ECOPATH WITH ECOSIM: A USER’S GUIDE by Villy Christensen, Carl J. Walters and Daniel Pauly October 2000 Edition Fisheries Centre University of British Columbia Vancouver, Canada and International Center for Living Aquatic Resources Management Penang, Malaysia No fish is an island… Christensen, V, C.J. Walters and D. Pauly. 2000. Ecopath with Ecosim: a User’s Guide, October 2000 Edition. Fisheries Centre, University of British Columbia, Vancouver, Canada and ICLARM, Penang, Malaysia. 130 p. 2 TABLE OF CONTENTS 1. ABSTRACT...................................................................................................................................... 7 2. INTRODUCTION ............................................................................................................................. 7 2.1 General conventions........................................................................................................................................8 2.2 How to obtain the Ecopath with Ecosim software...........................................................................................9 2.3 Software support, copyright and liability ........................................................................................................9 2.4 Installing and running Ecopath with Ecosim...................................................................................................9 2.5 Previous versions ............................................................................................................................................9 3. ECOPATH: MASS BALANCE MODELING ................................................................................... 10 3.1 About Ecopath...............................................................................................................................................10 3.2 On modeling..................................................................................................................................................10 3.3 The Ecopath model .......................................................................................................................................12 3.3.1 Mortality for a prey is consumption for a predator........................................................................................12 3.3.2 The energy balance of a box .........................................................................................................................15 3.4 Defining the system.......................................................................................................................................16 4. USING ECOPATH ......................................................................................................................... 17 4.1 Getting help...................................................................................................................................................17 4.2 File handling..................................................................................................................................................17 4.3 Edit menu ......................................................................................................................................................19 4.4 Units..............................................................................................................................................................20 4.5 Group information.........................................................................................................................................20 4.6 Other group manipulations (Edit menu)........................................................................................................22 4.6.1 Insert groups..................................................................................................................................................22 4.6.2 Delete groups ................................................................................................................................................22 4.7 Basic input.....................................................................................................................................................22 4.7.1 On the need for input parameters ..................................................................................................................23 4.7.2 Basic input menu...........................................................................................................................................23 4.7.3 Production.....................................................................................................................................................25 4.7.3.1 Total mortality catch curves..........................................................................................................................26 4.7.3.2 Total mortality from sum of components ......................................................................................................26 4.7.3.3 Total mortality from average length..............................................................................................................26 4.7.3.4 Production from empirical relationships .......................................................................................................26 4.7.4 Consumption .................................................................................................................................................27 4.7.5 Other mortality..............................................................................................................................................28 4.7.6 Alternative input............................................................................................................................................28 4.7.7 Diet composition ...........................................................................................................................................29 4.7.8 Detritus fate...................................................................................................................................................30 4.7.9 Migration.......................................................................................................................................................30 4.7.10 Representing movement of organisms across modeled area boundaries due to migration and ontogenetic habitat shifts ..................................................................................................................................................31 4.7.11 Fishery information and non-market value....................................................................................................32 4.7.12 Growth ..........................................................................................................................................................35 5. ADDRESSING UNCERTAINTY .................................................................................................... 36 5.1 Ecoranger ......................................................................................................................................................36 5.1.1 Labeling probability distributions for Ecoranger ..........................................................................................37 5.1.2 Sampling/Importance resampling..................................................................................................................38 5.2 Pedigree: categorizing data sources ..............................................................................................................39 5.3 Sensitivity......................................................................................................................................................43 6. PARAMETER ESTIMATION, EVALUATION, AND BASIC ANALYSIS......................................... 43 6.1 The estimation procedure..............................................................................................................................44 6.2 Parameter evaluation.....................................................................................................................................44 3 6.2.1 Are the EE’s between 0 and 1? .....................................................................................................................44 6.2.2 Ecotrophic efficiency of detritus ...................................................................................................................45 6.2.3 Are the ‘efficiencies’ possible? .....................................................................................................................45 6.3 Balancing a model.........................................................................................................................................45 6.4 Basic analysis................................................................................................................................................47 6.4.1 Flow to the detritus........................................................................................................................................47 6.4.2 Amounts exported or eaten............................................................................................................................48 6.4.3 Net efficiency................................................................................................................................................48