Grey seal diet at the southern limit of its European distribution: combining dietary analyses and fatty acid profiles

Type Article
Date 2007-02
Language English
Author(s) Ridoux Vincent1, 4, Spitz J2, Vincent Cecile1, 4, Walton M3
Affiliation(s) 1 : Univ La Rochelle, UMR 6217, Ctr Rech Ecosyst Littoraux Anthropises, La Rochelle 17071, France
2 : Univ La Rochelle, CRMM, La Rochelle 17071, France
3 : Univ St Andrews, Sea Mammal Res Unit, St Andrews KY16 8LB, Fife, Scotland
Source Journal of the Marine Biological Association of the United Kingdom (0025-3154) (Cambridge University Press), 2007-02 , Vol. 87 , N. 1 , P. 255-264
DOI 10.1017/S002531540705463X
WOS© Times Cited 21
Abstract The north-east Atlantic grey seal, Halichoerus grypus, is widely distributed along the European coastline from northern Russia to France, with the core population centred around Scotland. To date, very little is known of the diet of the species at the southern margin of the species range. However, because grey seal numbers have been increasing over the last few decades in France, the issue of their potential interactions with coastal fisheries is frequently raised. The diet of grey seal in the Molene Archipelago was investigated by combining scat, stomach content and fatty acid analyses, since all three approaches have complementary potentials to reveal feeding habits of a predator. A total of 145 scats mostly of moulting adult males, 14 stomach contents of yearlings and 14 blubber samples from animals of all ages were analysed following standard methodologies. Scats revealed a diet mainly constituted of 50.6% by mass (M) of wrasse, Libridae (mostly Labrus bergylta), 20.7%M conger eel, Conger conger, and 11.9%M sea bass, Dicentrarchus labrax. Stomach contents were made up of 52.3%M cuttlefish, Sepia officinalis, 9.5%M sole, Solea solea, and 9.4%M conger eel. All these prey are different from the diet observed in core areas. Fatty acid analysis from the blubber confirmed that the diet differed between the Molene Archipelago and one of the Scottish breeding sites. It also showed that most of the inter-individual variability was explained by variation in seal body masses, which could be linked to behavioural ontogeny of foraging strategies. Most of he prey species indentified in the food of the grey seal in Brittany are also targeted by professional and/or recreational fisheries in the area; additionally, several prey size-ranges also partly overlap with marketed size-ranges for several species.
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