1. Predator–prey interactions in the face of management regulations: changes in Mediterranean small pelagic species are not due to increased tuna predation
- Author
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Sylvain Bonhommeau, Luisa Metral, Blandine Brisset, Marko Jusup, Pablo Brosset, Claire Saraux, Elisabeth Van Beveren, Anne-Elise Nieblas, Jean-Marc Fromentin, Robert Bauer, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), Délégation de La Réunion, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), and Hokkaido University [Sapporo, Japan]
- Subjects
0106 biological sciences ,Yellowfin tuna ,sea ,Sprattus sprattus ,[SDE.MCG]Environmental Sciences/Global Changes ,atlantic bluefin tuna ,Aquatic Science ,010603 evolutionary biology ,01 natural sciences ,Predation ,Energy density ,[SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems ,Anchovy ,anchovy ,sardine ,sprat ,bluefin tuna ,Gulf of Lion ,Dynamic Energy Budget modelling ,ecosystem approach ,top-down control ,14. Life underwater ,Ecology, Evolution, Behavior and Systematics ,biology ,010604 marine biology & hydrobiology ,fish condition ,Sprat ,food-consumption ,Pelagic zone ,biology.organism_classification ,Fishery ,Proximate composition ,thunnus-thynnus ,fisheries ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology ,Tuna ,Thunnus ,anchovy engraulis-encrasicolus - Abstract
International audience; Recently, the abundance of young Atlantic bluefin tuna (Thunnus thynnus) tripled in the northwestern Mediterranean following effective management measures. We investigated whether its predation on sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) could explain their concurrent size and biomass decline, which caused a fishery crisis. Combining the observed diet composition of bluefin tuna, their modelled daily energy requirements, their population size, and the abundance of prey species in the area, we calculated the proportion of the prey populations that were consumed by bluefin tuna annually over 2011-2013. To assess whether tuna could alter the size structure of the three small pelagic fish populations (anchovy, sardine, and sprat (Sprattus sprattus)), the size distributions of the consumed prey species were compared with those of the wild populations. We estimated that the annual consumption of small pelagic fish by bluefin tuna is less than 2% of the abundance of these populations. Furthermore, size selectivity patterns were not observed. We thus concluded that tuna predation is unlikely to be the main cause of major changes in the small pelagic fish populations from this area.
- Published
- 2017
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