Using shape analysis to inform variation in otolith morphology with life stages of Dissostichus mawsoni

Abstract

As the most important domestic fish in the Antarctic Ocean, Antarctic toothfish (Dissostichus mawsoni) has an important ecological role and high commercial value. The otolith morphology of fish species differs across stages of life history. Therefore, otolith shape analysis can be used to infer life history of D. mawsoni. In this study, otoliths from 120 D. mawsoni individuals with four life stages randomly collected from the Ross Sea, Amundsen Sea, Weddell Sea and Lazarev Sea were used to analyze the otolith morphological differences of D. mawsoni at life stages by conventional measurement and elliptical Fourier analysis. The results showed that variation in otolith morphology occurred across life stages. Generally, the morphology of otolith was changed from smooth and low comple-xity to zigzagging and high complexity. The growth rate of otolith along the longitudinal direction was lower than that along the transverse direction. The characteristic parts of otolith, such as antirostrum, changed significantly across life stages. Compared to the linear discriminant analysis (71.9%), the elliptical Fourier analysis had the higher discrimination rate (85.4%), indicating that the elliptical Fourier analysis was more suitable to analyze the otolith morphology of D. mawsoni.