Stable hydrogen isotopic composition of fishes reflects that of their environment

Otolith microchemistry and isotopic analyses have emerged as effective techniques for providing insights into fish environmental history that are difficult to obtain by other means. Stable hydrogen isotope ratio (H-2/H-1 or D/H, expressed as delta D) is a possible environmental marker that has not been employed in fish provenance research, although it has been applied as a natural tracer of terrestrial organism migrations. We illustrate the potential of delta D to serve as a new natural marker of fish environmental history by demonstrating that significant linear relationships (r(2) >= 0.97) exist between fish otolith and muscle delta D and delta D of waters that fish inhabit. Differences between mean water delta D and both muscle and otolith delta D were not significantly correlated with fish total length and were not significantly different among species, indicating that water-fish delta D relationships are consistent across fish sizes and species. High r(2) values for regressions of otolith and muscle delta D on water delta D for fishes inhabiting locations with diverse thermal regimes suggest that relationships between water and fish delta D are not strongly affected by water temperature. Demonstration that fish delta D clearly reflects water delta D provides a foundation for future research to reconstruct fish movement among locations with distinct delta D signatures.