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

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

Probability function Probability estimated as number of inspections devided by number of landings This assumes: probability of detection when inspected is 1

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 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% 108% 121% Minimum effort f.c. 2,000 1.9 Optimal effort 1,800 1.7 -7 -128 37.6 67% 102% No enforcement 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 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% 108% 121% Minimum fine for full compliance 1,800 Range of optimal fines 0-1700 -9 -129 30.0 33% 112% 1,700

Varying the complete penalty: Full compliance and optimal penalty at current effort Varying the complete penalty: for instance penalty of 90% of current penalty means that 90% of catches are confiscated and the fine is 90% of current fine Penalty % of current penalty PB SB NC sole NC plaice Biomass sole Biomass plaice Minimum penalty for full compliance 100% -10 - 130.0 0% 108% 121% Optimal penalty 90% -9 - 129.6 50% 107%

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 67% 108% 102% 10% 1.6 20% 1.4 -127 50% 1,880 0.9 -9 -119 33.8 107%

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

Comparing penalty structures P: proportional fine C: 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% C: Minimum penalty for full compliance 100% P: Optimal fine at current effort C: Optimal penalty, current effort 90% -9 - 129.6 50% P: Optimal effort at that fine level 8.4€/kg 1,752 1.7 -128.3 8% C: Optimal effort, current fine 1,800 -7 -128.0 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?

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% 1,600 26,000 -126 1,400 61,000 -124

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 -127 200% 1,480 -125

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 33.8 107% 200% 1,360 1.3 -124