COBECOS model simulations.

Dutch beam trawl fishery

Model

• Two species: sole and plaice

• One enforcement instrument: port inspections

• One type of offence: over-quota catches

Private benefit function (1)

• Penalty structure: Fine plus confiscation of over-quota catch

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Social benefit function

• Social benefits = private benefits excl payments of fines – shadow value fished biomass – enforcement costs

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Probability function

• Probability estimated as number of inspections devided by number of landings

• This assumes: probability of detection when inspected is 1

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Enforcement costs function

• Enforcement costs estimated as a linear function of enforcement effort

• Costs per inspection: € 965

Simulations

• Effects of varying effort and penalty• Full compliance and optimal level of effort

at current penalty• Full compliance and optimal level of

penalty at current effort• Effects of alternative penalty structure on

optimal effort, compliance and social benefits

Simulations (2)

Current situation (2006):• Enforcement effort: 2028 port inspections per year (8%

of landings controlled)• Penalty: confiscation of over quota catches plus fine

€2200• Private benefits of the beam trawl fleet: -10 mEUR• Total revenues of the beam trawl fleet: 160 mEUR

Definitions• Non compliance (NC) = over quota catch as % of quota• Biomass effect = biomass next year as % of biomass in

simulation year

Full compliance effort and optimal effort at current penalty

Effort

Enforcement costs mEUR PB SB

Sole landings (kt)

Plaice landings (kt)

NC sole

NC plaice

Biomass sole

 Biomass plaice

Current effort 2,028 2.0 -10 -130 13.0 22.5 0% 0% 108% 121%

Minimum effort f.c. 2,000 1.9 -10 -130 13.0 22.5 0% 0% 108% 121%Optimal

effort 1,800 1.7 -7 -128 13.0 37.6 0% 67% 108% 102%

No enforcem

ent 0 0.0 52 -166 21.0 78.8 62% 250% 70% 50%

Effects of varying effort on the level of Non- compliance

Minimum effort for full compliance: 2000 insp.

Effect of varying enforcement effort on private benefits

Lowering effort from 2000 to 0 increases private benefits from -10 tot 50 mEUR

Effect of varying effort on social benefits

Optimal effort: 1800 inspections per year

Effect of varying effort on private and social benefits

NPB = SB – PB = payed fines - shadow value – enforcement costs

Effects of changing enforcement effort on biomass of plaice and sole

Biomass effect = Biomass as % of biomass in previous year

Full compliance fine and optimal fine at current effort

Fine (€) PB SB

Catch sole (kt)

Catch plaice

NC sole

NC plaice

Biomass sole

Biomass plaice

Current fine

2,200 -10 -130 13.0 22.5 0% 0%108

%121

%Minimum fine for full compliance 1,800 -10 -130 13.0 22.5 0% 0%

108%

121%

Range of optimal fines 0-1700

0 -9 -129 13.0 30.0 0% 33%108

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1,700 -10 -129 13.0 30.0 0% 33%108

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Varying the complete penalty: Full compliance and optimal

penalty at current effort

Penalty

% of current penalty PB SB NC sole

NC plaice

Biomass sole

Biomass plaice

Minimum penalty for full compliance 100% -10 - 130.0 0% 0% 108% 121%

Optimal penalty 90% -9 - 129.6 0% 50% 108% 107%

Varying the complete penalty: for instance penalty of 90% of current penaltymeans that 90% of catches are confiscated and the fine is 90% of current fine

Effect of varying the penalty on compliance

Effect of varying the penalty on private and social benefits

Effect of varying the penalty on biomass

Impact of more efficient enforcement on optimal effort

Decrease of

enforcement

costs per unit

Optimal Effort

Enforcement costs PB SB

sole (kt)

Plaice (kt)

NC sole

NC plaice

Biomass sole

 Biomass plaice

0%1,800 1.7 -7 -128 13.0 37.6 0% 67% 108% 102%

10%1,800 1.6 -7 -128 13.0 37.6 0% 67% 108% 102%

20%1,800 1.4 -7 -127 13.0 37.6 0% 67% 108% 102%

50%1,880 0.9 -9 -119 13.0 33.8 0% 50% 108% 107%

Impact of an alternative penalty structure

• Does a different penalty structure change the optimal level enforcement effort?

• And does it change social benefits at the optimal solution?

• Current penalty: fine (€2200) + confiscation of over-quota catch

• Alternative penalty: fine proportional to over-quota catch

Private benefit function (2)

• Penalty structure: Fine proportional to over-quota catch

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Comparing penalty structuresP: proportional fineC: confiscation + fine Fine Effort

Enforcement costs PB SB

NC sole

NC plaice

P: Minimum fine for full compliance at current effort

8.4 €/kg 2,028 2.0 -10 -130.0 0% 0%

C: Minimum penalty for full compliance 100% 2,028 2.0 -10 -130.0 0% 0%P: Optimal fine at current effort

8.4 €/kg 2,028 2.0 -10 -130.0 0% 0%

C: Optimal penalty, current effort 90% 2,028 2.0 -9 - 129.6 0% 50%P: Optimal effort at that fine level 8.4€/kg 1,752 1.7 -9 -128.3 8% 0%C: Optimal effort, current fine 100% 1,800 1.7 -7 -128.0 0% 67%

Conclusions /Discussion

• Different penalty structures may provide different incentives for fishermen and can lead to different private and social benefits

• Partial analysis of: landings inspections are also used for other offences (undersized fish, logbook etc); optimal effort may be different when other offences taken into account

Discussion / Questions

• Should the shadow value of discards be included in the social benefit function?? If discards are related to landings this would influence the optimizing process.

• What does it mean when social benefits are negative? Is society better off without fishing? Have we included all social benefits?

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The End

Increasing social benefits by lowering effort and increasing

the fine

Enforcement effort

Minimum fine full compliance (€) PB SB

Catch sole (kt)

Catch plaice (kt) NC sole

NC plaice

1,800 9,000 -10 -128 13.0 22.5 0% 0%

1,600 26,000 -10 -126 13.0 22.5 0% 0%

1,400 61,000 -10 -124 13.0 22.5 0% 0%

Higher penalties: minimum level of effort for f.c.

Penalty Effort PB SB

Landings sole (kt)

Landings plaice (kt)

Biomass sole

 Biomass plaice

100% 2,000 -10 -130 13.0 22.5 108% 121%

150% 1,680 -9 -127 13.0 22.5 108% 121%

200% 1,480 -10 -125 13.0 22.5 108% 121%

Higher penalties: optimal level of effort

Penalty Effort

Enforcement costs PB SB

Landings sole (kt)

Landings plaice (kt)

Biomass sole

 Biomass plaice

100% 1,800 1.7 -7 -128 13.0 37.6 108% 102%

150% 1,600 1.6 -10 -125 13.0 33.8 108% 107%

200% 1,360 1.3 -7 -124 13.0 37.6 108% 102%