A demographic model for the conservation and management of the European eel: an application to a Mediterranean coastal lagoon

Danièle Bevacqua (1) , Paco Melià (2) , Marcello Schiavina (2) , Alain Crivelli (3) , Giulio A de Leo (4) , Marino Gatto (2)

1 PSH - Unité de recherche Plantes et Systèmes de Culture Horticoles
2 DEIB - Dipartimento di Elettronica, Informazione e Bioingegneria
3 Institut de recherche de la Tour du Valat
4 Hopkins Marine Station [Stanford]

We present a general size and age-structured demographic model of the continental phase of catadromous eels' life cycle, allowing for the incorporation of (i) fluctuations of juvenile recruitment, (ii) density-dependent settlement and sex determination, (iii) plastic body growth and sexual dimorphism, and (iv) vital rates driven by body size rather than age. The model can be used to assess (i) standing stock, (ii) fishing yield, and (iii) spawner production under different recruitment and management scenarios. We demonstrate the model by applying it to a European eel stock (Camargue lagoons, southern France) that was continuously monitored for 17 years (1993-2009). Results indicate that the upper limit to settlement in the Camargue water system is ~419 eels ha ─1 per year. A balanced sex ratio occurs for a settlement of ~94 eels ha ─1 , shifting towards males at higher densities. Catchability is higher in adult silver eels than in sub-adult yellow eels, possibly due to behavioural differences. Estimated standing stock ranged between 7 and 19 kg ha ─1. Fishing yield was 5-7 kg ha ─1 per year, while spawner escapement ranged between 0 and 13 kg ha ─1 per year (<30% of what would occur in the absence of fishing and obstacles to migration). How to cite : Bevacqua D., Melià P., Schiavina M., Crivelli A.J., De Leo G.A., Gatto M. 2019. A demographic model for the conservation and management of the European eel: an application to a Mediterranean coastal lagoon.

Mots clés: stock assessment; Anguilla anguilla; density dependence; European eel; stochastic demographic models; fish population dynamics; life history variation; plasticity in vital traits; size-dependent demography

Domaines: Biodiversité et Ecologie; Ingénierie de l'environnement; Ecosystèmes

Danièle Bevacqua, Paco Melià, Marcello Schiavina, Alain Crivelli, Giulio A de Leo, et al.. A demographic model for the conservation and management of the European eel: an application to a Mediterranean coastal lagoon. ICES Journal of Marine Science, 2019, 76 (7), pp.2164-2178. ⟨10.1093/icesjms/fsz118⟩. ⟨hal-02467800⟩