Analysis of stable isotope ratio of vertebrae of blue shark (Prionace glauca) in the eastern Pacific Ocean

Vertebrae are usually used to determine age and growth for sharks. Recent studies have shown that vertebrae contain important information about feeding and trophic level. In this study, vertebrae of blue shark (Prionace glauca) were used to estimate stable isotope ratios of 13C and 15N which were -16.64~-13.08, 9.29~22.37, and 2.73~5.73, respectively. The vertebra samples were sub-sampled from the origin, middle and outer edge of centrum. The 13C, 15N, and TL between origin and middle, between middle and outer edge, and between origin and outer edge were not significantly different, indicating sub-sampling might be made at any of these positions. This results provide important information for further studies on trophic dynamics of pelagic sharks.