Fourier analysis of otolith banding patterns to discriminate among hatchery, tributary, and lake shore incubated sockeye salmon (Oncorhynchus nerka) juveniles in Tustumena Lake, Alaska

Abstract

Otolith banding patterns formed during incubation were used to discriminate among hatchery and wild sockeye salmon (Oncorhynchus nerka) fry from Tustumena Lake, Alaska. Banding patterns were described by Fourier analysis of otolith luminance profiles. Amplitudes of individual Fourier harmonics were used as discriminant variables. Estimates of total correct classification of otoliths to hatchery or wild origin were as high as 83.1% using quadratic discriminant function analysis on 10 Fourier amplitudes. The maximum total classification rate estimate among hatchery and five wild groups was 45.7% using linear discriminant function analysis on 14 Fourier amplitudes. Although classification rates for any individual group of wild incubated fry never exceeded 64%, site specific information was evident for all groups because the probability of classifying an individual to its true incubation location was significantly greater than chance. Results indicate phenotypic differences in otolith microstructure amongst incubation sites separated by < 10 km.