Sulfur isotopes in otoliths allow discrimination of anadromous and non-anadromous ecotypes of sockeye salmon (Oncorhynchus nerka)

• DOI: 10.1007/s10641-010-9689-7
• Publication Date: 2010-07-28T09:49:30Z
• Authors: Lyse Godbout; Marc Trudel; James R. Irvine; Chris C. Wood; Marty J. Grove; Axel K. Schmitt; Kevin D. McKeegan
• Keywords: δ34S; Chinook wind; Smoltification

Oncorhynchus nerka occur both as anadromous sockeye salmon that spend most of their life in the ocean, and non-anadromous kokanee remain fresh water entire lives. We assessed whether stable isotopes sulfur (δ34S) otoliths could be used to distinguish ecotypes are otherwise difficult identify when they share a common freshwater rearing environment. also investigated chemical link between diet by measuring δ34S various fish tissues (eggs, muscle, scales) zooplankton. (mean±SE) eggs (18.7 ± 0.4‰) marine zooplankton (20.5 0.1‰) were enriched 10–14‰ compared with otolith cores (19.2 0.7‰) (5.3 1.1‰) similar zooplankton, respectively, indicating core is derived from maternal yolk tissue reflects diet. growth zone did not differ significantly (5.9 (4.4 1.2‰), was The mean difference first year 13.3 1.4‰ for 0.65 1.3‰ salmon. A quadratic discriminant function developed measurements known origin provided perfect classification rates cross-validation tests. Thus, isotope ratios effective discriminating O. nerka.