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Brussels the 3rd of December 2008 - COBECOS 1
COMPUTER MODEL
Costs and Benefits of Control StrategiesSIXTH FRAMEWORK PROGRAMME
Policy-Oriented Research
Jenny Nord, Brussels 3rd of December 2008
Brussels the 3rd of December 2008 - COBECOS 2
Outline
1. Description
2. Functionality
3. Simulations using different levels of
• Enforcement effort • Fines• Shadow value of biomass
4. Future work
Brussels the 3rd of December 2008 - COBECOS 3
COBECOS Computer model
Written in the statistical programme R
Based on the theory developed within the COBECOS
Available with manual, tutorial and example data
R and text editors are freely downloadable online
Two versions of the programme:
• Basic version - single exploited stock and single enforcement type.• Extended version - allows for multiple stock and multiple enforcement
types.
Brussels the 3rd of December 2008 - COBECOS 4
Functionality of the programme
Defines:
theoretical relationships between enforcement effort and enforcement costs
and enforcement effort and probability of detecting violations.
Defines functional forms of private and social benefit
Evaluate the private and social benefit at different levels of enforcement effort
Finds the optimal level of enforcement level and evaluates the social benefits at this level
Allows the user to investigate the robustness of the estimated parameters by introducing stochasticity
Brussels the 3rd of December 2008 - COBECOS 5
Simulations
Example fishery: Hake with onboard observers
Is the social benefit from the Hake fishery maximized at the current level onboard inspections?
How will the harvest rate of Hake change if the fines for violation are increased?
Taking costly enforcement into consideration how many onboard inspections should we invest in?
How does a change in the value of leaving the Hake behind to let it grow and spawn influence the social benefit?
Brussels the 3rd of December 2008 - COBECOS 6
Relationship between enforcement effort (e) and costs and enforcement effort (e) and probability of detection Π (e)
Type Enforcmenteffort
Cost
Observer 0.115 1.237
Observer 0.376 1.716
Observer 0.518 1.87
Observer 0.551 1.899
Type Enforcement Effort
Probability
Observer 0.201575 0.517901
Observer 0.3725307 0.811373
Observer 0.448659 0.895643
Observer 0.630469 0.99
Type EP.Model EPpar1 EPpar2 EPpar3 EC.Mod ECpar1 ECpar2 ECpar3 Effort_Min Effort_Max
Observer NA NA NA NA nonlinear NA 0 NA 0 1
Brussels the 3rd of December 2008 - COBECOS 7
Relationship between enforcement effort and C(e) and enforcement effort and Π (e)
0.0 0.2 0.4 0.6 0.8 1.0
0.0
0.2
0.4
0.6
0.8
1.0
Enforcement effort
Pro
ba
bili
ty
Observer EP relationship
0.0 0.2 0.4 0.6 0.8 1.00
.00
.51
.01
.52
.0
Enforcement effort
Co
st
Observer EC relationship
Brussels the 3rd of December 2008 - COBECOS 8
Calculating the social benefits
Two options:
1. User defined enforcement effort. The programme displays the associated private and social benefits as well as the harvest rate.
2. Optimisation of social benefit. The program finds the enforcement level that maximizes the social benefit.
Parameter Value
Price 1
Costs 0.5
Biomass 1000
Fine 1
Shadow value 0.2
Enforcement effort 0.1
Brussels the 3rd of December 2008 - COBECOS 9
Calculating social benefits
Brussels the 3rd of December 2008 - COBECOS 10
Optimization of enforcement effort
Brussels the 3rd of December 2008 - COBECOS 11
Increased fine level by 70 % (1-1.7)
Brussels the 3rd of December 2008 - COBECOS 12
Increased shadow value (0.2 – 0.5)
Brussels the 3rd of December 2008 - COBECOS 13
Accuracy of the results
Brussels the 3rd of December 2008 - COBECOS 14
Future development
Tested and used with real data by each case study
Modifications and improvements
Inclusion of multiple enforcement types in the basic model?
Development of a user friendly interface
Brussels the 3rd of December 2008 - COBECOS 15
Thank you for your attention!