A comparison of otolith microchemistry and otolith shape analysis for the study of spatial variation in a deep-sea teleost, Coryphaenoides rupestris

The study of the morphological and chemical characteristics of otoliths have recently been proposed as complementary tools for fish stock identification. However, their effectiveness remains to be fully assessed, especially in species whose life history is still poorly understood. The relative efficiency of otolith microchemistry and otolith shape analysis in discriminating samples of the deep-sea macrourid Coryphaenoides rupestris collected in different areas in the North Atlantic was examined. Otolith microchemistry based on LA/ICP-MS found significant differences in the concentrations of lithium, manganese and barium among sample sites. This allowed for very high classification accuracy (92%), when using discriminant function analysis. Otolith shape analysis based both on linear shape measurements and elliptical fourier analysis revealed a contrasting weak discrimination, with only 43% classification success. Otolith microchemistry appears to be a more effective tool in identifying individual fish from different locations. The implications for the study of population structure are discussed taking into account the limitations of the methodologies employed.