ISSN 0429-9345 FAO FISHERIES 477 TECHNICAL PAPER 477 Models for an ecosystem approach to fisheries Models for an ecosystem approach to fisheries This report reviews the methods available for assessing the impacts of interactions between species and fisheries and their implications for marine fisheries management. A brief description of the various modelling approaches currently in existence is provided, highlighting in particular features of these models that have general relevance to the field of ecosystem approach to fisheries (EAF). The report concentrates on the currently available models representative of general types such as bionergetic models, predator-prey models and minimally realistic models. Short descriptions are given of model parameters, assumptions and data requirements. Some of the advantages, disadvantages and limitations of each of the approaches in addressing questions pertaining to EAF are discussed. The report concludes with some recommendations for moving forward in the development of multispecies and ecosystem models and for the prudent use of the currently available models as tools for provision of scientific information on fisheries in an ecosystem context. FAO Cover: Illustration by Elda Longo FAO FISHERIES Models for an ecosystem TECHNICAL PAPER approach to fisheries 477 by Éva E. Plagányi University of Cape Town South Africa FOOD AND AGRICULTURE AND ORGANIZATION OF THE UNITED NATIONS Rome, 2007 The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these have been endorsed or recommended by the Food and Agriculture Organization of the United Nations in preference to others of a similar nature that are not mentioned. The views expressed in this publication are those of the author(s) and do not necessarily reflect the views of the Food and Agriculture Organization of the United Nations. ISBN 978-92-5-105734-6 All rights reserved. Reproduction and dissemination of material in this information product for educational or other non-commercial purposes are authorized without any prior written permission from the copyright holders provided the source is fully acknowledged. Reproduction of material in this information product for resale or other commercial purposes is prohibited without written permission of the copyright holders. Applications for such permission should be addressed to: Chief Electronic Publishing Policy and Support Branch Communication Division FAO Viale delle Terme di Caracalla, 00153 Rome, Italy or by e-mail to: [email protected] © FAO 2007 iii Preparation of this document The increased awareness of the importance of taking into account interactions among fishery resources and the ecosystem in fisheries management has prompted the need to improve the knowledge base on how ecosystems function including how they are impacted by marine capture fisheries. Over time this has led to the development of different approaches for the modelling of ecological interactions in marine ecosystems exploited by fisheries. This paper reviews the models available for assessing the impacts of ecological (indirect) direct interactions between species and fisheries and the implications these have for fisheries management. As this is a broad and rapidly-evolving issue, the report provides an overview of the main types of modelling approaches rather than detail each aspect of the models. Moreover, it includes a critical analysis of the advantages, disadvantages and limitations of each modelling approach for representing ecosystem dynamics and interactions between ecosystems and human activities, including in particular, fisheries. This report is expected to serve as a useful reference for fisheries scientists and managers seeking an overall view of the relative merits of the main types of modelling approaches available for fisheries assessment in an ecosystem context. The report was funded by the FAO project “Capacity Building for an Ecosystem Approach to Fisheries” (GCP/INT/920/JPN). iv Abstract This report reviews the methods available for assessing the impacts of interactions between species and fisheries and their implications for marine fisheries management. A brief description of the various modelling approaches currently in existence is provided, highlighting in particular features of these models which have general relevance to the field of the ecosystem approach to fisheries (EAF). The report concentrates on the currently available models representative of general types such as bionergetic models, predator-prey models and minimally realistic models. Short descriptions are given of model parameters, assumptions and data requirements. Some of the advantages, disadvantages and limitations of each of the approaches in addressing questions pertaining to EAF are discussed. The report concludes with some recommendations for moving forward in the development of multi-species and ecosystem models and for the prudent use of the currently available models as tools for provision of scientific information on fisheries in an ecosystem context. Plagányi, É.E. Models for an ecosystem approach to fisheries. FAO Fisheries Technical Paper. No. 477. Rome, FAO. 2007. 108p. v Contents Preparation of this document iii Abstract iv List of tables and figures vii Acknowledgements viii Abbreviation and acronyms ix Executive summary xi 1. Introduction 1 2. Review of current modelling approaches 3 2.1 Whole ecosystem and dynamic system models 10 2.1.1 ECOPATH with ECOSIM (EwE) 10 2.1.2 Biogeochemical models 14 2.1.3 ERSEM and SSEM 14 2.1.4 IGBEM, BM2 and ATLANTIS 15 2.1.5 SEPODYM/SEAPODYM 18 2.2 Minimum realistic models 20 2.2.1 The original MRM 21 2.2.2 ESAM (Extended Single-species Assessment Models) 24 2.2.3 MSVPA approach 25 2.2.4 MULTSPEC, BORMICON and GADGET 27 2.2.5 Multi-species statistical models 29 2.3 Individual-based models 30 2.3.1 OSMOSE 30 2.3.2 INVITRO 32 2.4 Bioenergetic models 33 2.5 CCAMLR model development 34 2.5.1 Predator-prey models 34 2.5.2 KPFM (Krill-Predator-Fishery Model) 35 2.5.3 EPOC model (Ecosystem Productivity Ocean Climate Model) 36 2.5.4 Mori and Butterworth multi-species model 36 2.5.5 SMOM (Spatial Multi-species Operating Model) 37 3. Comparison of models 39 3.1 Level of complexity and realism 39 3.2 Functional response formulations 39 3.3 Whole ecosystem models vs MRMs 42 3.4 Advantages, disadvantages and limitations 43 4. Potential of tools to address multi-species research questions 45 5. Roles for models in operational management procedure development 49 6. Moving models forward – future developments 51 7. Prudent use of the precautionary principle 53 8. Pointers from previous studies and workshops 55 8.1 Modelling interactions between marine mammals and fisheries 55 8.2 Areas of focus 57 8.3 General guidelines 57 8.4 Ecosystem-based management strategies 58 8.5 Practical steps to implementing an EAF 58 vi 9. Summary of model comparisons and recommendations 61 10. References 65 Appendix 81 Tables A 1a-d Model comparison 83 Tables A 2a-d Model comparison 95 Tables A 3a-d Summary of advantages, disadvantages and limitations of each method 103 Tables A 4 Model comparison to address EBFM questions 107 vii List of tables and figures Table 1 List of model acronyms 5 Table 2 Categorization of models according to model units, feeding relationships assumed 7 Figure 1 Flowchart summarizing the classification of various models 4 Figure 2 Schematic summary showing the trophic level focus of different multi-species models 8 Figure 3 Schematic summarizing the typical (current) number of modelled species or model compartments for selected models 9 Figure 4 Schematic comparing consumption rate formulations for two contrasted cases 40 viii Acknowledgements This study was funded by the Fisheries and Aquaculture Department of the Food and Agriculture Organization of the United Nations (FAO), Rome, with logistical support provided by the University of Cape Town, South Africa. This report benefited enormously from frequent discussions and inputs from Prof. Doug Butterworth at the University of Cape Town. Dr Beth Fulton is thanked for having been the most thorough critic and contributor, and she also wrote the section on INVITRO. The other reviewers, Dr Villy Christensen, Dr Mariano Koen-Alonso and Prof. Gunnar Stefannson and the editors, Drs Kevern Cochrane and Marcelo Vasconcellos, also provided useful suggestions and additions leading to a greatly improved manuscript. I am grateful for the assistance of Drs Kerim Aydin, Andrew Constable, Patrick Lehodey, John Tschirhart and George Watters, who provided me with necessary material and answers to queries. Sections of this manuscript are drawn from the author’s PhD thesis and support from the Marine Resource Assessment and Management Group (MARAM) within the Department of Mathematics and Applied Mathematics at UCT is gratefully acknowledged. ix Abbreviations and acronyms (See also the list of model acronyms in Table 1.) ABM Agent-Based Models ADMB AD Model Builder AGGMULT Simplified version of MULTSPEC with only the age structure retained ASPM Age-Structured Production Model BENEFIT Benguela Environment Fisheries Interaction