Beacham: The use of DMA variation for stock identification of Oncorhynchus keta 



617 



Mixture data 



A series of hypothetical fishery samples that 

 contained fish from a specific region or stock 

 were analyzed in order to evaluate the use 

 of minisatellite DNA for stock composition. 

 Test samples of 100 fish were generated 50 

 times by randomly resampling with replace- 

 ment stocks from the appropriate river or 

 region; then the mean and standard devia- 

 tion of the 50 estimates were computed. 

 Stock compositions of the mixture were de- 

 termined under the assumption that the 

 baseline data were perfectly representative 

 of the stocks (fixed-frequency distribution) 

 and by simulating random variation in- 

 volved in the collection of baseline samples 

 (resampled distribution). Each baseline 

 stock was resampled with replacement to 

 obtain new distributions of the principal 

 components with the same sample size as 

 in the original sample (Millar, 1990). 



Results 



Geographic variation in Ssa-A33 

 allele frequencies 



Allele size varied from 4.1 to 21.3 kbp (Fig. 

 2). Major alleles were observed at the 4.1 to 



4.4 kbp (bin 1), 6.0 to 6.5 kbp (bin 6), and 



8.5 to 9.3 kbp (bin 10) (Fig. 1; Table 1). Varia- 

 tion in allele frequencies was observed 

 among Japanese, Russian, and Yukon riv- 

 ers, and other North American stocks. An 

 allele between 4.1 and 4.4 kbp was fairly 

 common in Japanese stocks (mean frequency 

 0.25), less common in Russian stocks (0.12), 

 and absent in North American stocks south 

 of the Yukon River (Table 1). Similarly, alle- 

 les greater than 16.0 kbp were fairly rare in 

 Asian stocks (Japanese stock mean frequency: 

 0.11; Russian: 0.13) but were more common 

 in North American stocks (regional frequen- 

 cies: 0.24-0.26). Clear differences in allele fre- 

 quencies were observed in chum salmon 

 stocks in broadly separated geographic areas. 



In North American stocks, regional dif- 

 ferences in allelic frequencies were ob- 

 served. Mean frequency of the 11.0-13.0 kbp 

 allele was 0.01 for Yukon River stocks, 0.05 

 for southeast Alaska and northern British 

 Columbia stocks, 0.11 for west coast of 

 Vancouver Island (WCVI) stocks, and 0.24 



