Morphological variability of the shape of striped red mullet Mullus surmuletus in relation to stock discrimination between the Bay of Biscay and the eastern English Channel

Striped red mullet Mullus surmuletus L. 1758 is an economically important species in the Mediterranean Sea and in the northern Atlantic Ocean, where it is exploited from the Bay of Biscay to the southern North Sea (ICES, 2010). In Atlantic waters, there are two main areas where this species is caught, the Bay of Biscay and the eastern English Channel. This species was initially exploited by the Spanish fleets along the Spanish coast inside the Bay of Biscay. Originally considered as valuable by-catch (Marchal, 2008), the growing exploitation ofM. surmuletus and a conspicuous increase in landings in the English Channel and the southern North Sea by French, English and Dutch fleets have been observed from the 1990s onwards. This was attributed to an increase in the migratory distribution and abundance of this species in these areas, which is largely heightened by the decline of traditionally targeted species and the trend for sea water warming (Poulard&Blanchard, 2005; Marchal, 2008; ICES, 2010)