Bassirou Diop

The aim of this thesis was to understand the economic functioning of fisheries and to propose management policies for fishery resources. The main focus was on the shrimp fishery in French Guiana. An initial analysis was carried out using a historical database. The first findings were that this fishery had been marked by a sharp decline in its stock, effort and production, leading to the closure of some businesses. The initial results showed that production in this fishery is highly dependent on the stock and that the sharp decline in the stock is not linked to overfishing. In fact, despite a considerable reduction in fishing effort and catches, the stock has continued to collapse, suggesting that other factors may be to blame. In particular, the fishing area is characterised by an Amazonian environment with a large mangrove swamp and numerous rivers. The inclusion of mangroves in the analysis, despite the fact that their surface area decreased in the 1990s, did not explain the observed collapse of the stock. However, the inclusion of other factors, such as river flow and ocean surface temperature, provided a better understanding of the decline in the stock in this sector. The shrimp fishery in French Guiana appears to be strongly affected by global change, particularly the rise in water temperature in harvesting areas. In addition, the final chapter suggests that certain phenomena endogenous to the fishery, such as the effects of congestion between fishing vessels, make the fishery as a whole more sensitive to exogenous technological, economic or biological shocks, by amplifying the impact of the latter on companies' optimal decisions regarding fishing effort. In order to preserve the shrimp fishery in French Guiana, it therefore seems essential to try to limit the sources of climate change as far as possible, rather than making radical changes to the sector's economic practices.