Correlation between δ13C and δ15N in flying fish (Exocoetus volitans) muscle and scales from the South China Sea

We collected flying fish (Exocoetus volitans) from the South China Sea to determine whether fish scale isotope values correlate with those from muscle, and discuss relevant eco-environmental implications. A significant positive correlation was determined between fish scales and muscle delta C-13 and delta N-15, rendering a fish scale an alternative to muscle tissue for stable isotope analysis. However, muscle and scale isotopic offsets should be fully considered when using delta C-13 and delta N-15 to analyze the actual trophic level of fish and their food source. The average offsets of delta C-13 and delta N-15 between muscles and scales are -2.1 +/- 0.5% and 2.3 +/- 0.6%, respectively, though these values vary slightly with fish mass. Weak correlations were found between delta C-13 and delta N-15, both in the flying fish muscle and scales, suggesting that other factors are influencing delta C-13 and delta N-15. Fish delta N-15 also correlates with the size of individuals, while delta C-13 reflects the marine habitat. Based on our data, it appears that more eco-environmental processes can be revealed from modern or ancient flying fish scales.