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…