Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Nonlinear Analysis Real World Applications 447-460 population dynamics age size structure system of partial differential equations initial boundary value problem variational formulation positivity 2005 fdi:010042250 ENG Nonlinear Analysis Real World Applications 1468-1218 CC:0002281685-0003 3 10.1016/j.nonrwa.2004.09.005 https://www.documentation.ird.fr/hor/fdi:010042250 6 Horizon (IRD) The goal of this paper is to present a generic multi-region nonlinear age-size structured fish population model, and to assess its mathematical well-posedness. An initial-boundary-value problem is formulated. Existence and uniqueness of a positive weak solution is proved. Eventually, a comparison result is derived: the population of all regions decreases as the mortality rate increases in at least one region. (c) 2004 Elsevier Ltd. All rights reserved. 040