Spyros Fifas

A bioeconomic analysis of the impact of decommissioning programs: Application to a limited-entry french scallop fishery

The objective of this paper is to assess the benefits and costs of decommissioning policies aimed at reducing fleet capacity through premiums offered by the public authority to fishermen to scrap their vessels. A case study, the limited entry scallop fishery of the Saint Brieuc Bay, France, is used to consider the problem of excess capacity and to model the bioeconomic consequences of disinvestment behavior. Special attention is paid to the assessment of fishermens willingness to leave the fishery and to the implementation of public policy in terms of budget level and premiums offered to the fishermen. Spreadsheet simulations show that the impact of decommissioning programs is positive in terms of net surplus, even in the case of increasing technical efficiency of the vessels.

Application of Leslie's model on a population of common dolphins (Delphinus delphis): Sensitivity study

Abstract The rapid development of the albacore tuna (Thunnus alalunga) driftnet fishery in the Bay of Biscay (Atlantic ocean, France) has incited European management authorities to ask for a study of its ecological impact on populations of common dolphins and striped dolphins. A programme with onboard observers has been led during 1992 and 1993, and a sighting survey has allowed the evaluation of the abundances of fractions of populations in the studied area. For the population of common dolphins, the biological parameter estimation has allowed the building of a discrete age-structured model based on a Leslie matrix. Sensitivity studies have been conducted using four model parameters (age of first reproduction, interval between births, juvenile and adult survival rates). Results show that the increase rate of the population presents the highest sensitivity versus adult survival rate and, in second place versus the interval between births.