Review of major ecosystem model

classes

Éva PlagányiDept. of Maths & Applied Maths, University of Cape

Town

Reference: Plagányi 2007. Models for an Ecosystem Approach to Fisheries. FAO Fisheries Technical paper 477

Report of Modelling Ecosystem Interactions for Informing an Ecosystem Approach to Fisheries: Best Practices in Ecosystem Modeling, Tivoli, July 3-6, 2007

National Ecosystem Modeling Workshop (NEMoW)August 29-31 2007, NMFS Santa Cruz

With thanks to Doug Butterworth and MARAM

OUTLINE OF TALK

Ecosystem Model Objectives Ecosystem Model Types Questions for EAF* Modelling Ecosystem Model Classification Considerations in Model Building

and the Best Practice Approach Role of Management Procedures Data requirements Conclusions

Biological interactions described

Predator prey feedback

Handles the environment and lower trophic levels

Technical interaction models MSYPRMurawski 1984

Predators added to single-species models e.g. SEASTARGulland 1983; Livingston and Methot1998; Hollowed et al. 2000; Plagányi2004; Tjelmeland and Lindstrøm 2005

No

No

Yes

Yes

Handles age/size structureHandles age

structure

No Yes

Aggregate system models e.g. EwE, SKEBUB, SSEM

Spatial dynamic systems models e.g. ATLANTIS, ERSEM, SEAPODYM

Multispecies Production Models e.g. Horbowy 2005

YesNo

Dynamic multi-species models BORMICON, GADGET, MRMs,MSVPA& MSFOR, MSM, MULTSPEC, OSMOSE

No

Handles spatial structure

Yes

No

Dynamic systems models e.g. some recent EwEapplications

YesHandles spatial structureNo

Spatial aggregate systems models e.g. ECOSPACE

Yes

Ecosystem Models and Management Advice

• Conceptual/understanding: of the structure, functioning and interactions of the ecosystem, or sub-system, under consideration. May not be used explicitly in decision-making or scientific advice but forms the underlying context for any detailed management planning and decision-making

• Strategic decisions: linked to policy goals and are generally long-range, broadly-based and inherently adaptable

• Tactical decisions: aimed at the short-term (e.g. next 3-5 years), linked to an operational objective and in the form of a rigid set of instructions e.g. tactical decision to change quota

Ecosystem models generally intended to complement not replace single-species assessment models

OUTLINE OF TALK

Ecosystem Model Objectives Ecosystem Model Types Questions for EAF* Modelling Ecosystem Model Classification Considerations in Model Building

and the Best Practice Approach Role of Management Procedures Data requirements Conclusions

Model typesI. Whole ecosystem models: models that

attempt to take into account all trophic levels in the ecosystem

II. Minimum Realistic Models (MRM): limited number of species most likely to have important interactions with a target species of interest

III. Dynamic System Models (Biophysical): represent both bottom-up (physical) and top-down (biological) forces interacting in an ecosystem

IV. Extensions of single-species assessment models (ESAM): expand on current single-species assessment models taking only a few additional inter-specific interactions into account

Ecosystem ModelsI. Whole ecosystem models MODEL NAMEEwE and ECOSPACE

Ecopath with Ecosim

ATLANTIS ATLANTIS

IGBEM Integrated Generic Bay Ecosystem Model

INVITRO INVITRO

GEEM General Equilibrium Ecosystem Model

Ecosystem Models- plankton focus (NPZ-fish) MODEL NAMEERSEM II European

Regional Seas Ecosystem Model

SSEM Shallow Seas Ecological Model

Ecosystem ModelsII. Minimum Realistic Models

MODEL NAMEMRM Minimally Realistic

Models

Ecosystem ModelsII. Minimum Realistic Models MODEL NAMEGADGET Globally applicable

Area Disaggregated General Ecosystem Toolbox

BORMICON BOReal Migration and CONsumption model

MULTSPEC Multi-species model for the Barents SeaSimplified version is AGGMULT which is also connected to a ECONMULT - a model describing the economies of the fishing fleet

Ecosystem ModelsII. Minimum Realistic Models cont.MODEL NAMEMSVPA and MSFOR(and derivatives)

Multi-species Virtual Population Analysis; Multi-species Forecasting Model

MSM Multi-species Statistical Model

IBM Individual-Based Models

Bioenergetic/allometric

e.g. Koen-Alonso & Yodzis 2005

Ecosystem Models- Antarctic ModelsMODEL NAMEFOOSA Previously KPFM

(Krill- Predator-Fishery Model)

SMOM Spatial Multi-species Operating Model

EPOC Ecosystem Productivity Ocean Climate model

Other CCAMLR models e.g. Mori & Butterworth 2005, 2006

Ecosystem ModelsIII. Dynamic System ModelsMODEL NAMESEAPODYM Spatial Ecosystem

and Population Dynamics Model

OSMOSE Object-oriented Simulator of Marine ecOSystem Exploitation

SystMod System Model for the Norwegian and Barents Sea

Ecosystem ModelsIV. Extended Single-Species ModelsMODEL NAMEESAM Extended Single-Species

Models e.g. Livingston and Methot 1998; Hollowed et al. 2000; Tjelmeland and Lindstrøm 2005

SEASTAR Stock Estimation with Adjustable Survey observation model and TAg-Return dataTarget

SpeciesPredator

Catch Catch

OUTLINE OF TALK

Ecosystem Model Objectives Ecosystem Model Types Questions for EAF* Modelling Ecosystem Model Classification Considerations in Model Building

and the Best Practice Approach Role of Management Procedures Data requirements Conclusions

Questions for EAF Modelling Issues pertaining to the management of target and

related species:

• Impact of a target species on other species in the ecosystem?

• Limitations of single-species-based assessment

• Targeting of relatively unexploited species • What are the impacts of retained by-catch?• What is the effect on top predators of

removing the predators themselves and their prey?

• What is the extent of competition between fisheries and species of concern such as marine mammals, turtles, seabirds and sharks.

Questions for EAF Modelling Issues pertaining to species:

• What are the impacts of fishing on biodiversity?

• What are the impacts of commencing fishing on a previously unexploited species about which little is known.

• Effects of the introduction of non-native species.

• What are the impacts of non-retained by-catch?

Questions for EAF Modelling Environmental and unintentional impacts on

ecosystems

• Effects of physical/environmental factors on the resources on which fisheries depend.

• Changes in ecosystem state, e.g. regime shift, change to a less productive/less desirable state.

• Anthropogenic effects.• Effects of habitat modification e.g.

trawling damaging benthic habitats

1 2 3 4 5 6 7 8 9 10

RESEARCH QUESTION/

MODEL

Ecopath with Ecosim and ECOSPACE IGBEM ATLANTIS INVITRO ERSEM II SSEM KPFM*

MRM e.g. Punt and Butterworth (1995)

MSVPA and MSFOR MSM

1a. Understanding - subset of ecosystem

1b. Understanding - complete ecosystem

2. Impact of target species

3. Effect of top predators

4. Competition: marine mammals - fisheries

5. Rebuilding depleted fish stocks

6. Biases in single-species assessment

7. Ways to distribute fishing effort among fisheries

8. Under-exploited species

9. Change in ecosystem state

10. Spatial concentration of fishing

11. Environmental/physical effects

12. Effects of habitat modification

13. Effects of by-catch

14. Introduction of non-native species* Still being developed

11 12 13 14 15 16 17 18 19 20

MULTSPEC GADGET

Bioenergetic/allometric models OSMOSE SEAPODYM

CCAMLR models EPOC* SMOM* ESAM SEASTAR

1a. Understanding - subset of ecosystem

1b. Understanding - complete ecosystem

2. Impact of target species

3. Effect of top predators

4. Competition: marine mammals - fisheries

5. Rebuilding depleted fish stocks

6. Biases in single-species assessment

7. Ways to distribute fishing effort among fisheries

8. Under-exploited species

9. Change in ecosystem state

10. Spatial concentration of fishing

11. Environmental/physical effects

12. Effects of habitat modification

13. Effects of by-catch

14. Introduction of non-native species* Still being developed

OUTLINE OF TALK

Ecosystem Model Objectives Ecosystem Model Types Questions for EAF* Modelling Ecosystem Model Classification Considerations in Model Building

and the Best Practice Approach Role of Management Procedures Data requirements Conclusions

Pg. 4

NO

EN

VIR

ON

ME

NT

ENVIRONMENT

AGE STRUCTUREAGE STRUCTURE

Biological interactions described

Predator prey feedback

Handles the environment and lower trophic levels

Technical interaction models MSYPRMurawski 1984

Predators added to single-species models e.g. SEASTARGulland 1983; Livingston and Methot 1998; Hollowed et al. 2000; Plagányi 2004; Tjelmeland and Lindstrøm 2005

No

No

Yes

Yes

Handles age/size structureHandles age

structure

No Yes

Aggregate system models e.g. EwE, SKEBUB, SSEM

Spatial dynamic systems models e.g. ATLANTIS, ERSEM, SEAPODYM

Multispecies Production Models e.g. Horbowy 2005

YesNo

Dynamic multi-species models BORMICON, GADGET, MRMs, MSVPA& MSFOR, MSM, MULTSPEC, OSMOSE

No

Handles spatial structure

Yes

No

Dynamic systems models e.g. some recent EwE applications S

PA

TIA

L S

TR

UC

TU

REYes

Handles spatial structureNo

Spatial aggregate systems models e.g. ECOSPACE

Yes

Ew

E

NO

. O

F S

PE

CIE

S /

CO

MP

ON

EN

TS

30 +

20

10

5

3

2

AT

LAN

TIS

ER

SE

M,

INV

ITR

O,

OS

MO

SE

GA

DG

ET

BO

RM

ICO

N,

MS

VP

A,

MU

LT

SP

EC

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MS

M,

SE

AP

OD

YM

ES

AM

, M

RM

, S

EA

ST

AR

, B

ioe

ne

r -

ge

tic t

ype

EwE, ATLANTIS, INVITRO

External forcing

Phytoplankton, detritus

Zooplankton, filter-feeders

Clupeoids, demersals etc

Marine mammals, sharks etc

TR

OP

HIC

LE

VE

L

ERSEM SSEM

MRM, MSVPA, GADGET, SEASTAR, SEAPODYM, IBM, MSM, Bioenergetic

OS

MO

SE

OUTLINE OF TALK

Ecosystem Model Objectives Ecosystem Model Types Questions for EAF* Modelling Ecosystem Model Classification Considerations in Model Building

and the Best Practice Approach Role of Management Procedures Data requirements Conclusions

Strategical Model Considerations Strategical Model Considerations and the Best Practice Approachand the Best Practice Approach

(based on report from the July 2007 FAO Workshop)(based on report from the July 2007 FAO Workshop)

Consideration in Model Development

Best practice approach : ‘ideal’ practices, i.e. considerations when developing models. Not anticipated that these practices are always achievable or required.

Setting up a model

How many species or groups?

Aggregate based on shared characteristics of the species and omit the least important to keep web tractable

Include age, size or stage structure of the species of interest?

Include if there are major shifts over the course of the life history

Modelling predator-prey interactions:

How much detail in representing predator-prey interactions?

Represent as bi-directional unless it can be motivated sufficiently strongly that it is adequate to include a one-way interaction only in which the predator ration is fixed and changes in prey abundance have no effect on predator populations

Which functional response?

Test sensitivity and robustness to alternative functional relationships

PREY DENSITY

PR

EY

KIL

LED

PE

R P

RE

DA

TO

R P

ER

UN

IT T

IME

a) Type I

b) Type II

c) Type III

Predator abundance Bj

To

tal c

on

sum

ptio

n r

ate

Qij

(fo

r fix

ed

pre

y a

bu

nd

an

ce B

i)

Bj (Input)

Default assumption is that thisis the present (input) situation

limit

limit/2

EwE Foraging arena

Spatial considerations Spatial considerations Best Practice ApproachBest Practice Approach

Include spatial structure?

Include where there are major shifts in the location of the species of interest over the course of its life history

Include seasonal and temporal structure?

Where there are large differences in the seasonal dynamics in species movement or production

Defining boundary conditions

Basing boundaries on biological rather than anthropogenic considerations such as national boundaries

Is fishery harvesting more than one stock of a particular species?

Model needs to distinguish such different stocks when the harvesting practice is such as might impact these stocks to different extents; this will necessitate spatially structured models

Distinguish different fleets?

If for the same mass of catch, they make substantially different impacts on target and bycatch species or on the habitat

Model componentsModel components Best Practice ApproachBest Practice Approach

Explicitly represent primary productivity and nutrient cycling

May only be necessary when bottom-up forces or lower trophic levels are of key concern. Can be highly informative for some strategic modelling exercises.

Include environmental forcing?

Only if it is an absolute requirement for capturing system dynamics. When it is included there must be some means of generating future forcing for use in predictions and closed loop simulations.

Model Model componentscomponents

Best Practice ApproachBest Practice Approach

How to model recruitment?

Recruitment may be included either as an emergent property or as a derived relationship Likely important for tactical and risk analyses, but not strict requirement for strategic models.

Mainly emergent recruitment

Mainly derived property

e.g. EwE, Atlantis, OSMOSE, GADGET

e.g. MSVPA, SEAPODYM, MSM

Model componentsModel components Best Practice ApproachBest Practice Approach

How to model movement?

Testing sensitivity to a range of movement hypotheses. Parameterising movement matrices by fitting to these data. Decision rules check if resultant changes in distribution are sensible

EXAMPLES:

OSMOSE: Spatially explicit with fish schools moving to areas with highest potential prey biomass

GADGET: migration matrices specifying movement between areas; can parameterise by fitting to data

SEAPODYM: Movement model linked to habitat quality

External forcingExternal forcing Best Practice ApproachBest Practice Approach

Other process error considerations

Other process error, arising from natural variation in model parameters, needs to be included when variation contributes substantially to uncertainty

Other anthropogenic forcing?

Their influence on shallow coastal and estuarine systems should be considered in conceptual models ; should be empirically included

Alternative stable states?

Strategic models in particular need to ensure forecasting the consequences of environmental change…

Explicitly consider fleet dynamics?

Important to consider if substantial changes to the spatial distribution of fishing may result from, for example, the declaration of an MPA.

Technical and non-Technical and non-trophic:trophic:

Best Practice ApproachBest Practice Approach

Technical interactions(e.g. multi-stock fisheries; by-catch)

If the bycaught species are themselves also subject to management, including stock rebuilding, or if the model aims to inform the level of bycatch of a threatened species.

Non-trophic interactions(e.g. habitat dependency and habitat mediated interactions and processes)

If a critical determinant of the dynamic of interest (e.g. biomass or abundance of a target group), or if management could be based around this interaction

Dealing with Dealing with uncertaintyuncertainty

Best Practice ApproachBest Practice Approach

Should the model be fit to data?

Fitting to data is best practice, and this requires careful specification of likelihoods.

Taking account of parameter uncertainty

Include clear statements about uncertainties in model parameters; Bayesian methods and bootstrapping in ESAM and MRMs; …..

Model structure uncertainty

Identify alternative qualitative hypotheses for all of the processes considered likely to have an important impact on model outputs

What features to include in closed loop simulations?

Evaluation of feedback control harvest strategies should involve simulating the scheme that is likely to be actually used to determine management actions

Implementation uncertainty

Implementation uncertainty needs to be linked to consideration of fleet dynamics and is largely driven by, and must be included in, economic considerations…

Use and outputsUse and outputs Best Practice ApproachBest Practice Approach

Should code be freely available

Documentation and source code must be freely available to allow for review and understanding of the model. Using existing models can be of great help in learning, but careful thought is required when using a pre-existing model so that the tool is not misused

Social and economic outputs

Have economic experts collaborating with fisheries ecologists when designing a model implementation of economic factors

Ease of modularization

Best is object-oriented design

e.g. EwE, GADGET, SEPODYM

e.g. GADGET, new EwE

Recent trends in model development• Modularisation – e.g. substitute different

growth, functional response modules• Fitting to time series data• Computing constraints – e.g. running on

multiple computers in parallel using PVM

• Spatial considerations• Representation of socio-economic

factors and human behavioural drivers• Multiple sector dynamics and

management • Representation of biodiversity • Multi-species/ecosystem MSEs

OUTLINE OF TALK

Ecosystem Model Objectives Ecosystem Model Types Questions for EAF* Modelling Ecosystem Model Classification Considerations in Model Building

and the Best Practice Approach Role of Management Procedures Data requirements Conclusions

Operating Model to simulate “true dynamics of resource

OP

ER

AT

ING

M

OD

EL

Sim

ulatio

n testin

g

Explore uncertainties re model specification and fit to data

Methods and rules to compute Catch per ssmu

Use “future” data to compute Catch per ssmu

MA

NA

GE

ME

NT

P

RO

CE

DU

RE

Role of OMP/MP/MSE’s(MP = Management procedure; MSE = Management Strategy Evaluation)

From Rademeyer et al. 2007

Role of OMP/MP/MSE’s(MP = Management procedure; MSE = Management Strategy Evaluation)

• Approach involves an evaluation of the implications of alternative combinations of monitoring data, analytical procedures, and decision rules to provide advice on management measures that are robust to inherent uncertainties in all inputs and assumptions used.

• MSE or MP frameworks are used to identify and model uncertainties and to balance different resource dynamics representations.

• They provide key examples of formal methods for addressing uncertainty issues.

More re Dealing with Uncertainty

• Few ecosystem models with applications to practical fisheries management

• Management Procedure testing procedures can use changes in single species parameters (such as carrying capacity K) as a surrogate for ecological ecosystem effects e.g. climate change that are difficult to incorporate explicitly in operating models

• Technical ecosystem effects such as bycatch concerns can also be included as Robustness tests in the MP testing process

• These additions constitute a first step towards incorporating ecosystem aspects into practical fisheries management advice

• Multi-species/Ecosystem MPs being developed

Pg. 52

Multi-species/Ecosystem MPs• ATLANTIS used to evaluate the

performance of ecological indicators • ATLANTIS used to test ecosystem

models such as EwE by generating simulated data with known parameters

• South African Pelagic OMP - food requirements of predators such as penguins need to be accounted for in the management process

• CCAMLR: FOOSA and SMOM – spatially explicit multi-species MP frameworks

Spatial Multi-species Operating Model (SMOM) of Krill-Predator Interactions

Area 3 Feedback comparison

Peng

uin

num

bers

Seal

num

bers

0

50000

100000

150000

200000

250000

300000

2005

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2020

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2030

2035

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2045

0.00

0.10

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0.80

0.90

2005

2008

2011

2014

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2023

0.00

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0.70

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

0.00

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0.60

0.80

1.00

1.20

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

0.00

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1.00

1.50

2.00

2.50

3.00

3.50

4.00

2005

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0.00

1.00

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3.00

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7.00

8.00

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

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2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

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2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

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2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

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2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024

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60000

70000

80000

90000

2005

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1000000

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0

5000000000000

10000000000000

15000000000000

20000000000000

25000000000000

30000000000000

35000000000000

40000000000000

2005

2011

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2023

0

2000000000000

4000000000000

6000000000000

8000000000000

10000000000000

12000000000000

14000000000000

16000000000000

2005

2008

2011

2014

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2026

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0

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10000000000000

15000000000000

20000000000000

25000000000000

2005

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2026

2029

2032

2035

2038

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2044

Area 10 Feedback comparison

0

200000

400000

600000

800000

1000000

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2005

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10000000000000

15000000000000

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2005

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2029

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0

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1000000000000

1500000000000

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2005

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2015

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2019

2021

2023

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2027

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2039

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1000000000000

1500000000000

2000000000000

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2005

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SMOM-predicted change in predator abundance with a) no feedback in spatial catch allocations and b) using a feedback control rule based on a moderate amount monitoring information available for all SSMUs.

No feedback

Feedback

OUTLINE OF TALK

Ecosystem Model Objectives Ecosystem Model Types Questions for EAF* Modelling Ecosystem Model Classification Considerations in Model Building

and the Best Practice Approach Role of Management Procedures Data requirements Conclusions

Data Requirements

MRM DETAILED DATA RE FEW SPECIES – USUALLY SIZE/AGE STRUCTURE DATA

WHOLE ECO-

SYSTEM

LESS DATA RE MORE SPECIES

MORE DATA RE MORE SPECIES e.g. ADDING AGE STRUCTURE

SPATIAL

DATA RE MOVEMENT / DISTRIBUTIONS

ENVIRONMENT, ECONOMIC, SOCIAL, FISHING FLEET, ANTHROPOGENIC

Some conclusions• A good range of models have been developed

for the task of EAF, but greater focus is needed on strengthening these approaches and conducting the necessary data collection and experimentation to underpin confidence in these approaches

• Management decisions will be enhanced by exploring the same issue with different models; confidence in the decisions will increase when the models independently converge on the same management decisions and when uncertainties in the results have been adequately considered.

• MSE/MP approach is best practice• Strategical modelling will mainly be used to

inform and evaluate the Ecosystem Approach to Fisheries, with use in tactical decisions rare