Spatial and ontogenetic variations in sardine feeding conditions in the Bay of Biscay through fatty acid composition

Type Article
Date 2022-01
Language English
Author(s) Bertrand Mathilde1, 2, Brosset PabloORCID1, 2, 3, Soudant PhilippeORCID2, Lebigre ChristopheORCID1
Affiliation(s) 1 : Ifremer, Laboratoire de Biologie Halieutique, ZI Pointe du Diable - CS 10070, 29 280, Plouzané, France
2 : Université de Brest - UMR 6539 CNRS/UBO/IRD/Ifremer, Laboratoire des sciences de l'environnement marin, IUEM, Rue Dumont D'Urville, 29280, Plouzané, France
3 : ESE Ecologie et Santé des Ecosystèmes, Agrocampus Ouest, INRAE, 65 rue de Saint-Brieuc, 35042, Rennes Cedex, France
Source Marine Environmental Research (0141-1136) (Elsevier BV), 2022-01 , Vol. 173 , P. 105514 (12p.)
DOI 10.1016/j.marenvres.2021.105514
WOS© Times Cited 6
Keyword(s) Fatty acids, Lipids, Size-at-age, Sardina pilchardus, Small pelagic fish, NE Atlantic

Food characteristics are amongst the most influential factors determining the fish life history traits as quantitative and qualitative changes in individuals' diet can lead to a decline in the energy allocated to their growth, and hence influence natural populations' characteristics. The size-at-age and weight of European sardines (Sardina pilchardus) in the Bay of Biscay (BoB) have decreased substantially over the last decade, especially for the youngest age classes, and the factors underlying such changes have not yet been identified. We therefore analysed the fatty acid (FA) composition in the neutral (NL) and polar (PL) lipids in samples collected across the BoB to determine whether the diet of sardines changes with their ages. We found that the total FA contents in both lipid fractions varied mainly with the sampling locations and age. Indeed, sardines aged 1 and 2 years living in South BoB had particularly high contents in FA specific to non-diatom phytoplankton, while older sardines living in the Northern part had higher total FA content and more FA specific to copepods. These differences probably resulted from differences in prey availability and to a lesser extend a change in feeding behaviour with age. The strong dependence of younger sardines’ diet to phytoplankton in spring suggests that changes in primary production may explain their decline in size-at-age. Finally, NL clearly reflect finest feeding variations in comparison to PL imprinted by diet variations at longer time scale. Future studies should consider separately NL and PL fractions.

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