Gall et al Geographic variation in population genetics of Oncorhynchus tshawytscha 



79 



(Allendorf and Thorgaard 1984, Waples 1988). How- 

 ever, our method of scoring increases the power of 

 maximum-Hkelihood estimates of stock composition by 

 equalizing the importance of variant alleles at isoloci 

 and non-duplicated loci. Furthermore, our system was 

 maintained for consistency with other research (Gall 

 et al. 1989, Brodziak et al. 1992). 



A missing heteromeric isozyme between GPI-1 and 

 GPI-3 was observed in some fish. We scored this pat- 

 tern, as described in Bartley and Gall (1990), by as- 

 signing variation to an artificial locus named GPI-H and 



labeling the common and variant alleles Gpi-H(lOO) 

 and Gpi-H(*), respectively. However, Utter et al. (1989) 

 described breeding data that indicated the variation 

 should be assigned to either GPI-1 or GPI-3. 



Due to the difficulty of identifying heterozygote 

 banding patterns from GPI-H, LDH-1, and MDHP-2, 

 allele frequencies at these loci were calculated from the 

 square root of the frequency of the alternate homo- 

 zygote. The frequency of the Tpi-3(106) allele also was 

 calculated from the square root of the frequency of the 

 homozygous Tpi-3(106) pattern. 



