A brief introduction to ecosystem modeling using Ecopath with Ecosim Daniel Pauly and Villy...
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A brief introduction to ecosystem modeling using Ecopath with EcosimA brief introduction to ecosystem modeling using Ecopath with Ecosim
Daniel Pauly and Villy Christensen
Fisheries Centre,
University of British Columbia, Vancouver, Canada
United Nations University Fisheries Training Programme
Institute of Marine Science,
December 17, 2002
Reykjavik, Iceland
• The Ecopath with Ecosim software package includes mass-balance (Ecopath), time-dynamic (Ecosim) and spatial simulation (Ecospace) models, and can be used to: – Evaluate biomasses and fluxes;
– Address ecological questions;
– Evaluate ecosystem effects of fishing;
– Evaluate effects of environmental changes.
– Explore management policy options;
– Evaluate impact and placement of marine protected areas;
– Quantify bioaccumulation, and more.
• The Ecopath with Ecosim software package includes mass-balance (Ecopath), time-dynamic (Ecosim) and spatial simulation (Ecospace) models, and can be used to: – Evaluate biomasses and fluxes;
– Address ecological questions;
– Evaluate ecosystem effects of fishing;
– Evaluate effects of environmental changes.
– Explore management policy options;
– Evaluate impact and placement of marine protected areas;
– Quantify bioaccumulation, and more.
The software: Ecopath with Ecosim The software: Ecopath with Ecosim
Ecopath Master Equation (I)Ecopath Master Equation (I)
Production= predation
+ fishery
+ biomass accumulation
+ net migration
+ other mortality
Production= predation
+ fishery
+ biomass accumulation
+ net migration
+ other mortality
Ecopath Master Equation (II)Ecopath Master Equation (II)
Consumption = production
+ unassimilated food
+ respiration
Consumption = production
+ unassimilated food
+ respiration
Other mortalityOther mortality
HarvestHarvest
ConsumptionConsumption
PredationPredation
PredationPredation
PredationPredation
Predation
Other mortality
Other mortality
Other mortality
PredationPredation Respi- rationRespi- ration
HarvestHarvest
Unassi-milated food
Unassi-milated food
Respi- rationRespi- ration
Unassi-milated food
Unassi-milated food
Unassi-milated food
Unassi-milated food
Respi- rationRespi- ration
Mass balance: cutting the pieMass balance: cutting the pie
Ecopath Master Equation (I): How it is actually implementedEcopath Master Equation (I):
How it is actually implemented
Bi * P/Bi * EEi = Catchi
+ j Bj Q/Bj DCji
+ Net migrationi
+ Biomass accumulationi
• Most common input: B, P/B, Q/B, Catch, Net migration (NM), biomass
accumulation rate (BA), and diet compositions (DC).
• B, P/B, Q/B, EE, NM or BA is estimated by Ecopath.
• DC’s are usually modified as required to ensure that EE’s are 1.
Bi * P/Bi * EEi = Catchi
+ j Bj Q/Bj DCji
+ Net migrationi
+ Biomass accumulationi
• Most common input: B, P/B, Q/B, Catch, Net migration (NM), biomass
accumulation rate (BA), and diet compositions (DC).
• B, P/B, Q/B, EE, NM or BA is estimated by Ecopath.
• DC’s are usually modified as required to ensure that EE’s are 1.
Key data requirements for EcopathKey data requirements for Ecopath
• Biomass (t·km-2)• Production / Biomass (t·km-2 ·year-1)• Consumption / Biomass (t·km-2 ·year-1)• Ecotrophic efficiency (proportion)• Diets (proportion)• Catches (by fleet) (t·km-2 ·year-1)• Growth parameters for PSD & Ecosim
It is possible to use ranges for all parameters (see Ecoranger).
• Biomass (t·km-2)• Production / Biomass (t·km-2 ·year-1)• Consumption / Biomass (t·km-2 ·year-1)• Ecotrophic efficiency (proportion)• Diets (proportion)• Catches (by fleet) (t·km-2 ·year-1)• Growth parameters for PSD & Ecosim
It is possible to use ranges for all parameters (see Ecoranger).
• Pedigree for input data and overall index of model quality;
• Sensitivity analysis for documenting the effect of inputs on estimated parameters;
• Ecoranger routine for explicit consideration, in a Bayesian context, of the uncertainty inherent in all input;
• Closed-loop policy simulations for evaluating the effect of uncertain inputs on the management process.
• Pedigree for input data and overall index of model quality;
• Sensitivity analysis for documenting the effect of inputs on estimated parameters;
• Ecoranger routine for explicit consideration, in a Bayesian context, of the uncertainty inherent in all input;
• Closed-loop policy simulations for evaluating the effect of uncertain inputs on the management process.
Addressing uncertainty:Addressing uncertainty:
EcorangerEcoranger• Semi-Bayesian parameter estimation for Ecopath• Semi-Bayesian parameter estimation for Ecopath
Input rangesInput
ranges
Acceptable inputs
Acceptable inputs
Resampling (Sampling Importance Resampling)
Resampling (Sampling Importance Resampling)
Selection of possible models
Selection of possible models
Selection of ‘best’ modelSelection of ‘best’ model
‘Priors’‘Priors’
Mass balance & physiological constraints
Mass balance & physiological constraints
‘Posteriors’‘Posteriors’
10,000 x
10,000 x
Accepted inputsAccepted inputs OutputsOutputs
EwE can incorporate all functional EwE can incorporate all functional groups (100+) and all fisheries (20+)groups (100+) and all fisheries (20+)
• Ecopath routines for entry of key data on the biology and exploitation of ecosystem groups, and for establishing mass-balance in semi-automatic fashion;
• FishBase bridge (www.fishbase.org) established for input data;
• Econet: network analysis for study of ecosystem form and functioning, incl. particle size distribution (PSD);
• Ecowrite routine for documentation of data and assumptions used when constructing and validating models. Incorporates reference database;
• Ecoempire module with empirical relationships, etc.
• Ecopath routines for entry of key data on the biology and exploitation of ecosystem groups, and for establishing mass-balance in semi-automatic fashion;
• FishBase bridge (www.fishbase.org) established for input data;
• Econet: network analysis for study of ecosystem form and functioning, incl. particle size distribution (PSD);
• Ecowrite routine for documentation of data and assumptions used when constructing and validating models. Incorporates reference database;
• Ecoempire module with empirical relationships, etc.
Key Ecopath routinesKey Ecopath routines
• Ecosim builds on Ecopath
• First step is to construct an Ecopath model using the constraints offered by mass-balance and thermodynamics to ensure that parameters are compatible and realistic
• Ecosim builds on Ecopath
• First step is to construct an Ecopath model using the constraints offered by mass-balance and thermodynamics to ensure that parameters are compatible and realistic
To get started with Ecosim
Unavailable prey B-VUnavailable prey B-V
Available prey VAvailable prey V
B = Total prey biomass;V = Vulnerable prey biomass;v = Behavioral exchange rate;P = Total predator biomass;a = Predator rate of search.
B = Total prey biomass;V = Vulnerable prey biomass;v = Behavioral exchange rate;P = Total predator biomass;a = Predator rate of search.
v(B-V)v(B-V)
vVvV
Fast equilibration
between B-V and V
implies
V=vB/(2v+aP)
Fast equilibration
between B-V and V
implies
V=vB/(2v+aP)
PredatorP
PredatorP
aVPaVP
Representing limited prey vulnerability in EcosimRepresenting limited prey vulnerability in Ecosim
Data requirements for EcosimData requirements for Ecosim
1. Flow-control: (top-down to bottom-up);– Incorporates five methods for evaluating this
sensitive parameter (sensitivity analysis, time series fitting, two-model comparison, Bunfished/B0 , Fmax/M);
• Feeding time adjustment rate;• Predator effect on feeding time;
• Ecological interpretation of all parameters;• Monte-Carlo routine linking to Ecoranger.
1. Flow-control: (top-down to bottom-up);– Incorporates five methods for evaluating this
sensitive parameter (sensitivity analysis, time series fitting, two-model comparison, Bunfished/B0 , Fmax/M);
• Feeding time adjustment rate;• Predator effect on feeding time;
• Ecological interpretation of all parameters;• Monte-Carlo routine linking to Ecoranger.
• Ontogenetic changes (juvenile/adult life history, variable stage, growth/reproduction allocation strategy, seasonal egg production);
• Food related behavior changes (diets, feeding time, handling time)
• Trophic effects (predator/prey dynamics); • Mediation effects, (e.g., tuna/small pelagics/birds);• Forcing functions (seasonal/long-term; environmental,
productivity, …) ;• Fisheries effects (bioeconomic model);• Density-dependent catchability; …
• Ontogenetic changes (juvenile/adult life history, variable stage, growth/reproduction allocation strategy, seasonal egg production);
• Food related behavior changes (diets, feeding time, handling time)
• Trophic effects (predator/prey dynamics); • Mediation effects, (e.g., tuna/small pelagics/birds);• Forcing functions (seasonal/long-term; environmental,
productivity, …) ;• Fisheries effects (bioeconomic model);• Density-dependent catchability; …
Ecosim incorporates:Ecosim incorporates:
Ecosim predicts ecosystem effects of changes in fishing effort
Ecosim predicts ecosystem effects of changes in fishing effort
Fishing effort over time
Biomass/original biomass
• Ecosim can incorporate (analyses indeed benefit from) time series data on:– Relative or absolute biomasses;
– Mortality rates, F, Z, catches;
– Effort data;
– Forcing factors (notably primary productivity)
• Incorporates goodness of fit measure (weighted SS)• Incorporates anomaly fitting (productivity, recruitment);• Sensitivity of the crucial Ecosim parameters can be
evaluated, and the model fitted to data;• Ecosim thus incorporates much of the information
commonly obtained through single species assessment.
• Ecosim can incorporate (analyses indeed benefit from) time series data on:– Relative or absolute biomasses;
– Mortality rates, F, Z, catches;
– Effort data;
– Forcing factors (notably primary productivity)
• Incorporates goodness of fit measure (weighted SS)• Incorporates anomaly fitting (productivity, recruitment);• Sensitivity of the crucial Ecosim parameters can be
evaluated, and the model fitted to data;• Ecosim thus incorporates much of the information
commonly obtained through single species assessment.
Building on the past: time series
North Sea time series from MSVPA (•) compared to Ecosim (line)
North Sea time series from MSVPA (•) compared to Ecosim (line)
Ecosim inter-face for evalua-tingtrends over time
Ecosim inter-face for evalua-tingtrends over time
Ecospace is a spatial simulation tool for prediction of spatial patternsand impact of protected areas
Ecospace is a spatial simulation tool for prediction of spatial patternsand impact of protected areas
EcospaceEcospace
• Ecospace builds on Ecopath and Ecosim
• Ecospace builds on Ecopath and Ecosim
To get started with EcospaceTo get started with Ecospace
• Use Ecosim to check model behavior
• Build an Ecospace scenario (map, habitats, …)
• Use Ecosim to check model behavior
• Build an Ecospace scenario (map, habitats, …)
• Replicates Ecosim dynamics over spatial grid of ‘homogeneous’ cells;
• Links cells through dispersal of organisms, and fishing effort movement/allocation;
• Incorporates an advection model.
• Accounts for spatial variation in productivity and cost of fishing;
• Represents habitat ‘preferences’ by differential dispersal, feeding and predation rates;
• Replicates Ecosim dynamics over spatial grid of ‘homogeneous’ cells;
• Links cells through dispersal of organisms, and fishing effort movement/allocation;
• Incorporates an advection model.
• Accounts for spatial variation in productivity and cost of fishing;
• Represents habitat ‘preferences’ by differential dispersal, feeding and predation rates;
Ecospace: a spatial, meso-scale version of Ecosim
Ecospace: a spatial, meso-scale version of Ecosim
BijBij
Equal m’s (symmetrical mixing,except at shores, toward preferred habitats)Equal m’s (symmetrical mixing,except at shores, toward preferred habitats)
mi,j+1Bijmi,j+1Bij
Ecospace dispersal linkageEcospace dispersal linkage
Ecospace: basemapEcospace: basemap
Ecospace can consider advectionEcospace can consider advection
Ecospace predicts spatial distributions and impact of protected areas & habitat changesEcospace predicts spatial distributions and
impact of protected areas & habitat changes
Ecoseed• A routine of Ecospace
for optimal location and sizing of MPAs;
• Ecoseed evaluates one seed cell for each run;
• The ‘best’ seed cell is selected as an MPA cell;
• Adjacent cells become seed cells;
• Process continues until all cells are MPAs.
• A routine of Ecospace for optimal location and sizing of MPAs;
• Ecoseed evaluates one seed cell for each run;
• The ‘best’ seed cell is selected as an MPA cell;
• Adjacent cells become seed cells;
• Process continues until all cells are MPAs.
Non-market value
Relative rent
% MPA
0.0
0.5
1.0
1.5
2.0
2.5
0 10 20 30 40 50 60 70 80
-0.6-0.5-0.4-0.3-0.2-0.10.00.10.2
Existence value
Rent of fishery
Ecoseed: results from test model
Documentation of methodsDocumentation of methods• Ecopath: Ecol. Modelling (1992) 61: 169-185;
• Ecosim: Fish Biol. Fisheries (1997) 7:139-172;
• Ecosim: Ecosystems (2000) 3: 70-83;
• Ecospace: Ecosystems (1999) 2: 539-554
• EwE overview: ICES J. of Marine Science (2000)
• ‘EwE Methods, capabilities and limitations:’ Fisheries Centre Research Report (2001) and Ecol. Modeling (in press)
• ‘EwE: A User’s Guide’ (2000);
• Ecopath –Autobalance routine: Ecol. Modelling (in press);
• Also EwE incorporates complete context-sensitive help.
• Ecopath: Ecol. Modelling (1992) 61: 169-185;
• Ecosim: Fish Biol. Fisheries (1997) 7:139-172;
• Ecosim: Ecosystems (2000) 3: 70-83;
• Ecospace: Ecosystems (1999) 2: 539-554
• EwE overview: ICES J. of Marine Science (2000)
• ‘EwE Methods, capabilities and limitations:’ Fisheries Centre Research Report (2001) and Ecol. Modeling (in press)
• ‘EwE: A User’s Guide’ (2000);
• Ecopath –Autobalance routine: Ecol. Modelling (in press);
• Also EwE incorporates complete context-sensitive help.
DisseminationDissemination
• Distributed free-of-charge• 2000+ users in some 150
countries (half in the tropics);
• Present rate: 2 new users a day;
• 20+ international workshops/training courses;
• 150+ published models;• 50+ models known to be in
preparation;
• Distributed free-of-charge• 2000+ users in some 150
countries (half in the tropics);
• Present rate: 2 new users a day;
• 20+ international workshops/training courses;
• 150+ published models;• 50+ models known to be in
preparation;
• 90 peer reviewed papers, incl. some high profile;
• 40 other publications;
• 12+ universities offering courses;
• 13 PhD’s completed;
• 10 MSc’s completed;
• On average 100 visitors per day to www.ecopath.org.
• 90 peer reviewed papers, incl. some high profile;
• 40 other publications;
• 12+ universities offering courses;
• 13 PhD’s completed;
• 10 MSc’s completed;
• On average 100 visitors per day to www.ecopath.org.
Models are not like religion Models are not like religion
and you don’t have to believe them.
Thank you.
and you don’t have to believe them.
Thank you.
you can have more than one…you can have more than one…