Quantification of muscle condition using digital image analysis in Dicentrarchus labrax larvae, and relationship with survival

Abstract

Digital image analysis was applied to quantify the degradation of muscle in sea bass Dicentrarchus labrax (Pisces: Moronidae) larvae. The measure obtained was the percentage muscle fibre separation (MFS). This measurement was compared to that obtained through classical scoring. The percentage MFS classified correctly a larger number of larvae from different feeding treatments (Fed, Starved and Delayed treatments) and paralleled nutritional condition, both by age and by size. It also yielded a significant correlation with the survival of the Starved larvae. The onset of the mass mortality of Starved larvae was used to define a critical value (Mmax) of 6% MFS which would severely handicap survival. We regard MFS as a useful contribution to the determination of condition in fish larvae. It is a relatively fast quantitative method, and its use would reduce the bias caused by discrete grading (scores) and by differences in individual expertise.