Managing interacting species in unassessed fisheriesJournal articleNicolas Quérou and Agnès Tomini, Ecological Economics, Volume 93, Issue C, pp. 192-201, 2013

This paper addresses the management of multispecies fisheries, and suggests the use of restricted fishing policies as an interesting option for unassessed fisheries (as is the case within developing countries). Specifically, we consider a predator'prey system under two potential management policies: an unrestricted regime where agents can compete to harvest from both species, and a second one where they are allowed to harvest only predators. The performance of both policies is compared from an ecological and an economic point of view. For a sufficiently large number of agents (or for strong biological interaction parameters) the assumed restricted fishing policy yields both higher long run stock levels and profits. Thus, this contribution suggests that such a policy, while requiring weaker monitoring/governance than instruments based on outputs (such as quotas or taxes), would meet environmental and economic objectives. Finally, several features of the analysis are discussed, including targeting prey instead of predator and the issue of compliance.

Water Conservation Versus Soil Salinity ControlJournal articleAlain Ayong Le Kama and Agnès Tomini, Environmental Modeling & Assessment, Volume 18, Issue 6, pp. 647-660, 2013

This paper tackles the increasingly significant problem of irrigation-induced soil salinity within a groundwater management model. Irrigation can result not only in heavier salt concentrations but also in the removal of salt from the soil through return flows. Given these contradictory observations, we are interested in the effects on soil salt concentration if irrigation efficiency is improved. We develop a model of salt concentration patterns in both soil and groundwater. We introduce a negative externality to the production process by assuming that soil degradation due to higher soil salinity affects total factor productivity. Within this framework, we show that in the presence of this externality, increasing irrigation efficiency can lead to higher or lower soil salt concentration, depending on the social cost of transferring salt from one reservoir to another.

Water Shortages and ConflictJournal articleAntoine Soubeyran and Agnès Tomini, Revue d'économie politique, Volume 122, Issue 2, pp. 279-297, 2012

This study analyzes the risk of a conflict between countries sharing freshwater. While some scholars claim that water-based conflicts can never occur, this analysis identifies a negotiation interval whose size depends on water availability and asymmetry in productive ability between countries. This interval is assimilated to the probability-toconflict which is decreasing with its size. We show that the risk of conflict increases with scarcer water resources but, as well, the higher the asymmetry level, the higher is the probability-to-conflict. Whenever this heterogeneity is extremely large, there is no opportunity for cooperation. Then, given the existence of this negotiation interval, we turn to the Nashbargaining solution to highlight the optimal water allocation. We show that the amount of water allocated to a country is decreasing as long its productive ability increases.

Individuals doubts and policy implementation: Risk premium and contingent valuationJournal articleHubert Stahn and Agnès Tomini, Environmental Economics, Volume 2, Issue 2, pp. 8-18, 2011

This paper is concerned with discrete choice contingent value estimate when the respondents are uncertain about the environmental amenities. Within a class of indirect utility functions often used in empirical studies, the authors put forwards the effect of the risk premium on the willingness to pay (WTP). Then, it is shown how this risk premium also
modifies the estimation procedure. A Monte Carlo simulation concludes the paper by putting forward a misestimation of the WTP. When this uncertainty is ignored, more precisely, the authors focus on the effect of the risk premium.