Download Ecosim - IMBER

Ecosim
Beth Fulton
2012
Ecosim
 Time dynamic
 Ecopath = initial conditions
 Define
− Duration
− Environmental drivers
− Contaminants option
− Fleet dynamics option
ECOPATH, ECOSIM and ECOSPACE
Ecosim
 Basic equation
dBi
 gi  Qji   Qij  Ii  Mi  Fi  ei Bi
dt
j
j
ECOPATH, ECOSIM and ECOSPACE
Ecosim – Group info
 Flow-control: (top-down to bottom-up)
− Sensitive parameter
− check with sensitivity analysis, time series fitting, twomodel 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 Covers…
 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 – Forcing functions
 Forcing functions (seasonal, long-term, environmental,
productivity…)
ECOPATH, ECOSIM and ECOSPACE
Ecosim Covers…
 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 - Mediation
 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 – vulnerabilties
 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
 Vulnerable prey
Predator
P
aVP
Unavailable prey
B-V
v(B-V)
Available prey
V
vV
B = Total prey biomass;
V = Vulnerable prey biomass;
v = Behavioral exchange rate;
P = Total predator biomass;
a = Predator rate of search.
Fast equilibration
between B-V and V
implies V=vB/(2v+aP)
Ecosim – forecasts fishing effects
Biomass/original biomass
Fishing effort over time
Ecosim – check Ecopath
 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
 Input ► Fishing rate
− pick fleet
− sketch a disturbance (fishing rate change)
ECOPATH, ECOSIM and
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 – using past time series








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
 Compare
time series
Ecosim – sensitivity analysis
 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 Extras
 Fisheries policy search (economic, social, biological
objectives)
Ecosim Extras - MSE
 Management Strategy Cycle (reproducing
management cycle)
Ecosim Extras - MSE
 Enter options, regulations etc
Ecosim Extras - MSE
 Multiple runs to see probability of outcomes
Ecosim Example
Ecosim Example
 Catch and effects at different levels of depletion
Example
 Compared to other
models
Thank you