Spatio-temporal Variability of Otolith Shape of the Red Band Parrotfish (Sparisoma aurofrenatum) in Martinique

Otolith is widely used in the study of stocks identification essential for fisheries management. Scaridae are ecologically important in the Caribbean reef fish fauna and are exploited by traditional fisheries. Sagittal otoliths of the red-band parrotfish Sparisoma aurofrenatum were examined in order to analyze geographical and temporal variations of populations. Shape indices (roundness, rectangularity) and Fourier descriptors were compared between fishes caught by traps in 2007 in March (dry season) and October (wet season), between fishes from Caribbean and Atlantic sites and between protected and unprotected areas within sites. Temporal and spatial differences both site-specific and level of protection-specific were found. Canonical discriminant analysis based on Fourier descriptors indicated a strong discrimination of Sparisoma aurofrenatum populations: 1) between dry and wet seasons, 2) between Atlantic and Caribbean sites and 3) between protected and unprotected areas, with high classification rates. The observed differences in otolith shape may result of environmental effects like stress, type and quality of habitat inducing differences in food quality and quantity. The combination of shape indices and external outline analysis showed that otolith shape is a powerful indicator for population discrimination.