Estimation of nitrogen stable isotope turnover rate of Oncorhynchus nerka
Estimation of the isotopic turnover rate in the tissues of organisms allows us to estimate the temporal relationship between the isotope ratio of an organism and its prey, and to analyze seasonal variations of food webs and migratory patterns of animals. We analyzed the isotopic turnover rate in the tissue of lacustrine sockeye salmon, Oncorhynchus nerka, of three age classes in a laboratory food alteration experiment to clarify the isotopic turnover rate. The contribution of growth to isotopic turnover was higher in young and fast-growing lacustrine sockeye salmon than in older and slow-growing fish. Maturation masks the relationship between the contributions of growth and metabolism to isotopic change. Our estimate of the isotopic time lag of lacustrine sockeye salmon can be used to research trophic relationships of anadromous sockeye salmon.