Mercredi 8 avril à 11h00, Daniele BEVACQUA (Dept. Env. Sciences, Univ. Parma, Italy) présentera à la Tour du Valat un séminaire intitulé : « A demographic model for the continental phase of anguillid eels and its application to Vaccarès-Impériaux lagoons. »
Eel stocks of the northern hemisphere are facing a dramatic decline. Catches and recruitment of European, Japanese and American eels have severely dropped in the last 3 decades. Developing realistic models of population dynamics can help scientists and decision-makers identifying the key variables affecting the viability of eel stocks and the consequences of environmental changes and management policies on their conservation. We present a general size- and age-structured life cycle model for anguillid eels, explicitly accounting for the most peculiar features of the continental phase of eel demography: (1) annual fluctuations of juvenile recruitment; (2) density-dependent juvenile survival; (3) body growth characterized by high plasticity and sexual dimorphism; (4) vital rates (sex differentiation and maturation, natural and fishing mortality) driven by body size rather than age. The model can be applied to eel populations for which data on recruitment, body growth and exploitation are available. We exemplify the use of the model by applying it to a long-term dataset collected in a Mediterranean costal lagoon between 1993-2006. We show that the model can be effectively used to assess the impact of different fishing policies on the status of local populations and on the escapement success of adult eels towards spawning sites.