© 2005 International Council for the Exploration of the Sea
Quantitative ecosystem indicators for fisheries management
a Centre de Recherche Halieutique Méditerranéenne et Tropicale IRD – IFREMER, and Université Montpellier II Avenue Jean Monnet, BP 171, 34203 Sète Cedex, France
b Fisheries Centre, University of British Columbia 2259 Lower Mall, Vancouver BC, Canada V6T 1Z4
*Correspondence to P. M. Cury: tel: +33 499 573234; fax: +33 499 573295. e-mail: pcury{at}ifremer.fr; v.christensen{at}fisheries.ubc.ca.
Spring in Paris (31 March to 3 April 2004) helped to attract more than 250 participants from 53 countries to a symposium on "Quantitative Ecosystem Indicators for Fisheries Management". The symposium was hosted by the Intergovernmental Oceanographic Commission at the UNESCO headquarters next to the Eiffel Tower, and co-organized with the Scientific Committee on Oceanic Research (SCOR). Four years of preparation had borne fruit, and the stage was set with a programme of 40 presentations and nearly 150 posters.
The symposium was centred on using ecosystem indicators for fisheries management, and as such reflects the growing understanding that exploited fish populations must be considered as integral components of ecosystem function, rather than units that operate independently of their environment. Internationally, there has been wide recognition of the need to move towards an ecosystem approach to fisheries, a development spearheaded by FAO through their Code of Conduct for Responsible Fisheries (Garcia, 2000), and supported by many regional and national institutions as well as academia, NGOs, and the general public. Intergovernmental organizations providing management advice, such as ICES and PICES, require meaningful indicators that adequately reflect the state of marine ecosystems.
As we move to embrace an ecosystem perspective, we need new measuring sticks. Ecosystem approaches to fisheries require consideration of the interdependent way we utilize ecosystems. At a minimum, the components to be addressed cover ecological, economic, social, technological, and governance aspects. When considering the ecosystem, we must include not only target species, but also their effects on dependent or competing non-target species, as well as on the habitats shared by the species. An important question thus arises, related to trade-offs. Management interventions directed at one target species may have consequences for many other species, including some that are targets of other fisheries. How do we evaluate the trade-offs involved, and how do we determine the direction that a society should take, based on the implications for marine ecosystems?
To answer such questions, analyses must be based on well-founded science as well as on information on societal priorities. At the Paris Symposium the focus was on the scientific aspects of ecosystem approaches to fisheries, with the intention to provide information and guidelines about how to develop, test, and apply indicators, or frameworks of indicators.
Internationally, the first major initiative related to the use of ecosystem indicators for sustainable fisheries development was undertaken by the Government of Australia in cooperation with the FAO, through a Consultation in Sydney in January 1999 (Garcia and Staples, 2000). The consultation resulted in Technical Guidelines No. 8 for the FAO Code of Conduct for Responsible Fisheries: Indicators for Sustainable Development of Marine Capture Fisheries. The Guidelines were produced to support the implementation of the Code of Conduct; they deal mainly with the development of frameworks, and they set the stage for using indicators in the decision process.
The Guidelines do not, however, discuss the properties of indicators, nor how they are used and tested in practice. This became the task of an international working group, established jointly by the Scientific Committee on Oceanic Research (SCOR) and the Intergovernmental Oceanographic Committee (IOC) of UNESCO. SCOR/IOC Working Group 119 on "Quantitative Ecosystem Indicators for Fisheries Management" was established in 2001, with 32 members drawn from 19 countries. The working group was designed to develop the scientific basis of using indicators for an ecosystem approach to fisheries, to review existing knowledge in the field, to evaluate the utility and perspectives for new indicators that reflect the exploitation and the state of marine ecosystems, and to consider frameworks for their implementation.
The working group met twice to plan and report on progress; in Reykjavík in October 2001, and in Cape Town in December 2002, organizing its efforts with a series of task forces working in parallel on: (i) environmental indicators including habitat changes; (ii) species-based indicators; (iii) size-based indicators; (iv) trophodynamic indicators; (v) integrated indicators; (vi) selection criteria; (vii) data sets and reviews; and (viii) frameworks for implementing indicators. As part of their work, the task forces reviewed the current status of indicator usage for ecosystem approaches to fisheries, as well as seeking to develop new theory, applying it, and evaluating performance of indicators. The major results of these endeavours formed the core of the presentations at the Paris Symposium.
More than 200 abstracts were submitted; the Programme Committee therefore faced a challenging but difficult task of selection for oral and poster presentation. This overwhelming interest clearly indicated that the timing was perfect for evaluating the role of indicators for an ecosystem approach to fisheries. The same conclusion may be reached from the generous and enthusiastic support the Symposium received from a large number of organizations (see Acknowledgements). PICES in particular supplied logistic support in getting the Symposium organized, handling registration, submission of abstracts, producing the book of abstracts, staffing the Symposium Office during the event, and funding the participation for several scientists working around the North Pacific.
The symposium fits into a series of recent international scientific events to discuss research on marine ecosystems and fisheries management, and to develop this topic further: the Montpellier Symposium on "Ecosystem Effects of Fishing" in 1999 (Gislason et al., 2000), the Reykjavík Conference on "Responsible Fisheries in the Marine Ecosystem" in 2001 (Sinclair and Valdimarsson, 2003), and the 4th World Fisheries Congress on "Reconciling Conservation and Exploitation" in 2004 are important predecessors. We have moved a long way towards an ecosystem approach to fisheries within a relatively short time, and the Symposium contributed to this challenge by addressing two major themes.
Theme 1 discussed how indicators synthesize the structure and functioning of ecosystems in time and space, and in turn how fisheries influence them. It considered how the indicators have been or should be applied to different types of ecosystems or fisheries exploitation, and covered the following topics: (i) environmental indicators that quantify climate change or environmental variability and their ecosystem effects (e.g. regime shifts) as well as the quantification of habitat modification induced by fisheries; (ii) ecological indicators that characterize the functioning and the dynamics of marine exploited ecosystems on the basis of species composition, size distribution, and trophodynamics; (iii) fisheries indicators that quantify the impact of fishing on exploited and unexploited components of ecosystems.
The session presentations outlined a vast array of well-defined indicators for fisheries management, described their properties, evaluated how they can be used at an ecosystem level to describe the impact of fisheries, and also evaluated the relative contribution of environmental and fisheries impacts. Given the number of available, applied indicators, it is also clear that emphasis must be given to methodologies for selecting indicators and evaluating how capable they are of detecting trends in a noisy environment.
Theme 2 addressed the evaluation, implementation, communication, and use of indicators. Quantitative indicators of ecosystem status have many uses, and ecosystems have many properties that are critical to conservation and management. As a consequence, a large number of indicators have already become available within a relatively short time. Evaluating indicators relative to management objectives needs to be achieved by defining appropriate criteria. Several contributions presented methodologies for evaluating and comparing various indicators, as well as methods for elaborating and constructing data sets for evaluation of indicators.
To implement an operational ecosystem approach to fisheries, selected indicators have to be assembled into frameworks within which they can be aggregated and combined. Institutional frameworks may include indicators of the exploitation and state of ecosystems, and indicators relating to social and economic aspects. Contributions showed how such frameworks can facilitate indicator development and implementation. Studies of trade-offs between frameworks that tend to make incremental improvements to conventional methods vs. the more difficult design and implementation of completely new approaches for aggregating indicators were also debated.
Communicating the relevance of indicators among stakeholders is an important aspect of their usefulness, and means for achieving this were addressed. Contributions reviewed how indicators can be communicated efficiently in practical situations. These reviews include aspects of decision-making, and of how ecosystem indicators are currently or may be used.
Recognizing that communication is an important aspect of scientific work, the workshop was organized with only plenary sessions for oral presentations, and with ample time set aside for poster sessions. Approximately three-quarters of the 160 Symposium presentations were displayed as posters, indicating the important role posters play in international symposia. At the Symposium itself, a Poster Session Committee led by Bob O'Boyle evaluated all contributions and selected the following contributions for special recognition in the form of poster awards:
Best Poster prizes were awarded to L. Ciannelli, B. Robson, R. Francis, K. Aydin, and R. Brodeur (Boundaries of open marine ecosystems: an application of ecosystem energetics and foraging theory), to S. Libralato, V. Christensen, and D. Pauly (Identification of keystone species from ecosystem models), and to S. Tudela, M. Coll, and I. Palomera (Developing an operational reference framework for fisheries management based on a two-dimensional indicator on ecosystem impact). In addition, Best Poster Design prizes were awarded to A. Colomb, Y-M. Bozec, E. Chassot, M. Laurans, and D. Gascuel (Using trophic spectra in an ecosystem individual-based simulator: impact of fishing), to K. Hauge, H. Heldal, E. Olsen, and H. Skjoldal (A framework for making qualities of indicators transparent), and to I. Ortiz and R. Francis (Dynamic foodwebs in space). That two of these posters plus several other posters were ultimately accepted for the present volume again emphasizes the relevance of good poster presentations in international symposia.
Some of the findings from the symposium are listed below.
- Defining, selecting, evaluating, and implementing indicators is an achievable task given present knowledge, available data, and existing frameworks.
- Environmental and low-trophic-level indicators (e.g. for plankton) capture environmental change and bottom-up effects in a spatially explicit manner. However, the global effect of environmental change on higher trophic levels in the foodweb is not well captured by most indicators (e.g. regime shifts).
- Top predators or high-trophic-level indicators (e.g. birds, marine mammals) summarize changes in the fish communities, which are most often (but not always) related to exploitation. Top-down effects, such as trophic cascades, that occur in several ecosystems can be quantified using trophodynamic indicators.
- Several trophodynamic indicators are needed to measure the strength of the interactions between the different living components, and of structural ecosystem change resulting from exploitation. Those indicators are sometimes sensitive to the choice of trophic level made for certain species.
- Size-based indicators have received considerable scientific attention and are perceived as promising for characterizing fish community dynamics in a context of overexploitation.
- An ecosystem approach to fisheries (EAF) requires integration of the spatial dynamics of the various components (including fishers). It also requires quantification of the interactions between different components of the ecosystem. Spatial indicators are currently developed in many ecosystems, and are key to understanding the interaction between the different components of the ecosystem and human activities.
- No single indicator (nor single ecosystem model) describes all aspects of ecosystem dynamics; we need a suite of indicators (covering different data, groups, and processes), because indicator performance may differ (with ecosystem, history of exploitation, and other pressures, e.g. pollution).
- Aggregated indicators can provide a quick evaluation of the state of marine ecosystems; they should be used simultaneously with a suite of indicators to understand the mechanisms and processes that are acting.
- Ecosystem-based indicators are conservative in the sense that they only show if the ecosystem is strongly affected, so trends and rapid changes must be acknowledged in and evaluated by management, even if reference points are lacking.
- Interpretation of indicators requires scientific expertise because of potential, often subtle, error and bias in their analysis.
- Considering both target reference points (TRP) and limit reference points (LRP) in the same framework or model represents a promising way to reconcile constraints and objectives when exploiting natural resources. This may be a promising way also to reconcile the principles of conservation and exploitation.
- Several indicators are better used for surveillance than for prediction. Regime shifts, a feature often associated with the north Pacific Ocean, illustrates a situation where surveillance indicators may be useful.
- In an EAF, the objective is not to find the best indicator, but rather a relevant suite of indicators with known properties; developing methodologies for selecting indicators forms an integral part of the process. Guidelines for how to test indicators and develop frameworks for their application are essential.
- Analysis of single-species vs. ecosystem harvest strategies shows that we need to provide explicit protection for those species whose value derives in part from support of other species as well as from harvesting. Harvesting all species at their single-species maximum sustainable yield may lead to ecosystem erosion.
- Reinforce (or start) the process of implementing ecosystem-based indicators (TRP and LRP) and a framework for fisheries worldwide. Pragmatic approaches need to be taken to move towards an EAF. This may be viewed as a stepwise process that needs to integrate scientific results (data, models, indicators) and management expertise in a spatially explicit manner.
- A strong feedback between scientific expertise and management is necessary to ameliorate indicators and their practical use.
The conclusion of the Symposium as expressed through a closing panel discussion is clear: with regards to ecosystem indicators, the science that is needed to make an ecosystem approach to fisheries operational is in place. We hope that these proceedings will serve to show that the science is indeed ready for the challenge, and will become a reference publication for the scientific aspects of using ecosystem indicators as part of an EAF. The next step is to reinforce (or to start) the process of implementing ecosystem-based indicators and a framework for fisheries using a pragmatic, but scientifically sound approach. In this process, scientific information (data, models, indicators) and management expertise (stock assessment) has to be integrated in a new and efficient manner.
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Acknowledgements |
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The conveners thank the Scientific Committee on Oceanic Research (SCOR) and the Intergovernmental Oceanographic Committee (IOC) of UNESCO for organizing and supporting SCOR/IOC Working Group (WG) 119. The 32 WG members drawn from 19 countries produced an impressive array of work during the years of activity leading up to the Paris Symposium, and we are honoured to be associated with their work. The WG and this document are partially supported by the U.S. National Science Foundation under Grant No. 0003700. Organization and the running of the symposium went smoothly, which we attribute to the appreciated efforts of Symposium Manager Elizabeth Gross, Finance Officer, SCOR, and Skip McKinnell, Julia Yazvenko, Christina Chiu, and Alexander Bychkov from PICES. Thanks are due to Mrs Le Conan (IOC) for her help in organizing the Symposium in Paris. Our special gratitude goes to Professor Gotthilf Hempel, for evaluating all the presentations at the Symposium and providing a detailed review summing-up the Symposium achievements; Bob O'Boyle, Alida Bundy, Coleen Moloney, and Dan Ricard, for thoroughly reviewing all posters, selecting best ones, and presenting an overview of the posters as part of the closing session; and the closing session panellists, Poul Degnbol, Serge Garcia, Gotthilf Hempel, Jake Rice, Marie-Joëlle Rochet, Daniel Pauly, and Nico Willemse. All these, plus the many participants, contributed in making this Symposium successful. The Symposium was generously sponsored by SCOR, IOC, IRD (Institut de Recherche pour le Développement), FAO, NOAA, IFB (Institut Français de la Biodiversité), the UBC Sea Around Us Project, South Africa's Department of Environmental Affairs and Tourism, ICES, IFREMER, GLOBEC, and especially PICES. PMC thanks EUR-OCEANS for their support and for promoting the results of the symposium through their Network of Excellence. Finally, we thank ICES and the ICES Journal of Marine Science management for dedicating a special issue of its Journal to the proceedings from the Symposium – this raised the scientific profile of the initiative.
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1 Tel: +1 604 822 5751; fax: +1 604 822 8934.
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Garcia S.M. (2000) The FAO definition of sustainable development and the Code of Conduct for Responsible Fisheries: an analysis of the related principles, criteria and indicators. Marine and Freshwater Research 51:535–541.[CrossRef][Web of Science]
Garcia S.M. and Staples D.J. (2000) Sustainability reference systems and indicators for responsible marine capture fisheries: a review of concepts and elements for a set of guidelines. Marine and Freshwater Research 51:385–426.[CrossRef][Web of Science]
Gislason H., Sinclair M., Sainsbury K., O'Boyle R. (2000) Symposium overview: incorporating ecosystem objectives within fisheries management. ICES Journal of Marine Science 57:468–475.
In Sinclair M. and Valdimarsson G. (Eds.). Responsible Fisheries in the Marine Ecosystem (2003) (FAO, Rome) 426 pp.
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