4 présentations

• 
  08h30 - 09h00

  Links between sustainability standards, maximin, and viability: methods and applications

  • Pedro Gajardo, prés., Departamento de Matemática, Universidad Técnica Federico Santa María, Valapraiso, Chili

  The maximin criterion, as the highest performance that can be sustained over time, promotes intergenerational equity, a pivotal issue for sustainability. The viable control approach, by investigating trajectories and actions complying over time with various standards and constraints, provides major insights into strong sustainability. In this presentation we addresses the links between maximin and viability approaches in a multi-criteria context, showing practical methods for computing sustainability standards based in dynamic programming principle and level-set approach, together with some cases of studies concerning Chilean marine resources. This talk is based on joint works with Luc Doyen, Cristopher Hermosilla, and Sebastián Torres.

• 
  09h00 - 09h30

  Fisheries management spillovers mediated by international fish markets

  • Martin Quaas, prés., Leipzig University
  • Till Requate, Kiel University

  Global fish markets couple harvesting incentives across fisheries world-wide. We set up a theoretical model to study how unilateral management changes for a domestic stock affect bio-economic dynamics of a foreign fish stock that is harvested under open access conditions. We find that more restrictive fishing quotas for the domestic stock may shift the open-access equilibrium for the foreign stock from a relatively productive state to a collapsed state with low harvest rates. We further find that unilaterally optimal domestic fisheries management should take the terms-of-trade effect on the world-market price into account, as this also tends to stabilize the productive steady state in the foreign country. If domestic fisheries management additionally takes into account existence values, a combination of a tariff (export subsidy) and a domestic quota is shown to be second best optimal. The outcomes for the foreign fishery may be stabilizing or destabilizing depending on the relative preference for domestic or foreign stock existence.

• 
  09h30 - 10h00

  Assessing fishery sustainable management and rebuilding plans under uncertainties through stochastic viability theory

  • Hector Ramírez, prés., Universidad de Chile

  This talk discusses about the application of the stochastic viability theory to the management of natural resources. More specifically, we use this approach to propose and to assess exploitation strategies, as well as rebuilding plans, that permits a long-term sustainable fishery management. This methodology is applied to some Chilean fisheries.

• 
  10h00 - 10h30

  Data representation and the collective management of natural commons

  • Bernard Sinclair-Desgagné, prés., HEC Montréal

  Environmental services are typically subject to threshold effects: if encroachment on their supporting ecosystem exceeds a certain level, their supply will collapse. Moreover, the specific location of these thresholds is often uncertain. Current economic wisdom holds, though, that such uncertainty should have a positive impact on the preservation of natural services, because risk-aversion would lead all members of the commons to reduce their individual consumption. This conclusion, however, is not robust to whether data about an uncertain threshold yields a unimodal or a multimodal distribution (the latter being a source of greater uncertainty and polarization). Using a variant of the Nash demand game with two random thresholds, two types of Nash equilibria typically coexist: cautious (respectively, dangerous) equilibria in which agents coordinate on the lower threshold (resp. the higher threshold). When both types of equilibria coexist, the symmetric dangerous equilibrium remains Pareto dominated by the symmetric cautious equilibrium, and the latter is always Pareto efficient. We use an experimental setting to assess the severity of the coordination and equilibrium selection problem. While cautious (resp. dangerous) play is decreasing (resp. increasing) in the probability that the threshold is high, coordination failures are salient for intermediate probabilities where the likelihood of coexistence of both type of equilibria is high. We find that there is a U-shaped relationship between overall coordination and the probability that the threshold is high.