Fisheries Research Articles

Elevated salinity and isotopic composition of fish otolith carbonate: stock delineation of pink snapper, Pagrus auratus, in Shark Bay, Western Australia

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Marine Biology


Print: 0025-3162 Electronic: 1432-1793


Aquaculture and Fisheries | Marine Biology


Analysis of stable isotopes of oxygen and carbon in the otolith carbonate of pink snapper, Pagrus auratus, from several locations in Shark Bay, Western Australia, indicated that snapper are highly location specific. The hypersaline (36 to > 60%) Shark Bay, on the coast of Western Australia, generated strongly characteristic isotopic signatures in the otolith carbonate of snapper collected from the various locations indicating low levels of individual movement of the species. Oxygen isotopes showed enrichment in 18O in otolith carbonate with salinity (0.10: Δ δ18O/Δ salinity %) typical for the evaporation of seawater. The enrichment in 13C (up to 1.75%) was attributed to the incorporation of metabolically derived CO2 from an enrichment of 13C in the food web within Shark Bay. This was possibly a result of lower concentrations of dissolved CO2 with increasing salinity causing a reduction in isotope fractionation during photosynthesis. Results complement recent genetic and tagging studies and provide further evidence of the complex nature of snapper stock structure in the Shark Bay region.



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