ecosim beth fulton 2012. time dynamic ecopath = initial conditions define duration environmental...

Ecosim

Beth Fulton2012

Time dynamicEcopath = initial conditionsDefine − Duration− Environmental drivers− Contaminants option− Fleet dynamics option

ECOPATH, ECOSIM and ECOSPACE

Ecosim

Basic equation

iiiiij j

ijjiii BeFMIQQg

dtdB

ECOPATH, ECOSIM and ECOSPACE

Ecosim

Flow-control: (top-down to bottom-up)− Sensitive parameter − check with sensitivity analysis, time series fitting, two-

model comparison, Bunfished/B0 , Fmax/M)

Feeding time adjustment rate Predator effect on feeding time− 1.0 = stop feeding if predation risk high − 0.0 = ignore predation risk high

Other mortality (top predators sensitive to this) Catchability Environmental tolerances

Ecosim – Group info

ECOPATH, ECOSIM and ECOSPACE

Ecosim – Group info

Ontogenetic changes (growth vs reproduction, egg production)

Feeding related changes (diets, feeding time, handling time)

Trophic effects (predator/prey dynamics)

ECOPATH, ECOSIM and ECOSPACE

Ecosim Covers…

Forcing functions (seasonal, long-term, environmental, productivity…)

ECOPATH, ECOSIM and ECOSPACE

Ecosim – Forcing functions

Drawn or imported Apply to different groups / interactions on ‘Apply FF’ Primary productivity over time (apply to primary

producers or their interactions)

ECOPATH, ECOSIM and ECOSPACE

Ecosim Covers…

Mediation effects

ECOPATH, ECOSIM and ECOSPACE

Ecosim - Mediation

How you put in non-trophic interactions− done in very similar way to forcing (apply using

‘Apply FF’ sheet but select mediation option)

Ecosim - Mediation

Vulnerability = rate become vulnerable to predators

ECOPATH, ECOSIM and ECOSPACE

Ecosim – vulnerabilties

Parameterise which wins out hunger or fear

Depending on parameterisation can create many alternative functional responses (LV, Holling types, ratio dependent etc)

ECOPATH, ECOSIM and ECOSPACE

Ecosim – vulnerabilties

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

Ecosim – vulnerabilties

Vulnerable prey

Fishing effort over time

Biomass/original biomass

Ecosim – forecasts fishing effects

Output ► Run Ecosim− is everything flat (or changing according to the

Biomass Accumulation)?− if ‘wild’ look at balance, small plankton, discard effects

ECOPATH, ECOSIM and ECOSPACE

Ecosim – check Ecopath

ECOPATH, ECOSIM and ECOSPACE

Input ► Fishing rate− pick fleet− sketch a disturbance (fishing rate change)

Ecosim – check Ecopath

Go to Output and rerun− if everything OK the trajectories come back to initial

value (eventually)− are all groups reacting at the speed you expect them

to?

Ecosim – check Ecopath

Relative or absolute biomasses Mortality rates, F, Z, catches Effort data Forcing factors (primary productivity) Incorporates goodness of fit measure (weighted SS) Anomaly fitting (productivity, recruitment) Fit to data Similar to single species assessment

Ecosim – using past time series

Compare time series

Group info parameters Vulnerabilities− high v = Lotka-Volterra like with small perturbations

= top-down − low v = bottom-up− explore settings to edge of stability− fit to data

Ecosim – sensitivity analysis

Remove fishery− check system evolution− should maintain all species− recheck vulnerabilities (higher less stable)− fit to data

Ecosim – sensitivity analysis

Fisheries policy search (economic, social, biological objectives)

Ecosim Extras

Management Strategy Cycle (reproducing management cycle)

Ecosim Extras - MSE

Enter options, regulations etc

Ecosim Extras - MSE

Multiple runs to see probability of outcomes

Ecosim Extras - MSE

Ecosim Example

Catch and effects at different levels of depletion

Ecosim Example

Compared to other models

Example

Thank you