criteria, and comparison of potential economic and conservation trade-offs that stem from management actions.     

Unsuitability of TAC management within an ecosystem approach to fisheries: An ecological perspective

Fisheries management in European waters is gradually moving from a single-species perspective towards a more holistic ecosystem approach to management (EAM), acknowledging the need to take all ecosystem components into account. Prerequisite within an EAM is the need for management processes that directly influence the ecological effects of fishing, such as the mortality of target and non-target species. Up until recently, placing limits on the quantities of fish that can be landed, through the imposition of annual total allowable catches (TACs) for the target species, has been the principal management mechanism employed. However, pressure on non-target components of marine ecosystems is more closely linked to prevailing levels of fishing activity, so only if TACs are closely related to subsequent fishing effort will TAC management serve to control the broader ecosystem impacts of fishing. We show that in the mixed fisheries that characterise the North Sea, the linkage between variation in TAC and the resulting fishing effort is in fact generally weak. Reliance solely on TACs to regulate fishing activity is therefore unlikely to mitigate the impacts of fishing on non-target species. Consequently, we conclude that the relationship between TACs and effort is insufficient for TACs to be used as the principal management tool within an EAM. The implications, and some alternatives, for fisheries management are discussed.     

An integrated approach for assessing the relative significance of human pressures and environmental forcing on the status of Large Marine Ecosystems

An ecosystem approach to the management of the marine environment has received considerable attention over recent years. However, there are few examples which demonstrate its practical implementation. Much of this relates to the history of existing marine monitoring and assessment programmes which (for many countries) are sectoral, making it difficult to integrate monitoring data and knowledge across programmes at the operational level.To address this, a scientific expert group, under the auspices of the International Council for the Exploration of the Sea (ICES), prepared a plan for how ICES could contribute to the development of an Integrated Ecosystem Assessment (IEA) for the North Sea by undertaking a pilot study utilising marine monitoring data. This paper presents the main findings arising from the expert group and in particular it sets out one possible integrated approach for assessing the relative significance of environmental forcing and fishing pressure on the ecological status of the North Sea, it then compares the findings with assessments made of other Large Marine Ecosystems (LMEs).We define the North Sea ecosystem on the basis of 114 state and pressure variables resolved as annual averages between 1983 and 2003 and at the spatial scale of ICES rectangles. The paper presents results of integrated time-series and spatial analysis which identifies and explains significant spatial and temporal gradients in the data. For example, a significant shift in the status of the North Sea ecosystem (based upon 114 state-pressure variables) is identified to have occurred around 1993. This corresponds to previously documented shifts in the environmental conditions (particularly sea surface temperature) and changes in the distribution of key species of plankton (Calanus sp.), both reported to have occurred in 1989. The difference in specific timing between reported regime shifts for the North Sea may be explained, in part, by time-lag dependencies in the trophic structure of the ecosystem with shifts in higher trophic levels occurring later than 1989.By examining the connection (or relatedness) between ecosystem components (e.g. environment, plankton, fish, fishery and seabirds) for the identified regime states (1983–1993; 1993–2003) we conclude that both the North Sea pelagic and benthic parts of the ecosystem were predominantly top-down (fishery) controlled between 1983 and 1993, whereas between 1993 and 2003 the pelagic stocks shifted to a state responding mainly to bottom-up (environment) influences. However, for the demersal fish stocks between 1993 and 2003 top-down (fishery) pressure dominated even though over this period significant reductions in fishing pressure occurred. The present analysis, therefore, provides further evidence in support of the need for precautionary management measures taken in relation to setting fishery quotas.     

Flexible management of fishing rights and a sustainable fisheries industry in Europe

Although overexploitation of commercial fish stocks in European waters has been in the public debate now for more than 20 years, the European Union has so far failed to implement sustainable fisheries management. Millions in subsidies paid to the fishing industry have led to significant excess capacity in the fishing fleet. Various feeble attempts to stop overexploitation of marine resources have failed. The cause is that fishing policy is highly dominated by short-term socioeconomic interests. There is an urgent need for a new fisheries management system in Europe that supports reductions in the fishing fleet, increases responsibility among fishers and guarantees long-term conservation of natural marine resources.Transferable rights to fish have proved a reliable and effective means of creating incentives to conserve marine resources. By strengthening individual fishing rights under flexible quota management systems, the EU Member States could, within the Common Fisheries Policy, make a significant contribution to conserving fish stocks, to reducing excess capacity and to raising the profitability of the fisheries industry. A closer look at existing reservations against a flexible management system shows most of the objections to be overstated or capable of resolution.     

Developing a sustainable indicator system based on the pressure–state–response framework for local fisheries: A case study of Gungliau,Taiwan

To sustain fishery development and ensure the supply of fish, the role that a sustainable development indicator system plays in the evaluation of fishery management performance is becoming increasingly important. A sustainable indicator system based on the Pressure–State–Response (PSR) framework was developed for local fisheries in Gungliau, Taiwan, between 1995 and 2003. Factor analysis and canonical correlation analysis were also applied to aggregate indicators and analyse the linkage of indicators. The most serious problem facing fishery system in Gungliau is conflicting local and higher levels of enforcement that result in the problems of effort, harvest and fleet age composition related to the pressure component. Fishery resources and the state of ecosystem were also affected by marine environmental change, especially by El Ñino. Consequently, fishermen adjusted their effort and investment to the variation of Fishery resources, leading Gungliau fisheries to unsustainability.     

Nuts and bolts in fisheries management—a technological approach to sustainable fisheries?

According to the Food and Agriculture Organization of the United Nations, overcapacity in the fishing fleet poses a fundamental challenge in fisheries. Overcapacity leads to an increased pressure on fish stocks and a decrease in economic profit. The fishing fleet is marginalised economically, and overcapacity creates allocation conflicts between different gear and vessel groups. In addition, the expenses to control and management increase. Although Norwegian authorities have introduced several restrictions, for example total allowable catch, licenses, vessel quotas, and other regulatory measures, this article shows that the problems connected to overcapacity persist. Analyses of the technical capacity development show that there is an overall capacity expansion although the number of vessels is reduced. This development is an indicator of the dynamics of technological development over time, and the article discusses whether the concept of technology is sufficiently integrated into fisheries management. The important question now is whether analyses of the technical capacity development can serve as a positive supplement to the traditional fisheries management, which largely is based on input from the scientific disciplines biology and economics.     

溢油对海洋生态系统内在价值损害的评估——以“塔斯曼海”轮溢油事故为例

作者籍以能值和生态炯分析,将海洋生态内在价值补充到溢油损害评估中,并以"塔斯曼海"轮溢油事故为例,分析了生态系统内在价值损害评估的特点。结果表明溢油生态内在价值损害大于对生态服务价值的损害,前者是后者的6.9倍;能值变化反映对资本积累的损害,生态炯更突出了溢油对初级生产力的生态系统的影响。本评价是现有溢油损害评价的补充,可为彻底、有效环境治理、生态修复提供保障,对海洋开发管理决策和公众环保意识的提高将有积极的影响。     

The Norwegian plan for integrated ecosystem-based management of the marine environment in the Norwegian Sea

A White Paper on a new integrated management plan for the Norwegian Sea was launched by the Norwegian government in May 2009. Following international guidelines for ecosystem-based management, the plan provides an overall framework for managing all human activities (mainly oil and gas industry, fishing, and shipping) in the area to ensure the continued production and function of the ecosystem. The plan is based on an assessment of the present and projected future impact of human activities and of the interactions between them, taking into account deficits in current knowledge of ecosystem state and dynamics. Areas of particular value in terms of biodiversity or biological production were identified. In each of these valuable areas, any access for substantial human activity is to be carefully managed. To monitor the overall development of the Norwegian Sea, a set of indicators with associated environmental quality objectives have been selected. The approach used builds upon experience gained from the first integrated Norwegian management plan for a marine area, the Barents Sea–Lofoten region, developed in 2002–2006. Work towards a Norwegian management plan for the North Sea, including Skagerrak, was initiated in 2009.     

渤海生态系统健康评价及对策研究

根据2014~2016年渤海各航次监测数据,选择22项因子构建表征研究区水环境、沉积环境、生态系统健康状态的评价指标体系,利用AHP层次分析方法对渤海生态系统的健康状况进行了评价。结果表明,渤海综合生态指数CEI为0.643,健康等级为中级,表明渤海生态系统整体处于亚健康的状态。生态健康较差和差的区域主要集中在莱州湾-渤海湾及其毗连地带的黄河三角洲地区;唐山-秦皇岛-葫芦岛近海及其纵深海域大体处于中级健康水准;渤海中部海区及其毗连的渤海海峡区域,海洋生态健康水平较高。根据评价结果,认为陆源输入、围填海工程是莱州湾和渤海湾的主要胁迫因子,并探讨了相应对策,以期为渤海的综合管理提供决策支持。     

A knowledge base for management of the capital-intensive fishery for small pelagic fish off South Africa

As a contribution to South Africa's move towards an ecosystem approach to fisheries management, this study explores the existence of common perceptions about South Africa's pelagic fishery between resource users and scientists. It represents a collaborative research effort of social and natural scientists. A brief overview is given of the southern Benguela upwelling ecosystem and small pelagic fish resources, the fishery, and management of the fishery. Stakeholder knowledge and views were determined by conducting open-ended qualitative local knowledge interviews. Candidate indicators to address five major issues raised in the interviews were selected: length-at-50% maturity, total mortality, exploitation rate, proportion of bycatch, mean length of catch, and centre of gravity of catches. The indicator approach is shown to be a useful tool to manage the South African small pelagic fishery, and can be made compatible with existing management approaches. The foundation of a good adaptive fisheries management system is a data collection system that enables multi-disciplinary analysis and provides a basis on which decisions can be made.