SIZE AND AGE AT ONSET OF METAMORPHOSIS IN SOLE (SOLEA-SOLEA (L)) OF THE GULF OF GASCOGNE

This study describes seasonal, interannual and spatial variations of size and age at the onset of metamorphosis of sole, Solen solea. Length at the onset of metamorphosis was significantly less variable than age and weight: coefficient of variation CV length<CV age<CV weight (0.08, 0.2, 0.25, respectively). Length and age at the onset of metamorphosis were not significantly correlated (r(2)=0.02). Sole larvae began metamorphosis at a relatively constant length 8.5 +/- 1.3 mm and seasonal, interannual and spatial comparisons showed that length was not significantly variable. Unlike length, seasonal and interannual variations of age al the onset of metamorphosis were high, and resulted from differences in growth rates which were influenced by both temperature and food availability. Analysis of otolith increment width suggest that these growth differences between slow-growing and fast-growing larvae occurred chiefly after the 10th day following the mouth-opening stage and seemed to diminish at the end of the larval period. These findings are discussed in terms of survival and recruitment variability.