Description du sujet de thèse

This doctoral project investigates how fishermen adapt to the constraints imposed by European fishing quotas, and how their behaviors diffuse within and across markets. While the bioeconomic literature has extensively studied the biological and economic impacts of quotas, the microeconomic and behavioral mechanisms by which fishermen accept, circumvent, or collectively respond to these constraints remain largely unexplored.

Since the 1980s, fish stocks have come under increasing pressure due to overfishing and climate change. The European Union has responded by reinforcing fishing quotas policies. Yet, in 2022, only 56% of French fisheries were considered sustainable (Ifremer, 2023), revealing significant challenges in both regulation and compliance. This PhD aims to understand how individual fishermen's decisions—shaped by prices, peer behavior, and institutional constraints—affect macro-level outcomes such as quota compliance and resource sustainability, and vice versa.

We will focus on fish markets in northeastern France to examine two main questions:

Price Formation and Quota Variation – How do fish prices evolve as quotas are progressively depleted and eventually closed?

Individuals behaviours and prices diffusion – How do overfishing practices and strategic adaptations spread among fishermen (peer effects) and across markets (price effects)?

The research will combine:

Empirical data analysis (e.g., from FranceAgriMer and EU sources),

Field interviews with institutional and sectoral actors,

Mathematical modeling, via:

Agent-Based Models to simulate heterogeneous behavior,

Epidemic-like diffusion models (e.g., SIR) to capture propagation dynamics,

Coupling with market pricing models.

These tools will allow to evaluate different diffusion mechanisms (peer influence vs. price adaptation) and simulate policy scenarios.

Methodology & Interdisciplinarity
This project sits at the intersection of microeconomics, computational sociology, and applied mathematics, with strong empirical basis. It requires the PhD student to be comfortable with modeling, simulation, and data analysis, as well as engaging with fieldwork and qualitative surveys.

Expected Outcomes
A better understanding of how fishermen adapt and how practices spread.

New modeling frameworks for fisheries management.

Insights for more participatory and effective fisheries governance at the EU level.

Contexte de travail

This research will be conducted as part of a project funded by the CNRS (Prime 80 initiative) and will benefit from a collaboration between researchers from CAMS (UMR 8557)—with joint supervision by Annick Vignes and Jean-Pierre Nadal—and the Centre Borelli (UMR 9010), involving Argyris Kalogeratos and Julien Randon-Furling. The doctoral student will be primarily based at CAMS, with regular interactions with the Centre Borelli.

CAMS (Centre d'Analyse et de Mathématique Sociales) is a joint research unit of the CNRS and EHESS, located at 54 boulevard Raspail, within the EHESS premises in Paris. This research center pursues a dual ambition: to contribute at the highest international level to mathematical research in its fields of expertise, and to serve as a hub of innovation and cross-disciplinary transfer—from mathematics, computer science, and theoretical physics to the social sciences, and vice versa, through the formalization and modeling of social science problems using mathematical and computational tools.

The Centre Borelli, a joint research unit of the CNRS and ENS Paris-Saclay, is located on the ENS Paris-Saclay campus in Saclay. Actively engaged in industrial transfer, biomedical applications, and societal transformations, the Centre Borelli brings together interdisciplinary research teams in mathematics and computer science, neuroscience and biology, as well as the humanities and social sciences, all within a modeling-oriented research framework.

Contraintes et risques

The project is highly interdisciplinary. The PhD candidate must be able to interact with researchers from different fields at both CAMS and the Centre Borelli. He/she should also be comfortable engaging with non-academic stakeholders, including field actors such as fishers and public policy makers, and demonstrates strong adaptability in these interactions.