Review of major ecosystem model classes

Review of major ecosystem model classes

Éva PlagányiDept. of Maths & Applied Maths,

University of Cape TownReference: 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

POKOK BAHASAN

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

SUMBER: www.st.nmfs.noaa.gov/.../03_Review_...National Marine Fisheries Service

Ecosystem Models and Management Advice1. 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

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

3. 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


Tipe-tipe Model

I. 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 ATLANTISIGBEM Integrated

Generic Bay Ecosystem Model

INVITRO INVITROGEEM 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 2005SUMBER: www.st.nmfs.noaa.gov/.../03_Review_...National Marine Fisheries Service

Ecosystem Models- Antarctic Models

MODEL 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 Models

MODEL 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 Models

MODEL 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 data

Target Species

Predator

Catch Catch


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 10RESEARCH 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 ecosystem1b. Understanding - complete ecosystem

2. Impact of target species

3. Effect of top predators4. Competition: marine mammals - fisheries

5. Rebuilding depleted fish stocks6. Biases in single-species assessment7. Ways to distribute fishing effort among fisheries

8. Under-exploited species

9. Change in ecosystem state10. Spatial concentration of fishing11. Environmental/physical effects12. Effects of habitat modification

13. Effects of by-catch14. Introduction of non-native species* Still being developed


Pg. 4

NO E

NVIR

ONM

ENT

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

PATI

AL

STR

UC

TUR

EYesHandles spatial structureNo

Spatial aggregate systems models e.g. ECOSPACE

Yes


Ew

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, M

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Bio

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EwE, ATLANTIS, INVITRO

External forcing

Phytoplankton, detritus

Zooplankton, filter-feeders

Clupeoids, demersals etc

Marine mammals, sharks etc

TRO

PH

IC L

EV

EL

ERSEM SSEM

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

OSM

OSE


Strategical Model Considerations and the Best Practice Approach

(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

DAT

OR

PE

R U

NIT

TIM

E

a) Type I

b) Type II

c) Type III

Predator abundance Bj

Tota

l con

sum

ptio

n ra

te Q

ij

(for f

ixed

pre

y ab

unda

nce

B i)

Bj (Input)

Default assumption is that thisis the present (input) situation

limit

limit/2

EwE Foraging arenaSUMBER: www.st.nmfs.noaa.gov/.../03_Review_...National Marine Fisheries Service

Spatial considerations Best Practice ApproachInclude 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 components Best Practice ApproachExplicitly 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 components

Best 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, MSMSUMBER: www.st.nmfs.noaa.gov/.../03_Review_...National Marine Fisheries Service

Model components Best Practice ApproachHow 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 biomassGADGET: migration matrices specifying movement between areas; can parameterise by fitting to dataSEAPODYM: Movement model linked to habitat quality


External forcing Best Practice ApproachOther 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-trophic:


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 uncertainty


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 outputs Best Practice ApproachShould 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 TALKEcosystem 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

OPE

RAT

ING

M

OD

EL

Simulation testing

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

GEM

ENT

PRO

CED

UR

ERole of OMP/MP/MSE’s

(MP = Management procedure; MSE = Management Strategy Evaluation)

From Rademeyer et al. 2007SUMBER: www.st.nmfs.noaa.gov/.../03_Review_...National Marine Fisheries Service

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. 52SUMBER: www.st.nmfs.noaa.gov/.../03_Review_...National Marine Fisheries Service

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

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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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1.20

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

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Area 10 Feedback comparison

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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


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


KESIMPULAN1. 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

2. 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.

3. MSE/MP approach is best practice4. Strategical modelling will mainly be used to inform and

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


Documents

Review of major ecosystem model classes