title: A global viability assessment of the European eel.
abstract: The global European eel (Anguilla anguilla) stock is critically endangered according to the IUCN, and the European Commission has urged the development of conservation plans aimed to ensure its viability. However, the complex life cycle of this panmictic species, which reproduces in the open ocean but spends most of its prereproductive life in continental waters (thus embracing a huge geographic range and a variety of habitat types), makes it difficult to assess the long-term effectiveness of conservation measures. The interplay between local and global stressors raises intriguing cross-scale conservation challenges that require a comprehensive modelling approach to be addressed. We developed a full life cycle model of the global European eel stock, encompassing both the oceanic and the continental phases of eel's life, and explicitly allowing for spatial heterogeneity in vital rates, availability of suitable habitat and settlement potential via a metapopulation approach. We calibrated the model against a long-term time series of global European eel catches and used it to hindcast the dynamics of the stock in the past and project it over the 21st century under different management scenarios. Although our analysis relies on a number of inevitable simplifying assumptions and on data that may not embrace the whole range of variation in population dynamics at the small spatiotemporal scale, our hindcast is consistent with the general pattern of decline of the stock over recent decades. The results of our projections suggest that (i) habitat loss played a major role in the European eel decline; (ii) the viability of the global stock is at risk if appropriate protection measures are not implemented; (iii) the recovery of spawner escapement requires that fishing mortality is significantly reduced; and (iv) the recovery of recruitment might not be feasible if reproductive output is not enhanced.
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Parma, viale Usberti 11/A, 43100, Parma, Italy.|INRA, UR1115 PSH, 84914, Avignon, France.
authors.forename: Daniele
authors.initials: D
authors.lastname: Bevacqua
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, via Ponzio 34/5, 20133, Milano, Italy.|Consorzio Interuniversitario per le Scienze del Mare, Piazzale Flaminio 9, 00196, Roma, Italy.
authors.forename: Paco
authors.identifier: http://orcid.org/0000-0002-7763-9836
authors.initials: P
authors.lastname: Melià
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, via Ponzio 34/5, 20133, Milano, Italy.|Consorzio Interuniversitario per le Scienze del Mare, Piazzale Flaminio 9, 00196, Roma, Italy.
authors.forename: Marino
authors.initials: M
authors.lastname: Gatto
authors.affiliation: Dipartimento di Bioscienze, Università degli Studi di Parma, viale Usberti 11/A, 43100, Parma, Italy.|Hopkins Marine Station, Stanford University, 120 Oceanview blvd, 93950, Pacific Grove, CA, USA.
authors.forename: Giulio A
authors.initials: GA
authors.lastname: De Leo
mesh_terms: D000811:Anguilla / Q000502:physiology*; D000818:Animals; D001267:Atlantic Ocean; D003247:Conservation of Natural Resources; D017753:Ecosystem; D005060:Europe; D005398:Fisheries; D008954:Models, Biological; D011157:Population Dynamics
keywords: European eel; conservation; geographic variation of vital rates; habitat loss; metapopulations; population viability; reproductive success; sustainable fisheries management