阻止工业船只进入非洲沿海渔业

Policy Research Working Paper Deterring Industrial Vesselsfrom African Coastal Fisheries Aishwarya AgarwalGabriel Englander Policy Research Working Paper11222 Abstract Mauritania, Ghana, and Guinea). Second, bunching esti-mators obtain counterfactual vessel distributions that areuncontaminated by spillovers outside IEZ boundaries.Third, extensive-margin effects are captured by calibratinga discrete choice vessel location model to the bunchingestimates. Back-of-the-envelope bioeconomic calculationsindicate that IEZs increase annual artisanal fisher catch by Most African coastal nations prohibit industrial vessels fromfishing near their shores; these Inshore Exclusion Zones(IEZs) reserve the most productive locations for small-scale,artisanal fishers. However, previous descriptive research sug-gests that non-compliance by industrial vessels preventsIEZs from benefiting African economies, food security, andfish stocks. Radar data released in 2024 detect industrial Deterring Industrial Vessels from∗ Aishwarya Agarwal† JELclassification:Q22,Q28,O13,C21,O55Keywords:Africannaturalresourcesmanagement,Industrialandartisanalfisheries,Causalinference 1Introduction Effective management of renewable resources usually requires compliance with the regula-tions governing resource use. Compliance with these regulations has enabled, for example,the reduction of deforestation in the Brazilian Amazon, the rebuilding of US fish stocks, Small-scale, artisanal fisheries are vital to African countries, employing 9 million Africansand providing at least 20% of key micronutrients to 300 million more (Basurto et al., 2025).To protect these valuable resources, most African coastal nations have established InshoreExclusion Zones (IEZs) that prohibit industrial vessels from fishing near their shores, therebyreserving the most productive fishing grounds for artisanal fishers. However, non-compliance Previous research on IEZs has not applied causal inference methods and has sufferedfrom incomplete vessel data (Basurto et al., 2024, p. 6). Only in January 2024 was a datasetreleased that permits observation of all industrial fishing vessels (Paolo et al., 2024). We use Country-level regression discontinuity (RD) designs reveal which countries’ IEZs reduceindustrial fishing vessel presence and which do not. We demonstrate that fishing opportu-nities vary smoothly in the distance to countries’ coasts and IEZ boundaries.Therefore, Liberia, Mauritania, Ghana, and Guinea. These six countries principally differ from the oth-ers in having stronger fisheries enforcement systems, including more systematic patrols and While the RD analysis identifies where deterrence occurs, it produces upward-biasedtreatment effect estimates by comparing vessel presence just outside to just inside IEZ bound-aries. In the six countries with deterrence effects, the existence of the IEZ increases vessel We apply bunching estimators to recover counterfactual vessel density distributions thatare free of spillover bias (Kleven & Waseem, 2013).Analogous to a tax notch—whichincreases total tax liability discontinuously at an income threshold (by raising the average taxrate)—the IEZ boundary creates a discrete increase in expected punishment costs in the six Our bunching results correspond to intensive-margin effects—the reallocation of vesselsfrom inside IEZs to nearby areas outside IEZs.They assume vessels remain within eachcountry’s Exclusive Economic Zone (EEZ), the area extending up to 200 nautical miles We measure extensive-margin effects by embedding the bunching estimates in a nestedlogit model of vessel location choice. We estimate the disutility from locating inside an IEZ find that IEZs reduce EEZ-level industrial fishing vessel presence by between 8% (Nigeria) We use these country-level estimates in back-of-the-envelope bioeconomic calculationsillustrating the effects of IEZs on fish stocks and artisanal fisher catches. Even under open-access conditions, IEZs can increase stocks and catches. Because artisanal vessels use lower-productivity technologies than industrial vessels, they reach the zero-profit equilibrium at a Contributions.While previous descriptive research documents the importance of Africanartisanal fisheries and the IEZs designed to protect them, our paper is the first to evaluatethe causal effects of this widespread regulation (Basurto et al., 2024, 2025; Belhabib et al.,2020).We do so using new satellite-based radar data that observes industrial fishing ves-sels without selection, unlike research on other regulations whose data comes from vesselschoosing to operate transponders (Englander et al., 2025; Fern´andez-Villaverde et al., 2025). Sections 2 and 3 explain our institutional context and data. Sections 4, 5, and 6 detailour empirical strategies—RD, bunching, and discrete choice—–and present the corresponding 2Institutional Context Most African coastal nations have designated IEZs for the exclusive use of small-scale,