DISCRIMINATION AMONG POPULATIONS OF SOCKEYE-SALMON FRY WITH FOURIER-ANALYSIS OF OTOLITH BANDING-PATTERNS FORMED DURING INCUBATION

We used otolith banding patterns formed during incubation to discrimin ate among hatchery-and wild-incubated fry of sockeye salmon Oncorhynch us nerka from Tustumena Lake, Alaska. Fourier analysis of otolith lumi nance profiles was used to describe banding patterns; the amplitudes o f individual Fourier harmonics were discriminant variables. Correct cl assification of otoliths to either hatchery or wild origin was 83.1% ( cross-validation) and 72.7% (test data) with the use of quadratic disc riminant function analysis on 10 Fourier amplitudes. Overall classific ation rates among the six test groups (one hatchery and five wild grou ps) were 46.5% (cross-validation) and 39.3% (test data) with the use o f linear discriminant function analysis on 16 Fourier amplitudes. Alth ough classification rates for wild-incubated fry from any one site nev er exceeded 67% (cross-validation) or 60% (test data), location-specif ic information was evident for all groups because the probability of c lassifying an individual to its true incubation location was significa ntly greater than chance. Results indicate phenotypic differences in o tolith microstructure among incubation sites separated by less than 10 km. Analysis of otolith luminance profiles is a potentially useful te chnique for discriminating among and between various populations of ha tchery and wild fish.